Edge profiles of strengthened glass articles and associated methods and apparatus

Abstract

A glass article and associated brush polishing method are described. The glass article includes a polished edge extending between a first major surface and a second major surface. The polished edge exhibits at least one of: (a) an Ra surface roughness greater than or equal to 1 nm and less than or equal to 20 nm; (b) a root mean square surface roughness greater than or equal to 1 nm and less than or equal to 30 nm; and (c) a peak valley surface roughness greater than or equal to 10 nm and less than or equal to 50 nm. The glass article is strengthened prior to brush polishing such that a majority of the polished edge is not under compressive stress. The brush polishing process is performed such that the first compressive stress layer extends to the polished edge.

Description

Cross Reference to Related Applications

[0001] This application claims the benefit of priority of U.S. Provisional Application Serial No. 63 / 524,007, filed June 29, 2023, the contents of which are relied upon and incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to edge profiles of strengthened glass articles and associated methods. More particularly, the present disclosure relates to glass articles that are polished after strengthening and exhibit high mechanical strength. BACKGROUND

[0003] There is a strong and growing demand for thin glass display substrates with complex form factors and high edge strength. While the demand for such substrates has conventionally existed in the consumer electronics field (e.g., handheld electronic devices), there is now a rapid increase in demand in new fields such as automotive and even advanced optical applications. Much like their handheld electronic device counterparts (cell phones and tablets), new thin glass substrates of complex form are typically made of thin glass to meet consumer requirements for overall weight (as in the case of automotive glass products), surface cleanliness (as in the case of electrochromic windows in the field of architectural glass), and functionality (as in the case of automotive interior products), while maintaining high mechanical edge strength.

[0004] Conventional singulation of thin substrates (such as glass substrates) of relatively high strength typically involves multiple mechanical edge grinding and polishing steps. Typically, the edges can be shaped using a process grind material, which can cause subsurface damage to the edges of the substrate. To reduce the subsurface damage caused during the initial edge shaping, a series of grinding steps can be performed on the edges using multiple grinding wheels of decreasing abrasive size. The edge grinding steps can be used to reduce the subsurface damage caused by the initial grind or other edge shaping processes. Such mechanical grinding can damage the edges of the substrate, leaving cuts, nicks, and other defects that reduce the mechanical edge strength of the substrate. To eliminate the damage caused by the mechanical grinding, and thereby increase the edge strength, the edges are typically polished using a series of polishing wheels. Such conventional edge shaping and finishing processes can be time consuming, capital inefficient, and costly, often including one of the most expensive and time consuming processes of substrate shaping Accordingly, there is a need in the art for an improved edge shaping and finishing process suitable for manufacturing high strength, complex form, thin substrates. SUMMARY

[0005] The following presents a simplified summary of one or more embodiments of the present disclosure in order to provide a basic understanding of such embodiments. This summary is not an extensive overview of all contemplated embodiments, and is intended to neither identify key or critical elements of all embodiments nor delineate the scope of any or all embodiments.

[0006] Aspect (1) of the present disclosure is directed to a glass article comprising: a first major surface; a second major surface disposed opposite the first major surface; and a polished edge extending between the first major surface and the second major surface, wherein: the polished edge comprises at least one of: (a) an Ra surface roughness greater than or equal to 1 nm and less than or equal to 20 nm; (b) a root mean square surface roughness greater than or equal to 1 nm and less than or equal to 30 nm; and (c) a peak to valley surface roughness greater than or equal to 10 nm and less than or equal to 50 nm, the glass article is chemically strengthened such that the glass article comprises a first compressive stress layer extending from the first major surface to a first depth of compression (DOC1) and a second compressive stress layer extending from the second major surface to a second depth of compression (DOC2), wherein a majority of the polished edge is not under compressive stress, and at least one of the first compressive stress layer and the second compressive stress layer extends to the polished edge.

[0007] Aspect (2) of the present disclosure is directed to the glass article according to Aspect (1), wherein: the polished edge comprises a plurality of brush marks arranged thereon in a substantially parallel configuration, the brush marks being produced by a brush polishing process.

[0008] Aspect (3) of the present disclosure is directed to the glass article according to any one of Aspects (1) to (2), wherein a plurality of the glass articles having the same composition, thickness, and chemical strengthening exhibit a Weibull distribution with a B10 value greater than or equal to 500 MPa when subjected to a mechanical edge strength test according to ASTM C158-02 using a four-point bend test.

[0009] Aspect (4) of the present disclosure is directed to the glass article according to any one of Aspects (1) to (3), wherein the polished edge exhibits all of (a), (b), and (c).

[0010] Aspect (5) of the present disclosure is directed to the glass article according to any one of Aspects (1) to (4), wherein: the glass article comprises a maximum thickness (T) measured between major surfaces of the glass article, and the polished edge comprises a length greater than T - DOC1 - DOC2.

[0011] Aspect (6) of the present disclosure pertains to the glass article of any one of aspects (1) through (5), wherein in a cross-section of the glass article taken in a direction normal to the polished edge and the first major surface, the first major surface comprises a first peripheral region in which material of the glass article is removed from the first major surface during a brush polishing process, wherein the first peripheral region comprises a width measured in a direction normal to the polished edge that is less than or equal to 200 pm.

[0012] Aspect (7) of the present disclosure pertains to the glass article of aspect (6), wherein: the first peripheral region comprises a curved region extending inwardly from the polished edge, wherein in the cross-section, the polished edge transitions to the curved region at a boundary of an outer surface of the glass article, and at the boundary, the outer surface exhibits a minimum radius of curvature that is greater than or equal to twice a maximum thickness of the glass article as measured between the first major surface and the second major surface.

[0013] Aspect (8) of the present disclosure pertains to the glass article of aspect (7), wherein the curved region comprises: a width taken in the direction normal to the polished edge that is less than or equal to , and a depth taken in a direction normal to the first major surface at a geometric center of the first major surface that is less than or equal to .

[0014] Aspect (9) of the present disclosure pertains to the glass article of any one of aspects (6) through (8), wherein in the cross-section, the second major surface comprises a second peripheral region in which material of the glass article is removed from the second major surface during the brush polishing process.

[0015] Aspect (10) of the present disclosure pertains to the glass article of aspect (9), wherein the first and second peripheral regions comprise different shapes such that the glass article comprises an asymmetric chamfer.

[0016] Aspect (11) of the present disclosure pertains to the glass article of any one of aspects (1) through (10), further comprising an anti-reflective coating disposed on the first major surface, the anti-reflective coating comprising alternating layers of high and low refractive index materials, wherein a periphery of the first major surface exhibits a golden hue when viewed from a normal angle of incidence and illuminated with a diffuse D65 light source simulating ambient lighting conditions.

[0017] Aspect (12) of the present disclosure pertains to the glass article of any one of aspects (1) through (11), wherein the first and second major surfaces are free of brush marks associated with a brush polishing process performed on the polished edge.

[0018] Aspect (13) of the present disclosure pertains to the glass article of aspect (12), wherein the first and second major surfaces comprise a slurry flow line comprising a maximum width of less than 3 pm.

[0019] Aspect (14) of the present disclosure pertains to the glass article of any one of aspects (1) through (13), further comprising an ink layer disposed on the second major surface, the ink layer comprising an outer boundary offset from the polished edge by a distance of less than 160 pm, the distance measured perpendicular to the polished edge.

[0020] Aspect (15) of the present disclosure pertains to the glass article of aspect (14), wherein the outer boundary comprises a slurry flow line from a polishing slurry flow associated with a brush polishing process, the slurry flow line extending substantially parallel to the outer boundary.

[0021] Aspect (16) of the present disclosure pertains to a glass article comprising: a first major surface; a second major surface disposed opposite the first major surface; and a polished edge extending between the first major surface and the second major surface, wherein: the polished edge comprises at least one of: (a) an Ra surface roughness of greater than or equal to 1 nm and less than or equal to 20 nm; (b) a root mean square surface roughness of greater than or equal to 1 nm and less than or equal to 30 nm; and (c) a peak to valley surface roughness of greater than or equal to 10 nm and less than or equal to 50 nm, the glass article is chemically strengthened such that the glass article comprises at least a first compressive stress layer extending from the first major surface to a first depth of compression (DOC1), in a cross-section of the glass article taken in a direction normal to the polished edge and the first major surface, the first major surface comprises a first perimeter region in which material of the glass article was removed from the first major surface during a polishing process, wherein the first perimeter region comprises a depth measured in a direction normal to the first major surface at a geometric center of the first major surface, wherein the depth is less than or equal to such that a portion of the polished edge is under compressive stress, wherein a majority of the polished edge is not under compressive stress.

[0022] Aspect (17) of the present disclosure pertains to the glass article of Aspect (16), wherein the first peripheral region comprises a width measured in a direction perpendicular to the polished edge, the width being less than or equal to 200 pm.

[0023] Aspect (18) of the present disclosure pertains to the glass article of Aspect (17), wherein the width is less than or equal to .

[0024] Aspect (19) of the present disclosure pertains to the glass article of any one of Aspects (16) to (18), wherein: the first peripheral region comprises a curved region extending inwardly from the polished edge, wherein, within the cross-section, the polished edge transitions to the curved region at a boundary of an outer surface of the glass article, and at the boundary, the outer surface exhibits a minimum radius of curvature that is greater than or equal to twice a maximum thickness of the glass article as measured between the first major surface and the second major surface.

[0025] Aspect (20) of the present disclosure pertains to the glass article of any one of Aspects (16) to (19), wherein, in the cross-section, the second major surface comprises a second peripheral region in which material of the glass article is removed from the second major surface during the brush polishing process.

[0026] Aspect (21) of the present disclosure pertains to the glass article of Aspect (20), wherein the first and second peripheral regions comprise different shapes such that the glass article comprises an asymmetrically chamfered edge.

[0027] Aspect (22) of the present disclosure pertains to the glass article of any one of Aspects (16) to (21), further comprising an anti-reflective coating disposed on the first major surface, the anti-reflective coating comprising alternating layers of high and low refractive index materials, wherein a periphery of the first major surface exhibits a golden hue when viewed from a normal angle of incidence and illuminated with a diffuse D65 light source simulating ambient lighting conditions.

[0028] Aspect (23) of the present disclosure pertains to the glass article of any one of Aspects (16) to (22), wherein: the polished edge comprises a plurality of brush marks arranged thereon in a substantially parallel configuration, the brush marks being produced by a brush polishing process.

[0029] Aspect (24) of the present disclosure pertains to the glass article of Aspect (23), wherein the first and second major surfaces are free of the brush marks.

[0030] Aspect (25) of the present disclosure relates to the glass article of aspect (24), wherein the first and second major surfaces comprise a stream of slurry comprising a maximum width of less than 3 pm.

[0031] Aspect (26) of the present disclosure relates to the glass article of any one of aspects (16) through (25), further comprising an ink layer disposed on the second major surface, the ink layer comprising an outer boundary offset from the polished edge by a distance of less than 160 pm, the distance measured perpendicular to the polished edge.

[0032] Aspect (27) of the present disclosure relates to the glass article of aspect (26), wherein the outer boundary comprises a stream of slurry from a polishing slurry stream associated with a brush polishing process, the stream of slurry extending substantially parallel to the outer boundary.

[0033] Aspect (28) of the present disclosure relates to the glass article of any one of aspects (16) through (27), wherein the polished edge exhibits all of (a), (b), and (c).

[0034] Aspect (29) of the present disclosure relates to a method of finishing an edge surface of a strengthened glass substrate, the method comprising: disposing the strengthened glass substrate between a first interlayer and a second interlayer; applying a compressive force to the strengthened glass substrate and the interlayers; and polishing an edge surface of the strengthened substrate by removing material of the strengthened glass substrate using a rotating brush and a polishing slurry stream, wherein the rotating brush comprises a plurality of brush filaments, wherein contact between the strengthened glass substrate and the rotating brush is concentrated on the edge surface of the substrate, wherein the polishing slurry stream is concentrated on a major surface of the strengthened glass substrate.

[0035] Aspect (30) of the present disclosure relates to the method of aspect (29), wherein the first and second interlayers have a thickness greater than a dso grain size of the polishing slurry stream.

[0036] Aspect (31) of the present disclosure relates to the method of any one of aspects (29) through (30), wherein the polishing comprises at least two brush polishing passes.

[0037] Aspect (32) of the present disclosure relates to the method of any one of aspects (29) through (31), wherein during the polishing, at most 50 pm of the material of the strengthened glass substrate is removed from the edge surface.

[0038] Aspect (33) of the present disclosure pertains to the method of any one of aspects (29) through (32), wherein the material of the strengthened glass substrate is removed from a peripheral portion of a major surface of the strengthened glass substrate, the peripheral portion having a width less than or equal to 200 pm.

[0039] Aspect (34) of the present disclosure pertains to the method of aspect (33), wherein, after the polishing, the peripheral portion has a depth that is less than a compressive depth associated with a compressive stress layer on one of the major surfaces.

[0040] Aspect (35) of the present disclosure pertains to the method of any one of aspects (29) through (34), wherein each of the plurality of brush filaments comprises a filament diameter, wherein the first and second interlayers comprise a thickness that is less than the filament diameter so as to concentrate the contact on the edge surface.

[0041] Aspect (36) of the present disclosure pertains to the method of aspect (35), wherein the filament diameter is less than half of the thickness of the first and second interlayers.

[0042] Aspect (37) of the present disclosure pertains to the method of any one of aspects (35) through (36), wherein: the plurality of brush filaments comprises a filament length, the filament diameter is greater than 0.1 mm, and during the chamfering and polishing, the rotating brush is disposed at a distance from the strengthened glass substrate such that at least one-third of the filament length of the plurality of brush filaments is engaged with the edge surface.

[0043] Aspect (38) of the present disclosure pertains to the method of any one of aspects (29) through (34), wherein: the plurality of brush filaments comprises a filament length and a filament diameter, and one of: (i) during the polishing, the rotating brush is disposed at a distance from the strengthened glass substrate such that less than one-fifth of the filament length of the plurality of brush filaments is engaged with the edge surface, and (ii) the plurality of brush filaments comprises a filament diameter that is less than or equal to 0.1 mm.

[0044] Aspect (39) of the present disclosure pertains to the method of aspect (38), wherein the filament diameter is less than a thickness of the first and second interlayers.

[0045] Aspect (40) of the present disclosure pertains to the method of any one of aspects (29) through (39), further comprising disposing an ink layer around a periphery of a major surface of the strengthened glass substrate prior to the polishing, wherein a portion of the ink layer is removed by the polishing slurry stream during the polishing.

[0046] Aspect (41) of the present disclosure pertains to the method of any one of aspects (29) through (40), further comprising near-net-shaping the strengthened glass substrate prior to the polishing.

[0047] Aspect (42) of the present disclosure pertains to the method of aspect (41), wherein the near-net-shaping comprises forming nano-perforations along a contour line in the strengthened glass substrate using a pulsed laser beam, and separating a strengthened glass sheet at the contour line by one of thermal separation or self-separation.

[0048] Aspect (43) of the present disclosure pertains to the method of any one of aspects (29) through (42), wherein the strengthened glass substrate is a chemically strengthened glass substrate.

[0049] While several embodiments have been disclosed, still other embodiments of the present disclosure will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. As will be realized, the various embodiments of the present disclosure are capable of modifications in various obvious respects, all without departing from the spirit and scope of the present disclosure. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature, and not as restrictive. BRIEF DESCRIPTION OF DRAWINGS

[0050] While the specification concludes with claims particularly pointing out and distinctly claiming that which is regarded as the present disclosure, it is believed that the present disclosure will be better understood from the following description in conjunction with the accompanying drawings, in which: Figure 1A A perspective view of a glass substrate according to one or more embodiments of the present disclosure is schematically depicted; Figure 1B A cross-sectional view of a glass substrate according to one or more embodiments of the present disclosure is schematically depicted through line I-I in Figure 1A Figure 1C A close-up view of cross-sectional area II depicted in Figure 1B Figure 2 is a flow chart of a method for manufacturing a glass substrate according to one or more embodiments of the present disclosure; Figure 3 is a process flow chart for brush polishing a workpiece to provide a glass substrate having an edge profile described herein according to one or more embodiments of the present disclosure; Figure 4A and 4B ​​A rotating brush for batch brush polishing disposed proximate to a stack of a workpiece and an interposer is schematically depicted in accordance with one or more embodiments of the present disclosure; Figure 5 An apparatus for measuring mechanical edge strength of a glass substrate using a 4-point bend test is schematically depicted in accordance with one or more embodiments of the present disclosure; Figure 6 An image of a counterexample formed by brush polishing with a strong force material on a major surface of a workpiece in accordance with one or more embodiments of the present disclosure; Figure 7 An image of a workpiece after near-net-shaping by laser singulation proximate to a border of a decorative ink layer prior to brush polishing in accordance with one or more embodiments of the present disclosure; Figure 8 Depicted is an example substrate formed by a brush polishing process described herein with respect to Figure 3 one or more embodiments of the present disclosure; Figure 9 An image example substrate formed by a brush polishing process described herein with respect to Figure 3 one or more embodiments of the present disclosure, the substrate including a brush polished decorative border; Figure 10 A graph of Weibull distribution of mechanical edge strength including examples and counterexamples formed by a brush polishing process described herein with respect to Figure 3 one or more embodiments of the present disclosure; Figure 11A An image of a workpiece in accordance with one or more embodiments of the present disclosure, the workpiece being a glass-glass laminate after near-net-shaping and prior to brush polishing; Figure 11B An image of a workpiece depicted in Figure 11A after being brush polished by a process described herein with respect to Figure 3 one or more embodiments of the present disclosure; Figure 11C A graph of Weibull distribution of a workpiece including before and after polishing Figure 11A and 11B depicted in one or more embodiments of the present disclosure; Figure 12 A graph of edge impact resistance results of examples formed using the processes of the present disclosure when tested by a drop ball impact test in accordance with one or more embodiments of the present disclosure; and Figure 13 An image of an example formed using the processes of the present disclosure having a decorative ink layer disposed thereon in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION

[0051] The present disclosure relates to processes and apparatuses by which glass articles that can be near-net shaped by a series of cutting and separating techniques can be edge shaped and finished to simultaneously remove corresponding damage remaining on the edge in the regions formed by the cutting and separating, while applying a desired edge profile and achieving a desired mechanical edge strength. The processes and apparatuses of the present disclosure can be used to achieve a substrate edge (or "polished edge") having defects typically less than 2.0 microns in length (or depth from the polished edge) and a mechanical edge strength of up to or exceeding 500 MPa (B10 value) as tested according to ASTM C158-02 with a four-point bend test. The polished edges of the articles described herein are typically smooth and free of relatively large defects, exhibiting at least one of (a) an Ra surface roughness of greater than or equal to 1 nm and less than or equal to 20 nm; (b) a root mean square surface roughness of greater than or equal to 1 nm and less than or equal to 30 nm; and (c) a peak to valley surface roughness of greater than or equal to 10 nm and less than or equal to 50 nm. In aspects, the glass substrates formed using the brush polishing processes described herein include all of (a), (b), and (c).

[0052] In all respects, the edge profile achievable by the processes and apparatus described herein is particularly advantageous when used for strengthened glass articles such that the polished edge extends between the main surfaces of the glass article. Such strengthened glass articles include at least a first compressive stress layer extending from a first main surface into the article to a first compressive depth (DOC1) and optionally a second compressive stress layer extending from a second main surface into the article to a second compressive depth (DOC2). Strengthening can be carried out by chemical strengthening (e.g., by ion exchange), thermal strengthening, or by using glass-glass laminates comprising different glass compositions with different coefficients of thermal expansion, the glass compositions being in contact with each other in a molten state to generate a compressive stress layer upon cooling. The processes and apparatus described herein can be used such that they produce polished substrate edges, wherein at least a portion of the polished edge is under compressive stress after polishing removes at least 10 µm of material from the substrate edge (after slitting and before polishing in a direction perpendicular to the substrate edge). That is, after the brush polishing process is completed, at least one compressive stress layer extends to the polished edge. In other words, the compressive stress layer on the substrate persists on the polished edge even after undergoing any of the polishing processes described herein (through contact with at least one of a polishing brush, polishing wheel, or other suitable polishing agent) and after the polishing process is performed to remove at least 10 µm of material from the edge. This compressive stress remains even if no chemical strengthening is performed after polishing. When no chemical strengthening is performed after polishing, the compressive stress exists only in a portion of the polished edge (closer to the main surface). This contrasts sharply with some existing processes that strengthen the edge after polishing, placing the entire edge under compressive stress.

[0053] In one embodiment, in a cross-section of the glass article taken along a direction perpendicular to the polished edge and the first main surface, the first main surface includes a first peripheral region in which material of the glass article is removed from the first main surface during the polishing process. In such embodiments, this first peripheral region includes a portion less than or equal to [a certain value] measured along a direction perpendicular to the first main surface. The depth of the polished edge results in a portion of it being under compressive stress. The process and apparatus of this disclosure limit the removal of material from the main surface of the glass article during polishing, causing a layer of compressive stress present on the entire main surface before polishing to remain covering the entire main surface after polishing, and also present on the polished edge. Some existing polishing processes remove excess material from the main surface, thereby eliminating the compressive stress layer at the edge of the part, resulting in reduced edge strength. The article described herein focuses material removal at the polished edge and avoids this drawback.

[0054] The processes and apparatuses described herein address various issues in manufacturing processes involving near-net-shaping of glass substrates after strengthening (e.g., after ion exchange) and decoration. Some of the benefits associated with such post-strengthening shaping processes compared to other existing processes, in which strengthening is performed after near-net-shaping, are described in U.S. Patent Application Serial No. 17 / 621,049, filed December 20, 2021, which is hereby incorporated by reference in its entirety. In particular, the processes and apparatuses described herein facilitate the recovery of the mechanical edge strength of a strengthened article after near-net-shaping without the need for additional processing steps, such as etching after mechanical polishing (e.g., by pass through a polishing brush or wheel). Further, the processes and apparatuses described herein enable near-net-shaping (e.g., singulation) at the boundary of a decorative layer (e.g., an ink decoration, such as an organic ink decoration and / or a black matrix ink decoration) disposed on a major surface of an article very close (e.g., within 100 pm, within 70 pm, within 50 pm) to the decorative boundary by applying the laser cutting techniques described herein in order to increase glass material utilization. When using the laser cutting techniques so close to the decorative boundary, the polishing techniques described herein can be used to improve the uniformity (e.g., in terms of flatness) of the decorative layer boundary, resulting in reduced light leakage compared to articles further processed away from the decorative boundary. Such clear decorative boundary is smooth, straight, and more visually appealing than boundaries associated with articles processed by other methods. The polished edge can be disposed at a lateral distance (measured parallel to the major surface) of less than 150 pm (e.g., less than or equal to 125 pm, less than or equal to 100 pm, less than or equal to 70 pm, less than or equal to 60 pm, less than or equal to 50 pm) from the post-polish decorative boundary.

[0055] In aspects, the edge profile described herein is achieved by chamfering and polishing the edge surface of the article after near-net-shaping. For example, the chamfering and polishing can use a rotary brush comprising a plurality of brush filaments to remove material from the article, with a polishing slurry stream. It has been found that concentrated contact of the brush filaments to the edge of the substrate, rather than to the major surface of the article, can contribute to achieving the edge profile described herein. The polishing slurry stream is directed to the major surface to create a perimeter region of limited material removal thereon. The material removal by the slurry stream is less in magnitude than the material removal by the brush, so the size of the perimeter region of material removal on the major surface is limited to avoid removal of the compressive stress layer present at the major surface from strengthening. After completion of the brush polishing, the material removal by the slurry stream creates a curved perimeter region of the major surface. Such curved perimeter region can extend to the polished edge, and transition to the polished edge through a rounded boundary (e.g., a corner) of the outer surface of the article. Such rounded boundary can exhibit a relatively high radius of curvature (the minimum radius of curvature of the boundary is greater than or equal to twice the maximum thickness of the article). Thus, directing the brush contact away from the major surface of the article has the advantage of avoiding relatively sharp corners on the glass article that can concentrate stress and reduce edge strength.

[0056] In aspects, the concentrated contact between the brush filaments of the rotary brush and the edge of the article can be achieved by at least one of controlling the spacing of the article from adjacent components in a stacked formation, and the engagement between the brush filaments and the article. In embodiments, for example, the article can be arranged in a stacked formation with a plurality of other glass articles, with adjacent articles separated from each other by a plurality of intervening layers. It has been found that a plurality of brush filaments having a diameter greater than the thickness of the intervening layers can cause concentrated brush contact at the edge of the article, as there is insufficient space for the brush filaments to enter between the articles and contact the major surface. In embodiments, concentrated brush contact at the edge can be achieved by passive brush engagement, regardless of the spacing of the articles in the stack. Such passive brush engagement can be achieved by limiting the brush engagement (e.g., to less than one fifth of the length of the plurality of brush filaments), and / or by using brush filaments that are relatively small in diameter (e.g., less than or equal to 0.1 mm). By rotating the brush at a sufficient speed (e.g., at least 100 rpm for a 292 mm diameter cylindrical brush), a polishing slurry stream is directed to the interstitial space between the articles in the stack.

[0057] As used herein, the terms "depth of layer" and "DOL" refer to the depth of compression layer determined using a commercially available instrument such as FSM-6000 by a surface stress meter (FSM) measurement.

[0058] As used herein, the terms "depth of compression" and "DOC" refer to the depth within the glass at which the stress changes from compressive to tensile. At the DOC, the stress changes from positive (compressive) stress to negative (tensile) stress and thus has a value of zero.

[0059] As described herein, unless otherwise specified, compressive stress (CS) and central tension (CT) are expressed in megapascals (MPa), and layer depth (DOL) and depth of compression (DOC) are expressed in micrometers (μm), where 1 μm = 0.001 mm, and thickness t in this document is expressed in millimeters, where 1 mm = 1000 μm.

[0060] refer to Figure 1A , 1B According to example embodiments, 1C, a glass substrate 52 is shown. The glass substrate 52 is formed by the processes described herein and is depicted in the state after a workpiece has been cut from a blank (e.g., a large glass sheet) using any of the near-net-shape techniques described herein, and subsequently polished according to the parameters described herein to form the glass substrate 52. Figure 1A A perspective view of the glass substrate 52 is depicted. Figure 1B Depicting crossing Figure 1A A cross-sectional view of line II, wherein line II extends through the geometric center C of the part and extends in a direction perpendicular to the polished edge 58 of the glass substrate. Figure 1C Depicting Figure 1B A close-up view of cross-sectional portion II depicted in the figure. As shown, the glass substrate 52 includes a first main surface 54, a second main surface disposed opposite to the first main surface 56, and a plurality of polished edges 58 extending around the periphery of the glass substrate 52 between the first main surface 54 and the second main surface 56. The substantial (e.g., majority) portions of the first and second main surfaces 54 and 56 may extend parallel to each other. The central portions of the first and second main surfaces may be substantially flat in shape, wherein such portions of the first main surface 56 that are not modified during polishing are located at... Figures 1A-1C In the XY plane depicted in [the text]. The XY plane can represent [the plane] when relative to [the text]. Figures 1A-1C The vertical position of the average surface height (measured by white light interferometry) of the unmodified portion of the first principal surface 54 when measured at the common reference point in the coordinate system represented in the figure. Although Figures 1A-1C A glass substrate 52 with a rectangular perimeter shape is depicted, but it should be understood that this disclosure is applicable to glass substrates with any shape and any number of prominent polished edges (e.g., a circular glass substrate may have a single polished edge). Embodiments in which the main surface of the glass substrate 52 is not planar are also contemplated (e.g., the main surface may be curved).

[0061] As a result of the polishing process described herein, the first primary surface 54 includes a first peripheral region 60 extending outward from a boundary 62 to a polishing edge 58. The boundary 62 represents a series of points on the first primary surface 54 where any material of the workpiece is removed during the polishing process described herein. Therefore, the first peripheral region 60 represents a portion of the first primary surface 54 that is modified during such a polishing process, and in embodiments employing a brush polishing process, may include slurry flow lines or other markings of the polishing process. The first peripheral region 60 may have a maximum linear dimension 64 along either the X or Y direction (away from the corners of the glass substrate 52). As described herein, particularly in embodiments of the strengthened glass substrate 52, it has been found that limiting the maximum linear dimension 64 to less than or equal to 200 µm, or less than or equal to 175 µm, or less than or equal to 150 µm, or less than or equal to 140 µm, or less than or equal to 130 µm, or less than or equal to 120 µm, or less than or equal to 110 µm, or less than or equal to 100 µm, or less than or equal to 90 µm, or even less than or equal to 80 µm, can help prevent the beneficial effects of the strengthened glass substrate 52 from being eliminated. As described herein, limiting the maximum linear dimension 64 can prevent the compressive stress layer in the glass substrate 52 from being polished away during any of the polishing processes described herein, thereby providing improved edge strength compared to articles manufactured using certain existing polishing processes.

[0062] like Figure 1B As shown, the second primary surface 56 includes a second peripheral region 70 extending outward from boundary 72 to polished edge 58. The second peripheral region 70 represents a portion of the second primary surface 56 where material from the blank is removed during the polishing process. The second peripheral region 70 represents a portion of the second primary surface 56 modified during the polishing process and may include slurry flow lines or other markings from the polishing process. It is advantageous to limit the maximum linear dimension 74 of the second peripheral region 70 in a manner similar to the maximum linear dimension 64 of the first peripheral region 60 to provide improved edge strength. In embodiments, the material removal by the polishing process described herein is symmetrical, so the shapes of the first and second peripheral regions 60 and 70 are substantially similar. In embodiments, the material removal is asymmetrical, such that one of the first and second primary surfaces 54 and 56 has a larger material removal area than the other. In such embodiments, the maximum linear dimensions 64 and 74 may differ from each other, and the precise surface shapes of the first and second peripheral regions 60 and 70 may differ.

[0063] Various structural and compositional details of the glass substrate 52 will now be provided. In embodiments, the glass substrate 52 has a thickness t (e.g., interior to the first and second perimeter regions 60 and 70) that is substantially constant with respect to the width and length of the glass substrate 52. The thickness t is defined as the distance between the first major surface 54 and the second major surface 56 (along the z-direction). In various embodiments, t can refer to the average thickness or the maximum thickness (interior to the boundaries 62 and 72) of the glass substrate 52. Additionally, the glass substrate 52 comprises a width W defined as a first maximum dimension of one of the first major surface 54 or the second major surface 56 that is orthogonal to the thickness t, and a length L defined as a second maximum dimension of one of the first major surface 54 or the second major surface 56 that is orthogonal to both the thickness and the width. In various embodiments, the width W and the length L range from 5 cm to 250 cm In various embodiments, the thickness t is 2 mm or less. In particular, the thickness t is from 0.30 mm to 2.0 mm. For example, the thickness t can be in a range from about 0.30 mm to about 2.0 mm, about 0.40 mm to about 2.0 mm, about 0.50 mm to about 2.0 mm, about 0.60 mm to about 2.0 mm, about 0.70 mm to about 2.0 mm, about 0.30 mm to about 1.9 mm, about 0.30 mm to about 1.8 mm, about 0.30 mm to about 1.7 mm, about 0.30 mm to about 1.6 mm, about 0.30 mm to about 1.5 mm, about 0.30 mm to about 1.4 mm, about 0.30 mm to about 1.4 mm, about 0.30 mm to about 1.703 mm, about 0.30 mm to about 1.2 mm, about 0.30 mm to about 1.1 mm, about 0.30 mm to about 1.0 mm, about 0.30 mm to about 0.90 mm, about 0.30 mm to about 0.80 mm, about 0.30 mm to about 0.70 mm, about 0.30 mm to about 0.60 mm, or about 0.30 mm to about 0.40 mm. In other embodiments, t is within any of the precise numerical ranges set forth in this paragraph.

[0064] The composition of the glass substrate 52 is not particularly limited. In embodiments, the glass substrate 52 can be formed from any suitable glass composition including soda-lime glass, aluminosilicate glass, borosilicate glass, boroaluminosilicate glass, alkali-containing aluminosilicate glass, alkali-containing borosilicate glass, alkali-containing boroaluminosilicate glass.

[0065] In embodiments, the glass substrate 52 can be strengthened to include compressive stress extending from the surface to a depth of compression (DOC). The compressive stress region is balanced by a central portion exhibiting tensile stress. At the DOC, the stress transitions from positive (compressive) stress to negative (tensile) stress. As used herein, the DOC is defined as the depth from the surface at which the stress transitions from compressive to tensile.Figure 1B As shown, in the depicted embodiment, the glass substrate 52 includes a first compressive stress layer 76 extending from the first major surface 54 along the Z-direction to a first depth of compression (DOC1) and a second compressive stress layer 78 extending from the second major surface 56 to a second depth of compression (DOC2). A tensile stress layer 80 extends between the first and second compressive stress layers 76, 78. The first and second compressive stress layers 76, 78 can be formed by various techniques. For example, in embodiments, the glass substrate 52 can be mechanically strengthened by creating compressive stress zones and a central zone exhibiting tensile stress using a mismatch in the coefficient of thermal expansion between portions of the glass. Alternatively, the glass substrate 52 can be thermally strengthened by heating the glass to a temperature above the glass transition point and then rapidly quenching.

[0066] In embodiments, the glass substrate 52 can be chemically strengthened by ion exchange. In the ion exchange process, ions at or near the outer surface 81 of the glass substrate 52 are replaced or exchanged with larger ions of the same valence or oxidation state. The outer surface 81 is the combination of the first major surface 54, the second major surface 56, and the plurality of polished edges 58. In embodiments in which the glass substrate 52 comprises an alkali aluminosilicate glass, the ions and larger ions in the surface layer of the article are monovalent alkali metal cations such as Li+, Na+, K+, Rb+, and Cs+. Alternatively, the monovalent cations in the surface layer can be replaced by monovalent cations other than alkali metal cations, such as Ag+, and the like. In such embodiments, the monovalent ions (or cations) exchanged into the glass article create stress.

[0067] Ion exchange processes are typically performed by immersing a glass article in a molten salt bath (or two or more molten salt baths) containing larger ions to be exchanged with smaller ions in the glass article. It should be noted that aqueous salt baths can also be utilized. Additionally, the composition of the bath can include more than one type of larger ion (e.g., Na+and K+) or a single larger ion. Those skilled in the art will appreciate that the parameters of the ion exchange process, including but not limited to bath composition and temperature, immersion time, number of immersions of the glass article in the salt bath(s), use of multiple salt baths, additional steps (such as annealing, washing, etc.), are generally determined by the composition of the glass layer of the decorative glass structure (including the structure of the article and any crystalline phases present) and the desired DOC and CS of the glass layer of the decorative glass structure resulting from strengthening. Exemplary molten bath compositions can include nitrates, sulfates, and chlorides of larger alkali metal ions. Typical nitrates include KNO3, NaNO3, LiNO3, NaSO4, and combinations thereof. The temperature of the molten salt bath is typically in the range of about 380 °C to about 450 °C, while the immersion time is in the range of about 15 minutes to about 100 hours, depending on the glass thickness, bath temperature, and glass (or monovalent ion) diffusivity. However, different temperatures and immersion times than those described above can also be used.

[0068] In embodiments, the glass substrate 52 can be immersed in a molten salt bath having 100% NaNO3, 100% KNO3, or a combination of NaNO3and KNO3at a temperature of about 370 °C to about 480 °C. In some embodiments, the glass substrate 52 can be immersed in a molten mixed salt bath including about 5% to about 90% KNO3and about 10% to about 95% NaNO3. In one or more embodiments, after immersion in a first bath, the glass article can be immersed in a second bath. The first and second baths can have different compositions and / or temperatures from one another. The immersion times in the first and second baths can be different. For example, the immersion in the first bath can be longer than the immersion in the second bath. In embodiments, the glass substrate 52 can be immersed in a molten mixed salt bath including NaNO3and KNO3(e.g., 49% / 51%, 50% / 50%, 51% / 49%) at a temperature of less than about 420 °C (e.g., about 400 °C or about 380 °C) for less than about 5 hours, or even about 4 hours or less.

[0069] Compressive stress (CS) is measured using those means known in the art, such as by using a surface stress meter (FSM) of a commercially available instrument, such as the FSM-6000 manufactured by Orihara Industrial Co., Ltd. (Japan). Surface stress measurement relies on accurate measurement of the stress optical coefficient (SOC) associated with the birefringence of the glass. The SOC is in turn measured by those methods known in the art, such as the fiber method and the four point bend method, both of which are described in ASTM Standard C770-98 (2013) entitled "Standard Test Method for Measurement of Glass Stress-Optical Coefficient," the contents of which are incorporated herein in its entirety, as well as the bulk cylinder method. As used herein, CS can be the "maximum compressive stress," which is the highest compressive stress value measured within the compressive stress layer. In some embodiments, the maximum compressive stress is located at the surface of the glass article. In other embodiments, the maximum compressive stress can occur at a depth below the surface, giving the compressive profile the appearance of a "buried peak."

[0070] Depending on the strengthening method and conditions, the DOC (e.g., DOC1 and DOC2) can be measured by FSM or by scattered light polariscope (SCALP), such as the SCALP-04 scattered light polariscope available from Glas Stress Ltd. located in Tallinn Estonia. When a glass article is chemically strengthened by an ion exchange process, either FSM or SCALP can be used depending on which ions are exchanged into the glass article. When stresses in a glass article are created by exchanging potassium ions into the glass article, FSM is used to measure the DOC. When stresses are created by exchanging sodium ions into the glass article, SCALP is used to measure the DOC. When stresses in a glass article are created by exchanging both potassium and sodium ions into the glass, the DOC is measured by SCALP because it is believed that the exchange depth of sodium is indicative of the DOC and the exchange depth of potassium is indicative of a change in the magnitude of the compressive stress (but not a change in stress from compressive to tensile); the exchange depth of potassium in such glass articles is measured by FSM. Central tension tension or CT is the maximum tensile stress and is measured by SCALP.

[0071] Reference is made to Figure 1BIn embodiments, DOC1 and DOC2 can be equal to or greater than about 0.05t, equal to or greater than about 0.1t, equal to or greater than about 0.11t, equal to or greater than about 0.12t, equal to or greater than about 0.13t, equal to or greater than about 0.14t, equal to or greater than about 0.15t, equal to or greater than about 0.16t, equal to or greater than about 0.17t, equal to or greater than about 0.18t, equal to or greater than about 0.19t, equal to or greater than about 0.2t, equal to or greater than about 0.21t. In some embodiments, DOC1 and DOC2 can be in a range of about 0.08t to about 0.25t, about 0.09t to about 0.25t, about 0.18t to about 0.25t, about 0.11t to about 0.25t, about 0.12t to about 0.25t, about 0.13t to about 0.25t, about 0.14t to about 0.25t, about 0.15t to about 0.25t, about 0.08t to about 0.24t, about 0.08t to about 0.23t, about 0.08t to about 0.22t, about 0.08t to about 0.21t, about 0.08t to about 0.2t, about 0.08t to about 0.19t, about 0.08t to about 0.18t, about 0.08t to about 0.17t, about 0.08t to about 0.16t, or about 0.08t to about 0.15t. In some cases, DOC1 and DOC2 can be about 20 pm or less. In one or more embodiments, the DOC can be about 40 pm or greater (e.g., about 40 pm to about 300 pm, about 50 pm to about 300 pm, about 60 pm to about 300 pm, about 70 pm to about 300 pm, about 80 pm to about 300 pm, about 90 pm to about 300 pm, about 100 pm to about 300 pm, about 110 pm to about 300 pm, about 120 pm to about 300 pm, about 140 pm to about 300 pm, about 150 pm to about 300 pm, about 40 pm to about 290 pm, about 40 pm to about 280 pm, about 40 pm to about 260 pm, about 40 pm to about 250 pm, about 40 pm to about 240 pm, about 40 pm to about 230 pm, about 40 pm to about 220 pm, about 40 pm to about 210 pm, about 40 pm to about 200 pm, about 40 pm to about 180 pm, about 40 pm to about 160 pm, about 40 pm to about 150 pm, about 40 pm to about 140 pm, about 40 pm to about 130 pm, about 40 pm to about 120 pm, about 40 pm to about 110 pm, or about 40 pm to about 100 pm).

[0072] In embodiments, the first and second compressive stress layers 76 and 78 can have a CS (which can be found at a surface or depth within the glass article) of about 200 MPa or more, 300 MPa or more, 400 MPa or more, about 500 MPa or more, about 600 MPa or more, about 700 MPa or more, about 800 MPa or more, about 900 MPa or more, about 930 MPa or more, about 1000 MPa or more, or about 1050 MPa or more. In embodiments, the tensile stress layer 80 exhibits a maximum tensile stress or central tension tension (CT) of about 20 MPa or more, about 30 MPa or more, about 40 MPa or more, about 45 MPa or more, about 50 MPa or more, about 60 MPa or more, about 70 MPa or more, about 75 MPa or more, about 80 MPa or more, or about 85 MPa or more. In some embodiments, the maximum tensile stress or central tension tension (CT) can be in a range from about 40 MPa to about 100 MPa.

[0073] Referring to Figure 1B and 1C The shape of the outer surface 81 of the glass substrate 52 is specifically designed based on the strengthening of the glass substrate 52 (e.g., by one of chemical strengthening, thermal strengthening, or mechanical strengthening) such that the glass substrate 52 substantially maintains mechanical strength even after being cut from a billet by any of the near-net-shaping processes described herein. In this regard, as described in greater detail herein, the polished edge 58 is formed by the concentrated contact of the brush filaments with the edge of the workpiece to remove material from the edge of the workpiece. That is, the brush filaments are avoided from being in concentrated contact with the first and second major surfaces 54 and 56 to limit the size of the first and second peripheral regions 60 and 70 such that the first and second compressive stress layers 76 and 78 extend outwardly and onto the polished edge 58. Thus, portions of the polished edge 58 are under compressive stress. As a result, the entire first and second major surfaces 54 and 56 are under compressive stress. In other words, there are no points on the first and second major surfaces 54 and 56 that are under tensile stress. The specific design of the polishing process and edge profile described herein prevents any portion of the first and second compressive stress layers 76 and 78 from being completely removed from the workpiece, thereby maximizing the edge strength of the glass substrate 52 as described herein.

[0074] With particular reference to Figure 1CThe design of the edge profile will be described in more detail. As shown, the first peripheral region 60 of the first primary surface 54 includes a first region 82 (extending outward from the boundary 62), a curved region 84, and an outer edge 86. The first region 82 represents a portion of the first primary surface 54 that is modified during polishing (by means of the polishing slurry flow described herein) but still retains a substantially planar shape with minimal deviation from the XY plane in any perceptible pattern. Material removal by the polishing slurry flow is less in the first region 82 than in the curved region 84, and therefore the overall shape of the first primary surface 54 changes minimally in the first region 82. In the curved region 84, the cross-sectional shape of the first primary surface 54 deviates from the XY plane along a curve approximating a relaxation spline curve. This shape is a result of the controlled polishing slurry flow in the gap region between the substrates in the polishing process described herein. The concentrated slurry flow causes the removal of workpiece material in a relaxed spline shape, such that within the curved region 84, the distance along the Z direction between the first primary surface 54 and the XY plane increases with the lateral distance from the boundary 62 (along the Y direction) (see [reference]). Figures 1A-1B Material removal via the polishing slurry flow is gradual, such that even with a relatively large number of polishing cycles to form the polished edge 58 (e.g., 4, 5, 6, 7, 8, 9, 10 cycles), the lateral extent of the curved region 84 is limited to avoid removing the first compressive stress layer 76. In an embodiment, the curved region 84 includes a depth 88 represented by the maximum distance along the Z direction between the curved region 84 and the XY plane, said depth being less than DOC1 (preferably less than...). or even more preferably less than or equal to This allows a portion of the polished edge 58 to be under compressive stress. For example, the depth 88 may be less than or equal to 200 µm, less than or equal to 100 µm, or preferably less than or equal to 90 µm, or even more preferably less than or equal to 80 µm. The material removal by the polishing process described herein will produce a depth 88 of at least 1 µm.

[0075] In an embodiment, the curved region 84 includes a width 90, which is represented by the maximum lateral distance along the Y direction between the outer edge 86 and the inner boundary of the curved region 84, the width being less than... (Preferably less than) And even more preferably smaller than ). In embodiments, the width 90 is less than or equal to 200 pm, or more preferably less than or equal to 150 pm, or more preferably less than or equal to 125 pm, or more preferably less than or equal to 100 pm. The width 90 is generally greater than the depth 88. As described herein, the depth 88 and width 90 can be controlled by controlling parameters of the polishing process used to remove material from the workpiece (e.g., a particle size distribution associated with a polishing slurry). Controlling the polishing process to achieve the above-described dimensions of the first perimeter region 60 (and the second perimeter region 70) facilitates achieving the advantageous edge profiles described herein. Still referring to FIG. 2, the outer edge 86 represents a boundary between the polished edge 58 and the first major surface 54. The outer edge 86 represents a demarcation line between a region where workpiece material is aggressively removed (e.g., by engagement with a plurality of brush filaments) during the polishing process to form the polished edge 58 and the first perimeter region 60 where material is less aggressively removed. It has been found that avoiding a sharp boundary on the outer surface 81 (see FIG. 2) helps to reduce stress concentrations in the glass substrate 52 during an impact event and, thus, improves edge strength. Accordingly, at the outer edge 86, the outer surface 81 can exhibit a minimum radius of curvature that is greater than or equal to Figure 1C , preferably greater than or equal to Figures 1A-1B , or even more preferably greater than or equal to . In embodiments, the minimum radius of curvature at the outer edge 86 is greater than or equal to 1 mm, greater than or equal to 1.5 mm, greater than or equal to 2.0 mm, or even greater than or equal to 2.5 mm. The minimum radius of curvature described herein can be measured using a commercially available optical CMM to examine a cross-section of the part taken perpendicular to the edge being measured.

[0076] The polished edge 58 is achieved by the polishing process described herein. The polished edge 58 can exhibit any desired shape. In embodiments, the polished edge 58 can exhibit a substantially planar shape with similar flatness attributes as the central portions of the first and second major surfaces 54 and 56. In embodiments, one or more of the polished edges 58 can exhibit a curvature (with a minimum radius of curvature that is greater than or equal to 1 mm and less than or equal to 5000 mm).

[0077] In embodiments, the polished edge 58 exhibits a relatively low surface roughness. For example, in embodiments, the polished edge 58 exhibits an Ra value that is greater than or equal to 1 nm and less than or equal to 20 nm. As used herein, the term “Ra value” refers to a surface roughness measurement of the arithmetic mean of the filtered roughness profile determined from deviations from the centerline of the filtered roughness. For example, the Ra value can be determined based on the relationship: (1) ​​where H i is a surface height measurement of the surface, and H CL corresponds to a centerline (e.g., a center between maximum and minimum surface height values) surface height measurement between data points of the filtered profile. Filter values (e.g., cutoff wavelengths) used to determine the Ra values described herein can be found in ISO 25178. Surface heights can be measured using a variety of tools, such as an optical interferometer, a stylus-based profilometer, or a laser confocal microscope. Unless otherwise noted herein, Ra, rms, and PV values are measured by an optical interferometer. Alternatively or additionally, the polished edge 58 can exhibit a root mean square roughness of greater than or equal to 1 nm and less than or equal to 30 nm (calculated from the same measurements used to determine Ra values). Alternatively or additionally, the polished edge can exhibit a peak to valley surface roughness of greater than or equal to 10 nm and less than or equal to 50 nm. Thus, the polished edge 58 described herein can exhibit at least one of: (a) a Ra surface roughness of greater than or equal to 1 nm and less than or equal to 20 nm; (b) a root mean square surface roughness of greater than or equal to 1 nm and less than or equal to 30 nm; and (c) a peak to valley surface roughness of greater than or equal to 10 nm and less than or equal to 50 nm. The polished edge 58 preferably exhibits each of (a), (b), and (c). The first and second peripheral regions 60 and 70 (see FIG. 2) can exhibit at least one (or any one) of (a), (b), and (c), while the portions of the first and second major surfaces 54 and 56 disposed inside the boundaries 62 and 72 (which are unmodified upon polishing) can exhibit each of (a), (b), and (c). Figure 1A and 1B ) can exhibit at least one (or any one) of (a), (b), and (c), while the portions of the first and second major surfaces 54 and 56 disposed inside the boundaries 62 and 72 (which are unmodified upon polishing) can exhibit each of (a), (b), and (c).

[0078] Referring to Figure 1B Another benefit associated with the polishing process described herein is that the process can be used to decorate a part with minimal damage to the decoration applied to the part. As shown, a decorative layer 92 is disposed on the second major surface 56. The decorative layer 92 can be any suitable decoration for providing a desired appearance to the glass substrate 52. For example, in an embodiment, the decorative layer 92 is a suitable black matrix ink applied by an existing process (e.g., inkjet printing, screen printing). In an embodiment, the decorative layer 92 is a black ink that includes a thickness of less than 100 pm and exhibits an optical density of at least 3.0 in the visible spectrum of 400 nm to 700 nm. The particular pattern formed by the decorative layer 92 on the second major surface 56 is not particularly limited. For example, the decorative layer 92 can include a central opening (not shown) having a peripheral shape that corresponds to the peripheral shape of the glass substrate 52, such that the decorative layer 92 is a frame that covers the periphery of the second major surface 56.

[0079] The decorative layer 92 can include an outer boundary 94 disposed proximate the polished edge 58. In embodiments, the outer boundary 94 is disposed interior to the second perimeter region 70. Thus, the outer boundary 94 can be formed during the polishing process described herein such that the portion of the decorative layer 92 that is damaged during near-net-shaping is removed during polishing to form a clear, visually aesthetic boundary. In embodiments, the outer boundary 94 is disposed a maximum lateral distance (in a direction parallel to the X-Y plane and perpendicular to the nearest polished edge 58) from the nearest polished edge 58 (and / or a polished edge 58 to which the outer boundary 94 is disposed parallel) that is less than or equal to 150 pm (e.g., less than or equal to 125 pm, less than or equal to 100 pm, less than or equal to 90 pm, less than or equal to 80 pm, less than or equal to 70 pm, less than or equal to 60 pm, or even less than or equal to 50 pm). In embodiments employing brush polishing to achieve the edge profile described herein, the decorative boundary 94 can exhibit a slurry stream line visible in a 50 to 100x magnified image. The dimensions of the slurry stream line are typically 0.5 pm to 3 pm (width). The first and second major surfaces 54 and 56 can be free of brush marks from the polishing brush that are larger than the slurry stream line and can disrupt the clear edge of the decoration.

[0080] The compatibility of the polishing process described herein with the decorative layer 92 facilitates the formation of the glass substrate 52 in processes in which the workpiece is cut at a boundary relatively close to the material of the decorative layer 92 when disposed on the blank. Cutting proximate the decorative boundary facilitates maximizing the utilization of the blank and avoiding material waste. Thus, the polishing process described herein facilitates reducing manufacturing costs by improved material utilization over existing processes in which any damage to the decorative material is avoided during near-net-shaping.

[0081] Turning now to Figure 2 , a manufacturing process 200 for manufacturing the glass substrate 52 described herein with respect to Figures 1A-1C is shown. In describing the process 200, reference will be made to the various components depicted in Figures 1A-1C . At block 202, a strengthened glass blank is provided. For example, a glass sheet can be manufactured using any known process in which batch materials are melted and mixed in a suitable process and a forming process, such as a float process or a down-draw process, is performed. The glass sheet can then be subjected to a suitable strengthening process to form the blank. In embodiments, for example, an aluminosilicate glass sheet is formed by a fusion down-draw process in any of the thicknesses described therein to provide the thickness t required for the glass substrate 52. The glass sheet can then be subjected to a suitable ion exchange process, such as those described herein with respect to Figures 1A-1C . Thus, the first and second compressive stress layers 76 and 78 are formed in the blank.

[0082] At frame 204, a decorative layer is applied to the main surface of the blank. There are no particular limitations on the composition or appearance of the decorative layer. The decorative layer can be patterned on the main surface using any suitable technique (e.g., screen printing, inkjet printing). In an embodiment, the decorative layer is patterned into multiple discrete regions on the main surface, each region corresponding to a separate part to be formed from the blank. Each pattern can be separate from each other and / or represent a pattern associated with a separate part.

[0083] At frame 206, the blank is near-net-shape formed into multiple workpieces. The workpieces can be near-net-shape formed using any suitable method. In one embodiment, the workpieces can be near-net-shape formed using mechanical scoring and fracture processes, where the blank is scored with the outline of the component to be formed and finished, and the component is mechanically separated from a larger sheet along the score lines. In other embodiments, near-net-shape forming can be performed using nano-perforation and thermal separation, for example, using a laser system provided by Corning Laser Technologies (CLT). In some embodiments, near-net-shape forming may include a first step of laser nano-perforation and a second step of thermal separation using a CO2 laser or other suitable laser device. In other embodiments, near-net-shape forming may include nano-perforation and self-separation (e.g., the second step of thermal separation may not be required). Laser-based near-net-shape forming processes are preferred because they produce relatively flat edges and close boundary control of the finishing layer associated with a particular part, thereby increasing material utilization.

[0084] At frame 208, the edges of the workpiece are polished to remove material and form glass substrate 52. In embodiments, this can be achieved through the methods described herein. Figure 3 The batch brush polishing process described herein is used for polishing. In embodiments, another suitable polishing process can be used, which is capable of stronger material removal at the workpiece edges than on the main surface (e.g., in terms of unit thickness per pass), to limit material removal from the main surface and form the material described herein. Figures 1A-1C The described edge profile. For example, it has been determined that a fixed abrasive polishing wheel, such as the fixed abrasive polishing wheel described in U.S. Patent No. 10,173,916 B2 (hereinincorporated in its entirety by reference), can be used to manufacture glass substrates having the edge profile described herein. Examples of such processes will be described in the examples herein. However, it has been determined that the present invention relates to... Figure 3 The described brush polishing method is preferred because it is more consistent and controllable. Additionally, the abrasive polishing wheel contains abrasive particles larger than 10 µm, resulting in defects of comparable size on the polished edge 58. Such defects can reduce edge strength. Since material is removed through a combination of brush contact and slurry flow, this document discusses…Figure 3 The described brush polishing process is preferred. The combination of a relatively soft brush filament and fine slurry, by adding chemical action in the edge finishing by brush polishing, produces smaller defects in the final product (< 2 pm), resulting in superior mechanical edge strength.

[0085] At block 210, after brush polishing, a coating and / or surface treatment is applied to the surface of the glass substrate 52 not occupied by the decorative layer 92. Such coating and / or surface treatment can include any suitable combination of known additives to provide any desired functionality (e.g., optical performance) to the glass substrate 52. For example, in an embodiment, at block 210, an anti-glare surface treatment is applied to the first major surface 54 (e.g., by a suitable etching or blasting technique). In an embodiment, at block 210, an anti-reflective coating is applied to the entire first major surface 54, including the first perimeter region 60. The anti-reflective coating can include alternating layers of relatively high and low index of refraction materials configured to provide suitable optical performance to the glass substrate 52. Alternatively or additionally, the surface treatment can include applying an easy-to-clean coating. Such coatings can be applied using a suitable physical or chemical deposition process (e.g., physical vapor deposition, chemical vapor deposition, sputtering) at high temperatures, where the glass substrate is heated to high temperatures (in excess of 150 °C). It has been found that certain existing brush polishing processes result in chipping at the edge of the part, and decorating these gaps with such coatings increases the visibility of these defects. However, the polishing processes described herein, particularly the brush polishing process, do not have such defects, as no such chipping is observed after decoration. Examples of coatings and surface treatments that can be applied to the glass substrate 52 are described in U.S. Patent Application No. 16 / 977,332 entitled “Anti-Reflective Coatings and Articles and Methods of Forming the Same,” which is hereby incorporated by reference in its entirety.

[0086] When an anti-reflective coating is deposited on the first major surface 54 using a physical vapor deposition process, a particular optical phenomenon is observed. Specifically, the anti-reflective coating is deposited over the entire first major surface 54, including the first peripheral region 60, using a coating configured to provide particular optical properties on the central (unmodified) portion of the first major surface 54. The coating is configured to exhibit transparency in the visible spectrum when the glass substrate 52 is viewed normally from the first major surface 54. However, the curved shape of the first major surface 54 causes the glass substrate 52 to exhibit a golden hue when the first peripheral region 60, particularly the curved region 84, is viewed at its local surface normal. When illuminated with a diffuse D65 light source and viewed at the first peripheral region 60 in a direction normal to the first major surface 54, the glass substrate 54 exhibits a color having a value (according to the CIELAB color space) greater than 0. This color is different from the color exhibited when the glass substrate 54 is viewed in a direction normal to the central portion of the first major surface 54.

[0087] Reference is now made to Figure 3 FIG. 3, which illustrates a process 300 of polishing a near-net-shape workpiece from a glass sheet blank, in accordance with example embodiments. The process 300 can be used to remove material from the edges and surfaces of the workpiece and form the glass substrate 52 described herein with respect to Figures 1A-1C For example, the process 300 can be used as a component of the process 200 described herein with respect to Figure 2 The process 300 is a brush polishing process in which contact between brush filaments associated with a polishing brush is used to remove material on the edges of the workpiece more aggressively (in terms of volume of material per unit of time) than on the major surfaces of the workpiece. A relatively high flow of polishing slurry is used to remove material at the peripheral regions of the major surfaces of the workpiece less aggressively so as to form the polished edges 58 as well as the first and second peripheral regions 60 and 70 described herein.

[0088] In embodiments, the process 300 is a component of a batch manufacturing process in which multiple glass substrates described herein are formed in conjunction with one another. For example, as described herein, the process 300 can be used to cut multiple workpieces from a glass sheet blank and simultaneously polish the edges. Thus, at block 302, after near-net-shaping (e.g., after block 206 of the process 200 described herein with respect to), the workpieces are arranged in a stack between first and second interlayers. Figure 2 Figure 4A and 4B FIG. 4 depicts an example stack 400 including a plurality of workpieces 402 and a plurality of interlayers 404 interleaved between the plurality of workpieces, in accordance with example embodiments. The plurality of workpieces 402 can be cut from a glass sheet (e.g., after strengthening and decoration, as described herein with respect to the process 200). For example, each workpiece of the plurality of workpieces 402 can have a shape as described herein with respect to​​Figures 1A-1C A structure similar to the structure of the glass substrate 52 is depicted, but prior to polishing. As shown, the substrate includes original cut edges 405, which are in a state that varies depending on the manner in which near-net shaping is performed. The original cut edges 505 can have reduced edge strength as compared to the strengthened substrate from which they are formed due to the relatively large defects (e.g., caused by the cutting process) contained therein. While in Figure 4A In the embodiments of FIGS. 4A-4C, the plurality of workpieces 402 are structurally depicted as being identical, it should be understood that embodiments in which the plurality of workpieces 402 differ from one another in at least one respect (e.g., in workpiece thickness or glass composition) are also contemplated and within the scope of the present disclosure. 4B In the embodiments of FIGS. 4A-4C, the plurality of workpieces 402 are structurally depicted as being identical, it should be understood that embodiments in which the plurality of workpieces 402 differ from one another in at least one respect (e.g., in workpiece thickness or glass composition) are also contemplated and within the scope of the present disclosure.

[0089] The plurality of intermediate layers 404 are used to separate the plurality of workpieces 402 to facilitate formation of the desired edge profile, as described herein. In accordance with the present disclosure, a variety of different techniques can be used to form the plurality of intermediate layers 404. For example, in embodiments, the plurality of intermediate layers 404 are preformed articles of suitable material and are disposed between the plurality of workpieces 402. In such embodiments, the plurality of intermediate layers 404 can be precisely patterned to an exact shape based on the desired perimeter shape of the glass substrate 52. In such precise patterning, an intermediate layer precursor material is disposed on one or more of the workpieces 402 in a desired pattern (e.g., cross-hatching, stripes, dot matrix). In such embodiments, the plurality of intermediate layers 404 can be formed on the plurality of workpieces 402. For example, the plurality of intermediate layers 404 can be formed by depositing a liquid precursor material onto a surface of at least one of the plurality of workpieces 402 (e.g., using screen printing, inkjet printing, or other suitable process), which can subsequently be solidified into the plurality of intermediate layers. Such precise patterning is preferred as it avoids the complexities associated with disposing preformed intermediate layers, while also enabling efficient switching of the intermediate layer pattern of discrete parts. Inkjet printing of intermediate layers is preferred for its precision, speed, efficiency, and minimal material waste.

[0090] In embodiments, each of the plurality of intermediate layers 404 can have a planar shape with first and second side surfaces 407. In embodiments, the size and shape of each of the plurality of intermediate layers 404 can be set to correspond to a particular workpiece or desired end shape associated with the glass substrate 42. For example, when the glass substrate 52 has a circular perimeter shape, the corresponding intermediate layer can also have a circular perimeter shape. In embodiments, the size of the plurality of intermediate layers 404 is set based on the desired size of the polished glass substrate 52. For example, in embodiments, each of the plurality of intermediate layers 404 is a parallelepiped shape, similar to the embodiments described herein with respect to FIGS. 2A-2C. In embodiments, the plurality of intermediate layers 404 can be formed from a variety of different materials, including, but not limited to, glass, ceramic, metal, and / or polymer. In embodiments, the plurality of intermediate layers 404 can be formed from a material that is the same as or different from the material of the plurality of workpieces 402. Figures 1A-1CThe glass substrate 52 described and includes a length L and a length W corresponding to the glass substrate 52. In embodiments, the plurality of interposers 404 can be sized to be slightly smaller than the finished glass substrate 52 after polishing. For example, when the substrate is configured to have a final length of 100 mm, the corresponding interposers can have a length L of 99 mm, 98 mm, 97 mm, 96 mm, 95 mm, or a different length. Such a configuration can facilitate access to the surface of the workpiece 402. The plurality of interposers 404 can have a smaller or larger size configured to correspond to the particular substrate to be processed.

[0091] The plurality of interposers 404 are positioned such that each of the plurality of interposers 404 includes an entrance 406 from the original cut edge 405 of the most recent workpiece of the plurality of workpieces 402. The entrance 406 represents the maximum lateral distance (measured in a direction parallel to the major surface of the most recent workpiece of the plurality of workpieces 402) that the interposer edge is separated from the original cut edge 405 of the most recent workpiece. The extent of the entrance 406 is determined by the size difference between the plurality of workpieces 402 and the plurality of interposers 404. In embodiments, the plurality of interposers 404 are sized such that the entrance 406 is 0.0 mm (e.g., the interposers can have the same size as the workpieces and have aligned perimeter edges). In embodiments, the size of the interposers and workpieces are configured and positioned (e.g., where the plurality of interposers 404 are sized to be smaller than the plurality of workpieces 402 and are collectively centered) such that the entrance 406 is less than or equal to 10.0 mm (e.g., less than or equal to 5.0 mm, less than or equal to 2.0 mm, less than or equal to 1.0 mm).

[0092] Each of the plurality of interposers 404 can have a thickness 408 that determines the spacing between adjacent workpieces of the plurality of workpieces 402. In some embodiments, the thickness 408 can be about 0.01 times to about 10 times the thickness of the corresponding substrate to be shaped and finished. For example, when the glass substrate 52 has a thickness of 1 mm, the plurality of interposers can have a thickness 408 of between about 0.01 mm to about 10 mm. The size of the thickness 408 of the plurality of interposers 404 can be configured to control the contact of the substrate material with the brush filaments, as described below.

[0093] In some embodiments, the plurality of interposers 404 can have one or more through-holes (not shown) extending between the two side surfaces 407. Each interposer can have 1 to 10 or more through-holes spaced across the interposer symmetrically or otherwise strategically. In some embodiments, the through-holes can each be configured to receive a stabilizing agent or stabilizing material. The stabilizing agent or stabilizing material can include one or more rubbers or other moldable materials configured to have a higher coefficient of friction with the workpiece material than the surrounding interposer material. In some embodiments, the stabilizing agent can be easily removed from the through-holes. In some embodiments, arranging the substrates between the first and second interposers can include placing the stabilizing agent or stabilizing material into each through-hole before, during, or after arranging each interposer in the stack 400.

[0094] In embodiments, up to 5, up to 10, up to 20, up to 50, up to 100, up to 200, up to 300, up to 400, or up to 500 substrates can be arranged together in the stack 400. In some embodiments, end caps or chucks can be arranged at each end (e.g., top and bottom) of the stack of parts. The end caps or chucks can be composed of one or more metals or other suitable materials. In some embodiments, the interposers can be screen printed directly onto the substrates. For example, a first substrate can be positioned in the stack, an interposer having a desired shape and size can be screen printed directly onto the side surface of the substrate, and a second substrate can be arranged in the stack above the printed interposer. In such embodiments, the interposers can be removed mechanically and / or chemically after the brushing operation.

[0095] Referring again to Figure 3 After the workpieces are arranged in the stack, at block 304, a compressive force is applied to the stack 400. The compressive force is applied by Figure 4A and 4BThe arrows 410 in the first and second intermediate layers. For example, when the workpieces are arranged between the first and second intermediate layers, a compressive force can be applied to the first intermediate layer to compress the substrate and intermediate layer from the first side, to the second intermediate layer to compress the substrate and intermediate layer from the second side, or to both the first and second intermediate layers. The compressive force can be applied using any suitable means, and can be in a range of about 1 psi to about 1000 psi. In some embodiments, the magnitude of the pressure or force applied to the stack 400 can depend on the size and / or number of workpieces. For example, when one or more workpieces in the stack have a length and width of 100 mm, a compressive force of about 650-700 psi can be applied to the stack 400. As another example, when one or more workpieces in the form of the stack are square shaped with a diagonal length of 635 mm, a compressive force of about 30-40 psi can be applied to the stack 400. It will be appreciated that the compressive force can be applied with a surface area large enough to spread the compressive force and not cause the 400 to break or fracture. The compressive force can be configured to hold the workpieces and intermediate layers together in the stack 400 and generally prevent the components from sliding or twisting relative to one another. The compressive force can be applied using any suitable means. In some embodiments, for example, a clamp can be arranged on the stack and a nut or bolt can be tightened to apply the desired force.

[0096] At block 306, the workpiece edges are brushed to form the glass substrates 52. Brushing can include contacting the as-cut edges 405 (see FIG. 4A) with a brush and polishing material or slurry. The brush and slurry can be configured to remove material from the as-cut edges 405 to remove notches, cuts, or other defects therefrom. Additionally, in some embodiments, the brush and slurry can be configured to simultaneously shape the edge surfaces of the substrates by mechanically and / or chemically removing substrate material to achieve a desired shape. Figures 4A-4B

[0097] It has been found that the beneficial edge profiles described herein with respect to Figures 1A-1C may be formed by concentrated contact between the bristles of a brush and the workpieces at the as-cut edges 405. This can be achieved by configuring a brush and polishing slurry stream as described herein. Figures 4A-4B A rotating brush 412 is depicted that can be used to brush polish the as-cut edges 405 to remove material from the plurality of workpieces 402 and form a plurality of glass substrates 52 described herein with respect to Figures 1A-1C The rotating brush 412 generally includes a base portion 414 and a plurality of bristles 416 extending from the base portion 414. The base portion 414 can be rotated about a rotation axis 418, and the plurality of bristles 416 can extend radially outward from the base portion 414 such that the plurality of bristles 416 contact the as-cut edges 405 of the plurality of workpieces 402. Figure 4A ​A rotating brush 412 is depicted translating relative to the stack 400 (e.g., above the stack 400) to demonstrate lateral positioning that the rotating brush 412 can assume relative to the stack 400 during brush polishing. As shown, the rotating brush 412 can be positioned relative to the stack 400 such that an engagement length 420 (also referred to herein as a "contact") of the plurality of brush filaments 416 contacts the original cutting edge 405. The engagement length 420 can represent the maximum extent to which the brush filaments contact the plurality of workpieces 402. A greater engagement length can enable more aggressive material removal of the plurality of workpieces 402 (other factors of the filaments remaining constant, such as diameter, overall length, and material). As described herein, it can be preferable to provide an engagement length 420 that is at least one-third of the minimum length of the plurality of brush filaments 416 to facilitate relatively aggressive material removal and a relatively small amount of polishing time.

[0098] In embodiments, the plurality of brush filaments 416 includes a tubular body having a length along a central axis thereof and a diameter measured in a direction perpendicular to the central axis. In some embodiments, the plurality of brush filaments 416 can be composed of one or more polymers, resinous materials, or carbon fiber materials. In other embodiments, other suitable filament materials can be used. In embodiments, the plurality of brush filaments 416 can each have a diameter of no greater than 0.500 mm. It can be preferable to avoid brush filament diameters greater than 0.300 mm to avoid leaving noticeable brush marks on the polished edge in certain implementations. Thus, in some embodiments, the plurality of brush filaments 416 can have a diameter of about 0.01 mm to about 0.300 mm. In some embodiments, the filaments can have a circular or polygonal cross-sectional shape. In embodiments, the plurality of brush filaments can have a length of about 1 mm to about 200 mm. In embodiments, portions of the length of the plurality of brush filaments 416 are inserted into the base portion 414. In some embodiments, the brush filaments can have different lengths and / or different diameters.

[0099] Further, the brush filaments can be arranged in discrete tufts or bundles, each having a diameter of about 1.0 mm to about 10.0 mm. The individual filaments or tufts of filaments can be arranged in a particular pattern on the brush base. For example, the bundles or tufts can be arranged in a straight line, a spiral, a staggered, random, or other pattern. Additionally, the brush can have a brush density (or filament density) of about 10% to about 95%, or about 30% to about 90%, or about 50% to about 85%. In at least one embodiment, the brush of the present disclosure can have a brush density of about 68.5%. In other embodiments, the filaments and tufts can have any other suitable size and configuration.

[0100] In embodiments, the rotating brush 412 is configured to rotate about a rotation axis 418 while it is moved laterally along the edge of the stack 400, while the substrate and 414 are fixed. The lateral positioning of the rotating brush 412 during such movement can be set to achieve a desired length of engagement 420 between the plurality of bristles 416 and the original cut edge 405. In embodiments, the stack 400 can additionally or alternatively be configured to rotate about a central axis of the stack 400, which can be parallel to the rotation axis 418. In some embodiments, the brushing step can be performed by rotating the rotating brush 414 in a first direction and additionally rotating the stack 400 in an opposite second direction. This can be particularly useful when the workpiece has a circular planar shape. It will be appreciated that the brushing process of the present disclosure can operate to polish the entire peripheral edge of a substrate using a single pass polar motion, and does not require corner dwell or circularization motion.

[0101] The rotating brush 412 can be operated to apply a polishing material or slurry to the substrate. The polishing material or slurry can be configured to remove substrate material chemically and / or mechanically to simultaneously shape and / or polish the periphery of multiple workpieces 402. In some embodiments, the polishing material can be or include an abrasive slurry, such as cerium oxide or diamond slurry. In some embodiments, the polishing material can include cerium oxide or another abrasive or chemical abrasive having a grit size ranging from about 0.01 microns to about 15.0 microns, or 0.05 to 7.0 microns, 0.1 to 1.0 microns, or 0.1 to 0.5 microns. In at least one embodiment, the polishing material can have cerium oxide or other abrasive or chemical abrasive having a grit size ranging from about 0.1 to about 0.3 microns. In embodiments, the polishing material can have a dso grit size greater than or equal to 0.5 pm (e.g., about 0.5 pm, 0.6 pm, 0.7 pm, 0.8 pm, 0.9 pm, 1.0 pm, 1.1 pm, 1.1 pm, 1.2 pm, 1.3 pm, 1.4 pm, 1.5 pm, 1.6 pm, 1.7 pm, 1.8 pm, 1.9 pm, 2.0 pm, 2.1 pm, 2.2 pm, 2.3 pm, 2.4 pm, 2.5 pm, 2.6 pm, 2.7 pm, 2.8 pm, 2.9 pm, 3.0 pm, or any size between such values). In embodiments, the polishing material can have a d95 grit size greater than or equal to 2.0 pm (e.g., about 2.0 pm, 2.1 pm, 2.2 pm, 2.3 pm, 2.4 pm, 2.5 pm, 2.6 pm, 2.7 pm, 2.8 pm, 2.9 pm, 3.0 pm, 3.1 pm, 3.2 pm, 3.3 pm, 3.4 pm, 3.5 pm, 3.6 pm, 3.7 pm, 3.8 pm, 3.9 pm, 4.0 pm, 5.0 pm, 6.0 pm, 7.0 pm, 8.0 pm, 9.0 pm, 10.0 pm, 11.0 pm, 12.0 pm, 13.0 pm, 14.0 pm, 15.0 pm, or any size between such values). The cerium oxide slurry or other polishing material can have an alkalinity ranging from pH 6 to pH 11. In at least one embodiment, the polishing material can include 50 ct / liter of DND Dia-Sol nano-diamonds having a diamond abrasive size ranging from about 30 nm to about 100 microns. Other polishing materials, including chemical and / or mechanical polishing materials, can also be used in other embodiments. In some embodiments, multiple polishing materials can be used continuously or simultaneously.

[0102] The properties of the polishing material used during the polishing process can determine the shape of the specific edge profile obtained. It is believed that the d50 grain size of the polishing material determines the lower limits of the depth 88 and width 90 of the curved region 84 described herein (see [link to relevant documentation]). Figure 1C Typically, a larger d50 grain size will increase the size of the bending region 84 (e.g., in terms of depth 88 and width 90) because material removal on the main surfaces of multiple workpieces 402 typically occurs due to concentrated slurry flow. It has been found that limiting the d50 grain size to less than or equal to 3.0 µm can effectively limit the size of the bending region 84 to retain the first compressive stress layer 76.

[0103] In some embodiments, the rotating brush 412 can be used to receive and dispense polishing material. For example, the base portion 414 may have perforations or channels configured to spray polishing material from the brush base onto the filaments and substrate. The perforations may be distributed throughout the base portion 414. Polishing material can be discharged through the perforations via an extrusion system or by the centripetal force of the rotating brush. The perforations may have a circular, polygonal, or any other suitable cross-sectional shape with any diameter suitable for achieving a desired flow rate of polishing material with a defined viscosity. In some embodiments, the base portion 414 may have a rotary joint configured to continuously refill polishing material from an external source as needed.

[0104] During the brushing operation, the rotating brush 412 can be driven at a rotational speed of approximately 10 to approximately 1000 rpm. In embodiments, the rotating brush 414 is driven at relatively high rotational speeds (e.g., greater than or equal to 100 rpm, greater than or equal to 200 rpm, greater than or equal to 300 rpm, greater than or equal to 400 rpm, greater than or equal to 500 rpm, greater than or equal to 600 rpm, greater than or equal to 700 rpm, greater than or equal to 800 rpm) to facilitate the generation of sufficiently high polishing slurry flow rates to penetrate the gap regions between the multiple workpieces 402 and polish their main surfaces. The rotating brush 412 can also be driven at a linear speed of 100 m / min to 1000 m / min around the periphery of the stack 400. Such high polishing slurry flow rates contribute to the generation of the polishing slurry described herein. Figures 1A-1CThe curved region 84 is described. In embodiments, the brush can be driven along the edge of the substrate at a linear speed of from about 1 to about 1000 m / min. Relatively low linear speeds (e.g., less than or equal to 100 mm / min, less than or equal to 75 mm / min, less than or equal to 50 mm / min, less than or equal to 40 mm / min, less than or equal to 30 mm / min) are preferred to facilitate the removal of a relatively large amount of material from the as-cut edge 405 during each pass of the rotating brush 414. As used herein, the term "polishing pass" refers to the movement of the rotating brush 414 about the entire perimeter of the stack 400 by relative movement between the rotating brush 414 and the stack 400. It is desirable to achieve the edge profile described herein using a minimum number of brush passes. Using a relatively low brush translation speed facilitates achieving this goal. In aspects, the mechanical strength and edge profile described herein can be achieved in less than or equal to 6 polishing passes, less than or equal to 5 polishing passes, less than or equal to 4 polishing passes, less than or equal to 3 polishing passes, less than or equal to 2 polishing passes, or even a single polishing pass. A relatively high engagement distance length value (e.g., greater than or equal to one-third of the maximum length of the plurality of brush filaments 416) enables a lower number of passes, especially when the filaments have a diameter greater than 0.1 mm. Figures 1A-1C The edge profile described. Using a relatively low brush translation speed facilitates achieving this goal. In aspects, the mechanical strength and edge profile described herein can be achieved in less than or equal to 6 polishing passes, less than or equal to 5 polishing passes, less than or equal to 4 polishing passes, less than or equal to 3 polishing passes, less than or equal to 2 polishing passes, or even a single polishing pass. A relatively high engagement distance length value (e.g., greater than or equal to one-third of the maximum length of the plurality of brush filaments 416) enables a lower number of passes, especially when the filaments have a diameter greater than 0.1 mm.

[0105] The brushing can be performed until the desired edge profile is achieved and until the maximum defect size or average defect size on the substrate edge is reduced to less than 3 microns, less than 2 microns, or less than 1 micron. The brushing steps can be operated to form a desired edge shape on the glass substrate 52, as described herein with respect to the edge shape described herein. Figures 1A-1C The edge shape described. In embodiments, the brushing steps can comprise a single stage brushing step. That is, in some embodiments, a single brush can be used to perform the appropriate number of passes over the edge surface to shape and polish the edge. In other embodiments, the brushing can be performed in multiple steps using, for example, more than one brush and / or more than one polishing material. For example, a first brushing step can be performed using a first brush and a polishing material having a first grit size, and a second brushing step can be performed using a brush and a polishing material having a second, smaller grit size.

[0106] It has been found that the edge shape described herein with respect to Figures 1A-1CThe described edge profile can be formed in a variety of different ways using the rotating brush 414. Generally, embodiments in which the rotating brush 414 is configured and operated to aggressively remove material from the original cut edge 405 are preferred because they provide processing efficiency by reducing the number of polishing passes required and reduce the processing time to provide a finished substrate. Such aggressive material removal can be achieved by using a wire diameter greater than 0.1 mm (e.g., about 0.2 mm). Further, in such aggressive material removal embodiments, the engagement length 420 in each polishing pass can be greater than or equal to 1 / 3 of the maximum length of the plurality of wires 416. In embodiments, to facilitate aggressive material removal, the engagement length 420 can be greater than or equal to 6 mm (e.g., greater than or equal to 6 mm and less than or equal to 8 mm when the plurality of wires 416 have a length less than or equal to 20 mm; greater than or equal to 12 mm and less than or equal to 20 mm when the plurality of wires have a length greater than or equal to 25 mm and less than or equal to 50 mm).

[0107] In embodiments in which material is aggressively removed by the rotating brush 414, contact between the plurality of wires 416 and the plurality of workpieces 402 is concentrated on the original cut edge 405 by limiting the minimum thickness 408 associated with the plurality of intermediate layers 404 to be less than the maximum diameter of the plurality of wires 416. For example, the minimum thickness 408 can be less than or equal to 0.75 times the maximum diameter of the plurality of wires 416. For example, when the plurality of wires 416 have a diameter of 0.2 mm, the minimum thickness 408 is less than 0.2 mm (e.g., less than or equal to 0.15 mm, less than or equal to 0.1 mm, less than or equal to 0.05 mm, greater than or equal to 0.01 mm, and less than 0.15 mm). Such spacing advantageously prevents the ends of the plurality of wires 416 from contacting the major surfaces of the plurality of workpieces 402, which prevents removal of excess material therefrom and prevents removal of the compressive stress layer that is created in the plurality of workpieces 402 as a result of their strengthening. As a result, the major surfaces of the plurality of workpieces 402 (corresponding to the first and second major surfaces 54 and 56 of the glass substrate 52) can be free of brush marks and contain only slurry stream lines from the polishing slurry stream. Such slurry stream lines can generally have a maximum width that is less than or equal to the D95 grain size associated with the slurry (e.g., less than or equal to 15 µm, or even less than or equal to 3 µm in some embodiments). As a result of being free of brush marks, the first and second peripheral regions 60 and 70 of the glass substrate 52 can exhibit lower PV surface roughness values than the polished edge 58, which can contain brush marks (e.g., having a maximum width greater than 5 µm or even greater than or equal to 10 µm).

[0108] Herein Figures 1A-1CThe described edge profile can also be achieved with a rotating brush 412 in a more passive material removal manner. In such passive embodiments, the thickness 408 of the plurality of interposers 404 is not particularly limited and can be greater than the diameter of the plurality of bristles 416. Such passive material removal can be achieved by limiting the bristle diameter to less than or equal to 0.1 mm. In such embodiments, due to the small bristle diameter, a variety of different filament lengths (e.g., 18 mm to 36 mm) and engagement lengths 420 values (e.g., 7 mm to 24 mm) can be used. Alternatively or additionally, such passive material removal can also be achieved by limiting the engagement length 420 to be less than one fifth of the maximum length of the plurality of bristles 416 when using bristles with a diameter greater than 0.1 mm. Such passive engagement generally prevents the rotating brush 412 from removing material on the major surfaces of the plurality of workpieces 402.

[0109] One advantage of the brush polishing process described herein is that the advantageous edge profile described herein can be achieved by removing a relatively small amount of material from the plurality of workpieces 402. In embodiments, the material removed from the as-cut edges 405 by contact with the plurality of bristles 416 is limited to less than 50 pm measured in a direction extending perpendicular to the as-cut edges 405. For example, in embodiments, the polished edges 58 are formed by removing 10 pm to 50 pm of material from each of the as-cut edges 405 associated with one of the plurality of workpieces 402. In examples, it has been found that two polishing passes can remove 20 pm to 30 pm of material from the as-cut edges 405 and produce the advantageous edge profile described herein. Such limited material removal improves material utilization when forming the plurality of glass substrates 52 from a single glass sheet blank.

[0110] Referring back to Figure 3 After the brush polishing process is complete, at block 308, the process 300 can include cleaning and other downstream process steps. For example, after the brushing step is complete and the edges of the substrates are shaped and polished, the substrates can be removed from the interposer stack and can be cleaned by any suitable cleaning method to remove polishing material, substrate dust, or other material from the substrate surfaces. For example, cleaning can include a rinse or water bath. Additional downstream processes can include decoration such as printing ink, attachment of electronic components, additional strengthening such as an IOX strengthening process, and / or other downstream processes. In some embodiments, the polished substrate edges can be further strengthened by an etching process.

[0111] It should be understood that, in some embodiments, the above-described process 300 can be operated to simultaneously shape and finish the edge surface of the substrate without mechanical grinding. That is, when a polishing material is brushed over the edge surface, edge chamfering or other edge shaping can be provided through the chemical and / or mechanical interaction between the polishing material and the substrate material. The above-described process can be operated to form and shape the edge surface without causing the damage often resulting from mechanical grinding (such as from grinding wheels). It should be further understood that relatively high edge strength can be achieved using the above-described process without scratches, notches, and / or other defects caused by mechanical grinding.

[0112] The above-described process 300 can provide a finished substrate with relatively high edge strength. As used herein, the term "edge strength" refers to the B10 value associated with a Weibull distribution (e.g., obtained from a single batch formed by stacking) of multiple glass substrates 52 when the mechanical edge strength of each substrate in the substrate is tested according to ASTM C158-02 using a four-point bending test. Reference now... Figure 5 The apparatus 150 is shown for determining the edge strength of a substrate formed using processes 200 and 300 described herein. Figure 5 A glass substrate 52 is depicted undergoing an edge strength test using device 150 after polishing. As shown, device 150 includes two first side loading points 152 and two second side loading points 154, which are rods that contact the glass surface on a line perpendicular to the edge intended for bending. The two first side loading points 152 and the two second side loading points 154 have blunt, rounded ends such that they can generate stress in the glass substrate 52 without forming surface defects at their contact points. For example, the ends of the first side loading points 152 and the two second side loading points 154 may include a radius of 5 mm. The first side loading points 152 are shown in contact with a first main surface 54 and the second side loading points 154 are shown in contact with a second main surface 56. The first side loading points 152 are laterally spaced closer to each other than the second side loading points 154. In operation, the first side loading point 152 translates in the first direction 153 to apply a force to the first main surface 54, thereby causing the second side loading point 154 (which does not translate) to also apply a force in the second direction 155, which is opposite to the first direction 153. For example, the first side loading point 152 can translate along the first direction at a speed of 5 mm / s to apply a force to the glass substrate 52.

[0113] While not intending to be bound by theory, the apparatus 150 places a large area of the glass substrate 52 under approximately uniform stress. In operation, the applied force is increased and measured over time until the glass substrate 52 breaks along the profile 170. The maximum applied force corresponds to the force that causes the glass substrate 52 to break at one of the polished edges 58. Using the dimensions of the glass substrate 52 and the maximum applied force, the fracture stress can be calculated. The following equation can be used to calculate the stress at failure in megaPascals (MPa): (2) where L1 is the support span (mm), i.e., the distance between the two second side loading points 154, F is the applied load (Newtons), W W is the width of the transparent workpiece 160 (mm), and t is the thickness of the transparent workpiece 160 (mm). In the measurements made herein, W = 50 mm, L1 is 36 mm, and t = 1.3 mm. The span under the load, i.e., the distance between the two first side loading points 152, assumed above is the ½ distance of the support span distance L1 that holds the glass substrate 52. Individual glass substrates 52 can have higher or lower resistance to breakage, but on average, such 4-point bend measurements characterize the distribution of the part. Such distribution mean and its standard deviation can be reasonably characterized by breaking 5-10 glass substrates 52 of a batch, with more statistics being beneficial. In the case of edge strength, when the glass substrate 52 is subjected to 4-point bending, it is typically a defect along the polished edge 58 that is activated by the applied stress, thus the failure stress measures the "strength" of the outer edge.

[0114] In embodiments, the glass substrates 52 formed by the processes described herein can have a mechanical edge strength of at least 300 MPa, at least 500 MPa, at least 700 MPa, at least 900 MPa, at least 1 GPa, at least 1.25 GPa, or more. The edge strength values can vary depending on the level of ion exchange strengthening and the thickness of the glass substrate 52. It should be noted that, unless otherwise specified, the mechanical edge strength values described herein are not post-polishing strengthened (e.g., chemically strengthened, edge surface etched).

[0115] Example Embodiments of the disclosure can be further understood according to the following examples.

[0116] Counterexample In a first set of counterexamples, a quantity of 100.15 mm x 100.15 mm x 1.1 mm workpieces were produced from Corning Gorilla™ Glass 3 that were fully chemically strengthened by laser singulation. The workpieces were formed in a stack for brush polishing, with individual thin glass parts separated within this stack by a PTFE interlayer of dimensions (96 mm x 96 mm x 1.1 mm) that are significantly smaller than the dimensions of the corresponding thin glass substrate. Orange neoprene stabilizer was added to prevent the parts from sliding in the stack. The stack was brush polished using a rotating brush with a resin-filled filament brush featuring a filament length of 18 mm, a filament diameter of 0.200 mm, and a standard (33 turn) brush density. The brush rotational speed was set to 800 rpm, the feed rate was fixed at 27.5 mm / min, the engagement length was set to 6 mm, and a polishing test was performed for 6 complete brush polishing cycles.

[0117] The brush polishing process used to manufacture the first set of counterexamples did not follow the guiding principles provided with respect to the process 300 described herein. Given that the filament diameter is 0.2 mm and the filament length is 18 mm, the engagement length (6 mm) is relatively large, and the spacing between the workpieces is much greater than the filament diameter. Thus, this brush polishing apparatus does not sufficiently concentrate the contact between the brush filaments and the original cut edge, and has excessive contact between the brush filaments and the major surfaces. Figure 6 A microscope image of one of the counterexamples manufactured in this process is shown. As shown, FSM measurements taken indicate that the compressive stress layer has a DOL of approximately 43.4 pm. The brush polishing process removes excess material from the major surfaces, resulting in the complete removal of the compressive stress layer at a lateral distance of approximately 264 pm from the polished edge 602. Thus, the polished edge 602 is completely free of compressive stress. Using Figure 5 The depicted apparatus 150 tested the edge strength of the counterexample. Failure mode analysis indicated that the cause of the counterexample’s failure was a brush rub defect on the edge or surface in the brush polishing process.

[0118] Example according to a first embodiment A first set of examples was prepared according to the processes described herein. The workpieces were formed from Corning Gorilla™ Glass 3 that was fully chemically strengthened (DOL = 45 pm) with a thickness of 1.3 mm and decorated with an organic ink decoration. The workpieces had a compressive stress layer extending from each major surface, with a DOC similar to the DOC described above for the counterexamples. The workpieces were separated from the strengthened sheet using laser nanoperforation, followed by self-separation caused by inherent stresses in the ion-exchange material. The workpieces so formed had characteristic vertical edges and caused laser damage to the organic ink decoration bounded by the perimeter of the part. Figure 7An image depicting a portion of a workpiece 700 cut from a chemically strengthened glass sheet proximate to the border of an ink decoration 702. Nanoperforations were formed using a pulsed laser along a contour line proximate (e.g., less than 150 pm) to the border of the ink decoration 702. As shown, the laser-induced damage to the ink decoration 702 resulted in a virgin cut border 704 disposed approximately 45 pm from a virgin cut edge 706 of the workpiece 700. The laser-induced damage caused the virgin cut edge 706 to exhibit a relatively wavy shape, such that the distance from the virgin cut edge 706 varied significantly. As demonstrated, the virgin cut border 704 was substantially different from a linear shape. As shown, over a 1 mm section of the virgin cut border 704, the peaks and valleys of the virgin cut border 704 deviated from a line fitted thereto by as much as 20 pm. Such a wavy border can result in inconsistent amounts of light leakage (e.g., when the substrate is used as a cover glass for a light source such as a display), which can adversely affect the appearance if not corrected.

[0119] After near-net-shaping, the workpieces were stacked in preparation for brush polishing using individual sheets of high water-absorbing blue dust-free paper as an interlayer. Brush polishing was then performed using the following process conditions: • 36 mm brush filament length - implantation of brush base portion 5 mm deep; • 0.200 mm single brush filament diameter, with a filled resin construction; • Spiral brush filament design, with a standard 33 turns; • ≤ 100 pm interlayer thickness (individual dust-free paper), with a 1 mm uniform edge entry; • Calcined ceria slurry (MIREK HL-05 slurry, with a dso particle size of 1 pm and d95 of 3 pm) • Brush speed 800 - 1000 rpm (cylindrical brush of 292 mm diameter); • Brush engagement 15 mm; • ≤ 27.5 mm / min feed rate; and • 1 ≤ brush polishing cycle.

[0120] As shown by the above parameters, to provide a first set of examples, a strong brush engagement was performed in which the workpieces were spaced less than half the filament diameter from one another. This combination of interlayer thickness and filament diameter resulted in concentrated contact between the brush filaments and the virgin cut edge 706. Samples were formed by 2 polishing passes (also referred to herein as “BP cycles”), 3 polishing passes, and 6 polishing passes. Results for some of the examples (one of each of the number of polishing passes) are depicted in FIGS. 6A-6C. Figure 8A first substrate 800 is formed with 2 polishing passes and includes a first polished edge 802. A second substrate 804 is formed with 3 polishing passes and includes a second polished edge 806. A third substrate 808 is formed with 6 polishing passes and includes a third polished edge 810.

[0121] Figure 8 The distances in FIG. 8 represent the first and second maximum linear dimensions 64 and 74 described herein with respect to Figures 1A-1C Generally, the examples manufactured using two polishing passes result in less than 100 pm of material removal at the workpiece major surface. The examples manufactured using three polishing passes result in less than 120 pm of material removal at the workpiece major surface. The examples manufactured using six polishing passes result in less than 160 pm of material removal at the workpiece major surface. This is far less than the material removal in the counterexamples. Such limited material removal from the major surface is believed to result in the presence of a compressive stress layer at the first, second, and third polished edges 802, 806, and 810.

[0122] The examples formed using the brush polishing processes described herein also exhibit a clear decorative boundary. Figure 9 An image of a portion of a substrate 900 cut and polished from a chemically strengthened glass workpiece according to the processes described herein is depicted. The substrate 900 includes a polished edge 902 and a decorative layer 904 having a polished decorative boundary 906. In contrast to the as-cut boundary 704 described with respect to Figure 7 The polished decorative boundary 906 is sharper and more distinct than the as-cut decorative boundary 704. As shown, over a 1 mm section of the polished decorative boundary 906, the peaks and valleys of the polished decorative boundary 906 deviate from a line fitted thereto by no more than 10 pm. This is a result of the interaction between the decorative layer 904 and the polishing material described herein.

[0123] Mechanical edge strength measurements were taken and a first set of examples. For comparison, another set of counterexamples were formed from glass cut from the same glass sheet and subjected to the same chemical strengthening process, but stacked with three times the interlayer thickness (using three sheets of dust-free paper), such that the workpiece spacing was greater than the brush filament diameter. Each substrate was strengthened under partial IOX conditions (2 hour soak time) and full IOX conditions (4 hour soak time). The results are depicted in FIG. 10. Figure 10 Figure 10 An image including a first counterexample 1002 and a second counterexample 1004. Figure 10 ​The images also include a first example 1006 and a second example 1008. As shown, the 3x interlayer thickness causes the material at the corners of the workpiece to be removed more, resulting in removal of the compressive stress layer from the polished edge. However, the examples manufactured according to the present disclosure cause the compressive stress layer to remain on the polished edge. Weibull distributions of the mechanical edge strength values for each of the IOX treated examples and counterexamples are also provided. As shown, the counterexamples each exhibit a B10 value of less than 400 MPa, while each of the examples exhibits a B10 value of greater than 600 MPa. The results are consistent regardless of the ion exchange treatment. This indicates that brush polishing using the methods described herein results in a significant improvement in the mechanical edge strength of chemically strengthened parts.

[0124] Example according to a second embodiment A second set of examples were prepared according to the processes described herein. The workpieces were formed from Corning Gorilla™ Glass 3 with a thickness of 1.3 mm that was fully chemically strengthened (DOL = 45 pm) and decorated with an organic ink decoration. The workpieces had a compressive stress layer extending from each major surface, the DOC of the workpieces being similar to the DOC described above for the counterexamples. The workpieces were separated from the strengthened sheet using laser nanoperforation, followed by self-separation. Brush polishing was then performed using process conditions similar to those described above for the first example, except that the interlayer was applied in liquid form (e.g., by one of inkjet, roll coating, spray coating, screen printing, or other suitable technique) to have precise dimensions associated with each workpiece. There was an interlayer entrance of 0 mm in the second example. These interlayers had a d50 slurry grain size that was greater than and a thickness that was less than or equal to 100 pm. The advantageous edge profile described herein with respect to Figures 1A-1C the clear decoration boundary of these interlayer placements were achieved. These indicate that the advantageous edge profile can be achieved at various interlayer thicknesses within the ranges described herein and without an edge entrance.

[0125] Example according to a third embodiment A third set of examples were prepared according to the processes described herein. The workpieces were formed from Corning Gorilla™ Glass 3 with a thickness of 1.3 mm that was fully chemically strengthened (DOL = 45 pm) and decorated with an organic ink decoration. The workpieces had a compressive stress layer extending from each major surface, the DOC of the workpieces being similar to the DOC described above for the counterexamples. The workpieces were separated from the strengthened sheet using laser nanoperforation, followed by self-separation. The workpieces so formed had characteristic vertical edges and caused laser damage to the organic ink decoration bounded by the perimeter of the part. After near-net-shaping, the workpieces were stacked in preparation for brush polishing using a relatively thick interlayer. Brush polishing was then performed using the following process conditions: • 36 mm brush filament length - implanted 5 mm deep into brush base portion; • 0.200 mm single brush filament diameter, with filled resin construction; • Spiral brush filament design, with standard 33 turns; • 500 pm < interposer thickness, edge entry uniform to 5 mm; • Calcined ceria slurry (MIREK HL-05 slurry with a d50 particle size of 1 pm and a d95 of 3 pm) • Brush speed 800 - 1000 rpm (292 mm diameter cylindrical brush); • Brush engagement 2 mm to 5 mm; • < 27.5 mm / min feed rate; and • 1 < brush polishing cycles.

[0126] As shown, the third embodiment differs from the first and second embodiments in that the brush filament engagement is passive, as the engagement length is less than one-fifth of the brush filament length. Such passive brush engagement results in very low brush forces on the part edge, resulting in concentrated contact on the as-cut edge. The relatively large gap between the parts caused by the thick interposer also reduces the resistance to brush movement, further reducing the brush forces. Samples made according to this third embodiment exhibited the advantageous edge profile and smooth decorative border described herein with respect to Figures 1A-1C The described advantages of the edge profile and smooth decorative border. These results indicate that the advantageous edge profile can be achieved using both active and passive brush engagement.

[0127] Example according to a fourth embodiment A fourth set of examples were prepared according to the processes described herein. The workpieces were formed from Corning Gorilla™ glass 3 with a thickness of 1.3 mm that was fully chemically strengthened (DOL = 45 pm) and decorated with an organic ink decoration. The workpieces had a compressive stress layer extending from each major surface, with a DOC similar to that described above for the counterexamples. The workpieces were separated from the strengthened sheet using laser nanoperforation, followed by self-separation. The workpieces so formed had characteristic vertical edges and caused laser damage to the organic ink decoration bounded by the part perimeter. After near-net-shaping, the workpieces were stacked in preparation for brush polishing using individual sheets of high absorbency blue dust-free paper as interposers. Brush polishing was then performed using the following process conditions: • 36 mm brush filament length - implanted 5 mm deep into brush base portion; • < 0.1 mm single brush filament diameter, with filled resin construction; • Spiral brush filament design, with standard 33 turns; • 100 pm interlayer thickness, edge entry uniformity of 1 mm; • Calcined ceria slurry (MIREK HL-05 slurry with a d50 particle size of 1 pm and a d95 of 3 pm) • Brush speed 800 - 1000 rpm (cylindrical brush of 292 mm diameter); • Brush engagement 7 mm to 24 mm; • Feed rate of < 27.5 mm / min; and • 1 < brush polishing cycles.

[0128] As shown, the fourth embodiment differs from the first and second embodiments in that the brush filament engagement is passive, as the brush filament diameter is less than or equal to 0.1 mm. Such passive brush engagement results in very low brush forces on the part edge, resulting in concentrated contact on the as-cut edge. Samples manufactured according to this fourth embodiment exhibit the advantageous edge profile and smooth decorative border described herein with respect to Figures 1A-1C The results indicate that the advantageous edge profile can be achieved using both active and passive brush engagement. When the workpiece is only partially chemically strengthened, these embodiments do not remove the compressive stress layer from the polished edge at all, resulting in a compressive depth of between 20 pm and 25 pm. Even with such a reduction in compressive depth, the reduction in brush filament stiffness caused by the reduced diameter reduces the risk of the compressive stress layer being eroded.

[0129] Example according to a fifth embodiment A fifth set of examples were prepared according to the processes described herein. The workpieces were formed from Corning Gorilla™ glass 3 with a thickness of 1.3 mm that was fully chemically strengthened (DOL = 45 pm) and decorated with an organic ink decoration. The workpieces had a compressive stress layer extending from each major surface, the DOC of the workpieces being similar to the DOC described above with respect to the counterexample. The workpieces were separated from the strengthened sheet using laser nanoperforation, followed by self-separation. The workpieces so formed had characteristic vertical edges and caused laser damage to the organic ink decoration bounded by the part perimeter. After near-net-shaping, the workpieces were stacked in preparation for brush polishing. An interlayer was applied in liquid form (e.g., by one of inkjet, roll coating, spray coating, screen printing, or other suitable technique) to have precise dimensions associated with each workpiece. Brush polishing was then performed using the following process conditions: • 18 mm brush filament length - implant brush base portion 5 mm deep; • 0.2 mm single brush filament diameter, with a packed resin configuration; • Spiral brush filament design, with a standard 33 turns; ● The interposer thickness is greater than the d50 grain size and less than 100 µm, with no edge entry points; ● Calcined cerium oxide slurry (MIREK HL-05 slurry, d50 particle size is 1 µm and d95 is 3 µm) ● Brush speed 800 - 1000 rpm (cylindrical brush with a diameter of 292 mm); ● Brush joint 7 mm; ● Feed rate ≤ 27.5 mm / min; and ● 1 ≤ Brush polishing cycle.

[0130] As shown, compared to the first embodiment, the fifth embodiment involves a very strong brush bond due to the reduced filament length. This reduction in length increases the stiffness of the filament. The very narrow interlayer without an inlet further protects the peripheral area of ​​the main surface, facilitating the removal of such strong materials. These examples demonstrate the features described herein regarding... Figures 1A-1C The description highlights the advantages of the edge shape and smooth decorative borders.

[0131] Example according to a sixth embodiment The example according to the sixth embodiment was formed under brush polishing conditions similar to those discussed for the first embodiment. In the sixth embodiment, the workpiece is not chemically strengthened, but mechanically strengthened by forming a glass-glass laminate, wherein a core glass layer 1100 is centrally disposed on two cladding glass layers 1102 with different coefficients of thermal expansion (see...). Figure 11A Between these elements, the core layer is subjected to tensile stress and the cladding layer to compressive stress. The core glass layer 1100 has a core thickness of 600 µm, and the cladding glass layer 1102 has a cladding thickness of 50 µm. The core glass layer 1100 has a CTE of 84.7 ppm / °C, while the cladding glass layer 1102 has a CTE of 34.3 ppm / °C, to create compressive stress therein. Figure 11A An image depicting the original cut workpiece. Figure 11B The workpiece is depicted after polishing with six passes, resulting in the removal of approximately 77 µm of material from the original cut edge. As shown, the cladding layer 1102 was not completely removed from the polished sample at its polished edge 1104, thus retaining compressive stress across the entire main surface. (Using this document regarding...) Figure 5 The described device 150 measures the mechanical edge strength of the original cut workpiece and polished substrate prepared according to the sixth embodiment. The Weibull distribution is shown in... Figure 11CThe as-cut workpiece exhibited a B20 value of about 216.7 MPa, while the polished sample exhibited a B20 value of about 364.7 MPa. These results demonstrate the efficacy of the methods described herein for restoring the mechanical strength of cut parts of substrates that are strengthened using a variety of methods.

[0132] Referring now to FIG. 15, edge impact strength of examples according to the present disclosure were tested using a pendulum apparatus such that a weight impacted the edge of the major surface of a polished example at an angle of 9°. The impact energy was varied by changing the drop height of the weight on the pendulum. The impact energy was increased until a break was observed. The results are depicted in FIG. 15. Figure 12

[0133] The preceding six example embodiments use brush polishing on workpieces that contain printed ink decoration disposed thereon. Brush polishing is preferred on such workpieces because clear decoration boundaries can be obtained after the decoration boundaries are damaged during near-net-shape forming (see, e.g., US 10,173,916 B2). Directing a stream of polishing slurry to the gap region between workpieces can uniformly remove damaged portions of the ink decoration around the periphery of the part, thereby forming a clear decoration boundary. Figure 7 Figure 13 is an image of a polished decoration sample 1300. The decoration sample 1300 has a polished edge 1302 and exhibits the advantageous edge profile described herein. In addition, a decoration layer 1304 is disposed on the major surface of the decoration sample 1300. The decoration layer 1304 is subjected to one of the brush polishing processes described herein such that a portion of the decoration layer 1304 is removed by the stream of polishing slurry. As shown, the decoration layer 1304 contains a clear and uniform decoration boundary 1306 compared to that shown in Figure 7 The decoration boundary 1306 is generally parallel to the polished edge 1302, resulting in an aesthetically pleasing appearance. Other polishing means, such as a polishing wheel, generally cannot achieve such a clear decoration boundary.

[0134] Even fixed abrasive polishing wheels that are resistant to wear, such as those advocated in US 10,173,916 B2, contain diamond abrasive particles that are larger than 10 pm in size, such that the resulting edge defects are significantly larger than 2 pm. Even polishing by such means can achieve an edge profile having the shape described herein, but such substrates are at a disadvantage relative to those described herein because they contain defects that are deeper and wider than the brush marks associated with the brush polishing processes described herein. Such methods also struggle to control the degree of edge chamfering. Inconsistencies in abrasive polishing wheels can result in reduced material utilization and reduced edge strength. ​​

[0135] In some embodiments, the interposer of the present disclosure can be used to apply or assist in applying a decoration to a substrate. For example, the interposer of the present disclosure can have an electronic device layer or other desired decoration or layer affixed thereto in an opposing configuration. The device layer or other decoration or layer can be configured to be transferable such that when a substrate is arranged in contact with the interposer, the decoration or layer can be transferred from the interposer to the substrate. In some embodiments, a compressive force applied to the stack of the substrate and interposer can assist in transferring the decoration or layer from the interposer to the substrate. In some embodiments, an adhesive layer can be applied between the decoration and the substrate.

[0136] The simultaneous edge shaping and polishing process of the present disclosure can additionally save significant time as compared to conventional shaping and finishing processes. That is, the single stage brushing step described above can provide a more time and labor efficient process relative to a series of mechanical grinding steps to remove edge material and a series of polishing steps to remove defects caused by grinding.

[0137] It will be appreciated that the processes described herein can replace conventional mechanical near-net-shaping and edge finishing with a single step, semi-batch brush polishing process that simultaneously shapes and finishes thin glass edges. The above-described solution represents a greater opportunity to deploy superior finishing process technology in a number of programs. This is particularly evident in the case of automotive interior products. For example, the finished thin glass product edge quality specification for automotive interior products can be particularly demanding, requiring edge strengths as high as 215 MPa prior to chemical strengthening. For example, it is calculated that such a mechanical edge strength requirement results in a maximum defect of no more than 11 microns after grinding. As a result, production lines currently being installed and commissioned are unable to meet the commercial and / or cost model objectives for edge finished thin glass products. Additionally, there is an increasing demand from some manufacturers and industries for thin glass parts that can be cold formed; such capability requires a relatively high edge strength, potentially higher than what can be achieved by conventional mechanical edge grinding followed by chemical strengthening.

[0138] While the edge shaping and finishing processes described herein can be used to replace conventional grinding steps, it can be further appreciated that in some embodiments, the brushing processes described herein can be used in conjunction with substrate edge grinding. For example, a near-net-shape substrate can have an edge shaped by one or more mechanical grinding steps, after which the substrate can be arranged between interposers and subjected to the brushing processes described herein to polish the edge to achieve a desired edge strength. Mechanical grinding can be performed using an abrasive grinding media having a suitable abrasive size. Additionally, the edge shaping and finishing processes described herein can be used to replace or in combination with chemical edge strengthening processes, such as but not limited to, HF treatment and ion exchange treatment.

[0139] The shaping and finishing processes of the present disclosure can additionally provide more efficient and cost effective manufacturing. In particular, multiple substrates, including tens or even hundreds of substrates, can be arranged in a stack with interposers arranged between each substrate. The substrate stack can be simultaneously shaped and finished using the brushing processes described herein. Thus, the processing time for each part can be reduced to less than 10 minutes, less than 5 minutes, or less than 3 minutes. Additionally, the processes of the present disclosure can have less material waste compared to conventional shaping and finishing processes. In particular, the brush polishing can achieve the desired edge shape and polish with less material removal than can be required for conventional grinding processes. Furthermore, the processes of the present disclosure can provide improved processing efficiency by allowing edge shaping and finishing to be performed on the substrate after inks, devices, films, and / or other decorations are applied. By applying decorations prior to edge shaping and finishing, processing time can be significantly reduced. The shaping and finishing processes of the present disclosure can also be versatile in that such processes can be applied to a relatively wide range of substrate materials, including, for example, laminated materials and chemically strengthened materials, both of which can present challenges to conventional shaping and finishing processes.

[0140] A number of embodiments are described in the following paragraphs to provide some examples of the manufacturing processes of the present disclosure. It should be understood that the following embodiments are provided as examples only, and the present application is not limited to the following embodiments.

[0141] In at least one embodiment of the present disclosure, strengthened or laminated thin glass articles or other substrates can be prepared by a series of near net shape forming techniques, including but not limited to the techniques listed above. Strengthened or laminated thin glass substrates or other substrates can have edges that are simultaneously shaped to a desired edge profile and polished to a high quality edge finish by the processes described herein, the edges having a characteristic low residual damage and defect distribution and thus high mechanical edge strength.

[0142] In at least one embodiment of the present disclosure, strengthened and decorated thin glass substrates or other substrates prepared by screen printing multiple parts on an entire sheet with fiducials applied to enable picosecond laser cutting (nanoperforation followed by self-separation) can have edges that are simultaneously shaped to a desired edge profile and polished to a high quality edge finish by the processes described herein, the edges having a characteristic low residual damage and defect distribution and thus high mechanical edge strength.

[0143] In at least one embodiment of the disclosure, a strengthened and subsequently over- decorated thin glass substrate or other substrate prepared by screen printing multiple features on the entire sheet with fiducial points applied to enable picosecond laser cutting (nanoperforation, subsequent self-separation) can have edges simultaneously shaped to a desired edge profile and polished to a high quality edge finish by the processes described herein, with a characteristic low residual damage and defect profile and thus high mechanical edge strength. Strategic interlayers can be positioned between substrates in such a way as to simultaneously allow removal by polishing of a portion of the over-decorated surface to form a decorative border, rather than merely preserving the existing border.

[0144] In at least one embodiment of the disclosure, the substrate edges can be shaped and finished using mechanical slurry particles. A suitable mechanical slurry can be or include the DND Nano Diamond Slurry product suite (including the DIA-SOL HL product name and brand) manufactured and distributed by Fujimi Corporation - these slurries are produced in concentrated (50 ct / liter) form and in a variety of particle sizes (30 nm - 75 pm) and types (frangible, metal bonding). Other suitable mechanical slurry particles can additionally or alternatively be used. To achieve maximum efficiency, the slurry is dispensed in its most concentrated form (e.g., 50 ct / liter), but can be diluted with water as needed. The mechanical slurry particles can be easily rinsed clean after brushing.

[0145] In at least one embodiment of the present disclosure, a brush polishing can be performed using an interposer with a transferrable pattern (e.g., decal) such that the edge finishing can be performed while limiting the pressure of the stack while simultaneously transferring the pattern on the interposer to the surface of the thin glass substrate. For example, a stack can be created of alternating substrates and interposers. The interposers can be strategically positioned to control the contact of the edge to be polished with the polishing media and slurry. The interposers can be designed to have a combination of desired mechanical (relative dimensions, edge profile, compressibility, coefficient of sliding viscosity, coefficient of thermal expansion, wear resistance, static charge), chemical (resistance to polishing slurry, resistance to alkali), electrical (static charge), and / or magnetic material properties. The interposers can each additionally have a transferrable decorative material disposed thereon and configured to be activated by contact and pressure such that a desired decorative pattern can be transferred to the substrate being polished during the constraint by compression and brush polishing. The stack can be constrained by simple long duration mechanical compression. The substrate edge can be subjected to a brush polishing process in which a cylindrical brush is rotated at a prescribed speed (10 - 1000 rpm) and is brought into contact with a continuous stream of polishing slurry in a programmed set of operating motions, the cylindrical brush being composed of engineered filaments of small (< 0.200 mm) diameter and a range of lengths fastened together in a range of sizes (e.g., 3-5 mm), patterns (e.g., helical, interlaced, straight), and / or brush density. The filaments can be brought into controlled contact with the engineered stack of substrates. The substrates can be polished until near net shape resulting residual subsurface damage is reduced to a maximum feature defect size < 2 microns and a desired edge profile is imparted. The substrates can be further polished by a subsequent brush polishing step employing a separate brush using an engineered finer polishing slurry to further reduce residual subsurface damage. The substrates can be further chemically strengthened by exposure to HF and / or ion exchange.

[0146] In at least one embodiment, the brushing process of the present disclosure can reduce the number of polishing cycles compared to conventional polishing operations. For example, the brush can be operated to perform smooth polar polishing motions along the edge of the stack of substrates without deliberate dwell of polishing pressure and / or time on substrate corners or other edge features. In this manner, the brush of the present disclosure can be continuously moved along the perimeter edge of the substrate at a constant or near constant linear speed (e.g., between 5-100 mm / min or another suitable speed). It will be appreciated that the brush polishing operation of the present disclosure can be performed with a reduced number of pass cycles without the corner or other feature dwell or rounding motions typical in conventional brushing operations. Such compact polar polishing passes can be repeated to achieve a relatively high resolution.

[0147] In at least one embodiment, the interposer of the present disclosure can be or include one or more magnetically active materials. Further, in some embodiments, end caps or chucks arranged at each end of the part stack can be configured to provide electrostatic forces. The electrostatic end caps and the magnetic interposer can operate together to maintain alignment of the interposer and the substrate during brush machining. In some embodiments, this can be used to maintain alignment in addition to or instead of a compressive force applied to the stack.

[0148] The terms "substantially" or "generally," as used herein, refer to a complete or nearly complete range or degree of an act, characteristic, property, state, structure, item, or result. For example, an object that is "substantially" or "generally" enclosed would mean that the object is completely enclosed or nearly completely enclosed. In certain contexts, the precise degree of deviation allowable can depend on the particular context. However, in general, the close approximation of completion will be such, that the overall result is essentially the same as if absolute and total completion were obtained. The use of "substantially" or "generally" is also applicable when used in a negative connotation, referring to the complete or near complete lack of an act, characteristic, property, state, structure, item, or result. For example, an element, combination, embodiment, or composition that does not "substantially" or "generally" contain an element can still actually contain such element, so long as the overall effect of such element is essentially the same as if such element were not present.

[0149] To help the patent office and any readers of this application understand the claims, the applicant(s) wishes to note that the words "method" and "step" are used in the claims to mean any acts, characteristics, properties, states, structures, items, or results that can be performed, possessed, or obtained by an apparatus, device, or system. The terms "method" and "step" are not used to mean acts, characteristics, properties, states, structures, items, or results that must be performed, possessed, or obtained by a human.

[0150] Additionally, as used herein, the phrase "at least one of [X] and [Y]," where X and Y are different components that can be included in embodiments of the disclosure, means that the embodiment can include either component X without the other component Y, the embodiment can include either component Y without the other component X, or the embodiment can include both components X and Y. Similarly, when a phrase such as "at least one of [X], [Y], and [Z]" is used, it means that the embodiment can include any one of the three or more components, any combination or sub-combination of any of the three or more components, or all of the three or more components.

[0151] In the foregoing description, for the purposes of explanation, various embodiments of the present disclosure have been set forth in detail with reference to the drawings. The embodiments described are not intended to be exhaustive or to limit the disclosure to the precise forms described. Obvious modifications and alterations are possible in view of the above teachings. The different embodiments are chosen and described in order to provide the best teaching of the principles and its practical application to others skilled in the art to best utilize the various embodiments with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the present disclosure as determined by the appended claims as interpreted according to the full breadth and equitably due to them.

Claims

1. A glass article comprising: a first major surface; a second major surface disposed opposite the first major surface; and a polished edge extending between the first major surface and the second major surface, wherein: the polished edge comprises at least one of (a) an Ra surface roughness greater than or equal to 1 nm and less than or equal to 20 nm; (b) a root mean square surface roughness greater than or equal to 1 nm and less than or equal to 30 nm; and (c) a peak to valley surface roughness greater than or equal to 10 nm and less than or equal to 50 nm, the glass article is chemically strengthened such that the glass article comprises a first compressive stress layer extending from the first major surface to a first depth of compression (DOC1) and a second compressive stress layer extending from the second major surface to a second depth of compression (DOC2), wherein a majority of the polished edge is not under compressive stress, and at least one of the first compressive stress layer and the second compressive stress layer extends to the polished edge.

2. The glass article of claim 1, wherein: the polished edge comprises a plurality of brush marks disposed thereon in a substantially parallel configuration, the brush marks being produced by a brush polishing process.

3. The glass article of any of claims 1 to 2, wherein a plurality of the glass articles having the same composition, thickness, and chemical strengthening exhibit a Weibull distribution with a B10 value greater than or equal to 500 MPa when mechanically edge strength tested in accordance with ASTM C158-02 using a four-point bend test.

4. The glass article of any of claims 1 to 3, wherein the polished edge exhibits all of (a), (b), and (c).

5. The glass article of any of claims 1 to 4, wherein: the glass article comprises a maximum thickness (T) measured between major surfaces of the glass article, and the polished edge comprises a length greater than T - DOC1 - DOC2.

6. The glass article of any of claims 1 to 5, wherein in a cross-section of the glass article taken in a direction perpendicular to the polished edge and the first major surface, the first major surface comprises a first perimeter region in which material of the glass article is removed from the first major surface during a brush polishing process, wherein the first perimeter region comprises a width measured in a direction perpendicular to the polished edge, the width being less than or equal to 200 pm.

7. The glass article of claim 6, wherein: the first perimeter region comprises a curved region extending inwardly from the polished edge, wherein in the cross-section, the polished edge transitions to the curved region at a boundary of an outer surface of the glass article, and at the boundary, the outer surface exhibits a minimum radius of curvature greater than or equal to twice a maximum thickness of the glass article as measured between the first major surface and the second major surface. ​ 8. The glass article of claim 7, wherein the curved region comprises: a width taken in the direction perpendicular to the polishing edge that is less than or equal to and a depth taken at a geometric center of the first major surface in a direction perpendicular to the first major surface, the depth being less than or equal to .

9. The glass article of any one of claims 6 to 8, wherein, in the cross-section, the second major surface comprises a second peripheral region in which material of the glass article is removed from the second major surface during the brush polishing process.

10. The glass article of claim 9, wherein the first and second peripheral regions comprise different shapes such that the glass article comprises an asymmetric chamfer.

11. The glass article of any one of claims 1 to 10, further comprising an anti-reflective coating disposed on the first major surface, the anti-reflective coating comprising alternating layers of high and low refractive index materials, wherein a periphery of the first major surface exhibits a golden hue when viewed from a normal angle of incidence and illuminated with a diffuse D65 light source simulating ambient lighting conditions.

12. The glass article of any one of claims 1 to 11, wherein the first and second major surfaces are free of brush marks associated with a brush polishing process performed on the polished edge.

13. The glass article of any one of claim 12, wherein the first and second major surfaces comprise a slurry stream line, the slurry stream line comprising a maximum width of less than 3 pm.

14. The glass article of any one of claims 1 to 13, further comprising an ink layer disposed on the second major surface, the ink layer comprising an outer boundary offset from the polished edge by a distance of less than 160 pm, the distance measured perpendicular to the polished edge.

15. The glass article of claim 14, wherein the outer boundary comprises a slurry stream line from a polishing slurry stream associated with a brush polishing process, the slurry stream line extending substantially parallel to the outer boundary.

16. A glass article comprising: a first major surface; a second major surface disposed opposite the first major surface; and a polished edge extending between the first major surface and the second major surface, wherein: the polished edge comprises at least one of: (a) an Ra surface roughness of greater than or equal to 1 nm and less than or equal to 20 nm; (b) a root mean square surface roughness of greater than or equal to 1 nm and less than or equal to 30 nm; and (c) a peak to valley surface roughness of greater than or equal to 10 nm and less than or equal to 50 nm, the glass article is chemically strengthened such that the glass article comprises at least a first compressive stress layer extending from the first major surface to a first depth of compression (DOC1), In a cross-section of the glass article taken in a direction normal to the polished edge and the first major surface, the first major surface comprises a first perimeter region in which material of the glass article was removed from the first major surface during a polishing process, wherein the first perimeter region comprises a depth measured in a direction normal to the first major surface at a geometric center of the first major surface, wherein the depth is less than or equal to 0.5 microns. such that a portion of the polished edge is under compressive stress, wherein a majority of the polished edge is not under compressive stress.

17. The glass article of claim 16, wherein the first peripheral region comprises a width measured in a direction perpendicular to the polished edge, the width being less than or equal to 200 pm.

18. The glass article of claim 17, wherein the width is less than or equal to .

19. The glass article of any one of claims 16 to 18, wherein: The first perimeter region includes a curved region extending inwardly from the polished edge, wherein, within the cross-section, the polished edge transitions to the curved region at a boundary of an outer surface of the glass article, and At the boundary, the outer surface exhibits a minimum radius of curvature that is greater than or equal to twice a maximum thickness of the glass article as measured between the first major surface and the second major surface.

20. The glass article of any of Claims 16 to 19, wherein, in the cross-section, the second major surface includes a second perimeter region in which material of the glass article is removed from the second major surface during the brush polishing process.

21. The glass article of Claim 20, wherein the first and second perimeter regions include different shapes such that the glass article includes an asymmetric chamfer.

22. The glass article of any of Claims 16 to 21, further comprising an anti-reflective coating disposed on the first major surface, the anti-reflective coating including alternating layers of high and low refractive index materials, wherein a perimeter of the first major surface exhibits a golden yellow hue when viewed from a normal angle of incidence and illuminated with a diffuse D65 light source simulating ambient lighting conditions.

23. The glass article of any of Claims 16 to 22, wherein: the polished edge includes a plurality of brush marks arranged thereon in a substantially parallel configuration, the brush marks being produced by a brush polishing process.

24. The glass article of Claim 23, wherein the first and second major surfaces are free of the brush marks.

25. The glass article of Claim 24, wherein the first and second major surfaces include a slurry flow line, the slurry flow line including a maximum width of less than 3 pm.

26. The glass article of any of Claims 16 to 25, further comprising an ink layer disposed on the second major surface, the ink layer including an outer boundary offset from the polished edge by a distance of less than 160 pm, the distance being measured perpendicular to the polished edge.

27. The glass article of Claim 26, wherein the outer boundary includes a slurry flow line from a polishing slurry flow associated with a brush polishing process, the slurry flow line extending substantially parallel to the outer boundary.

28. The glass article of any of Claims 16 to 27, wherein the polished edge exhibits all of (a), (b), and (c).

29. A method of finishing an edge surface of a strengthened glass substrate, the method comprising: arranging the strengthened glass substrate between a first interlayer and a second interlayer; applying a compressive force to the strengthened glass substrate and the interlayers; and and A method of polishing an edge surface of a strengthened glass substrate by removing material of the strengthened glass substrate using a rotating brush and a polishing slurry stream, wherein the rotating brush includes a plurality of brush filaments, wherein contact between the strengthened glass substrate and the rotating brush is concentrated on the edge surface of the substrate, wherein the polishing slurry stream is concentrated on a major surface of the strengthened glass substrate.

30. The method of claim 29, wherein the first and second interlayers have a thickness that is greater than a dso grain size of the polishing slurry stream.

31. The method of any of claims 29 to 30, wherein the polishing includes at least two brush polishing passes.

32. The method of any of claims 29 to 31, wherein at most 50 pm of the material of the strengthened glass substrate is removed from the edge surface during the polishing.

33. The method of any of claims 29 to 32, wherein the material of the strengthened glass substrate is removed from a peripheral portion of a major surface of the strengthened glass substrate, the peripheral portion having a width that is less than or equal to 200 pm.

34. The method of claim 33, wherein after the polishing, a depth of the peripheral portion is less than a compressive depth associated with a compressive stress layer on one of the major surfaces.

35. The method of any of claims 29 to 34, wherein each of the brush filaments includes a filament diameter, wherein the first and second interlayers include a thickness that is less than the filament diameter so as to concentrate the contact on the edge surface.

36. The method of claim 35, wherein the filament diameter is less than half of the thickness of the first and second interlayers.

37. The method of any of claims 35 to 36, wherein: the plurality of brush filaments includes a filament length, the brush filament diameter is greater than 0.1 mm, and during chamfering and polishing, the rotating brush is disposed a distance from the strengthened glass substrate such that at least one-third of the filament length of the plurality of brush filaments is engaged with the edge surface.

38. The method of any of claims 29 to 34, wherein: the plurality of brush filaments includes a filament length and a filament diameter, and one of: (i) during the polishing, the rotating brush is disposed a distance from the strengthened glass substrate such that less than one-fifth of the filament length of the plurality of brush filaments is engaged with the edge surface, and (ii) the plurality of brush filaments includes a filament diameter that is less than or equal to 0.1 mm.

39. The method of claim 28, wherein the filament diameter is less than a thickness of the first and second interlayers.

40. The method of any of claims 29 to 39, further comprising disposing an ink layer around a periphery of a major surface of the strengthened glass substrate prior to the polishing, wherein a portion of the ink layer is removed by the polishing slurry stream during the polishing.

41. The method of any of claims 29 to 40, further comprising near-net-shaping the strengthened glass substrate prior to the polishing.

42. The method of claim 41, wherein the near-net-shaping comprises forming nanopores along a contour line in the strengthened glass substrate using a pulsed laser beam and separating a strengthened glass sheet at the contour line by one of thermal separation or self-separation.

43. The method of any of claims 29 to 42, wherein the strengthened glass substrate is a chemically strengthened glass substrate.

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