Materials, methods and techniques for textured steel articles

Abstract

A composite material may include a steel substrate having a surface, where the surface defines a pattern of recesses, and each recess has a maximum depth of 5 μm to 55 μm. A composite material may include an oxide layer on the surface of the steel substrate, where the oxide layer has a thickness between about 1 μm to about 4 μm, and where the oxide layer comprises Fe2O3.

Description

MATERIALS, METHODS AND TECHNIQUES FOR TEXTURED STEEL ARTICLESCROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims priority to U.S. Provisional Patent Application No.63 / 560,282, filed on March 1, 2024, the entire contents of which are incorporated herein by reference.TECHNICAL FIELD

[0002] The present disclosure relates to materials, methods, and techniques for textured steel articles. In some instances, exemplary textured steel articles may be particularly suited for vehicle-related applications.INTRODUCTION

[0003] Various surface treatment techniques are used to prepare a substrate for an intended use. In vehicle-related applications, such as with brakes, a wear surface may need to be bonded to a mounting surface. The bonding surfaces may be prepared using chemical treatment techniques or mechanical abrasion techniques. These techniques are intended to improve the adhesive properties of the bonding surfaces, which in turn improve bond fatigue resistance to failure during operation.SUMMARY

[0004] In some aspects, the techniques described herein relate to a textured steel article including: a steel substrate having a surface, the surface defining a pattern of recesses, each recess in the pattern of recesses having a maximum depth of 5 pm to 55 pm; and an oxide layer on the surface of the steel substrate, the oxide layer having a thickness between about 1 pm to about 4 pm; the oxide layer including Fe2O3.

[0005] In some aspects, the techniques described herein relate to a method for generating a textured steel article, the method including: laser etching a surface of a steel substrate, the laser etching being performed: with a spot size having a diameter between 50 pm and 80 pm; with a scan rate of up to 55 m / s; with a wavelength of 1060-1068 nm; with a pulse rate of 250 kHz-1000 kHz; whereby after laser etching, the surface of the steel substrate: defines a pattern of recesses,each recess in the pattern of recesses having a maximum depth of 5 pm to 55 pm; and includes an oxide layer.

[0006] In some aspects, the techniques described herein relate to a composite material. Exemplary composite materials may include a textured steel article including: a steel substrate having a surface, the surface defining a pattern of recesses, each recess in the pattern of recesses having a maximum depth of 5 pm to 55 pm; and an oxide layer on the surface of the steel substrate, the oxide layer having a thickness between about 1 pm to about 4 pm; the oxide layer including FezCh. Exemplary composite materials may include an adhesive on a surface of the oxide layer of the textured steel article.

[0007] Before any embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 shows a schematic side cross section of exemplary composite.

[0009] FIG. 2 is a schematic top view of a portion of an exemplary substrate.

[0010] FIG. 3 is a schematic top view of a portion of another exemplary substrate.

[0011] FIG. 4 shows various stages during experimental sample preparation after surface preparation.

[0012] FIG. 5A is a micrograph of a top surface of experimental Sample A, and FIG. 5B is a side view of experimental Sample A, annotated with measured recess depths.

[0013] FIG. 6A is a micrograph of a top surface of experimental Sample B, and FIG. 6B is a side view of experimental Sample B, annotated with measured recess depths.

[0014] FIG. 7A is a micrograph of a top surface of experimental Sample C, and FIG. 7B is a side view of experimental Sample C, annotated with measured recess depths.

[0015] FIG. 8A is a micrograph of a top surface of experimental Sample D, and FIG. 8B is a side view of experimental Sample D, annotated with measured recess depths.

[0016] FIG. 9 A is a micrograph of a top surface of experimental Sample E, and FIG. 9B is a side view of experimental Sample E, annotated with measured recess depths.

[0017] FIG. 10A is a micrograph of a top surface of experimental Sample F, and FIG. 10B is a side view of experimental Sample F, annotated with measured recess depths.

[0018] FIG. 11 A is a micrograph of a top surface of experimental Sample G, and FIG. 1 IB is a side view of experimental Sample G, annotated with measured recess depths.

[0019] FIG. 12A is a micrograph of a top surface of the Grit Blast sample, and FIG. 12B is a side view of the Grit Blast Sample, annotated with measured recess depths.

[0020] FIG. 13A and FIG. 13B are photographs of an experimental setup for Sample C.

[0021] FIG. 13C and FIG. 13D are photographs of an experimental setup for Sample D.

[0022] FIG. 14 is a schematic showing locations where hardness testing was performed on experimental specimens.

[0023] FIG. 15A is a photograph of an N653 disc manufactured using Sample A specifications.

[0024] FIG. 15B is a photograph of an EPD824 disc manufactured using Sample A specifications.

[0025] FIG. 15C is a photograph of an N653 disc manufactured using Sample B specifications.

[0026] FIG. 15D is a photograph of an EPD824 disc manufactured using Sample B specifications.

[0027] FIG. 16A is a photograph of an N653 disc manufactured using Sample C specifications.

[0028] FIG. 16B is a photograph of an EPD824 disc manufactured using Sample C specifications.

[0029] FIG. 16C is a photograph of an N653 disc manufactured using Sample D specifications.

[0030] FIG. 16D is a photograph of an EPD824 disc manufactured using Sample D specifications.DETAILED DESCRIPTION

[0031] Materials, methods, and techniques disclosed and contemplated herein relate to textured steel articles. Exemplary textured steel articles may be particularly suited for vehicle-related applications.

[0032] Previous methods for texturing steel articles included chemically etching and / or mechanical abrasion. However, both methods have drawbacks. As the name suggests, chemical etching processes require the use of chemicals. Exemplary chemicals used during etchingprocesses may be hazardous and thus pose a danger to human operators and require exacting disposal operations. Mechanical abrasion operations may involve impacting a target surface with abrasive particles at high velocity. Mechanical abrasion may introduce thermal distortions or otherwise negatively impact a flatness of the target surface.

[0033] In contrast, exemplary methods and techniques disclosed and contemplated herein may be capable of generating a pattern of recesses without introducing thermal distortions or impacting the flatness of the substrate. Exemplary methods and techniques may be capable of removing one or more of the following from a steel surface: dirt, furnace oxidation, residual cutting fluid, rust preventative, other chemicals, and combinations thereof. Exemplary methods and techniques generate a thin layer of oxide which, in combination with the recesses, improves adhesive bond fatigue resistance. Various aspects of exemplary materials, methods, and techniques are discussed below.I. Definitions

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present document, including definitions, will control. Methods and materials are described below, although methods and materials similar or equivalent to those described herein can be used in practice or testing of the present disclosure. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. The materials, methods, and examples disclosed herein are illustrative only and not intended to be limiting.

[0035] The terms “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s),” and variants thereof, as used herein, are intended to be open-ended transitional phrases, terms, or words that do not preclude the possibility of additional acts or structures. The singular forms “a,” “an” and “the” include plural references unless the context clearly dictates otherwise. The present disclosure also contemplates other embodiments “comprising,” “consisting of’ and “consisting essentially of,” the embodiments or elements presented herein, whether explicitly set forth or not.

[0036] As used herein, the term “about” is used to indicate that exact values are not necessarily attainable. Therefore, the term “about” is used to indicate this uncertainty limit. The term “about” may refer to plus or minus 10% of the indicated number. For example, “about 10%” may indicatea range of 9% to 11%, and “about 1” may mean from 0.9-1.1. Other meanings of “about” may be apparent from the context, such as rounding off, so, for example “about 1” may also mean from 0.5-1.4. The modifier “about” should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression “from about 2 to about 4” also discloses the range “from 2 to 4.”

[0037] For the recitation of numeric ranges herein, each intervening number there between with the same degree of precision is contemplated. For example, for the range of 6-9, the numbers 7 and 8 are contemplated in addition to 6 and 9, and for the range 6.0-7.0, the numbers 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, and 7.0 are contemplated. For another example, when a pressure range is described as being between ambient pressure and another pressure, a pressure that is ambient pressure is expressly contemplated.IL Exemplary Composites

[0038] Broadly, exemplary composites disclosed and contemplated herein comprise a steel substrate, an oxide layer, and an adhesive. Various aspects of exemplary composites are discussed below.

[0039] FIG. 1 shows a schematic side cross section of exemplary composite 100. As shown, composite 100 includes a textured steel article comprising steel substrate 102, oxide layer 112, and adhesive 114. Other embodiments may include more or fewer components.

[0040] Steel substrate 102 may have various end uses. In some instances, steel substrate 102 may be a component used in the automotive / trucking industry. As an example, steel substrate 102 may be a brake. As an example, steel substrate 102 may be a clutch. As an example, steel substrate 102 may be a vehicle door.

[0041] Various steels may be used for steel substrate 102. For instance, steel substrate 102 may be a 1040 steel, a 1050 steel, a 1075 steel, or a ferritic steel. In some instances, steel substrate 102 may be a hot rolled steel. In some instances, steel substrate 102 may be a cold rolled steel.

[0042] Steel substrate 102 has opposite surfaces: surface 104 and surface 106. In the embodiment shown, surface 106 defines a pattern of recesses 108. The pattern of recesses 108 comprises a plurality of recesses 110 arranged in a repeating fashion. In some implementations, both surface 104 and surface 106 may define a pattern of recesses 110.

[0043] Generally speaking, recesses 110 are formed by application of a laser directed towards surface 106. Additional details regarding exemplary methods for generating recesses 110 are discussed in greater detail below.

[0044] Exemplary recesses 110 shown in FIG. 1 are schematic only. In some implementations, exemplary recesses 110 may have an approximately rectangular cross section. In some implementations, exemplary recesses 110 may have an approximately semi-circular cross section. In some implementations, exemplary recesses 110 may have an approximately truncated cone cross section, where a width of the cone narrows moving away from surface 106. In some implementations, exemplary recesses 110 may have a cross section that is a combination of the aforementioned shapes.

[0045] Each recess 110 has a depth DI . Typically, depth DI is fairly uniform across the various recesses 110 on surface 106. For instance, in some implementations, depth DI varies less than 10%; less than 5%; less than 2%; or less than 1% among recesses 110 on surface 106.

[0046] Exemplary recesses 110 may have a depth DI of about 5 pm to about 55 pm. In various implementations, exemplary recesses 110 may have a depth DI between 5 pm to 55 pm; between 5 pm and 30 pm; between 30 pm and 55 pm; between 10 pm and 50 pm; between 15 pm and 45 pm; between 5 pm and 20 pm; between 20 pm and 35 pm; or between 35 pm and 55 pm. In various implementations, exemplary recesses 110 may have a depth DI no less than 5 pm; no less than 10 pm; no less than 15 pm; no less than 20 pm; no less than 25 pm; no less than 30 pm; no less than 35 pm; no less than 40 pm; no less than 45 pm; no less than 50 pm; or no less than 55 pm. In various implementations, exemplary recesses 110 may have a depth DI no greater than 55 pm; no greater than 50 pm; no greater than 45 pm; no greater than 40 pm; no greater than 35 pm; no greater than 30 pm; no greater than 25 pm; no greater than 20 pm; no greater than 15 pm; no greater than 10 pm; or no greater than 5 pm.

[0047] Each recess 110 may be spaced apart from adjacent recesses 110 by a given distance. For ease of discussion, a geometric center of a recess 110 may be used as a reference point to measure a distance between adjacent recesses 110. Typically, a distance between a center of adjacent recesses 110 may be no greater than about 160 pm. In various implementations, a distance between a center of adjacent recesses 110 may be between 80 pm and 160 pm; between 80 pm and 100 pm; between 100 pm and 120 pm; between 120 pm and 140 pm; between 140 pm and160 pm; or between 100 pm and 140 pm. In various instances, a distance between a center of adjacent recesses 110 may be no less than 80 pm; no less than 90 pm; no less than 110 pm; no less than 130 pm; no less than 150 pm; or no less than 160 pm. In various instances, a distance between a center of adjacent recesses 110 may be no greater than 160 gm; no greater than 140 gm; no greater than 120 gm; no greater than 100 gm; no greater than 90 gm; or no greater than 80 gm.

[0048] Exemplary recesses may have a maximum depth DI relative to the thickness D3 of the steel substrate 102. Typically, a maximum depth DI of recess 110 is no greater than 13% of thickness D3. In various implementations the maximum depth DI of recess 1 10 may be no greater than 13%; no greater than 12.4%; no greater than 10%; or no greater than 8% of thickness D3.

[0049] Typically, conducting surface texturing as disclosed herein imparts minimal or no thermal distortions, particularly when compared to mechanical abrasion techniques such as grit blasting, grinding, and sanding. In various implementations, a thickness D3 of the steel substrate 102 at a given location will vary less than 10%; less than 7%; less than 5%; less than 2%; or less than 1% when compared to a thickness D3 at a different location of the steel substrate 102. That is, when comparing the thickness D3 at two different locations of the steel substrate 102, the thickness D3 at one location will be within 10% of the thickness D3 at the second location different from the first location.

[0050] For a given substrate 102, most or all of surface 106 where adhesion is needed (which may be referred to as a “target bonding area”) may include a repeating pattern of recesses 110.

[0051] In some instances, an amount of textured surface may be described in relation to the target bonding area. In some implementations, between 50% and 99%; between 60% and 99%; between 70% and 99%; between 70% and 90%; between 75% and 95%; between 80% and 95%; or between 90% and 99% of a target bonding area of surface 106 includes a pattern of recesses 110. In various instances, no less than 50%; no less than 60%; no less than 70%; no less than 80%; no less than 90%; no less than 95%; or no less than 99% of a target bonding area of surface 106 includes a pattern of recesses 110. In various instances, no greater than 99%; no greater than 95%; no greater than 90%; no greater than 80%; no greater than 70%; no greater than 60%; or no greater than 50% of a target bonding area of surface 106 includes a pattern of recesses 110.

[0052] For a given substrate 102, a ratio of surface area to area size may be between about 1.07 to about 1.64. As used herein, a ratio of surface area to area size is defined as the total surface area,including recesses, for a selected portion of the surface. A ratio of surface area to area size may be determined, for instance, using a 3D optical profilometer, a commercially available example of which is the Keyence VR-6000 optical profilometer (available from Keyence, Itasca, Illinois). In various implementations, a ratio of surface area to area size may be between 1.03 and 1.64; between 1.07 and 1.30; between 1.30 and 1.64; between 1.2 and 1.5; between 1.4 and 1.64; or between 1.5 and 1.64. In various implementations, a ratio of surface area to area size may be no less than 1.03; no less than 1.07; no less than 1.2; no less than 1.3; no less than 1.4; no less than 1.5; or no less than 1 .6. In various implementations, a ratio of surface area to area size may be no greater than 1.64; no greater than 1.55; no greater than 1.45; no greater than 1.35; no greater than 1.25; no greater than 1.15; no greater than 1.1; or no greater than 1.07.

[0053] In some instances, an average surface roughness (Ra) of the steel substrate 102 may be between about 3.0 pm and about 15.4 pm. In various implementations, an average surface roughness (Ra) of the steel substrate 102 may be between 3.0 pm and 15.4 pm; between 3.0 pm and 9.0 pm; between 9.0 pm and 15.4 pm; or between 3.0 pm and 12.0 pm. In various implementations, an average surface roughness (Ra) of the steel substrate 102 may be no less than 3.0 pm; no less than 5.0 pm; no less than 7.0 pm; no less than 9.0 pm; no less than 11.0 pm; or no less than 13.0 pm. In various implementations, an average surface roughness (Ra) of the steel substrate 102 may be no greater than 15.4 pm; no greater than 13.0 pm; no greater than 11.0 pm; no greater than 9.0 pm; no greater than 7.0 pm; or no greater than 5.0 pm.

[0054] FIG. 2 is a schematic top view of a portion of an exemplary substrate 202. Surface 206 of substrate 202 defines a plurality of recesses 210. As shown, the plurality of recesses 210 are arranged in a repeating pattern. As used herein, a “repeating pattern” means within a given substrate 202, a size and spacing of recesses 210 for a given row or column is repeated for adjacent rows or columns. A “repeating pattern” may also mean that a spacing between adjacent rows and / or columns is repeated for adjacent rows and columns.

[0055] The pattern shown in FIG. 2 is referred to as a “dot pattern.” Recesses 210 in the dot pattern may have a generally circular cross section and a somewhat flat or rounded bottom surface.

[0056] As shown, the plurality of recesses 210 are aligned in parallel along a y-di recti on of the surface 206. In other implementations, the plurality of recesses 210 may be aligned in parallel along a different direction of the surface 206.

[0057] FIG. 3 is a schematic top view of a portion of an exemplary substrate 302. Surface 306 of substrate 302 defines a plurality of recesses 310. As shown, the plurality of recesses 310 are arranged in a repeating pattern.

[0058] The pattern shown in FIG. 3 is referred to as a “groove pattern.” The grooves 310 may have different lengths Lg in various implementations. In some instances, a groove length Lg may be no less than 12.5 millimeters (mm). In some implementations, a maximum groove length Lg may be equal to a straight-line length of the substrate between opposite edges. In some implementations, a maximum groove length Lg may be equal to about 95% to 98% of a straight- line length of the substrate between opposite edges.

[0059] As shown, the plurality of recesses 310 are aligned in parallel along an x-direction of the surface 306. In some instances, the plurality of recesses 310 may be equally spaced in a y- direction of the surface 306.

[0060] Referring again to FIG. 1, oxide layer 112 is formed on surface 106. Typically, oxide layer 112 also forms on the surface area of recesses 110.

[0061] Oxide layer 112 may comprise various oxide chemical species. For instance, oxide layer 112 may comprise FezOs. In some instances, oxide layer 112 may comprise more Fe20s than any other chemical species in terms of mol% or wt%. In some instances, oxide layer 112 may comprise Fe20s and FesO4.

[0062] Typically, exemplary processes disclosed herein avoid generation of FeO, FeOFb, and / or FeOHa in oxide layer 112. In various instances, oxide layer 112 may comprise no more than 1 wt% FeO. In various instances, oxide layer 112 may comprise no more than 1 wt% FeOFL. In various instances, oxide layer 112 may comprise no more than 1 wt% FeOFL.

[0063] Oxide layer 112 may have various thicknesses. In some instances, a thickness of oxide layer 112 may vary across surface 106 and recesses 110. At a given location, a thickness of oxide layer 112 may be between about 1 pm to about 4 pm. In various implementations, a thickness of oxide layer 112 may be between 1.0 pm and 4.0 pm; between 1.0 pm and 2.0 pm; between 1.0 pm and 2.5 pm; between 1.0 pm and 1.5 pm; between 2.0 pm and 3.5 pm; between 2.0 pm and 3.0 pm; or between 1.5 pm to 4.0 pm. In various implementations, a thickness of oxide layer 112 may be no less than 1.0 pm; no less than 1.5 pm; no less than 2.0 pm; no less than 2.5 pm; no less than 3.0 pm; no less than 3.5 pm; or no less than 4.0 pm. In various implementations, a thicknessof oxide layer 112 may be no greater than 4.0 gm; no greater than 3.5 gm; no greater than 3.25 gm; no greater than 3.0 gm; or no greater than 2.5 gm; no greater than 2.0 gm; no greater than 1.75 gm; no greater than 1.25 gm; or no greater than 1.0 gm.

[0064] Adhesive 114 is a layer applied or coated onto steel substrate 102 after generating recesses 110 and oxide layer 112. Various types of adhesives may be used, depending on the target application of the steel substrate 102. In some implementations, particularly wet friction environments, adhesive 114 may comprise a high temperature epoxy, a polyvinylbutyral (PVB) modified phenolic adhesive, or a nitrile phenolic adhesive. Commercially available example adhesives may include Hexion EPON 828 (from Hexion, Columbus, Ohio), Eurorigan WAF37 (Euro Rigan, Asti, Italy), Bostik 1389HV (Bostik, Wauwatosa, Wisconsin), Henkel PL-605 (Henkel Adhesive Technologies, Dusseldorf, Germany), and Ruscoe 5007 (Akron, Ohio).

[0065] Adhesive 114 may have various thicknesses, depending upon the target application of the steel substrate 102. In some implementations, adhesive 114 may have a thickness between 12 pm and 200 gm; between 12 gm and 100 gm; between 100 gm and 200 gm; or between 50 gm and 150 gm. In various instances, adhesive 114 may have a thickness no less than 12 gm; no less than 20 gm; no less than 40 gm; no less than 50 gm; no less than 75 gm; no less than 100 gm; no less than 125 gm; no less than 150 gm; no less than 175 gm; or no less than 200 gm. In various instances, adhesive 114 may have a thickness no greater than 12 gm; no greater than 20 gm; no greater than 40 gm; no greater than 50 gm; no greater than 75 gm; no greater than 100 gm; no greater than 125 gm; no greater than 150 gm; no greater than 175 gm; or no greater than 200 gm.

[0066] Exemplary composites may be characterized in terms of adhesive strengths between the adhesive and the textured steel article, which may be measured using a lap shear test. In some instances, an adhesive strength between the adhesive and the textured steel article may be greater than or equal to 10.34 MPa as measured by a lap shear test. An exemplary lap shear test is described in greater detail below.

[0067] Exemplary composites may be characterized in terms of performance in high temperature thermal abuse dynamometer wet brake testing. In some instances, exemplary composites may pass a high temperature thermal abuse dynamometer wet brake test comprising an initiation fluid temperature of 300 °C to 350 °C, a facing pressure of 1.38 MPa, and a unit energy of 1051.5 kJ / m2.III. Exemplary Methods of Making Textured Steel Articles

[0068] Exemplary textured steel articles disclosed and contemplated herein may be prepared by various methods.

[0069] An exemplary method may include laser etching a surface of a steel substrate. As used herein, “laser etching” generally means pulsing a laser beam at a target surface. During an exemplary method, a laser beam is pulsed and moved across a substrate surface.

[0070] Pulsing the laser beam generates a pattern of recesses on the substrate surface. Exemplary methods use steel substrates, examples of which are provided above. Exemplary recesses are also discussed in greater detail above, but generally, each recess has a depth between 5 pm to 55 pm.

[0071] Pulsing the laser beam onto the surface generates an oxide layer on the substrate surface. As discussed above, the oxide layer is formed on the substrate surface and in the pattern of recesses. Additional details regarding the oxide layer are discussed in greater detail above.

[0072] Exemplary methods may be conducted in various environments. For instance, laser etching may be conducted in an ambient environment. As an example, laser etching may be conducted at room temperature (e.g., 15 °C to 25 °C). As an example, laser etching may be conducted without external agitation of air, such as using a blower. As an example, laser etching may be conducted in an environment with about 78% nitrogen (N2) and 21% oxygen (O2).

[0073] Various spot sizes may be used during laser etching. In some instances, a laser spot size may have a diameter between about 50 pm and about 80 pm. In various implementations, a laser spot size may have a diameter between 50 pm and 80 pm; between 55 pm and 75 pm; between 50 pm and 65 pm; between 65 pm and 80 pm; between 50 pm and 60 pm; between 60 pm and 70 pm; or between 70 pm and 80 pm. In various implementations, a laser spot size may have a diameter no less than 50 pm; no less than 55 pm; no less than 60 pm; no less than 65 pm; no less than 70 pm; no less than 75 pm; or no less than 80 pm. In various implementations, a laser spot size may have a diameter no greater than 80 pm; no greater than 75 pm; no greater than 70 pm; no greater than 65 pm; no greater than 60 pm; no greater than 55 pm; or no greater than 50 pm.

[0074] Various scan rates may be used during laser etching. In some instances, a laser scan rate may be no greater than 55 meters per second (m / s). In various implementations a laser scan ratemay be between 30 m / s and 55 m / s; between 30 m / s and 55 m / s; between 35 m / s and 55 m / s; or between 45 m / s and 55 m / s. In various implementations, a laser scan rate may be no less than 30 m / s; no less than 40 m / s; no less than 45 m / s; no less than 50 m / s; or no less than 55 m / s. In various implementations, a laser scan rate may be no greater than 55 m / s; no greater than 50 m / s; no greater than 45 m / s; no greater than 40 m / s; or no greater than 35 m / s.

[0075] Various laser wavelengths may be used during laser etching. In some instances, a laser wavelength may be between about 1060 nm and about 1068 nm. In various implementations, a laser wavelength may be between 1060 nm and 1068; between 1062 nm and 1066 nm; between 1063 nm and 1065 nm; or 1064 nm. In various implementations, a laser wavelength may be no less than 1060 nm; no less than 1062 nm; no less than 1064 nm; or no less than 1066 nm. In various implementations, a laser wavelength may be no greater than 1068 nm; no greater than 1067 nm; no greater than 1065 nm; no greater than 1063 nm; or no greater than 1061 nm.

[0076] Various pulse rates may be used during laser etching. In some instances, a laser pulse rate may be no greater than 1000 kilohertz (Hz). In various implementations, a laser pulse rate may be between 250 kHz and 1000 kHz; between 250 kHz and 600 kHz; or between 600 kHz and 1000 kHz. In various implementations, a laser pulse rate may be no less than 250 kHz; no less than 350 kHz; no less than 450 kHz; no less than 550 kHz; no less than 650 kHz; no less than 750 kHz; no less than 850 kHz; or no less than 950 kHz. In various implementations, a laser pulse rate may be no greater than 1000 kHz; no greater than 900 kHz; no greater than 800 kHz; no greater than 700 kHz; no greater than 600 kHz; no greater than 500 kHz; no greater than 400 kHz; or no greater than 300 kHz.

[0077] Various pulse energies may be used during laser etching. In some instances, a pulse energy may be between about 1 millijoules (mJ) and about 2.5 mJ. In some instances, a dot pattern pulse energy may be between 1.5 mJ and 2.0 mJ. In some instances, a groove pattern pulse energy may be between 1.0 mJ and 1.5 mJ. In various implementations, a pulse energy may be between 1.0 mJ and 2.5 mJ; between 1.0 mJ and 1.5 mJ; between 1.5 mJ and 2.5 mJ; between 1.5 mJ and 2.0 mJ; between 1.75 mJ and 2.25 mJ; or between 1.9 mJ and 2.1 mJ. In various implementations, a pulse energy may be no less than 1.0 mJ; no less than 1.5 mJ; no less than 1.7 mJ; no less than 1.9 mJ; no less than 2.1 mJ; or no less than 2.3 mJ. In various implementations, a pulse energymay be no greater than 2.5 mJ; no greater than 2.4 mJ; no greater than 2.2 mJ; no greater than 2.0 mJ; no greater than 1.8 mJ; or no greater than 1.6 mJ.

[0078] Various numbers of pulses per location may be used. In some instances, for dot patterns, a single pulse per location may be used. In some instances, for groove patterns, multiple pulses per location may be used, such as 2 pulses, 3 pulses, or 4 pulses per location. For groove patterns, there may be overlap between adjacent pulse areas.

[0079] Exemplary processes may be capable of generating patterns at various rates. In some implementations, a dot pattern may be generated at a rate between 45 cm2 / second and 90 cm2 / second; between 45 cm2 / second and 70 cm2 / second; between 70 cm2 / second and 90 cm2 / second; or between 60 cm2 / second and 80 cm2 / second. In various instances, a dot pattern may be generated at a rate no less than 45 cm2 / second; no less than 55 cm2 / second; no less than 65 cm2 / second; no less than 75 cm2 / second; no less than 85 cm2 / second; or no less than 90 cm2 / second. In various instances, a dot pattern may be generated at a rate no greater than 90 cm2 / second; no greater than 80 cm2 / second; no greater than 70 cm2 / second; no greater than 60 cm2 / second; or no greater than 50 cm2 / second.

[0080] In some implementations, a groove pattern may be generated at a rate between 12.9 cm2 / second and 39 cm2 / second; between 13 cm2 / second and 26 cm2 / second; between 26 cm2 / second and 39 cm2 / second; or between 18 cm2 / second and 35 cm2 / second. In various instances, a groove pattern may be generated at a rate no less than 12.9 cm2 / second; no less than 15 cm2 / second; no less than 20 cm2 / second; no less than 25 cm2 / second; no less than 30 cm2 / second; no less than 35 cm2 / second; or no less than 39 cm2 / second. In various instances, a groove pattern may be generated at a rate no greater than 39 cm2 / second; no greater than 35 cm2 / second; no greater than 30 cm2 / second; no greater than 25 cm2 / second; no greater than 20 cm2 / second; or no greater than 15 cm2 / second.IV. Experimental Examples

[0081] Without limiting the scope of the instant disclosure, various experimental examples of embodiments discussed above were prepared and the results are discussed below.A. Lap Shear Test Procedures

[0082] The purpose of lap shear testing was to quantify the shear strength of a given prepped steel substrate (coupon / stick) with a given laminate film adhesive. Lap shear testing can help identify both the shear strength and the failure mechanism.

[0083] Experimental sticks were 25.4mm x 101.6mm x 1.65mm (nominal) 1.65mm thick (1” x 4” x 0.065”). Two sticks per specimen were used. The alloy range was 1010-1075 plain carbon steel.

[0084] Experimental sticks were subjected to various surface preparation techniques. For instance, experimental sticks were subjected to grit blasting and laser texturing.

[0085] FIG. 4 shows various stages during experimental sample preparation after surface preparation. Sample preparation included laminating with at least two layers of fdmed nitrile phenolic adhesive. Henkel PL-605 was used for the adhesive.

[0086] Two film samples were bonded film-side to film-side. The samples were held together under 1.4 MPa pressure at 93°C for 60 seconds. The film laminates were made in advance and stored at ambient temperature.

[0087] Next, one side of release paper was removed from the 2 laminate film layer segment. The adhesive (2 laminate film segments) was applied at one end of a sample stick, as shown in FIG. 4. The 2 film segments were applied to the prepped stick under 1.4 MPa pressure at 93°C for 60 seconds. The prepped film laminated sticks were stored in a moisture-proof bag at ambient temperature, with the release paper still attached to the laminate film.

[0088] Then overlapping sticks were bonded in a fixture die bonder. Bonding was conducted to maintain parallelism of radial cut edge of friction disc segment and end of the lap shear stick that form the overlapped region.

[0089] Test to test variation was minimized by limiting the introduction of a torsional component of the shear test and maintaining the same contact area for each lap shear specimen segmented from same part number.

[0090] Bonding was conducted at recommended nitrile phenolic conditions. In particular, bonding conditions included 5.17Mpa (750 psi) facing pressure or as required to get full contact, at 204 °C, for 8-10 minutes depending on steel thickness and specific adhesive bond line temperature requirements.

[0091] Lap shear testing was conducted using a universal tensile testing machine, specifically an Instron 3382 (Instron, Norwood, Massachusetts). Pulling was conducted at a constant rate (crosshead speed) of 2.54 mm / minute. The breaking load was set to be 15% < x < 85% of machine capacity, and used non-slip grips.

[0092] Experimental samples were oriented as follows: the sample was positioned in the bottom grip, where the top grip was positioned to within 12.5 mm of the overlap section of the shear specimen. For in-line grips, spacers may be required to minimize off z-axis distortion (peel component) with increased specimen thickness. Offset grips may be required if thicker specimen sticks are evaluated.

[0093] After positioning the specimen in the machine, pulling started. The max load was recorded, and a machine correction for groove area loss was performed. Then the corrected maximum shear strength (in pressure) at failure was reported.

[0094] Various adhesives were used. Specifically, experimental samples were made with Ashland 1166 adhesive, Henkel PL-605 adhesive, and Ruscoe 5007 adhesive.B. Dynamometer Testing

[0095] Experimental specimens were subjected to dynamometer testing. Generally speaking, the dynamometer testing is a high temperature, thermal abuse dynamometer wet brake test.

[0096] During testing, bonded experimental specimens were subjected to an initiation fluid temperature between 300-350 °C, a facing pressure of 1.38 MPa, and a unit energy of 1051.5 kJ / m2Experimental specimens were inspected after each 1000 cycles. Experimental testing continued until the material failed (wear out or debonding).C. Experimental Specimens

[0097] Experimental specimens falling within the scope of the instant disclosure were generated and compared to experimental specimens generated using grit blasting. Table 1 below shows the laser parameters for generating each experimental specimen. Recess depth was also measured for each experimental specimen, and those values are also provided in Table 1.Table 1. Manufacturing parameters for generating experimental specimens.

[0098] Micrographs of each specimen’s treated surface (top view) and side views were obtained. FIG. 5A is a micrograph of a top surface of Sample A, and FIG. 5B is a side view of Sample A, annotated with measured recess depths. FIG. 6A is a micrograph of a top surface of Sample B, and FIG. 6B is a side view of Sample B, annotated with measured recess depths. FIG. 7A is a micrograph of a top surface of Sample C, and FIG. 7B is a side view of Sample C, annotated with measured recess depths. FIG. 8A is a micrograph of a top surface of Sample D, and FIG. 8B is a side view of Sample D, annotated with measured recess depths. FIG. 9A is a micrograph of a top surface of Sample E, and FIG. 9B is a side view of Sample E, annotated with measured recess depths. FIG. 10A is a micrograph of a top surface of Sample F, and FIG. 1 OB is a side view of Sample F, annotated with measured recess depths. FIG. 11A is a micrograph of a top surface of Sample G, and FIG. 1 IB is a side view of Sample G, annotated with measured recess depths. FIG. 12A is a micrograph of a top surface of the Grit Blast sample, and FIG. 12B is a side view of the Grit Blast Sample, annotated with measured recess depths.C. Experimental Tests

[0099] Lap shear tests were conducted on each Sample shown in Table 1. Experimental procedures for lap shear testing are described in greater detail above. The results are provided below in Table 2.Table 2. Experimental lap shear results for specimens described in Table 1 using different adhesives.

[0100] Film oxide thickness, surface area / area size ratio, and weight percentage (wt%) oxygen (Ch) were also determined for the experimental specimens, and results are shown in Table 3 below.

[0101] Average film oxide thickness was determined using the following method. First, a cross section was cut through the surface. The cross section was mounted in epoxy resin, sanded, and polished to a very smooth surface. The surface was then examined with a microscope under 200x or 500x magnification. The oxide layer was visible in bright light as a dark layer on the surface of the steel. Using NIS Software from Nikon, the layer can be measured. The oxide layer thickness was the result of averaging 10 measurements.

[0102] Surface area to area size ratio was determined by using the Keyence VR-6000 optical profilometer (available from Keyence, Itasca, Illinois) and . The scan area size and surface area size were determined using the Volume and Area Software. The concave / convex feature was used to determine the total area beneath or above a certain determined height. If that height was set to encompass the entire surface above or below it, the total surface area was determined.

[0103] Weight percentage oxygen was determined using energy dispersive spectrometry. EDS is an analytical technique that uses x-ray light to identify elements in a sample in SEM. Electrons are emitted into the sample, slamming into lower level electrons within the electron cloud. When this, happens, x-ray light is produced. Different atoms will emit different wavelengths of x-ray light, allowing the identity and quantity of those atoms to be determined. Because EDS is not known for exact quantitative results, especially for oxygen, the weight percentage oxygen results below are taken to be approximate measures.Table 3. Film oxide thickness, surface area / area size ratio, and weight percentage (wt%) oxygen (O2) for the experimental specimens.

[0104] Run-out testing was performed on exemplary specimens generated on C7106 rotors, using machine parameters described above for Sample C and Sample D. The C7106 rotors were 0.889 mm thick.

[0105] FIG. 13A and FIG. 13B are photographs of an experimental setup for Sample C, where the specimens shown were cross sectioned 180 degrees apart from one another along the disc. FIG. 13C and FIG. 13D are photographs of an experimental setup for Sample D, where the specimens shown were cross sectioned 180 degrees apart from one another along the disc. Maximum run-out for Sample C was 0.03 mm and maximum run-out for Sample D was 0.02 mm.

[0106] Hardness testing was performed on various locations of the samples shown in FIG. 13A- 13D, and the results are in Table 4 and Table 5 below. Specifically, three surfaces within four different regions were tested for each sample, and the locations are shown in FIG. 14.Table 4. Microhardness testing of different locations relative to recesses in experimental specimens shown in FIG. 13 A and FIG. 13B.Table 5. Microhardness testing of different locations relative to recesses in experimental specimens shown in FIG. 13C and FIG. 13D.

[0107] The data shown in Table 4 and Table 5 indicate that there is minimal or no change in hardness of the textured regions of experimental substrates compared to untextured regions.

[0108] Experimental specimens were subjected to dynamometer testing as described above. Table 6 below provides results of the tests. Adhesives used during tests were either 1166 or 5007. Various part styles were tested, namely, an N653 disc and a EPD824 disc (part styles from Carlisle Brake & Friction, Medina, Ohio).

[0109] FIG. 15A is a photograph of an N653 disc manufactured using Sample A specifications. FIG. 15B is a photograph of an EPD824 disc manufactured using Sample A specifications. FIG. 15C is a photograph of an N653 disc manufactured using Sample B specifications. FIG. 15D is a photograph of an EPD824 disc manufactured using Sample B specifications. FIG. 16A is a photograph of an N653 disc manufactured using Sample C specifications. FIG. 16B is a photograph of an EPD824 disc manufactured using Sample C specifications. FIG. 16C is a photograph of an N653 disc manufactured using Sample D specifications. FIG. 16D is a photograph of an EPD824 disc manufactured using Sample D specifications.Table 6. Experimental dynamometer results for various experimental specimens.Exemplary Embodiments

[0110] For reasons of completeness, various aspects of the technology are set out in the following numbered embodiments:Embodiment 1. A textured steel article comprising: a steel substrate having a surface, the surface defining a pattern of recesses, each recess in the pattern of recesses having a maximum depth of 5 pm to 55 pm; and an oxide layer on the surface of the steel substrate, the oxide layer having a thickness between 1 pm to 4 pm; and the oxide layer comprising Fe2Ch.Embodiment 2. The textured steel article according to Embodiment 1, wherein the pattern of recesses comprises a plurality of pattern elements, each pattern element comprising a plurality of repeated recesses, wherein the plurality of pattern elements are aligned in parallel to each other along the surface of the steel substrate.Embodiment 3. The textured steel article according to Embodiment 2, wherein a distance between a center of adjacent pattern elements is no greater than about 160 pm.Embodiment 4. The textured steel article according to any one of Embodiments 1-3, wherein the surface of the steel substrate has an average surface roughness (Ra) of about 3.0 pm to about 15.4 pm.Embodiment 5. The textured steel article according to any one of Embodiments 1-4, wherein the surface of the steel substrate has a surface area to surface area size ratio of about 1.07 to about 1.64.Embodiment 6. The textured steel article according to any one of Embodiments 1-5, wherein the pattern of recesses comprises a dot pattern.Embodiment 7. The textured steel article according to any one of Embodiments 1-6, wherein the pattern of recesses comprises a groove pattern.Embodiment 8. The textured steel article according to any one of Embodiments 1-7, wherein the steel substrate is a circular steel brake, clutch, or car door.Embodiment 9. The textured steel article according to any one of Embodiments 1-8, where the maximum depth of the recesses is no greater than 12.4% of a thickness of the steel substrate.Embodiment 10. The textured steel article according to any one of Embodiments 1-9, wherein the steel substrate is a 1040 steel, a 1050 steel, a 1075 steel, or a ferritic steel.Embodiment 11. The textured steel article according to any one of Embodiments 1-10, wherein the oxide layer does not include FeO, FeOFE, and / or FeOHi.Embodiment 12. The textured steel article according to any one of Embodiments 1-11, wherein between 50% and 99% of a target bonding area of the surface includes the pattern of recesses.Embodiment 13. The textured steel article according to any one of Embodiments 1-12, wherein a thickness of the substrate at a first location is within 10% of a thickness of the substrate at a second location.Embodiment 14. A method for generating a textured steel article, the method comprising: laser etching a surface of a steel substrate, the laser etching being performed: with a spot size having a diameter between 50 pm and 80 pm; with a scan rate of up to 55 m / s; with a wavelength of 1060-1068 nm; with a pulse rate between 250 kHz 1000 kHz; whereby after laser etching, the surface of the steel substrate:defines a pattern of recesses, each recess having a maximum depth of 5 pm to 55 pm; and comprises an oxide layer.Embodiment 15. The method according to Embodiment 14, wherein the scan rate is between 30 m / s and 55 m / s; and wherein a pulse energy is between 1.0 mJ and 2.5 mJ.Embodiment 16. The method according to Embodiment 15, wherein laser etching comprises applying 2-4 pulses per location; wherein laser etching generates either a dot pattern or a groove pattern, and when laser etching generates the dot pattern, the dot pattern is generated at a rate between 45 cm2 / second and 90 cm2 / second; when laser etching generates the groove pattern, the groove pattern is generated at a rate between 12.9 cm2 / second and 39 cm2 / second.Embodiment 17. A composite material comprising: a textured steel article comprising: a steel substrate having a surface, the surface defining a pattern of recesses, each recess in the pattern of recesses having a maximum depth of 5 pm to 55 pm; and an oxide layer on the surface of the steel substrate, the oxide layer having a thickness between 1 pm to 4 pm; the oxide layer comprising Fe2O3; and an adhesive on a surface of the oxide layer of the textured steel article.Embodiment 18. The composite material according to Embodiment 17, wherein an adhesive strength between the adhesive and the textured steel article is greater than or equal to 10.34 MPa as measured by a lap shear test.Embodiment 19. The composite material according to Embodiment 17 or Embodiment 18, wherein the adhesive passes a high temperature thermal abuse dynamometer wet brake test comprising an initiation fluid temperature of 300 °C to 350 °C, a facing pressure of 1.38 MPa, and a unit energy of 1051.5 kJ / m2.Embodiment 20. The composite material according to any one of Embodiments 17-19, the adhesive being selected from: a high temperature epoxy, a polyvinylbutyral -modified phenolic adhesive, or a nitrile phenolic adhesive.

Claims

CLAIMS1. A textured steel article comprising: a steel substrate having a surface, the surface defining a pattern of recesses, each recess in the pattern of recesses having a maximum depth of 5 pm to 55 pm; and an oxide layer on the surface of the steel substrate, the oxide layer having a thickness between 1 pm to 4 pm; and the oxide layer comprising Fe2Ch2. The textured steel article according to claim 1, wherein the pattern of recesses comprises a plurality of pattern elements, each pattern element comprising a plurality of repeated recesses, wherein the plurality of pattern elements are aligned in parallel to each other along the surface of the steel substrate.

3. The textured steel article according to claim 2, wherein a distance between a center of adjacent pattern elements is no greater than about 160 pm.

4. The textured steel article according to claim 1, wherein the surface of the steel substrate has an average surface roughness (Ra) of about 3.0 pm to about 15.4 pm.

5. The textured steel article according to claim 1, wherein the surface of the steel substrate has a surface area to surface area size ratio of about 1.07 to about 1.64.

6. The textured steel article according to claim 1, wherein the pattern of recesses comprises a dot pattern.

7. The textured steel article according to claim 1, wherein the pattern of recesses comprises a groove pattern.

8. The textured steel article according to claim 1, wherein the steel substrate is a circular steel brake, clutch, or car door.

9. The textured steel article according to claim 1, where the maximum depth of the recesses is no greater than 12.4% of a thickness of the steel substrate.

10. The textured steel article according to claim 1, wherein the steel substrate is a 1040 steel, a 1050 steel, a 1075 steel, or a ferritic steel.

11. The textured steel article according to claim 1, wherein the oxide layer does not include FeO, FeOFfo, and / or FeOFF12. The textured steel article according to claim 1, wherein between 50% and 99% of a target bonding area of the surface includes the pattern of recesses.

13. The textured steel article according to claim 1, wherein a thickness of the substrate at a first location is within 10% of a thickness of the substrate at a second location.

14. A method for generating a textured steel article, the method comprising: laser etching a surface of a steel substrate, the laser etching being performed: with a spot size having a diameter between 50 pm and 80 pm; with a scan rate of up to 55 m / s; with a wavelength of 1060-1068 nm; with a pulse rate of 250 kHz- 1000 kHz; whereby after laser etching, the surface of the steel substrate: defines a pattern of recesses, each recess in the pattern of recesses having a maximum depth of 5 pm to 55 pm; and comprises an oxide layer.

15. The method according to claim 14, wherein the scan rate is between 30 m / s and 55 m / s; and wherein a pulse energy is between 1.0 mJ and 2.5 mJ.

16. The method according to claim 15, wherein laser etching comprises applying 2-4 pulses per location; wherein laser etching generates either a dot pattern or a groove pattern, and when laser etching generates the dot pattern, the dot pattern is generated at a rate between 45 cm2 / second and 90 cm2 / second; when laser etching generates the groove pattern, the groove pattern is generated at a rate between 12.9 cm2 / second and 39 cm2 / second.

17. A composite material comprising: a textured steel article comprising: a steel substrate having a surface, the surface defining a pattern of recesses, each recess in the pattern of recesses having a maximum depth of 5 pm to 55 pm; and an oxide layer on the surface of the steel substrate, the oxide layer having a thickness between 1 pm to 4 pm; the oxide layer comprising Fe20a; and an adhesive on a surface of the oxide layer of the textured steel article.

18. The composite material according to claim 17, wherein an adhesive strength between the adhesive and the textured steel article is greater than or equal to 10.34 MPa as measured by a lap shear test.

19. The composite material according to claim 17, wherein the adhesive passes a high temperature thermal abuse dynamometer wet brake test comprising an initiation fluid temperature of 300 °C to 350 °C, a facing pressure of 1.38 MPa, and a unit energy of 1051.

520. The composite material according to claim 17, the adhesive being selected from: a high temperature epoxy, a polyvinylbutyral-modified phenolic adhesive, or a nitrile phenolic adhesive.

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