Microcrystalline glass and preparation method therefor, and electronic device

Abstract

Provided in the present invention are microcrystalline glass and a preparation method therefor, and an electronic device. The microcrystalline glass comprises: a first surface having a defined thickness H, and a second surface opposite the first surface; and a compression stress area, the thickness of which is DOL, wherein DOL is less than 0.5 H, and as the depth increases, the compression stress in the compression stress area tends to first increase and then decrease. The microcrystalline glass of the present invention has a non-monotonic stress distribution characteristic, the stress intensity of the microcrystalline glass can be increased, and particularly, the stress intensity at a position deep in the microcrystalline glass can be increased, thereby improving the anti-falling performance of the microcrystalline glass and an electronic device formed by using the microcrystalline glass.

Description

Microcrystalline glass, preparation method thereof, and electronic device

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on September 18, 2023, with application number 202311205693.3 and application name “A kind of microcrystalline glass, its preparation method and electronic device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the technical field of glass materials, and in particular to a microcrystalline glass, a preparation method thereof, and an electronic device. Background Art

[0003] Glass-ceramics has a wide range of applications, such as in screen covers for mobile phones and other electronic products. However, in related technologies, properties such as stress strength of glass-ceramics need to be further improved.

[0004] Summary of the Invention

[0005] The present invention provides a glass-ceramic, a preparation method thereof, and an electronic device, which can improve the stress strength and other properties of the glass-ceramic, and effectively overcome the defects of the prior art.

[0006] In one aspect of the present invention, a microcrystalline glass is provided, comprising: a first surface with a limited thickness H and a second surface opposite to the first surface; a compressive stress zone, wherein the thickness of the compressive stress zone is DOL, and DOL is less than 0.5H; and the compressive stress in the compressive stress zone tends to first increase and then decrease with increasing depth.

[0007] According to one embodiment of the present invention, the maximum compressive stress in the compressive stress region is at a depth of DOL.P, and 5 μm≤DOL.P≤0.1H.

[0008] According to one embodiment of the present invention, the maximum compressive stress of the compressive stress zone is greater than or equal to 110 MPa.

[0009] According to one embodiment of the present invention, the maximum compressive stress of the compressive stress zone is 110 MPa to 300 MPa.

[0010] According to one embodiment of the present invention, the maximum value of the first-order derivative of the stress curve of the compressive stress zone in the depth range of 5 μm to 0.1H is greater than 2 MPa / μm.

[0011] According to one embodiment of the present invention, 0.1H≤DOL≤0.25H.

[0012] According to one embodiment of the present invention, 0.3 mm ≤ H ≤ 2 mm.

[0013] According to one embodiment of the present invention, the compressive stress zone further satisfies: CS50 ≥ 80 MPa, where CS50 is the compressive stress at a depth of 50 μm in the compressive stress zone; and / or CS80 ≥ 55 MPa, where CS80 is the compressive stress at a depth of 80 μm in the compressive stress zone.

[0014] According to one embodiment of the present invention, 80 MPa≤CS50≤250 MPa; and / or, 55 MPa≤CS80≤115 MPa.

[0015] According to one embodiment of the present invention, the compressive stress zone includes a first compressive stress zone and a second compressive stress zone; the first compressive stress zone extends from the first surface to the interior of the microcrystalline glass to a depth of DOL, and the second compressive stress zone extends from the second surface to the interior of the microcrystalline glass to a depth of DOL; the microcrystalline glass also includes a tensile stress zone located between the first compressive stress zone and the second compressive stress zone; wherein the average tensile stress of the tensile stress zone is greater than or equal to 45 MPa; and / or the maximum tensile stress of the tensile stress zone is greater than or equal to 65 MPa; and / or the tensile stress linear density of the tensile stress zone is greater than or equal to 25 KPa / m.

[0016] According to one embodiment of the present invention, the average tensile stress of the tensile stress zone is 45MPa to 120MPa; and / or the maximum tensile stress of the tensile stress zone is 65MPa to 200MPa; and / or the tensile stress linear density of the tensile stress zone is 25KPa / m to 65KPa / m.

[0017] According to one embodiment of the present invention, the damage resistance characteristic value of the microcrystalline glass is satisfy:

[0018] According to one embodiment of the present invention, the microcrystalline glass contains: Li2O, Na2O and K2O, and the sum of the molar contents of the Li2O, Na2O and K2O is 13% to 32%; SiO2, the molar content of the SiO2 is 58% to 72%; Al2O3, the molar content of the Al2O3 is 2% to 8%; P2O5, ZrO2 and TiO2, the sum of the molar contents of P2O5, ZrO2 and TiO2 is 2% to 13%; MgO, CaO and ZnO, the sum of the molar contents of MgO, CaO and ZnO is 0 to 3%; B2O3, the molar content of B2O3 is 0 to 5%.

[0019] According to one embodiment of the present invention, the microcrystalline glass includes a glass phase and a crystal phase, wherein the crystal phase includes one or more of quartz, spodumene, petalite, lithium silicate, lithium disilicate, and spinel; and / or the volume fraction of the crystal phase is greater than or equal to 20%.

[0020] Another aspect of the present invention provides a method for preparing glass-ceramics, comprising the following steps: contacting a glass raw material with a first salt bath to perform a first ion exchange treatment to produce the glass-ceramics; wherein the first ion exchange treatment is performed at a temperature T1 and for a time t1, satisfying: And / or, the preparation method further includes: contacting the glass material after the first ion exchange treatment with a second salt bath for a second ion exchange treatment, wherein the ratio of the amount of sodium element in the first salt bath to the sum of the amounts of all metal elements in the first salt bath is X1, the ratio of the amount of sodium element in the second salt bath to the sum of the amounts of all metal elements in the second salt bath is X2, the temperature of the second ion exchange treatment is T2, the time is t2, X1>X2, T1-T2≥40°C, and t2 / t1≤0.5.

[0021] In another aspect of the present invention, a microcrystalline glass is provided, which is obtained by the above-mentioned preparation method of the microcrystalline glass, and the microcrystalline glass includes: a first surface with a limited thickness H and a second surface opposite to the first surface; a compressive stress zone, wherein the thickness of the compressive stress zone is an area DOL, and DOL is less than 0.5H; the compressive stress in the compressive stress zone tends to first increase and then decrease with increasing depth.

[0022] Another aspect of the present invention provides an electronic device comprising the aforementioned glass-ceramics.

[0023] In the present invention, the thickness DOL of the compressive stress zone of the glass-ceramic is less than 0.5H, and the compressive stress in this compressive stress zone increases first and then decreases with increasing depth. As a result, the glass-ceramic of the present invention exhibits a non-monotonic stress distribution in the compressive stress zone, which can improve the stress strength and other properties of the glass-ceramic, thereby improving the drop resistance of the glass-ceramic and products such as electronic devices using the glass-ceramic.

[0024] In addition, the glass-ceramics of the present invention also has good surface quality and surface stress properties, and its central extrusion strength (average breaking force) is higher than 16 kgf and can even be as high as 22 kgf or more.

[0025] In addition, the microcrystalline glass of the present invention also has good weather resistance, and is not prone to corrosion or the like even when stored or used in a high temperature and high humidity environment. For example, if it is stored in a hot and humid environment with a temperature of 85°C and a humidity of 85% for 240 hours, no corrosion or residual marks will occur. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1 is a stress distribution curve diagram of Examples 1-23, Example 2-7, Comparative Example 1-1, and Comparative Example 2-1 (the ordinate is stress, and the abscissa is depth (i.e., the distance from the glass surface at a depth x within the glass-ceramic));

[0027] FIG2 is a first-order derivative function graph of stress distribution curves of Example 1-23, Example 2-7, Comparative Example 1-1, and Comparative Example 2-1;

[0028] FIG3 is a graph showing stress characteristics (CS50, CS80, CT.AV, CT.LD, DOL.P) of Example 1-23 and Comparative Example 1-1;

[0029] FIG4 is a graph showing the number of drop failures of the entire device in Example 2-7 and Comparative Example 2-1;

[0030] FIG. 5 is a schematic diagram of a stress distribution curve of a glass-ceramic according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific embodiments listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts are within the scope of protection of the present invention.

[0032] Glass-ceramics is widely used, for example, in screen covers (cover glass (CG)) of electronic products such as mobile phones. However, in related technologies, properties such as stress strength of glass-ceramics need to be further improved.

[0033] For example, the drop resistance of the screen cover determines the reliability of electronic devices (such as mobile electronic products). The screen cover is usually made of ordinary glass or microcrystalline glass after chemical strengthening. Its drop resistance is determined by the intrinsic mechanical properties of the material and the stress intensity generated by the chemical strengthening process. Therefore, improving the intrinsic mechanical properties and stress strength of the glass material are two effective ways to improve the drop resistance of the screen. Among them, one feasible way to improve the intrinsic mechanical properties of the glass material is to use microcrystalline glass with a glass phase and a nanoscale crystal phase. Compared with ordinary glass such as traditional alumina-silica-based glass, microcrystalline glass with high crystallinity has a denser microstructure and better intrinsic mechanical properties (such as higher Young's modulus and fracture toughness, etc.), which can improve the screen's drop resistance and damage resistance to a certain extent.

[0034] However, microcrystalline glass has problems such as low stress strength. Even if chemical strengthening processes such as ion exchange are used to strengthen the microcrystalline glass raw material, its dense microstructure will inhibit the ion exchange reaction, resulting in the chemically strengthened microcrystalline glass still having low stress strength and other mechanical properties.

[0035] Therefore, existing microcrystalline glass generally has defects such as low stress strength, especially its deep compressive stress is low. For example, CS50 (compressive stress at a depth of 50μm) and CS80 (compressive stress at a depth of 80μm) that determine the failure resistance in sharp contact scenarios are usually low, resulting in poor drop resistance and damage resistance of structural parts such as screen covers formed using this microcrystalline glass.

[0036] In view of this, an embodiment of the present invention provides a microcrystalline glass, as shown in the figure, the microcrystalline glass includes: a first surface with a limited thickness H and a second surface opposite to the first surface; a compressive stress zone, the thickness of the compressive stress zone (i.e., the depth of the compressive stress layer (DOL)) is DOL, DOL<0.5H; the compressive stress in the compressive stress zone tends to first increase and then decrease with increasing depth.

[0037] In the microcrystalline glass of the embodiment of the present invention, the above-mentioned compressive stress zone has a non-monotonic stress distribution characteristic, which can improve the stress strength and other properties of the microcrystalline glass, especially the deep compressive stress of the microcrystalline glass, thereby improving the drop resistance and damage resistance of the microcrystalline glass and structural parts such as screen cover plates using the microcrystalline glass.

[0038] In addition, the glass-ceramics of the embodiment of the present invention also has good surface quality and surface stress properties, and its central extrusion strength (average breaking force) is higher than 16 kgf and can even be as high as 22 kgf or more.

[0039] In addition, the microcrystalline glass of the embodiment of the present invention also has good weather resistance, and is not prone to corrosion or other phenomena even when stored or used in a high temperature and high humidity environment. For example, if it is stored in a hot and humid environment with a temperature of 85°C and a humidity of 85% for 240 hours, no corrosion or residual marks will occur.

[0040] Specifically, the first surface and the second surface are surfaces on opposite sides in the thickness direction of the microcrystalline glass (one of the surfaces on the opposite sides is the first surface and the other is the second surface), and the thickness of the microcrystalline glass is H; the compressive stress zone is a region where the stress of the microcrystalline glass manifests as compressive stress, which generally extends from the first surface or the second surface to the interior of the microcrystalline glass and has a thickness of DOL, that is, the compressive stress zone is specifically a region with a depth between 0 and DOL from the first surface or the second surface, that is, the compressive stress zone extends from the first surface or the second surface to the interior of the microcrystalline glass to a position with a depth of DOL.

[0041] Specifically, the above-mentioned compressive stress zone includes a first compressive stress zone and a second compressive stress zone. The first compressive stress zone extends from the first surface to the interior of the microcrystalline glass to a position with a depth of DOL (the position with a depth of DOL calculated from the first surface), that is, one side of the first compressive stress zone is the first surface, and the other side ends at a position with a depth of DOL calculated from the first surface (that is, the depth of the first surface is 0), that is, the thickness of the first compressive stress zone is DOL; the second compressive stress zone extends from the second surface to the interior of the microcrystalline glass to a position with a depth of DOL (the position with a depth of DOL calculated from the second surface), that is, one side of the second compressive stress zone is the second surface, and the other side ends at a position with a depth of DOL calculated from the second surface (that is, the depth of the second surface is 0), that is, the thickness of the second compressive stress zone is DOL.

[0042] Specifically, the thickness DOL of the above-mentioned compressive stress zone can satisfy 0.1H≤DOL≤0.25H (i.e., 0.1H≤DOL≤0.25H), that is, the ratio of the thickness DOL of the compressive stress zone to the thickness H of the microcrystalline glass (DOL / H) can be 0.1~0.25, and DOL / H is, for example, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.22, 0.25 or a range consisting of any two of them.

[0043] In some embodiments, the thickness DOL of the compressive stress zone may be 120 μm to 160 μm (i.e., 120 μm ≤ DOL ≤ 160 μm), and DOL may be, for example, 120 μm, 125 μm, 130 μm, 135 μm, 140 μm, 145 μm, 150 μm, 155 μm, 160 μm, or a range consisting of any two of them.

[0044] In some embodiments, the thickness H of the microcrystalline glass can be 0.3mm to 2mm (i.e., 0.3mm≤H≤2mm), and H is, for example, 0.3mm, 0.5mm, 0.7mm, 0.9mm, 1mm, 1.3mm, 1.5mm, 1.7mm, 1.9mm, 2mm or a range consisting of any two thereof.

[0045] Both the first compressive stress and the second compressive stress have the stress distribution described above (i.e., the compressive stress in the compressive stress zone first increases and then decreases with increasing depth). Specifically, the compressive stress in the first compressive stress zone first increases and then decreases with increasing depth (calculated from the first surface), i.e., the compressive stress in the first compressive stress zone first increases and then decreases in a direction away from the first surface; the compressive stress in the second compressive stress zone first increases and then decreases with increasing depth (calculated from the second surface), i.e., the compressive stress in the second compressive stress zone first increases and then decreases in a direction away from the second surface. Specifically, the trend of first increasing and then decreasing can be gradually increasing and then gradually decreasing.

[0046] Specifically, the thickness DOL of the first compressive stress zone and the thickness DOL of the second compressive stress zone may be equal or unequal, and are generally substantially equal. The stress distribution trend of the first compressive stress zone and the stress distribution trend of the second compressive stress zone may be axially symmetrical, and the axis of symmetry is the center position of the microcrystalline glass (i.e., the position at a depth of 0.5H from the first surface (or second surface)).

[0047] Specifically, Figure 5 is a stress curve of the microcrystalline glass, which is a curve showing the relationship between stress (the stress in the compressive stress zone is compressive stress) and depth. The horizontal coordinate x in the coordinate system is depth, and the vertical coordinate σ is stress. Figure 5 shows the stress curves of the first compressive stress zone and the second compressive stress zone in the same coordinate system (the stress curve of the first compressive stress zone is the first compressive stress curve, and the stress curve of the second compressive stress zone is the second compressive stress curve). The depth of the horizontal coordinate is the depth from the first surface (that is, the depth of the first surface is 0, and correspondingly, the depth of the second surface is H). It can be seen that the first compressive stress curve is in the range of 0 to DOL, and it has a bulge in this range, that is, it has a maximum value σ in this range. E1 (The maximum value σ E1 is the stress corresponding to the bulge of the first compressive stress curve, which is also the maximum compressive stress in the first compressive stress zone), that is, the first-order derivative function of the first compressive stress curve changes in the positive and negative signs in the range of 0 to DOL; the second compressive stress curve is in the range of DOL' to H (the position with a depth of DOL' from the first surface is the position with a depth of DOL from the second surface, DOL' = H-DOL), and it has a bulge in this range, that is, it has a maximum value σ in this range E2 (The maximum value σ E2 is the stress corresponding to the bulge of the second compressive stress curve, and is also the maximum compressive stress in the second compressive stress zone), that is, the positive and negative signs of the first-order derivative function of the second compressive stress curve change in the range of DOL' to H.

[0048] Among them, σ E1 and σ E2They may be substantially equal. As mentioned above, the stress distribution trend of the first compressive stress zone and the stress distribution trend of the second compressive stress zone may be axisymmetric, that is, the first compressive stress curve and the second compressive stress curve are axisymmetric.

[0049] Specifically, the maximum compressive stress in the compressive stress zone may be at a depth of DOL.P, that is, the compressive stress at the depth of DOL.P is greater than the compressive stress at other locations in the compressive stress zone. That is, DOL.P is the depth of peak compressive layer (DOL.P) in the compressive stress zone, and the maximum compressive stress in the compressive stress zone (that is, the maximum value of the stress curve) is the bulge stress intensity (that is, the compressive stress at DOL.P (CS.P)). It can be understood that for the first compressive stress zone, its maximum compressive stress is at a depth of DOL.P, where the depth is the depth from the first surface; for the second compressive stress zone, its maximum compressive stress is at a depth of DOL.P, where the depth is the depth from the second surface.

[0050] Specifically, in the stress curve shown in FIG5 , the maximum value σ of the first compressive stress curve is E1 (bulge stress intensity) corresponds to the horizontal axis DOL.P, that is, the first-order derivative function of the first compressive stress curve changes its sign at DOL.P; the maximum value σ of the second compressive stress curve E2 The horizontal axis corresponding to (bulge stress intensity) is DOL.P', that is, the positive and negative signs of the first-order derivative function of the second compressive stress curve change at DOL.P'.

[0051] Among them, DOL.P<DOL, DOL.P≥5μm (that is, the bulge stress depth in the compressive stress zone DOL.P≥5μm), which can increase the deep compressive stress of the microcrystalline glass and further improve its drop resistance performance.

[0052] In general, DOL.P≤0.1H, that is, DOL.P can satisfy 5μm≤DOL.P≤0.1H. That is, in the stress curve shown in FIG5 , the first compressive stress curve has a maximum value σ in the range of 5μm~0.1H. E1 (Correspondingly, in the stress curve shown in FIG5 , the second stress curve has a maximum value σ in the range of 0.9H to (H-5μm) E2 ).

[0053] For example, DOL.P may be less than or equal to 0.09H, or less than or equal to 0.08H, or less than or equal to 0.07H, etc. For example, DOL.P may be 0.01H, 0.02H, 0.03H, 0.04H, 0.05H, 0.06H, 0.07H, 0.08H, 0.09H, or a range consisting of any two thereof.

[0054] Exemplarily, DOL.P can be 5μm to 200μm, for example, 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm or a range consisting of any two of them.

[0055] Specifically, the maximum compressive stress in the above-mentioned compressive stress zone (i.e., the bulge stress intensity CS.P) can be greater than or equal to 110 MPa, that is, the maximum compressive stress in the first compressive stress zone can be greater than or equal to 110 MPa, and the maximum compressive stress in the second compressive stress zone can be greater than or equal to 110 MPa, which can further increase the deep compressive stress of the microcrystalline glass and enhance the drop resistance of the microcrystalline glass.

[0056] In some embodiments, the maximum compressive stress of the compressive stress zone may be 110 MPa to 300 MPa, that is, the maximum compressive stress of the first compressive stress zone may be 110 MPa to 300 MPa, and the maximum compressive stress of the second compressive stress zone may be 110 MPa to 300 MPa.

[0057] For example, the maximum compressive stress of the compressive stress zone (the first compressive stress zone and the second compressive stress zone) may be 110 MPa, 130 MPa, 150 MPa, 180 MPa, 200 MPa, 230 MPa, 250 MPa, 280 MPa, 300 MPa, or a range consisting of any two thereof. The maximum compressive stress of the first compressive stress zone and the maximum compressive stress of the second compressive stress zone may be equal or unequal, but are generally substantially equal (as described above, the stress distributions of the first compressive stress zone and the second compressive stress zone may be substantially axisymmetric).

[0058] In addition, the maximum value of the first-order derivative (first-order derivative function) of the stress curve of the compressive stress zone in the depth range of 5 μm to 0.1H is greater than 2 MPa / μm, that is, the maximum value of the first-order derivative (first-order derivative function) of the stress curve of the first compressive stress zone in the depth range of 5 μm to 0.1H is greater than 2 MPa / μm, and the maximum value of the first-order derivative (first-order derivative function) of the stress curve of the second compressive stress zone in the depth range of 5 μm to 0.1H is greater than 2 MPa / μm. The maximum value of the first-order derivative of the stress curve of the first compressive stress zone in the depth range of 5 μm to 0.1H and the maximum value of the first-order derivative of the stress curve of the second compressive stress zone in the depth range of 5 μm to 0.1H may be equal or unequal, but are generally substantially equal (as mentioned above, the stress distributions of the first compressive stress zone and the second compressive stress zone may be substantially axisymmetric).

[0059] It can be understood that, for the first compressive stress region, the depth (5 μm to 0.1H) is the depth calculated from the first surface, and for the second compressive stress region, the depth (5 μm to 0.1H) is the depth calculated from the second surface.

[0060] Specifically, in the stress curve shown in Figure 5, the maximum value of the first-order derivative of the first compressive stress curve in the first compressive stress zone in the range of 5μm to 0.1H is greater than 2MPa / μm, and the maximum value of the first-order derivative of the second compressive stress curve in the second compressive stress zone in the range of (H-0.1H) to (H-5μm) is greater than 2MPa / μm.

[0061] In addition, the compressive stress zone may also satisfy the following requirement: CS50 ≥ 80 MPa, where CS50 is the compressive stress at a depth of 50 μm in the compressive stress zone (CS50). That is, the CS50 of the first compressive stress zone (the compressive stress at a depth of 50 μm from the first surface) is greater than or equal to 80 MPa, and the CS50 of the second compressive stress zone (the compressive stress at a depth of 50 μm from the second surface) is greater than or equal to 80 MPa. The CS50 of the first compressive stress zone and the CS50 of the second compressive stress zone may be equal or unequal, but are generally substantially equal (as previously mentioned, the stress distributions of the first compressive stress zone and the second compressive stress zone may be substantially axisymmetric).

[0062] In some embodiments, the CS50 of the above-mentioned compressive stress zone (the first compressive stress zone and the second compressive stress zone) can specifically satisfy the following: 80 MPa≤CS50≤250 MPa, where CS50 is, for example, 80 MPa, 100 MPa, 120 MPa, 140 MPa, 150 MPa, 170 MPa, 190 MPa, 200 MPa, 230 MPa, 250 MPa or a range consisting of any two of them.

[0063] In addition, the compressive stress zone may also satisfy the following requirement: CS80 ≥ 55 MPa, where CS80 is the compressive stress at a depth of 80 μm in the compressive stress zone (CS80). This means that the CS80 of the first compressive stress zone (the compressive stress at a depth of 80 μm from the first surface) is greater than or equal to 55 MPa, and the CS80 of the second compressive stress zone (the compressive stress at a depth of 80 μm from the second surface) is greater than or equal to 55 MPa. The CS80 of the first compressive stress zone and the CS80 of the second compressive stress zone may be equal or unequal, but are generally substantially equal (as previously mentioned, the stress distributions of the first compressive stress zone and the second compressive stress zone may be substantially axisymmetric).

[0064] In some embodiments, the CS80 of the compressive stress region (the first compressive stress region and the second compressive stress region) may specifically satisfy the following: 55 MPa≤CS80≤115 MPa.

[0065] Continuing to refer to Figure 5, the microcrystalline glass also includes a tensile stress zone (or tensile stress zone) located between the first compressive stress zone and the second compressive stress zone. The tensile stress zone is a region where the stress of the microcrystalline glass manifests as tensile stress (tensile stress). As shown in Figure 5, in the direction from the first surface to the second surface (or in the direction from the second surface to the first surface), the tensile stress (absolute value) in the tensile stress zone shows a trend of first increasing and then decreasing, specifically, it may be gradually increasing first and then gradually decreasing.

[0066] Specifically, as shown in Figure 5, the tensile stress zone includes a first tensile stress zone connected to the first compressive stress zone, and a second tensile stress zone located between the first tensile stress zone and the second compressive stress zone, that is, the first compressive stress zone, the first tensile stress zone, the second tensile stress zone and the second compressive stress zone are connected in sequence, wherein the tensile stress (absolute value) of the first tensile stress zone tends to increase along the direction from the first surface to the second surface, and the tensile stress (absolute value) of the second tensile stress zone tends to decrease along the direction from the first surface to the second surface (the tensile stress (absolute value) of the second tensile stress zone tends to increase along the direction from the second surface to the first surface, and the tensile stress (absolute value) of the first tensile stress zone tends to decrease along the direction from the second surface to the first surface), so that the tensile stress of the entire tensile stress zone tends to first increase and then decrease.

[0067] As mentioned above, the compressive stress zone (the first compressive stress zone and the second compressive stress zone) is the area where the stress in the microcrystalline glass manifests as compressive stress, and the tensile stress zone (the first tensile stress zone and the second tensile stress zone) is the area where the stress in the microcrystalline glass manifests as tensile stress. Under normal circumstances, as shown in Figure 5, the stress at the position where the tensile stress zone and the compressive stress zone are connected is basically 0 (that is, the stress at the position where the first tensile stress zone and the first compressive stress zone are connected is basically 0, and the stress at the position where the second tensile stress zone and the second compressive stress zone are connected is basically 0).

[0068] Specifically, in the coordinate system shown in FIG5 , the stress curve with a positive stress value is the stress curve of the compressive stress zone (such as the first compressive stress curve and the second compressive stress curve), and the stress curve with a negative stress value is the stress curve of the tensile stress zone (including the first tensile stress curve of the first tensile stress zone (in the DOL-0.5H interval in the coordinate system shown in FIG5 ) and the second tensile stress curve of the second tensile stress zone (in the 0.5H-DOL' interval in the coordinate system shown in FIG5 )). The stress value corresponding to DOL is 0, that is, the position with a depth of DOL from the first surface is the junction of the first compressive stress zone and the first tensile stress zone; the stress value corresponding to DOL' is 0, that is, the position with a depth of DOL' from the first surface (also the position with a depth of DOL from the second surface) is the junction of the second tensile stress zone and the second compressive stress zone.

[0069] Specifically, the thickness of the first compressive stress zone, the total thickness of the tensile stress zone (i.e., the sum of the thickness of the first tensile stress zone and the thickness of the second tensile stress zone) and the thickness of the second compressive stress zone are equal to the thickness H of the microcrystalline glass (i.e., H = thickness DOL of the first compressive stress zone + thickness of the first tensile stress zone + thickness of the second tensile stress zone + thickness DOL of the second compressive stress zone).

[0070] The thickness of the first tensile stress region may be substantially equal to the thickness of the second tensile stress region, that is, the thickness of the first tensile stress region = 0.5H - DOL, and the thickness of the second tensile stress region = 0.5H - DOL.

[0071] Specifically, the stress distribution trend of the first tensile stress zone and the stress distribution trend of the second tensile stress zone can be axially symmetrical, and the axis of symmetry is the center position of the microcrystalline glass (i.e., the position with a depth of 0.5H from the first surface (or the second surface), which is usually also the center position of the tensile stress zone, and the position where the first tensile stress zone and the second tensile stress zone are connected), that is, the maximum tensile stress in the tensile stress zone (i.e., the maximum tensile stress at the central region (CT.CV)) can be specifically at the center position of the microcrystalline glass, that is, the tensile stress (absolute value) at the center position of the microcrystalline glass is greater than the tensile stress (absolute value) at other positions in the tensile stress zone.

[0072] Specifically, the maximum tensile stress in the tensile stress zone can be greater than or equal to 65 MPa (i.e., CT.CV ≥ 65 MPa), which can specifically be 65 MPa to 200 MPa (i.e., 65 MPa ≤ CT.CV ≤ 200 MPa), for example, 65, 70 MPa, 80 MPa, 90 MPa, 100 MPa, 110 MPa, 120 MPa, 130 MPa, 140 MPa, 150 MPa, 160 MPa, 170 MPa, 180 MPa, 190 MPa, 200 MPa or a range consisting of any two of them.

[0073] In addition, the average tensile stress at the central region (CT.AV) may be greater than or equal to 45 MPa, specifically 45 MPa to 120 MPa (i.e., 45 MPa ≤ CT.AV ≤ 120 MPa), for example, 45 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa, 110 MPa, 120 MPa, or a range consisting of any two thereof.

[0074] Specifically, the average tensile stress in the first tensile stress zone may be greater than or equal to 45 MPa, specifically 45 MPa to 120 MPa, for example, 45 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa, 110 MPa, 120 MPa or a range consisting of any two thereof; the average tensile stress in the second tensile stress zone may be greater than or equal to 45 MPa, specifically 45 MPa to 120 MPa, for example, 45 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa, 110 MPa, 120 MPa or a range consisting of any two thereof.

[0075] Generally, the average tensile stress of the first tensile stress zone, the average tensile stress of the second tensile stress zone, and the average tensile stress of the entire tensile stress zone are substantially equal. In specific implementations, the average tensile stress can be measured by integrating and summing the tensile stresses of the entire first tensile stress zone and then dividing the resulting value by the thickness of the first tensile stress zone. Alternatively, the average tensile stress can be measured by integrating and summing the tensile stresses of the entire second tensile stress zone and then dividing the resulting value by the thickness of the second tensile stress zone.

[0076] In addition, the tensile stress linear density (or tensile stress linear density (CT.LD)) of the tensile stress zone may be greater than or equal to 25 KPa / m (ie, CT.LD ≥ 25 KPa / m), and specifically may be 25 KPa / m to 65 KPa / m.

[0077] In addition, the above-mentioned microcrystalline glass may include a large-radius metal element, the atomic radius of which is larger than the atomic radius of lithium. Specifically, the large-radius metal element may include an alkali metal and / or alkaline earth metal having an atomic radius larger than the atomic radius of lithium (Li), for example, Na + , K + 、Ru + 、Cs + Mg 2+ One or more of .

[0078] In some embodiments, the content of the large-radius metal element in the compressive stress zone increases first and then decreases with increasing depth. That is, the content of the large-radius metal element in the first compressive stress zone increases first and then decreases with increasing depth, while the content of the large-radius metal element in the second compressive stress zone increases first and then decreases with increasing depth. However, the distribution pattern of the large-radius metal element in the compressive stress zone is not limited to this. In other embodiments, the large-radius metal element in the compressive stress zone (the first compressive stress zone and the second compressive stress zone) may also have other regular or irregular distribution patterns.

[0079] Generally, glass-ceramics contain lithium, and elements such as lithium and large-radius metal elements exist in the form of oxides.

[0080] In some specific embodiments, the above-mentioned microcrystalline glass may include: Li2O, Na2O and K2O, the sum of the molar contents of Li2O, Na2O and K2O is 13% to 32%; SiO2, the molar content of SiO2 is 58% to 72%; Al2O3, the molar content of Al2O3 is 2% to 8%; P2O5, ZrO2 and TiO2, the sum of the molar contents of P2O5, ZrO2 and TiO2 is 2% to 13%; MgO, CaO and ZnO, the sum of the molar contents of MgO, CaO and ZnO is 0 to 3%; B2O3, the molar content of B2O3 is 0 to 5%.

[0081] The glass-ceramics of the embodiment of the present invention may include one or more of lithium silicate system glass-ceramics, lithium disilicate system glass-ceramics, petalite system glass-ceramics, spinel system glass-ceramics, etc., but is not limited thereto.

[0082] In some embodiments, the microcrystalline glass includes a glass phase and a crystalline phase, wherein the crystalline phase includes one or more of quartz, spodumene, petalite, lithium silicate, lithium disilicate, and spinel, and the volume fraction of the crystalline phase can be greater than or equal to 20%.

[0083] The embodiment of the present invention can measure the volume fraction of the crystalline phase in the microcrystalline glass by conventional methods in the art, for example, by X-ray diffraction (XRD), that is, performing XRD analysis on the microcrystalline glass to obtain the XRD spectrum of the microcrystalline glass, and then determining its volume fraction based on the relative area of ​​the crystalline phase in the spectrum.

[0084] In addition, the damage resistance characteristic value of the microcrystalline glass of the embodiment of the present invention is (Figure of merits for damage resistance) can satisfy:

[0085] In some specific embodiments, For example, the range is 1.4, 1.43, 1.45, 1.48, 1.5, 1.53, 1.55, 1.58, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2 or any two thereof.

[0086] in,

[0087] SCE 50 is the total compressive stress elastic energy from the depth of 50 μm to the thickness of the compressive stress layer DOL (in μm) of the glass-ceramic (compressive stress zone), where SCE 50 Satisfies formula 2:

[0088] In formula 1 and formula 2, K IC is the fracture toughness of the glass-ceramic; v is the Poisson's ratio of the glass-ceramic; E is the Young's modulus of the glass-ceramic; H is the thickness of the glass-ceramic; H max is a constant, with a value of 0.75 mm; σ c (x) 2 is the compressive stress of the glass-ceramics at depth x.

[0089] Specifically, the glass-ceramics of the embodiment of the present invention can be made from glass raw materials through ion exchange treatment (chemical strengthening process). The glass raw materials used can generally be glass-ceramics raw materials containing glass phase and crystal phase. After the glass-ceramics raw materials are subjected to ion exchange treatment, the above-mentioned glass-ceramics of the embodiment of the present invention are formed. Generally, K in the above formula 1 and formula 2 is ICIt can also be the fracture toughness of the glass material, v can also be the Poisson's ratio of the glass material, and E can also be the Young's modulus of the glass material. The chemical strengthening process has little effect on the fracture toughness, Poisson's ratio and Young's modulus of the glass material. The microcrystalline glass product obtained after chemical strengthening (the above-mentioned microcrystalline glass in the embodiment of the present invention) is basically consistent with the fracture toughness, Poisson's ratio and Young's modulus of the glass material used.

[0090] An embodiment of the present invention further provides a method for preparing glass-ceramics, comprising the following steps: contacting a glass raw material with a first salt bath to perform a first ion exchange treatment to produce the glass-ceramics; wherein the first ion exchange treatment is performed at a temperature T1 and for a time t1, satisfying: And / or, the preparation method further includes: contacting the glass material after the first ion exchange treatment with a second salt bath for a second ion exchange treatment, wherein the ratio of the amount of sodium element in the first salt bath to the sum of the amounts of all metal elements in the first salt bath is X1, the ratio of the amount of sodium element in the second salt bath to the sum of the amounts of all metal elements in the second salt bath is X2, the temperature of the second ion exchange treatment is T2, the time is t2, X1>X2, T1-T2≥40°C, and t2 / t1≤0.5.

[0091] During the above-mentioned preparation process, the glass raw material is chemically strengthened by ion exchange treatment to produce the glass-ceramics (or chemically strengthened glass-ceramics) of the embodiments of the present invention. The chemically strengthened glass-ceramics can be produced by a single chemical strengthening treatment (i.e., the glass raw material is subjected to a single ion exchange treatment, i.e., the glass raw material is subjected to only a first ion exchange treatment), or by a multi-step chemical strengthening treatment (i.e., the glass raw material is subjected to multiple (at least two) ion exchange treatments, for example, a first ion exchange treatment and a second ion exchange treatment are sequentially performed to produce the glass-ceramics).

[0092] Specifically, in a one-step chemical strengthening process, the first ion exchange treatment satisfies

[0093] According to the inventors' research, by coordinating the temperature and duration of the first ion exchange treatment during a one-step chemical strengthening process, a non-monotonic stress distribution in the resulting glass-ceramics can be achieved through the surface relaxation effect. This one-step strengthening process also offers advantages such as high efficiency, low cost, and high production capacity.

[0094] In addition, according to the inventor's research, in the multi-step chemical strengthening process including the first ion exchange treatment and the second ion exchange treatment, the first ion exchange treatment is a positive strengthening process, through which the large radius metal ions (such as the aforementioned Na + , K+ 、Ru + 、Cs + Mg 2+ One or more of the following) replaces Li in the glass raw material + , which can generate sufficient surface compressive stress and central tensile stress in the glass; the second ion exchange treatment is a reverse strengthening process. Through the second ion exchange treatment, the deep compressive stress of the microcrystalline glass can be increased, while the surface tensile stress can be reduced. Therefore, by sequentially performing the first ion exchange treatment and the second ion exchange treatment on the glass raw material, the characteristics of non-monotonic stress distribution can be obtained.

[0095] Take Na + He Li + For example, in the first ion exchange process, the Na + The diffusion direction of Li in glass + The diffusion direction of Na + Diffusion from the glass surface to the center of the glass, and the Li in the glass + Then it diffuses from the center of the glass to the surface, and the monotonically distributed Na + The resulting packing effect makes the glass material after the first ion exchange treatment have a monotonic stress distribution characteristic (its stress distribution curve is similar to the stress curves of Comparative Example 1-1 and Comparative Example 2-1 shown in Figure 1). In the second ion exchange process, in order to obtain a non-monotonic stress distribution, it is necessary to increase the deep compressive stress of the glass while reducing the surface tensile stress. This requires that the Na + It must continue to diffuse internally (i.e., ), and also diffuse to the surface, i.e., Na + The content must reach its maximum value at a certain depth. + A non-monotonic distribution cannot guarantee a non-monotonic distribution of compressive stress, because it is also necessary to avoid stress decay caused by the relaxation effect (after decay, the stress from any surface to the center of the glass can easily return to a monotonic distribution). Therefore, taking the above factors into consideration, according to the inventors' research, a controllable reverse ion exchange reaction (forward strengthening process and reverse strengthening process) with a weak stress relaxation effect is used, and the Na in the forward strengthening process and the reverse strengthening process are coordinated to control the Na + The conditions such as the synergistic matching relationship between parameters such as concentration, processing temperature and time are achieved to obtain microcrystalline glass with non-monotonic stress distribution characteristics.

[0096] Illustratively, during the multi-step chemical strengthening treatment, T1-T2 may be 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, or a range consisting of any two thereof.

[0097] Illustratively, during the multi-step chemical strengthening treatment, t2 / t1 may be 0.02, 0.025, 0.04, 0.05, 0.0625, 0.07, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4 / 0.45, 0.5, or a range consisting of any two thereof.

[0098] For example, the temperature T2 of the second ion exchange treatment may be 350° C., 360° C., 370° C., 380° C., 390° C., 400° C., 410° C., or a range consisting of any two thereof.

[0099] Illustratively, the time t2 of the second ion exchange treatment can be 0.2h, 0.5h, 0.8h, 1h, 1.3h, 1.5h, 1.8h, 2h, 2.3h, 2.5h, 2.8h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h or a range consisting of any two thereof.

[0100] Specifically, the second salt bath contains sodium and lithium, and may contain or not contain other metal elements (such as potassium). The metal elements in the second salt bath exist in the form of ions. For example, sodium exists in the form of Na + Lithium exists in the form of Li + Potassium exists in the form of K + The second salt bath can be formed by melting salts containing these metal elements. For example, the second salt bath can be formed by melting lithium salt and sodium salt, or by melting lithium salt, sodium salt and potassium salt.

[0101] Illustratively, in the second salt bath, the salt containing the metal element may include nitrate, that is, the second salt bath may be formed by melting the nitrate of the metal element. For example, the lithium salt includes lithium nitrate, the sodium salt includes sodium nitrate, and the potassium salt includes potassium nitrate.

[0102] Generally, in the second salt bath, the mass of the sodium salt may be greater than, equal to, or less than the mass of the potassium salt. The second salt bath may contain potassium salt or not. Accordingly, the second salt bath may contain potassium element or not.

[0103] Illustratively, in the second salt bath, the ratio of the mass of the sodium salt to the sum of the masses of the sodium salt and the potassium salt may be 2% to 80%, for example, 2%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or a range consisting of any two thereof; correspondingly, the ratio of the mass of the potassium salt to the sum of the mass of the sodium salt and the potassium salt may be 20% to 98%, for example, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 98% or a range consisting of any two thereof.

[0104] Illustratively, the mass fraction of the lithium salt in the second salt bath (i.e., the mass ratio of the lithium salt to the second salt bath (i.e., the ratio of the mass of the lithium salt to the sum of the masses of all metal salts)) can be 0.005% to 5%, for example, 0.005%, 0.008%, 0.016%, 0.02%, 0.04%, 0.08%, 0.1%, 0.3%, 0.5%, 1%, 2%, 3%, 4%, 5% or a range consisting of any two thereof.

[0105] For example, the concentration of lithium in the second salt bath (i.e., lithium (Li + ) to the second salt bath (that is, the ratio of the mass of lithium element to the sum of the masses of all metal salts)) Y2 is 4ppm, 8ppm, 10ppm, 15ppm, 18ppm, 20ppm, 25ppm, 28ppm, 30ppm, 40ppm, 50ppm, 60ppm, 70ppm, 80ppm, 90ppm, 100ppm, 110ppm, 120ppm, 130ppm, 140ppm, 150ppm, 156ppm, 160ppm or a range consisting of any two thereof.

[0106] In addition, in the multi-step chemical strengthening process, the first ion exchange treatment can meet the following requirements: or, Preferred

[0107] For example, during one or more chemical strengthening processes, t1 and The difference can be 0, 1h, 2h, 3h, 4h, 5h, 6h or a range consisting of any two of them.

[0108] In some embodiments, during one or more chemical strengthening treatments, the temperature T1 of the first ion exchange treatment may be greater than or equal to 400° C. For example, the temperature T1 of the first ion exchange treatment may be 450° C., 460° C., 470° C., 475° C., 480° C., 485° C., 490° C., 495° C., 500° C., or a range consisting of any two thereof.

[0109] In some embodiments, during one or more chemical strengthening treatments, the first ion exchange treatment time t1 may be greater than or equal to 8 hours. For example, the first ion exchange treatment time t1 may be 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, or a range consisting of any two thereof.

[0110] Specifically, the first salt bath contains sodium and lithium, and may contain or not contain other metal elements (such as potassium). The metal elements in the first salt bath exist in the form of ions. For example, sodium exists in the form of Na + Lithium exists in the form of Li + Potassium exists in the form of K + The first salt bath can be formed by melting salts containing these metal elements. For example, the first salt bath can be formed by melting lithium salt and sodium salt, or by melting lithium salt, sodium salt and potassium salt.

[0111] Illustratively, in the first salt bath, the salt containing the metal element may include nitrate, that is, the first salt bath may be formed by melting the nitrate of the metal element. For example, the lithium salt includes lithium nitrate, the sodium salt includes sodium nitrate, and the potassium salt includes potassium nitrate.

[0112] Generally, the mass of the sodium salt in the first salt bath can be greater than, equal to, or less than the mass of the potassium salt. The first salt bath can contain potassium salt or not. Accordingly, the first salt bath can contain potassium element or not.

[0113] Illustratively, in the first salt bath, the ratio of the mass of the sodium salt to the sum of the mass of the sodium salt and the potassium salt may be 20% to 100%, for example, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 98%, 100% or a range consisting of any two thereof; accordingly, the ratio of the mass of the potassium salt to the sum of the mass of the sodium salt and the mass of the potassium salt may be 0% to 80%, for example, 0, 2%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or a range consisting of any two thereof.

[0114] In addition, the mass fraction of the lithium salt in the first salt bath (i.e., the mass ratio of the lithium salt to the first salt bath (i.e., the ratio of the mass of the lithium salt to the sum of the masses of all metal salts)) can be 0.005% to 5%, for example, 0.005%, 0.008%, 0.01%, 0.016%, 0.02%, 0.04%, 0.08%, 0.1%, 0.15%, 0.2%, 0.5%, 1%, 2%, 3%, 4%, 5% or a range consisting of any two thereof.

[0115] Illustratively, the concentration of lithium element in the first salt bath (i.e., the mass ratio of lithium element to the first salt bath (i.e., the ratio of the mass of lithium element to the sum of the masses of all metal salts)) Y1 is greater than 10 ppm. Y1 is, for example, 11 ppm, 15 ppm, 18 ppm, 20 ppm, 22 ppm, 24 ppm, 26 ppm, 28 ppm, 30 ppm, or a range consisting of any two thereof.

[0116] In some embodiments, the concentration of sodium in the first salt bath (i.e., the ratio of the amount of sodium to the sum of the amounts of all metal elements, also referred to as Na + The ratio of the amount of the substance of the first salt bath to the sum of the amounts of all cationic substances in the first salt bath) can be greater than or equal to 2%, for example, greater than or equal to 20%, or greater than or equal to 20%, or greater than or equal to 40%, or greater than or equal to 50%, or greater than or equal to 60%, or greater than or equal to 70%, or greater than or equal to 80%, or greater than or equal to 90%, or greater than or equal to 95%, etc.

[0117] In addition, during the multi-step chemical strengthening treatment, the concentration Y2 of the lithium element in the second salt bath can be greater than, equal to, or less than the concentration Y1 of the lithium element in the first salt bath, and the ratio of the mass of the sodium salt in the second salt bath to the sum of the masses of the sodium salt and the potassium salt can be greater than, equal to, or less than the ratio of the mass of the sodium salt to the sum of the masses of the sodium salt and the potassium salt in the first salt bath.

[0118] During specific implementation, the glass raw material can be preheated first and then subjected to the first ion exchange treatment. For example, in the above-mentioned multi-step chemical strengthening process including the forward strengthening process and the reverse strengthening process, the glass raw material can be preheated first and then subjected to the first ion exchange treatment and the second ion exchange treatment in sequence; in the above-mentioned one-step chemical strengthening process, the glass raw material can be preheated first and then subjected to the first ion exchange treatment.

[0119] The unit of temperature is ℃, and the preheating temperature T0 is greater than or equal to the glass transition temperature (T g ) and 150℃ (ie T g- 150℃), less than or equal to the difference between Tg and 100℃ (i.e. T g -100℃), that is, T g -150℃≤T0≤T g -100°C, the Tg of the glass raw material used can usually be around 500°C to 600°C, but is not limited thereto; the preheating time can be 0.5 to 4 hours.

[0120] In a specific implementation, the glass material can be placed in a salt bath and kept at a preset temperature for a preset time to perform an ion exchange treatment. After the ion exchange treatment is completed, the glass can be sequentially cleaned, polished, rinsed, and dried (in the case of multiple ion exchange treatments, all steps of the ion exchange treatment can be completed first, followed by cleaning, polishing, rinsing, and drying) to produce chemically strengthened microcrystalline glass. Specifically, water can be used for cleaning.

[0121] As mentioned above, in the preparation process of chemically strengthened microcrystalline glass, the glass raw materials used can generally be microcrystalline glass raw materials containing glass phase and crystal phase. The glass raw materials can specifically include one or more of microcrystalline glass raw materials of lithium silicate system, microcrystalline glass raw materials of lithium disilicate system, microcrystalline glass raw materials of petalite system, microcrystalline glass raw materials of spinel system, etc., but are not limited to these.

[0122] Specifically, the glass raw materials used may include Li2O, with the molar content of Li2O being 10% to 25%; SiO2, with the molar content of SiO2 being 58% to 72%; Na2O and K2O, with the sum of the molar contents of Na2O and K2O being 3% to 7%; Al2O3, with the molar content of Al2O3 being 2% to 8%; P2O5, ZrO2 and TiO2, with the sum of the molar contents of P2O5, ZrO2 and TiO2 being 2% to 13%; MgO, CaO and ZnO, with the sum of the molar contents of MgO, CaO and ZnO being 0 to 3%; and B2O3, with the molar content of B2O3 being 0 to 5%.

[0123] Generally speaking, compared with the original glass, after chemical strengthening treatment, the lithium element in the chemically strengthened microcrystalline glass produced will be slightly reduced, and the large-radius metal elements (such as sodium element, etc.) contained in the salt bath used will be slightly increased, while the other components are not much different.

[0124] Specifically, the Young's modulus of the glass raw material used may be greater than or equal to 90 GPa, for example, 90 GPa, 100 GPa, 110 GPa, 120 GPa, 130 GPa or 140 GPa.

[0125] The chemically strengthened glass-ceramics produced by the above-described glass-ceramics preparation method can specifically be the glass-ceramics of the aforementioned embodiment of the present invention, having the characteristics described above, namely, comprising: a first surface defining a thickness H and a second surface opposite the first surface; a compressive stress region having a thickness DOL, where DOL is less than 0.5H; and a compressive stress in the compressive stress region that first increases and then decreases with increasing depth. The specific stress distribution and other aspects of the glass-ceramics are described in the aforementioned description of the glass-ceramics of the embodiment of the present invention and will not be further elaborated here.

[0126] An embodiment of the present invention also provides an electronic device, which includes the aforementioned microcrystalline glass. As mentioned above, the microcrystalline glass of the embodiment of the present invention has a non-monotonic stress distribution characteristic, which can increase the stress strength of the microcrystalline glass, thereby improving its drop resistance, and further improving the drop resistance and damage resistance of the electronic device using the microcrystalline glass.

[0127] Specifically, the electronic device includes a structural member, which includes the above-mentioned microcrystalline glass. The structural member is, for example, cover glass (screen cover), and the electronic device is, for example, a mobile phone, tablet, computer, watch, and display screen (such as a car display screen).

[0128] The present invention is further described below with reference to specific embodiments. In the embodiments of the present application, in the stress curves shown in Figures 1 and 2, compressive stress is recorded as a positive value and tensile stress is recorded as a negative value; in the embodiments of the present invention, the stress curve (stress distribution curve) of the glass-ceramics can be measured by conventional methods in the art, for example, the stress curve of the glass-ceramics can be measured using the Japanese Orihara SLP2000. The stress curve can be directly read by the SLP2000, or the phase difference F measured by the SLP2000 can be calculated using the formula It is calculated that x is the depth of the microcrystalline glass, and C is a constant related to the photoelastic coefficient (C=200 for the microcrystalline glass used in the examples and comparative examples).

[0129] In the following examples and comparative examples, the microcrystalline glass raw materials 1 and 2 used respectively include Li2O, and the molar content of Li2O is 10% to 25%; SiO2, the molar content of SiO2 is 58% to 72%; Na2O and K2O, the sum of the molar contents of Na2O and K2O is 3% to 7%; Al2O3, the molar content of Al2O3 is 2% to 8%; P2O5, ZrO2 and TiO2, the sum of the molar contents of P2O5, ZrO2 and TiO2 is 2% to 13%; MgO, CaO and ZnO, the sum of the molar contents of MgO, CaO and ZnO is 0 to 3%; B2O3, the molar content of B2O3 is 0 to 5%; the properties of the microcrystalline glass raw materials 1 and 2 are shown in Table 1.

[0130] Table 1

[0131] Examples 1-23

[0132] The glass raw material used in this embodiment 1 is glass-ceramics raw material 1, which is subjected to a first ion exchange treatment (forward strengthening process) and a second ion exchange treatment (reverse strengthening process) in sequence to obtain glass-ceramics (thickness H = 0.65 mm). The specific preparation process is as follows:

[0133] (1) Preheating: Heat-treat the glass-ceramic raw material 1 at 400°C for 0.5h;

[0134] (2) First ion exchange treatment: the preheated glass-ceramic raw material 1 is placed in a first salt bath (furnace water) and kept at 470°C for 10 hours (i.e., T1 = 470°C, t1 = 10 hours); wherein the first salt bath is prepared by melting a mixture of sodium nitrate and lithium nitrate, wherein Li +The concentration (ie, lithium element concentration Y1) is approximately 25 ppm.

[0135] (3) Second ion exchange treatment: the glass-ceramic raw material 1 after the first ion exchange treatment is placed in a second salt bath (furnace water) and kept at 400° C. for 1.5 h (i.e., T2 = 400° C., t2 = 1.5 h);

[0136] The second salt bath is prepared by melting a mixture of sodium nitrate, potassium nitrate and lithium nitrate, wherein the mass ratio of sodium nitrate to potassium nitrate is about 3:7, and Li + The concentration (ie, lithium element concentration Y2) is approximately 30 ppm.

[0137] (4) The microcrystalline glass raw material 1 after the second ion exchange treatment is sequentially subjected to the processes of cleaning, polishing, washing and drying to obtain the microcrystalline glass of this embodiment 1-23; wherein, water is used for cleaning.

[0138] Comparative Example 1-1: Only the first ion exchange treatment was performed. The specific conditions are shown in Table 2. Except for the differences shown in Table 2, the other conditions were the same as those of Example 1-23.

[0139] Example 2-7: Glass-ceramics raw material 2 (thickness H=0.65 mm) was used to prepare glass-ceramics through a one-step chemical strengthening process. The preparation process is as follows:

[0140] (1) Preheat treatment: heat treat the glass-ceramic raw material 2 at 400°C for 0.5h;

[0141] (2) placing the preheated glass-ceramic raw material 1 in a salt bath (furnace water) and keeping it at 470°C for 11 hours;

[0142] The salt bath is prepared by melting a mixture of sodium nitrate, lithium nitrate and potassium nitrate, wherein the mass ratio of sodium nitrate to potassium nitrate is about 9.8:0.2, and Li + The concentration (i.e., lithium element concentration Y2) is approximately 20 ppm;

[0143] (3) The microcrystalline glass raw material 2 after ion exchange treatment is sequentially subjected to the processes of cleaning, polishing, washing and drying to obtain the microcrystalline glass of this embodiment 2-7; wherein, water is used for cleaning.

[0144] Comparative Example 2-1: Referring to the process of Example 2-7, microcrystalline glass was prepared; wherein, the conditions of ion exchange treatment (one-step chemical strengthening process) are shown in Table 2. Except for the differences shown in Table 2, the other conditions are the same.

[0145] The stress curves of the microcrystalline glass obtained in Examples 1-23, 2-7, Comparative Example 1-1 and Comparative Example 2-1 are shown in FIG1 ( FIG1 only shows the stress curves of the first compressive stress zone and the first tensile stress zone of the microcrystalline glass. The stress curve of the second compressive stress zone is symmetrical with the stress curve of the first compressive stress zone, and the stress curve of the second tensile stress zone is symmetrical with the stress curve of the first tensile stress zone, which will not be repeated). The first-order derivative function curve of the stress curve is shown in FIG2.

[0146] As can be seen from Figures 1 and 2, the stress distribution of the glass-ceramics in Comparative Examples 1-1 and 2-1 is monotonic; while the glass-ceramics in Examples 1-23 and 2-7 have non-monotonic stress distribution characteristics. The compressive stress in the compressive stress zone increases first and then decreases with increasing depth (DOL.P ≥ 5 μm, CS.P ≥ 110 MPa), and has a high deep compressive stress. The glass-ceramics in Examples 1-23 and 2-7 both meet the following conditions: the thickness of the compressive stress zone DOL < 0. 5H, 5μm≤DOL.P≤0.1H, 110MPa≤CS.P≤300MPa, the maximum value of the first derivative of the stress curve in the compressive stress zone in the depth range of 5μm~0.1H is greater than 2MPa / μm, 80MPa≤CS50≤250MPa, 55Mpa≤CS80≤115MPa, 45Mpa≤CT.AV≤120Mpa, 65Mpa≤CT.CV≤200Mpa, 30KPa / m≤CT.LD≤65KPa / m.

[0147] Specifically, taking Example 1-23 and Comparative Example 1-1 as examples, Figure 3 shows the CS50, CS80, CT.AV, CT.LD and DOL.P of the microcrystalline glass of Example 1-23 and Comparative Example 1-1. It can be seen that the CS50 of the microcrystalline glass of Comparative Example 1-1 is 90 MPa, CS80 is 51 MPa, CT.AV is 46 MPa, and CT.LD is 27.3 KPa / m. The CS50 of the microcrystalline glass of Example 1-23 is 123 MPa, CS80 is 74 MPa, CT.AV is 56 MPa, and CT.LD is 36.8 KPa / m, which are increased by about 37%, 45%, 20% and 35% respectively compared with Comparative Example 1-1. At the same time, DOL.P is also greatly improved from 0 μm in Comparative Example 1 to 26 μm.

[0148] This shows that the chemical strengthening process of the embodiment of the present invention can significantly improve the stress strength of the micro-ceramic glass, especially the deep compressive stress of the micro-ceramic glass, thereby improving the drop resistance of the micro-ceramic glass in more demanding scenarios.

[0149] The drop resistance of the glass-ceramics of Examples 1-23, Example 2-7, Comparative Example 1-1, and Comparative Example 2-1 was tested according to the following process: the glass-ceramics was made into a screen cover, which was then used to make a mobile phone; then the whole phone was dropped on 80-grit SiC sandpaper (i.e., the phone was dropped from a certain height above the sandpaper surface). The results showed that:

[0150] (1) The drop failure height of the entire device of Examples 1-23 and 2-7 is higher than 1.1m (i.e., the screen does not crack when the mobile phone is dropped from a height below 1.1m), and even close to 1.5m;

[0151] (2) When the mobile phone is dropped from a height of about 1 m, the number of drop failures of the entire device of Example 1-23 and Example 2-7 is greater than 100 times (i.e., the mobile phone does not crack after being dropped repeatedly 100 times. Compared with Comparative Example 1-1 and Comparative Example 2-1, the number of drop failures of Example 1-23 and Example 2-7 is increased by at least 100%. FIG4 specifically shows the number of drop failures of the entire device of Example 2-7 and Comparative Example 2-1).

[0152] It can be seen that compared with Comparative Example 1-1 and Comparative Example 2-1, the microcrystalline glass of Example 1-23 and Example 2-7 has a non-monotonic stress distribution characteristic, which can improve the stress strength of the microcrystalline glass, especially the deep stress strength of the microcrystalline glass, so that it can show significantly improved drop resistance in more harsh ground scenarios, thereby improving the drop resistance and damage resistance of electronic products such as mobile phones made of this microcrystalline glass.

[0153] In addition, the microcrystalline glass of Examples 1-23 and Examples 2-7, and the screen cover (mobile phone glass cover) made of the microcrystalline glass also show good weather resistance. When stored in a hot and humid environment with a temperature of 85°C and a humidity of 85% for 240 hours, no corrosion or residual marks will occur.

[0154] Example 1-1 to Example 1-21: Referring to the process of Example 1-23, microcrystalline glass was prepared; wherein, the conditions of the first ion exchange treatment and the second ion exchange treatment are shown in Table 2, and except for the differences shown in Table 2, the other conditions are the same.

[0155] Example 1-22: The difference from Example 1-1 is that only the first ion exchange treatment is performed (i.e., microcrystalline glass is produced through a one-step chemical strengthening process). The conditions of the first ion exchange treatment are shown in Table 2. Except for the differences shown in Table 2, the other conditions are the same.

[0156] Example 2-1 to Example 2-6: Referring to the process of Example 2-7, microcrystalline glass was prepared; wherein, the conditions of ion exchange treatment (one-step chemical strengthening process) are shown in Table 2. Except for the differences shown in Table 2, the other conditions are the same.

[0157] Table 2

[0158] Note: The boiler water ratio in Table 2 indicates the mass proportion of sodium nitrate and potassium nitrate respectively, based on the total mass proportion of sodium nitrate and potassium nitrate being 10 parts. For example, "3 sodium 7 potassium" means that sodium nitrate is 3 parts and potassium nitrate is 7 parts (i.e., the mass ratio of sodium nitrate to potassium nitrate is 3:7); "10 sodium" means that sodium nitrate is 10 parts and potassium nitrate is 0 parts (i.e., the salt bath does not contain potassium nitrate); and "9.8 sodium 0.2 potassium" means that sodium nitrate is 9.8 parts and potassium nitrate is 0.2 parts.

[0159] The stress curves of Examples 1-1 to 1-22 and Examples 2-1 to 2-6 are similar to those of Examples 1-23 and 2-7. The maximum value of the first-order derivative of their stress curves in the depth range of 5 μm to 0.1H is greater than 2 MPa / μm. Specifically, the CS50, CS80, AT.AV, CT.CV, DOL, DOL.P, CS.P, CT.LD, Table 3 shows the single-unit extrusion properties (average rupture force).

[0160] Among them, the single extrusion performance is measured according to the following process: the microcrystalline glass is made into a glass cover plate, and a spherical (or hemispherical) extrusion piece is used to squeeze the middle position (center) of the surface of the glass cover plate until the glass cover plate just begins to break. The load at this time is the average rupture force (or the central extrusion strength of the microcrystalline glass).

[0161] Table 3

[0162] It can be seen from Table 3 that the stress distribution state of the microcrystalline glass of Comparative Example 1-1 and Comparative Example 2-1 is a monotonic stress distribution (DOL.P=0, CS.P=0); while the microcrystalline glass of Examples 1-1 to 1-22 and Examples 2-1 to 2-6 has a non-monotonic stress distribution characteristic (DOL.P≥5μm, CS.P≥110MPa), and has a higher deep compressive stress, CS50≥86MPa, CS80≥51MPa, CT.AV≥48MPa, CT.LD≥26.7KPa / m.

[0163] The glass-ceramics of Examples 1-1 to 1-22 were also tested, and the failure rate after a complete drop on 80-grit sandpaper was higher than 1.1 m, even approaching 1.5 m. The glass-ceramics of Examples 2-1 to 2-6 all failed after a complete drop on 80-grit sandpaper more than 50 times, and generally reached 100 times or even more. Compared to Comparative Examples 1-1 and 2-1, the glass-ceramics of Examples 1-1 to 1-22 and 2-1 to 2-6 exhibited excellent drop resistance.

[0164] In addition, the central extrusion strength of the microcrystalline glass of Examples 1-1 to 1-23 and Examples 2-1 to 2-7 is higher than 16 kgf, and most of them are higher than 22 kgf, and they also show good surface quality and surface stress and other properties.

[0165] In addition, when the glass-ceramics of Examples 1-1 to 1-23 and Examples 2-1 to 2-7 were stored in a hot and humid environment at a temperature of 85° C. and a humidity of 85% for 240 hours, no corrosion or residual marks occurred, showing good weather resistance.

[0166] In summary, the microcrystalline glass produced in the embodiment of the present invention has a non-monotonic stress distribution characteristic, which enables the microcrystalline glass to have excellent resistance to high temperature and high humidity environments while maintaining excellent impact resistance and drop resistance.

[0167] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A glass-ceramic, characterized in that: include: a first surface defining a thickness H and a second surface opposite the first surface; A compressive stress region, wherein the thickness of the compressive stress region is DOL, and DOL is less than 0.5H; The compressive stress in the compressive stress zone increases first and then decreases with increasing depth.

2. The glass-ceramic according to claim 1, characterized in that: The maximum compressive stress in the compressive stress zone is at a depth of DOL.P, and 5 μm≤DOL.P≤0.1H.

3. The glass-ceramic according to claim 1 or 2, characterized in that: The maximum compressive stress in the compressive stress zone is greater than or equal to 110 MPa.

4. The glass-ceramic according to claim 3, characterized in that: The maximum compressive stress of the compressive stress zone is 110 MPa to 300 MPa.

5. The glass-ceramic according to claim 1, characterized in that: The maximum value of the first-order derivative of the stress curve of the compressive stress zone in the depth range of 5 μm to 0.1H is greater than 2 MPa / μm.

6. The glass-ceramic according to claim 1, characterized in that: 0.1H≤DOL≤0.25H.

7. The glass-ceramics according to claim 1 or 2, characterized in that: 0.3mm≤H≤2mm.

8. The glass-ceramic according to claim 1, characterized in that: The compressive stress zone also satisfies: CS50≥80MPa, wherein CS50 is the compressive stress at a depth of 50μm in the compressive stress zone; And / or, CS80≥55Mpa, wherein CS80 is the compressive stress at a depth of 80μm in the compressive stress zone.

9. The glass-ceramic according to claim 8, characterized in that: 80MPa≤CS50≤250MPa; And / or, 55Mpa≤CS80≤115MPa.

10. The glass-ceramic according to claim 1, characterized in that: The compressive stress zone includes a first compressive stress zone and a second compressive stress zone; the first compressive stress zone extends from the first surface to the inside of the microcrystalline glass to a depth of DOL, and the second compressive stress zone extends from the second surface to the inside of the microcrystalline glass to a depth of DOL; The microcrystalline glass further includes a tensile stress region between the first compressive stress region and the second compressive stress region; Wherein, the average tensile stress of the tensile stress zone is greater than or equal to 45MPa; and / or, the maximum tensile stress of the tensile stress zone is greater than or equal to 65 MPa; And / or, the tensile stress linear density of the tensile stress zone is greater than or equal to 25 KPa / m.

11. The glass-ceramic according to claim 10, characterized in that: The average tensile stress in the tensile stress zone is 45MPa to 120MPa; And / or, the maximum tensile stress of the tensile stress zone is 65MPa to 200MPa; And / or, the tensile stress linear density of the tensile stress zone is 25 KPa / m to 65 KPa / m.

12. The glass-ceramic according to claim 1, characterized in that: The damage resistance characteristic value of the glass-ceramic satisfy: in, SCE 50 is the total compressive stress elastic energy from the depth of 50 μm to the thickness of the compressive stress layer DOL of the glass-ceramics, where SCE 50 Satisfies formula 2: In Formula 1 and Formula 2: K IC is the fracture toughness of the glass-ceramics; v is the Poisson's ratio of the glass-ceramics; E is the Young's modulus of the glass-ceramics; H is the thickness of the glass-ceramic; H max is a constant, and its value is 0.75mm; σ c (x) 2 is the compressive stress of the glass-ceramics at depth x.

13. The glass-ceramic according to claim 1, characterized in that: The microcrystalline glass comprises: Li2O, Na2O and K2O, wherein the sum of the molar contents of Li2O, Na2O and K2O is 13% to 32%; SiO2, wherein the molar content of SiO2 is 58% to 72%; Al2O3, wherein the molar content of Al2O3 is 2% to 8%; P2O5, ZrO2 and TiO2, wherein the sum of the molar contents of P2O5, ZrO2 and TiO2 is 2% to 13%; MgO, CaO and ZnO, wherein the sum of the molar contents of MgO, CaO and ZnO is 0 to 3%; B2O3, wherein the molar content of B2O3 is 0 to 5%.

14. The glass-ceramic according to claim 1, characterized in that: The microcrystalline glass comprises a glass phase and a crystal phase, wherein: The crystalline phase includes one or more of quartz, spodumene, petalite, lithium silicate, lithium disilicate, and spinel; And / or, the volume fraction of the crystalline phase is greater than or equal to 20%.

15. A method for preparing glass-ceramics, characterized in that: The following steps are involved: The glass raw material is contacted with a first salt bath for a first ion exchange treatment to obtain the microcrystalline glass; wherein the temperature of the first ion exchange treatment is T1 and the time is t1, and the following conditions are satisfied: And / or, the preparation method further includes: contacting the glass raw material after the first ion exchange treatment with a second salt bath for a second ion exchange treatment, the ratio of the amount of sodium element in the first salt bath to the sum of the amounts of all metal elements in the first salt bath is X1, the ratio of the amount of sodium element in the second salt bath to the sum of the amounts of all metal elements in the second salt bath is X2, the temperature of the second ion exchange treatment is T2, the time is t2, X1>X2, T1-T2≥40°C, and t2 / t1≤0.

5.

16. A glass-ceramic, characterized in that: The microcrystalline glass is prepared according to the method for preparing microcrystalline glass according to claim 15, wherein the microcrystalline glass comprises: a first surface defining a thickness H and a second surface opposite the first surface; A compressive stress region, wherein the thickness of the compressive stress region is a region of DOL, DOL<0.5H; The compressive stress in the compressive stress zone increases first and then decreases with increasing depth.

17. An electronic device, characterized in that: Including the microcrystalline glass according to any one of claims 1 to 14 or the microcrystalline glass according to claim 16.

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