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

A microcrystalline glass, its preparation method, and an electronic device thereof.

[0001] This application claims priority to Chinese Patent Application No. 202311205693.3, filed on September 18, 2023, entitled “A microcrystalline glass and its preparation method and electronic device”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to the field of glass materials technology, specifically to a microcrystalline glass, its preparation method, and an electronic device thereof. Background Technology

[0003] Microcrystalline glass has a wide range of applications, such as screen covers for mobile phones and other electronic products. However, in related technologies, the stress strength and other properties of microcrystalline glass need further improvement.

[0004] Summary of the Invention

[0005] This invention provides a microcrystalline glass, its preparation method, and an electronic device, which can improve the stress strength and other properties of the microcrystalline glass and effectively overcome the defects of the prior art.

[0006] In one aspect, the present invention provides a microcrystalline glass, comprising: a first surface defining a thickness H and a second surface opposite to the first surface; a compressive stress region having a thickness DOL, where DOL < 0.5H; wherein the compressive stress in the compressive stress region first increases and then decreases with increasing depth.

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

[0008] According to one embodiment of the present invention, the maximum compressive stress in 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 in the compressive stress zone is 110MPa to 300MPa.

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

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

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

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

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

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

[0016] According to one embodiment of the present invention, the average tensile stress in the tension stress zone is 45MPa to 120MPa; and / or, the maximum tensile stress in the tension stress zone is 65MPa to 200MPa; and / or, the tensile stress linear density in the tension 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 satisfy:

[0018] According to one embodiment of the present invention, 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%; and B₂O₃, wherein the molar content of B₂O₃ is 0% to 5%.

[0019] According to one embodiment of the present invention, the microcrystalline glass comprises a glass phase and a crystalline phase, wherein the crystalline phase comprises 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%.

[0020] In another aspect, the present invention provides a method for preparing microcrystalline glass, comprising the following steps: contacting a glass raw material with a first salt bath to perform a first ion exchange treatment, thereby obtaining the microcrystalline glass; wherein the temperature of the first ion exchange treatment is T1 and the time is t1, satisfying: And / or, the preparation method further includes: contacting the glass raw material after the first ion exchange treatment with a second salt bath to perform a second ion exchange treatment, wherein the ratio of the amount of sodium 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 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℃, and t2 / t1≤0.5.

[0021] In another aspect, the present invention provides a microcrystalline glass, which is prepared by the aforementioned method for preparing microcrystalline glass, the microcrystalline glass comprising: a first surface with a defined thickness H and a second surface opposite to 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 region first increases and then decreases with increasing depth.

[0022] In another aspect, the present invention provides an electronic device comprising the aforementioned microcrystalline glass.

[0023] In this invention, the thickness DOL of the compressive stress zone of the microcrystalline glass is less than 0.5H, and the compressive stress in this zone first increases and then decreases with increasing depth. Therefore, the microcrystalline glass of this invention exhibits a non-monotonic stress distribution characteristic in the aforementioned compressive stress zone, which improves the stress strength and other properties of the microcrystalline glass, thereby enhancing the drop resistance of the microcrystalline glass and electronic devices using it.

[0024] In addition, the microcrystalline glass of the present invention also has good surface quality and surface stress properties, and its central compressive strength (average bursting force) is higher than 16 kgf, and can even reach more than 22 kgf.

[0025] In addition, the microcrystalline glass of the present invention has good weather resistance. Even when stored or used in a high temperature and high humidity environment, it is not easy to corrode or other phenomena. For example, when stored in a hot and humid environment of 85°C and 85% humidity for 240 hours, no corrosion or residual marks will appear. Attached Figure Description

[0026] Figure 1 shows the stress distribution curves of Examples 1-23, Examples 2-7, Comparative Examples 1-1 and 2-1 (the vertical axis represents stress, and the horizontal axis represents depth (i.e., the distance from the glass surface to the location at a depth of x inside the microcrystalline glass).

[0027] Figure 2 shows the first derivative curves of the stress distribution curves in Examples 1-23, Examples 2-7, Comparative Examples 1-1 and 2-1.

[0028] Figure 3 shows the stress characteristics (CS50, CS80, CT.AV, CT.LD, DOL.P) of Examples 1-23 and Comparative Examples 1-1;

[0029] Figure 4 shows the number of drop failures of the entire machine in Examples 2-7 and Comparative Example 2-1;

[0030] Figure 5 is a schematic diagram of the stress distribution curve of a microcrystalline glass according to an embodiment of the present invention. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Microcrystalline glass has a wide range of applications, such as in the screen covers (cover glass, CG) of electronic products like mobile phones. However, in related technologies, the stress strength and other properties of microcrystalline glass need further improvement.

[0033] For example, the drop resistance of the screen cover determines the reliability of electronic devices (such as mobile electronic products). Screen covers are usually made of chemically strengthened ordinary glass or microcrystalline glass. Their 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 intensity of the glass material are two effective ways to improve the drop resistance of the screen. One feasible way to improve the intrinsic mechanical properties of the glass material is to use microcrystalline glass with glass phase and nanoscale crystalline phase. Compared with ordinary glass such as traditional aluminosilicate glass, highly crystalline microcrystalline glass has a denser microstructure and better intrinsic mechanical properties (such as higher Young's modulus and fracture toughness), which can improve the drop resistance and damage resistance of the screen to a certain extent.

[0034] However, microcrystalline glass has problems such as low stress strength. Even when 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 suffers from defects such as low stress strength, especially its low deep compressive stress. For example, the 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 components such as screen covers made of this microcrystalline glass.

[0036] In view of this, embodiments of the present invention provide a microcrystalline glass, as shown in the figure, the microcrystalline glass includes: a first surface defining a thickness H and a second surface opposite to the first surface; a compressive stress region, the thickness of the compressive stress region (i.e., the depth of the compressive layer (DOL)) of which is DOL, DOL < 0.5H; the compressive stress in the compressive stress region shows a trend of first increasing and then decreasing with the increase of depth.

[0037] In the microcrystalline glass 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 components such as screen covers using the microcrystalline glass.

[0038] In addition, the microcrystalline glass of the present invention also has good surface quality and surface stress properties, and its central compressive strength (average bursting force) is higher than 16 kgf, and can even reach more than 22 kgf.

[0039] In addition, the microcrystalline glass of the present invention also has good weather resistance. Even when stored or used in a high temperature and high humidity environment, it is not easy to corrode or other phenomena. For example, when stored in a hot and humid environment of 85°C and 85% humidity for 240 hours, it will not corrode or leave any residual marks.

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

[0041] Specifically, the aforementioned 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 into the interior of the microcrystalline glass to a depth of DOL (the depth of DOL measured 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 depth of DOL measured from the first surface (i.e., the depth of the first surface is 0). In other words, the thickness of the first compressive stress zone is DOL. The second compressive stress zone extends from the second surface into the interior of the microcrystalline glass to a depth of DOL (the depth of DOL measured 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 depth of DOL measured from the second surface (i.e., the depth of the second surface is 0). In other words, the thickness of the second compressive stress zone is DOL.

[0042] Specifically, the thickness DOL of the aforementioned 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 to 0.25, and DOL / H can be, 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 any combination thereof.

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

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

[0045] Both the first and second compressive stresses exhibit the stress distribution described above (i.e., the compressive stress in the compressive stress zone initially increases and then decreases with increasing depth). Specifically, the compressive stress in the first compressive stress zone initially increases and then decreases with increasing depth (measured from the first surface), meaning the compressive stress in the first compressive stress zone initially increases and then decreases along the direction away from the first surface. Similarly, the compressive stress in the second compressive stress zone initially increases and then decreases with increasing depth (measured from the second surface), meaning the compressive stress in the second compressive stress zone initially increases and then decreases along the direction away from the second surface. The trend of initially increasing and then decreasing can specifically mean first 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, but are generally basically 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 glass-ceramic glass (i.e., at a depth of 0.5H from the first surface (or the second surface)).

[0047] Specifically, Figure 5 shows the stress curve of the microcrystalline glass. This stress curve is the relationship between stress (compressive stress in the compressive stress zone) and depth. In the coordinate system, the horizontal axis x represents depth, and the vertical axis σ represents stress. Figure 5 shows the stress curves of the first and second compressive stress zones 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 on the horizontal axis is the depth measured from the first surface (i.e., 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 exhibits a bulge in this range, meaning it has a maximum value σ in this range. E1 (the maximum value σ) E1 The stress corresponding to the bulge in the first compressive stress curve (also the maximum compressive stress in the first compressive stress zone) is the change in sign of the first derivative of the first compressive stress curve in the interval 0 to DOL. The second compressive stress curve is located in the interval DOL' to H (the position with depth DOL' from the first surface is the position with depth DOL from the second surface, DOL' = H - DOL), and it has a bulge in this interval, that is, it has a maximum value σ in this interval. E2 (the maximum value σ) E2 The stress corresponding to the bulge in the second compressive stress curve (which is also the maximum compressive stress in the second compressive stress zone) is the change in sign of the first derivative of the second compressive stress curve in the interval DOL' to H.

[0048] Where, σ E1 With σ E2They can be basically 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 can be axially symmetric, that is, the first compressive stress curve and the second compressive stress curve are axially symmetric.

[0049] Specifically, the maximum compressive stress in the aforementioned compressive stress zone can be located at a depth of DOL.P. That is, the compressive stress at depth DOL.P is greater than the compressive stress at other locations within the compressive stress zone. In other words, DOL.P is the depth of the peak compressive layer (DOL.P), and the maximum compressive stress in the compressive stress zone (i.e., the maximum value of the aforementioned stress curve) is the peak compressive stress intensity (i.e., the compressive stress at DOL.P (CS.P)). It can be understood that for the first compressive stress zone, its maximum compressive stress is located at a depth of DOL.P, which is the depth measured from the first surface; for the second compressive stress zone, its maximum compressive stress is located at a depth of DOL.P, which is the depth measured from the second surface.

[0050] Specifically, in the stress curves shown in Figure 5, the maximum value σ of the first compressive stress curve is... E1 The abscissa corresponding to (bulge stress intensity) is DOL.P, which is the sign change of the first derivative of the first compressive stress curve at DOL.P; the maximum value σ of the second compressive stress curve E2 The abscissa corresponding to (bulge stress intensity) is DOL.P', which means that the sign of the first derivative function of the second compressive stress curve changes at DOL.P'.

[0051] Among them, DOL.P < DOL and DOL.P ≥ 5μm (i.e., the bulging stress depth of the compressive stress zone DOL.P ≥ 5μm) can increase the deep compressive stress of the microcrystalline glass and further improve its drop resistance.

[0052] Generally, DOL.P ≤ 0.1H, meaning DOL.P can satisfy 5μm ≤ DOL.P ≤ 0.1H. In other words, in the stress curves shown in Figure 5, the first compressive stress curve has a maximum value σ in the interval of 5μm to 0.1H. E1 Correspondingly, in the stress curves shown in Figure 5, the second stress curve has a maximum value σ in the interval of 0.9H to (H-5μm). E2 ).

[0053] For example, DOL.P can 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 can be a range consisting of 0.01H, 0.02H, 0.03H, 0.04H, 0.05H, 0.06H, 0.07H, 0.08H, 0.09H, or any two of them.

[0054] For example, DOL.P can be 5μm to 200μm, such as 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm or any combination thereof.

[0055] Specifically, the maximum compressive stress (i.e., bulge stress intensity CS.P) in the above-mentioned compressive stress zone 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 improve 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 in the compressive stress zone can be 110MPa to 300MPa, that is, the maximum compressive stress in the first compressive stress zone can be 110MPa to 300MPa, and the maximum compressive stress in the second compressive stress zone can be 110MPa to 300MPa.

[0057] For example, the maximum compressive stress in the aforementioned compressive stress zones (the first compressive stress zone and the second compressive stress zone) can be a range of 110 MPa, 130 MPa, 150 MPa, 180 MPa, 200 MPa, 230 MPa, 250 MPa, 280 MPa, 300 MPa, or any combination thereof. The maximum compressive stress in the first compressive stress zone may be equal to or unequal to the maximum compressive stress in the second compressive stress zone, but is generally substantially equal (as mentioned above, the stress distribution in the first and second compressive stress zones can be substantially axially symmetrical).

[0058] Furthermore, the maximum value of the first derivative (first derivative function) of the stress curve in the aforementioned compressive stress zone within the depth range of 5 μm to 0.1H is greater than 2 MPa / μm. That is, the maximum value of the first derivative (first derivative function) of the stress curve in the first compressive stress zone within the depth range of 5 μm to 0.1H is greater than 2 MPa / μm, and the maximum value of the first derivative (first derivative function) of the stress curve in the second compressive stress zone within the depth range of 5 μm to 0.1H is also greater than 2 MPa / μm. The maximum value of the first derivative of the stress curve in the first compressive stress zone within the depth range of 5 μm to 0.1H may be equal to or unequal to the maximum value of the first derivative of the stress curve in the second compressive stress zone within the depth range of 5 μm to 0.1H, but they are generally approximately equal (as mentioned above, the stress distribution in the first and second compressive stress zones can be approximately axially symmetric).

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

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

[0061] Furthermore, the aforementioned compressive stress zones can also satisfy the following: CS50 ≥ 80 MPa, where CS50 is the compressive stress at a depth of 50 μm in the compressive stress zone. Specifically, the CS50 of the first compressive stress zone (compressive stress at a depth of 50 μm measured from the first surface) is greater than or equal to 80 MPa, and the CS50 of the second compressive stress zone (compressive stress at a depth of 50 μm measured from the second surface) is greater than or equal to 80 MPa. The CS50 of the first and second compressive stress zones may be equal or unequal, but are generally substantially equal (as mentioned earlier, the stress distribution in the first and second compressive stress zones can be substantially axially symmetrical).

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

[0063] Furthermore, the aforementioned compressive stress zones can also satisfy the following: CS80 ≥ 55 MPa, where CS80 is the compressive stress at a depth of 80 μm in the compressive stress zone. Specifically, the CS80 of the first compressive stress zone (compressive stress at a depth of 80 μm measured from the first surface) is greater than or equal to 55 MPa, and the CS80 of the second compressive stress zone (compressive stress at a depth of 80 μm measured from the second surface) is greater than or equal to 55 MPa. The CS80 of the first and second compressive stress zones may be equal or unequal, but are generally substantially equal (as mentioned above, the stress distribution in the first and second compressive stress zones can be substantially axially symmetrical).

[0064] In some embodiments, the CS80 of the above-mentioned compressive stress zone (first compressive stress zone and second compressive stress zone) can specifically satisfy: 55MPa≤CS80≤115MPa.

[0065] Referring again to Figure 5, the microcrystalline glass also includes a tensile stress region (or tensile stress region) located between the first compressive stress region and the second compressive stress region. The tensile stress region is the area where the stress of the microcrystalline glass is manifested as 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 region shows a trend of first increasing and then decreasing. Specifically, it can be that it first gradually increases and then gradually decreases.

[0066] Specifically, as shown in Figure 5, the tension stress zone includes a first tension stress zone connected to the first compressive stress zone and a second tension stress zone located between the first tension stress zone and the second compressive stress zone. That is, the first compressive stress zone, the first tension stress zone, the second tension stress zone, and the second compressive stress zone are connected sequentially. The tensile stress (absolute value) of the first tension stress zone increases along the direction from the first surface to the second surface, while the tensile stress (absolute value) of the second tension stress zone decreases along the direction from the first surface to the second surface (the tensile stress (absolute value) of the second tension stress zone increases along the direction from the second surface to the first surface, while the tensile stress (absolute value) of the first tension stress zone decreases along the direction from the second surface to the first surface), resulting in the tensile stress of the entire tension stress zone first increasing and then decreasing.

[0067] As mentioned above, the compressive stress zone (the first compressive stress zone and the second compressive stress zone) is the region in the glass-ceramic where the stress is compressive, and the tensile stress zone (the first tensile stress zone and the second tensile stress zone) is the region in the glass-ceramic where the stress is tensile. Generally, as shown in Figure 5, the stress at the junction of the tensile stress zone and the compressive stress zone is basically 0 (that is, the stress at the junction of the first tensile stress zone and the first compressive stress zone is basically 0, and the stress at the junction of the second tensile stress zone and the second compressive stress zone is basically 0).

[0068] Specifically, in the coordinate system shown in Figure 5, the stress curves with positive stress values ​​are the stress curves of the compressive stress zone (such as the first compressive stress curve and the second compressive stress curve), and the stress curves with negative stress values ​​are the stress curves of the tensile stress zone (including the first tensile stress curve of the first tensile stress zone (in the interval DOL~0.5H in the coordinate system shown in Figure 5) and the second tensile stress curve of the second tensile stress zone (in the interval 0.5H~DOL' in the coordinate system shown in Figure 5)). 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 (which is 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 thicknesses of the first tensile stress zone and the second tensile stress zone), and the sum of the thicknesses of the second compressive stress zone are equal to the thickness H of the microcrystalline glass (i.e., H = the thickness DOL of the first compressive stress zone + the thickness of the first tensile stress zone + the thickness of the second tensile stress zone + the thickness DOL of the second compressive stress zone).

[0070] The thickness of the first stress zone can be approximately equal to the thickness of the second stress zone, i.e., the thickness of the first stress zone = 0.5H-DOL, and the thickness of the second stress zone = 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. The axis of symmetry is the center position of the glass-ceramic (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 meet). 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 located at the center position of the glass-ceramic. In other words, the tensile stress (absolute value) at the center position of the glass-ceramic is greater than the tensile stress (absolute value) at other positions in the tensile stress zone.

[0072] Specifically, the maximum tensile stress in the tension stress zone can be greater than or equal to 65 MPa (i.e., CT.CV ≥ 65 MPa), which can 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 any combination thereof.

[0073] Furthermore, the average tensile stress at the central region (CT.AV) in the aforementioned tensile stress zone can 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 any combination thereof.

[0074] Specifically, the average tensile stress in the first stress zone can be greater than or equal to 45 MPa, specifically ranging from 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 any two of these ranges; the average tensile stress in the second stress zone can be greater than or equal to 45 MPa, specifically ranging from 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 any two of these ranges.

[0075] Generally, the average tensile stress in the first tension zone, the average tensile stress in the second tension zone, and the average tensile stress in the entire tension zone are basically equal. In practice, the average tensile stress can be obtained by integrating and summing the tensile stress over the entire first tension zone, and then dividing the result by the thickness of the first tension zone; or, the average tensile stress can be obtained by integrating and summing the tensile stress over the entire second tension zone, and then dividing the result by the thickness of the second tension zone.

[0076] In addition, the tensile stress linear density (or tensile stress linear density (CT.LD)) in the above-mentioned tensile stress zone can be greater than or equal to 25 kPa / m (i.e., CT.LD ≥ 25 kPa / m), specifically it can be 25 kPa / m to 65 kPa / m.

[0077] Furthermore, the aforementioned microcrystalline glass may include large-radius metallic elements, whose atomic radii are greater than that of lithium atoms. Specifically, these large-radius metallic elements may include alkali metals and / or alkaline earth metals with atomic radii greater than that of lithium (Li), such as Na. + K + Ru + Cs + Mg 2+ One or more of them.

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

[0079] Generally, microcrystalline glass contains lithium, and lithium and other large-radius metal elements exist in the form of oxides.

[0080] In some specific embodiments, the aforementioned microcrystalline glass may comprise: Li₂O, Na₂O, and K₂O, with the sum of the molar contents of Li₂O, Na₂O, and K₂O being 13%–32%; SiO₂, with the molar content of SiO₂ being 58%–72%; Al₂O₃, with the molar content of Al₂O₃ being 2%–8%; P₂O₅, ZrO₂, and TiO₂, with the sum of the molar contents of P₂O₅, ZrO₂, and TiO₂ being 2%–13%; MgO, CaO, and ZnO, with the sum of the molar contents of MgO, CaO, and ZnO being 0%–3%; and B₂O₃, with the molar content of B₂O₃ being 0%–5%.

[0081] The microcrystalline glass of the present invention may include one or more of the following: lithium silicate system microcrystalline glass, lithium disilicate system microcrystalline glass, lithium feldspar system microcrystalline glass, spinel system microcrystalline glass, etc., but is not limited thereto.

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

[0083] The volume fraction of the crystalline phase in the glass-ceramic can be measured using conventional methods in the art, such as X-ray diffraction (XRD). This involves performing XRD analysis on the glass-ceramic to obtain its XRD spectrum, and then determining the volume fraction based on the relative area of ​​the crystalline phase in the spectrum.

[0084] Furthermore, the damage resistance characteristic value of the microcrystalline glass in the embodiments of the present invention (Figure of merits for damage resistance) satisfies:

[0085] In some specific embodiments, For example, a range consisting of 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 of them.

[0086] in,

[0087] SCE 50 SCE represents the total compressive stress elastic energy from a depth of 50 μm in the microcrystalline glass (compressive stress zone) to the thickness DOL of the compressive stress layer (in μm), where SCE 50 Satisfying Equation 2:

[0088] In Equations 1 and 2, K IC ν 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 σ is a constant, with a value of 0.75 mm; c (x) 2 Let x be the compressive stress at depth x in the glass-ceramic.

[0089] Specifically, the microcrystalline glass of this invention can be obtained from glass raw materials through ion exchange treatment (chemical strengthening process). The glass raw materials used can generally be microcrystalline glass raw materials containing both a glass phase and a crystalline phase. After ion exchange treatment, the microcrystalline glass of this invention is formed. Typically, K in Formulas 1 and 2 above... ICThe fracture toughness, Poisson's ratio, and Young's modulus of the glass material can also be considered. 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 (the microcrystalline glass described in the embodiments of the present invention) obtained after chemical strengthening has essentially the same fracture toughness, Poisson's ratio, and Young's modulus as the glass material used.

[0090] This invention also provides a method for preparing microcrystalline glass, comprising the following steps: contacting a glass raw material with a first salt bath to perform a first ion exchange treatment, thereby obtaining microcrystalline glass; wherein the temperature of the first ion exchange treatment is T1 and the time is t1, satisfying: And / or, the preparation method further includes: bringing the glass raw material after the first ion exchange treatment into contact with a second salt bath for a second ion exchange treatment, wherein the ratio of the amount of sodium 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 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℃, and t2 / t1≤0.5.

[0091] In the above preparation process, the glass raw material is chemically strengthened through ion exchange treatment to obtain the microcrystalline glass (or chemically strengthened microcrystalline glass) of the present invention. Specifically, chemically strengthened microcrystalline glass can be obtained through a one-step chemical strengthening process (i.e., performing one ion exchange treatment on the glass raw material, i.e., only performing a first ion exchange treatment on the glass raw material), or it can be obtained through a multi-step chemical strengthening process (i.e., performing multiple (at least two) ion exchange treatments on the glass raw material, for example, sequentially performing a first ion exchange treatment and a second ion exchange treatment to obtain microcrystalline glass).

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

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

[0094] Furthermore, according to the inventors' research, in the multi-step chemical enhancement process including a first ion exchange treatment and a second ion exchange treatment, the first ion exchange treatment is a positive enhancement process. Through the first ion exchange treatment, large-radius metal ions in the salt bath (such as the aforementioned Na) are removed. + K+ Ru + Cs + Mg 2+ One or more of the following) replace Li in the glass raw material + The first ion exchange treatment 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 glass-ceramic can be increased while the surface tensile stress is reduced. Thus, by performing the first ion exchange treatment and the second ion exchange treatment on the glass raw material in sequence, the characteristics of non-monotonic stress distribution can be obtained.

[0095] Take Na + and Li + Taking ion exchange as an example, under normal circumstances, during the first ion exchange process, the Na in the first salt bath... + The diffusion direction is related to the Li in the glass. + The diffusion direction of Na is monotonic. + Li diffuses from the glass surface towards the center of the glass, while the Li in the glass... + Na diffuses monotonically from the center of the glass to the surface. + The resulting pile-up effect gives the glass material after the first ion exchange treatment a monotonic stress distribution characteristic (its stress distribution curve is similar to the stress curves of Comparative Examples 1-1 and 2-1 in Figure 1). In the second ion exchange treatment, 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 Na+ at a certain depth in the glass... + It must continue to diffuse inwards (i.e.,) while also diffusing outwards to the surface, that is, Na + The content needs to reach its maximum at a certain depth. However, Na... + Even a non-monotonic distribution cannot guarantee a non-monotonic distribution of compressive stress, because stress attenuation due to relaxation effects must be avoided (after attenuation, the stress from any surface to the center of the glass easily reverts to a monotonic distribution). Therefore, considering the above factors, based on the inventors' research, a controllable reverse ion exchange reaction with a weak stress relaxation effect (both forward and reverse strengthening processes) is used, and the Na in both processes is synergistically controlled. + By synergistically matching parameters such as concentration, processing temperature, and time, microcrystalline glass with non-monotonic stress distribution characteristics was obtained.

[0096] For example, in a multi-step chemical strengthening process, T1-T2 can be a range of 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃ or any two of these.

[0097] For example, in a multi-step chemical enhancement process, t2 / t1 can be a range of 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 any two of these.

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

[0099] For example, the time t2 of the second ion exchange treatment can be a range of 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 any combination thereof.

[0100] Specifically, the second salt bath contains sodium and lithium, and may or may not contain other metallic elements (such as potassium). The metallic elements in the second salt bath exist in ionic form; for example, sodium exists as 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 salts and sodium salts, or by melting lithium salts, sodium salts, and potassium salts.

[0101] For example, in the second salt bath, the salt containing the metal element may include nitrates, 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 sodium salt can be greater than, equal to or less than the mass of potassium salt. The second salt bath may or may not contain potassium salt, and correspondingly, the second salt bath may or may not contain potassium element.

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

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

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

[0106] Furthermore, in the multi-step chemical enhancement process, the first ion exchange treatment can satisfy: or, Preferred

[0107] For example, in one or more steps of chemical enhancement treatment, t1 and The difference can be a range of 0, 1h, 2h, 3h, 4h, 5h, 6h or any two of them.

[0108] In some embodiments, during one or more chemical enhancement processes, the temperature T1 of the first ion exchange treatment can be greater than or equal to 400°C. Exemplarily, the temperature T1 of the first ion exchange treatment can be, for example, a range of 450°C, 460°C, 470°C, 475°C, 480°C, 485°C, 490°C, 495°C, 500°C, or any combination thereof.

[0109] In some embodiments, during one or more steps of chemical enhancement treatment, the time t1 of the first ion exchange treatment can be greater than or equal to 8 hours. Exemplarily, the time t1 of the first ion exchange treatment can be, for example, a range of 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, or any combination thereof.

[0110] Specifically, the first salt bath contains sodium and lithium, and may or may not contain other metallic elements (such as potassium). The metallic elements in the first salt bath exist in ionic form; for example, sodium exists as 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, by melting lithium and sodium salts, or by melting lithium, sodium, and potassium salts.

[0111] For example, in the first salt bath, the salt containing the metal element may include nitrates, 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, in the first salt bath, the mass of sodium salt can be greater than, equal to, or less than the mass of potassium salt. The first salt bath may or may not contain potassium salt, and correspondingly, it may or may not contain potassium element.

[0113] For example, in the first salt bath, the ratio of the mass of sodium salt to the sum of the masses of sodium salt and potassium salt can be 20% to 100%, such as a range of 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 98%, 100%, or any two of these. Correspondingly, the ratio of the mass of potassium salt to the sum of the masses of sodium salt and potassium salt can be 0% to 80%, such as a range of 0%, 2%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or any two of these.

[0114] Furthermore, the mass fraction of lithium salt in the first salt bath (i.e., the mass ratio of lithium salt to the first salt bath (i.e., the ratio of the mass of lithium salt to the sum of the masses of all metal salts)) can be 0.005% to 5%, for example, a range of 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 any combination thereof.

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

[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 known as Na) + The ratio of the amount of substance of the cation to the sum of the amounts of all cations 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] Furthermore, in the multi-step chemical enhancement process, the lithium concentration Y2 in the second salt bath can be greater than, equal to, or less than the lithium concentration Y1 in the first salt bath, and the ratio of the mass of sodium salt in the second salt bath to the sum of the masses of sodium salt and potassium salt can be greater than, equal to, or less than the ratio of the mass of sodium salt in the first salt bath to the sum of the masses of sodium salt and potassium salt.

[0118] In practice, the glass material can be preheated first, and then the first ion exchange treatment can be performed. For example, in the multi-step chemical strengthening process that includes forward strengthening and reverse strengthening processes, the glass material can be preheated first, and then the first ion exchange treatment and the second ion exchange treatment can be performed in sequence; in the one-step chemical strengthening process, the glass material can be preheated before the first ion exchange treatment.

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

[0120] In practice, the raw glass material can be placed in a salt bath and kept at a preset temperature for a preset time to perform ion exchange treatment. After the ion exchange treatment, the glass can be subjected to a series of processes including cleaning, polishing, rinsing, and drying (in multiple ion exchange treatments, all steps of the ion exchange treatment can be completed first, followed by the cleaning, polishing, rinsing, and drying processes) to obtain chemically strengthened microcrystalline glass. Water can be used for cleaning.

[0121] As mentioned above, in the preparation process of chemically strengthened glass-ceramics, the glass raw materials used can generally be glass-ceramic raw materials containing both a glass phase and a crystalline phase. Specifically, the glass raw materials can include one or more of the following: lithium silicate system glass-ceramic raw materials, lithium disilicate system glass-ceramic raw materials, lithium feldspar system glass-ceramic raw materials, spinel system glass-ceramic raw materials, etc., but are not limited to these.

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

[0123] Generally, compared to the raw glass, the lithium content in the chemically strengthened glass will be slightly reduced after chemical strengthening treatment, while the content of large-radius metal elements (such as sodium) in the salt bath will be slightly increased, and the other components will remain largely the same.

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

[0125] The chemically strengthened microcrystalline glass prepared by the above-described method can specifically be the microcrystalline glass of the aforementioned embodiments of the present invention. This microcrystalline glass has the characteristics described above, namely: it includes: a first surface defining a thickness H and a second surface opposite to the first surface; a compressive stress region with a thickness DOL, where DOL < 0.5H; and the compressive stress in the compressive stress region first increases and then decreases with increasing depth. For the specific stress distribution and other morphology of this microcrystalline glass, please refer to the aforementioned description of the microcrystalline glass of the embodiments of the present invention, which will not be repeated here.

[0126] This invention also provides an electronic device comprising the aforementioned microcrystalline glass. As described above, the microcrystalline glass of this invention has a non-monotonic stress distribution characteristic, which can improve the stress intensity 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 component, which includes the aforementioned microcrystalline glass. This structural component is, for example, a cover glass (screen cover). The electronic device includes, for example, a mobile phone, tablet, computer, watch, and display screen (such as an automotive display screen).

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

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

[0130] Table 1

[0131] Examples 1-23

[0132] In this embodiment 1, the glass material used is microcrystalline glass material 1. After undergoing a first ion exchange treatment (forward strengthening process) and a second ion exchange treatment (reverse strengthening process) sequentially, microcrystalline glass (thickness H = 0.65 mm) is obtained. The specific preparation process is as follows:

[0133] (1) Preheating treatment: Heat-treat the microcrystalline glass raw material 1 at 400℃ for 0.5h;

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

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

[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 approximately 3:7. + The concentration (i.e., lithium element concentration Y2) is approximately 30 ppm.

[0137] (4) The microcrystalline glass raw material 1 after the second ion exchange treatment is sequentially cleaned, polished, cleaned and dried 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, and the specific conditions are shown in Table 2. Except for the differences shown in Table 2, the other conditions are the same as those in Examples 1-23.

[0139] Examples 2-7: Microcrystalline glass was prepared using microcrystalline glass raw material 2 (thickness H = 0.65 mm) through a one-step chemical strengthening process. The specific preparation process is as follows:

[0140] (1) Preheating treatment: Heat-treat the microcrystalline glass raw material 2 at 400℃ for 0.5h;

[0141] (2) Place the preheated microcrystalline glass material 1 in a salt bath (furnace water) and keep it at 470℃ 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 approximately 9.8:0.2. + The concentration (i.e., the lithium element concentration Y2) is approximately 20 ppm;

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

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

[0145] The stress curves of the microcrystalline glass prepared in Examples 1-23, 2-7, Comparative Examples 1-1 and 2-1 are shown in Figure 1 (Figure 1 only shows the stress curves of the first compressive stress region and the first tensile stress region of the microcrystalline glass; the stress curves of the second compressive stress region and the second tensile stress region are symmetrical with the stress curves of the first tensile stress region, which will not be described again). The first derivative curve of the stress curve is shown in Figure 2.

[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 a monotonic stress distribution; while the glass-ceramics in Examples 1-23 and 2-7 have non-monotonic stress distribution characteristics. The compressive stress in their compressive stress zone first increases and then decreases with increasing depth (DOL.P≥5μm, CS.P≥110MPa), and they have high deep compressive stress. The glass-ceramics in Examples 1-23 and 2-7 all satisfy the condition that the thickness of the compressive stress zone, DOL, is <0. 5H, 5μm≤DOL.P≤0.1H, 110MPa≤CS.P≤300MPa, the first derivative of the stress curve in the compressive stress zone has a maximum value greater than 2MPa / μm in the depth range of 5μm~0.1H, 80MPa≤CS50≤250MPa, 55MPa≤CS80≤115MPa, 45MPa≤CT.AV≤120MPa, 65MPa≤CT.CV≤200MPa, 30KPa / m≤CT.LD≤65KPa / m.

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

[0148] This demonstrates that the chemical strengthening process of this invention can significantly improve the stress strength of glass-ceramics, especially the deep compressive stress, thereby enhancing the drop resistance of glass-ceramics in harsher environments.

[0149] The drop resistance of the microcrystalline glass in Examples 1-23, 2-7, Comparative Example 1-1, and Comparative Example 2-1 was tested according to the following procedure: the microcrystalline glass was made into a screen cover, and then a mobile phone was made using the screen cover; then, a whole-device drop test was conducted under 80-grit SiC sandpaper conditions (i.e., the mobile phone was dropped from a certain height above the sandpaper surface). The results showed:

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

[0151] (2) The mobile phone was dropped from a height of about 1m. The number of drop failures of the whole device in Examples 1-23 and Examples 2-7 was greater than 100 (that is, the mobile phone was dropped 100 times without cracking. Compared with Comparative Examples 1-1 and Comparative Examples 2-1, the number of drop failures of Examples 1-23 and Examples 2-7 increased by at least 100%. Figure 4 shows the number of drop failures of the whole device in Examples 2-7 and Comparative Examples 2-1).

[0152] It can be seen that, compared with Comparative Examples 1-1 and 2-1, the microcrystalline glass of Examples 1-23 and 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 demanding ground scenarios, thereby improving the overall 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, as well as the screen cover (mobile phone glass cover) made from the microcrystalline glass, also exhibit good weather resistance. When stored in a humid and hot environment of 85°C and 85% humidity for 240 hours, no corrosion or residual marks will appear.

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

[0155] Examples 1-22: The difference from Examples 1-1 is that only the first ion exchange treatment is performed (i.e., microcrystalline glass is prepared by a one-step chemical strengthening process). The conditions for 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] Examples 2-1 to 2-6: Microcrystalline glass was prepared by referring to the process of Examples 2-7; wherein, the conditions for ion exchange treatment (one-step chemical strengthening process) are shown in Table 2, and the other conditions are the same except for the differences shown in Table 2.

[0157] Table 2

[0158] Note: The boiler water ratio in Table 2 represents the mass percentage of sodium nitrate and potassium nitrate, with a total mass percentage of 10 parts. For example, "3 sodium 7 potassium" means 3 parts sodium nitrate and 7 parts potassium nitrate (i.e., the mass ratio of sodium nitrate to potassium nitrate is 3:7), "10 sodium" means 10 parts sodium nitrate and 0 parts potassium nitrate (i.e., the salt bath does not contain potassium nitrate), and "9.8 sodium 0.2 potassium" means 9.8 parts sodium nitrate and 0.2 parts potassium nitrate.

[0159] The stress curves of Examples 1-1 to 1-22 and Examples 2-1 to 2-6 were similar to those of Examples 1-23 and 2-7. The maximum value of the first derivative of their stress curves in the depth range of 5 μm to 0.1 H was greater than 2 MPa / μm. Specifically, the CS50, CS80, AT.AV, CT.CV, DOL, DOL.P, CS.P, and CT.LD of the microcrystalline glass prepared in each example and comparative example were compared. The monomer extrusion properties (mean bursting force) are shown in Table 3.

[0160] The extrusion performance of the individual components is measured as follows: the microcrystalline glass is made into a glass cover plate, and a spherical (or hemispherical) extruder is used to extrude 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 point is the average value of the breaking force (or the center extrusion strength of the microcrystalline glass).

[0161] Table 3

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

[0163] Further measurements showed that the microcrystalline glass of Examples 1-1 to 1-22 had a drop failure height exceeding 1.1m, even approaching 1.5m, under 80-grit sandpaper conditions. The microcrystalline glass of Examples 2-1 to 2-6 exhibited a drop failure count exceeding 50 times under the same conditions, generally reaching 100 times or more. Compared to Comparative Examples 1-1 and 2-1, the microcrystalline glass of Examples 1-1 to 1-22 and Examples 2-1 to 2-6 demonstrated excellent drop resistance.

[0164] In addition, the microcrystalline glass of Examples 1-1 to 1-23 and Examples 2-1 to 2-7 all have a central compressive strength higher than 16 kgf, and most of them have a central compressive strength higher than 22 kgf. They also exhibit good surface quality and surface stress properties.

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

[0166] In summary, the microcrystalline glass prepared according to the embodiments of the present invention has a non-monotonic stress distribution characteristic, which enables the microcrystalline glass to maintain excellent impact resistance and drop resistance while having excellent resistance to high temperature and high humidity environments.

[0167] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions 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 microcrystalline glass, characterized in that, include: A first surface defining a 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 < 0.5H; The compressive stress in the compressive stress zone first increases and then decreases with increasing depth.

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

3. The microcrystalline glass 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 microcrystalline glass according to claim 3, characterized in that, The maximum compressive stress in the compressive stress zone is 110MPa to 300MPa.

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

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

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

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

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

10. The microcrystalline glass 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 into the interior of the microcrystalline glass to a depth of DOL, and the second compressive stress zone extends from the second surface into the interior of the microcrystalline glass to a depth of DOL; The microcrystalline glass also includes a tensile stress region located between the first compressive stress region and the second compressive stress region; The average tensile stress in the tension stress zone is greater than or equal to 45 MPa. And / or, the maximum tensile stress in the tension 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 microcrystalline glass according to claim 10, characterized in that, The average tensile stress in the tension stress zone is 45MPa to 120MPa; And / or, the maximum tensile stress in 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 microcrystalline glass according to claim 1, characterized in that, The damage resistance characteristics of the microcrystalline glass satisfy: in, SCE 50 The total compressive stress elastic energy is defined as the total compressive stress elastic energy from a depth of 50 μm to the thickness DOL of the compressive stress layer of the microcrystalline glass, where SCE 50 Satisfying Equation 2: In Equations 1 and 2: K IC The fracture toughness of the microcrystalline glass; v is the Poisson's ratio of the microcrystalline glass; E is the Young's modulus of the microcrystalline glass; H is the thickness of the microcrystalline glass; H max It is a constant, with a value of 0.75 mm; σ c (x) 2 Let x be the compressive stress at depth x of the microcrystalline glass.

13. The microcrystalline glass 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 0-5%.

14. The microcrystalline glass according to claim 1, characterized in that, The microcrystalline glass comprises a glass phase and a crystalline phase, wherein, The crystalline phase includes one or more of the following: 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 microcrystalline glass, characterized in that, Includes the following steps: The glass raw material is brought into contact 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, satisfying: And / or, the preparation method further includes: contacting the glass raw material after the first ion exchange treatment with a second salt bath to perform a second ion exchange treatment, wherein the ratio of the amount of sodium 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 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℃, and t2 / t1≤0.

5.

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

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

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