Glass article

Abstract

The present invention provides a glass article having excellent mechanical strength. In particular, the present invention enables the hardness of the glass article to be predicted from the composition of the glass article, thereby reducing the time and cost associated with fracture testing, while also minimizing variables caused by the measurer or measurement environment, and thus provides a glass article with excellent reliability.

Description

glass items

[0001] The present invention relates to a glass article having excellent mechanical strength.

[0002]

[0003] Glass is widely used in a variety of applications, including vehicle window screens, mirrors, cover glass for touch displays, solar cells, and even flexible display cover windows. Conventionally, glass with compositions such as aluminosilicate and alkali boroaluminosilicate have been used to enhance scratch and impact resistance. However, increasingly higher levels of mechanical strength are required for glass used in various applications, and methods for strengthening glass articles, such as increasing fracture toughness, reducing stress concentration factor, and applying compressive stress, are being employed, as disclosed by JI Lee et al., Ceramist, 24, 287-298.

[0004] The hardness of glass products, such as crack resistance, is typically measured using a Vickers diamond indenter, which induces intermediate or radial cracks (Vickers hardness). Other methods include Knoop hardness and three- or four-point bending tests using UTM equipment. However, these measurement methods require destructive measurements, which poses time constraints for conducting these tests on all glass products under development. Furthermore, results can vary depending on the measurer or measurement environment.

[0005] Accordingly, a technology is required that can predict the hardness of a glass article from its composition, thereby reducing the time and cost consumed in destructive measurement, and at the same time increasing reliability by minimizing variables caused by the measurer or measurement environment.

[0006]

[0007] The present invention provides a glass article with excellent mechanical strength. In particular, the present invention reduces the time and cost of fracture measurement by enabling prediction of the hardness of a glass article based on its composition, while minimizing variables caused by the measurer or measurement environment, thereby providing a glass article with excellent reliability.

[0008]

[0009] The present invention provides a glass article having a hardness (y) satisfying the following equation (1): (1) y = k[MgO] + b, where k is 6.2842±2.5616, b is c[Al2O3] / [SiO2] + d, c is 932.5265±139.825, d is 408.87664±23.87966, [MgO] is the content (mol%) of MgO with respect to the total content of the glass article, [Al2O3] is the content (mol%) of Al2O3 with respect to the total content of the glass article, and [SiO2] is the content (mol%) of SiO2 with respect to the total content of the glass article.

[0010]

[0011] The present invention provides an ultra-thin glass having excellent mechanical strength. In particular, the present invention allows the hardness of a glass article to be predicted based on its composition, thereby enabling non-destructive prediction of the hardness of the glass article. This reduces the time and cost associated with destructive measurements, while minimizing variables caused by the measurer or the measurement environment, thereby providing a highly reliable glass article. Furthermore, the present invention allows for controllable hardness based on the glass composition, thereby facilitating the manufacture of a variety of products suited to the application of the glass article.

[0012]

[0013] The present invention will be described in detail below. However, it is not limited to the following description, and each component may be modified or selectively mixed as needed. Therefore, it should be understood that all modifications, equivalents, and alternatives included within the spirit and technical scope of the present invention are included.

[0014] Vickers hardness is a value that indicates the resistance of a glass article to plastic deformation. Vickers hardness is known to be closely related to the ionic radius and ionic packing ratio of alkaline earth metals. In particular, the mechanical property related to the ionic radius and packing ratio is Young's modulus. Young's modulus can be calculated using the Makashima-Mackenzie model (MM model), and Young's modulus (E) can be expressed by the following equation.

[0015]

[0016] In the above formula,

[0017] is the filling density, , M is the molecular weight, And, is the mole fraction of the composition, Rc is the radius of the cation, R0 is the radius of the oxygen ion,

[0018] is the dissociation energy of the composition,

[0019] is the mole fraction of the composition.

[0020] Although the MM model above confirms that the ionic radii of cations and anions contained in the glass contribute to the filling factor, Young's modulus indicates the deformation of the glass article due to applied stress, and this is limited to the elastic deformation region. However, since Vickers hardness is in the plastic deformation region, Young's modulus alone, which is a mechanical property of the elastic deformation region, is insufficient for explanation.

[0021] Meanwhile, in relation to the relationship between Al and R2O in aluminosilicate glasses, the Anderson-Stuart model for ion conduction has been proposed based on the activation energy and Coulomb energy required for ion conduction, and the influence of glass structure deformation on ion conduction is known. These prior technologies have a higher correlation with the ion exchange depth related to ion movement than with the generation of compressive stress due to chemical toughening based on ion exchange. Recently, attempts have been made to explain the cause of compressive stress that approaches the glass structure, and the tendency of compressive stress for chemically toughened glasses has been identified, but the derivation of accurate result values ​​has not been possible.

[0022] The present invention takes into account that chemical toughening is achieved through ion exchange and that compressive stress can be generated by changes in the glass structure caused by the exchanged ions during ion exchange. Specifically, the composition of the glass was classified into glass network former, glass network intermediate, and glass network modifier according to the classification system (Sun classification) proposed by Kuan-Han Sun in 1947, and ionic conduction by the glass network modifier according to the Al2O3-R2O relationship and the Anderson-Stuart model was considered. Furthermore, the Al2O3-SiO2 relationship and the Al2O3-R2O relationship were considered in consideration of the cause of compressive stress. Comprehensively considering the above facts, experiments were conducted by dividing the glass composition elements classified by Sun classification into absolute amounts and ratios. As a result, factors that can significantly affect ionic conduction and glass structure were identified, and it was confirmed that the relationship between them was linear. From the above, it was confirmed that the present invention can accurately calculate Vickers hardness based on the composition of the glass alone.

[0023] The glass article of the present invention has a hardness (y) that satisfies the following equation (1).

[0024] (1) y = k[MgO] + b

[0025] In the above formula,

[0026] k is 6.2842±2.5616,

[0027] b is c[Al2O3] / [SiO2] + d,

[0028] c is 932.5265±139.825,

[0029] d is 408.87664±23.87966,

[0030] [MgO] is the content of MgO (mol%) relative to the total content of the glass article,

[0031] [Al2O3] is the content of Al2O3 (mol%) relative to the total content of the glass article,

[0032] [SiO2] is the content of SiO2 (mol%) relative to the total content of the glass article.

[0033] In the present invention, the hardness (y) of the glass article is proportional to [MgO] and [Al2O3] / [SiO2]. Depending on [MgO] and [Al2O3] / [SiO2], the atomic structure and the number of alkali metal ions inside the glass change, which in turn affects the hardness.

[0034] The glass article of the present invention comprises SiO2, Al2O3, R2O (R=Li) + , Na + , K + ), R'O (R'=Mg, Ca, Sr, Ba). The glass article of the present invention does not contain a glass-forming oxide with high hygroscopicity, such as B2O3 or P2O5.

[0035] SiO2 is a glass-forming oxide in aluminosilicate glass articles, and plays a role in providing strength to the glass.

[0036] With respect to the total content of the glass article, SiO2 may be included in an amount of 40 to 80 mol%, for example, 55 to 75 mol%. If the content of SiO2 is less than the aforementioned range, the strength of the glass may be reduced, and if it exceeds the aforementioned range, the melting temperature may be increased, which may impair the formability of the glass article.

[0037] Al2O3 functions as an intermediate, charge balancer, or glass-forming oxide in aluminosilicate glass articles, and together with SiO2, it provides strength to the glass. Al2O3 and alkali metal oxide R2O (R=Li) + , Na + , K + ) content affects the structure and properties of aluminosilicate glasses. When Al2O3 is included in the glass composition in excess of R2O, Al2O3 no longer acts as a Si 4+ Not substituted for, Al 5+ , Al 6+ The shape of the glass changes, and the liquid fragility index (m) increases, which can induce crystallization of the glass. In addition, the melting temperature increases as the content of Al2O3 increases, which can hinder the formability of the glass. On the other hand, when there is an excess of R2O than Al2O3, Al ions are substituted for Si, forming AlO4. - , and Li, Na, and K ions are added to AlO4 to play a charge compensation role. - Alkali metal ions that do not participate in chemical toughening can break the Si-O bonds of SiO2, a glass network former, resulting in a decrease in free volume within the glass, which in turn can reduce compressive stress and ion exchange depth.

[0038] The glass article may contain 5 to 25 mol% of Al2O3, for example, 8 to 15 mol%, based on the total content. If the content of Al2O3 is less than the aforementioned range, the strength of the glass may be reduced, and if it exceeds the aforementioned range, crystallization of the glass may be induced or the melting temperature may be increased, thereby hindering the formability of the glass article.

[0039] Alkali metal oxide R2O(R=Li + , Na + , K + ) functions as a modifier or charge compensator. R2O destroys the bonds of the glass former, breaking the Si-O bond to form a non-crosslinked oxide, which lowers the melting point and viscosity of the glass and affects the coefficient of thermal expansion of the glass. For example, Na2O and K2O can be used together as alkali metal oxides, in which case acid resistance can be increased.

[0040] The glass article may contain 8 to 30 mol%, for example, 10 to 25 mol%, of an alkali metal oxide, based on the total content of the glass article. For example, the glass article may contain 8 to 20 mol%, for example, 9 to 18 mol%, of Na2O, and 0 to 10 mol%, for example, 0 to 5 mol%, of K2O, based on the total content of the glass article. If the content of Na2O is less than the aforementioned range, the Na content inside the glass is small, and the number of alkali metals participating in chemical toughening is insufficient, which may lower the compressive stress. If the content of Na2O is more than the aforementioned range, the Si-O bond of SiO2 is broken, which may cause a decrease in the free volume inside the glass, and thus the ion exchange depth may be lowered. If the content of K2O is less than the aforementioned range, acid resistance may be weakened, and if it exceeds the aforementioned range, the Na content inside the glass is small, which may lower the compressive stress and hardness due to chemical toughening.

[0041] Alkaline earth metal oxides R'O (R'=Mg, Ca, Sr, Ba) can affect the Al-avoidance violation, resulting in changes in the internal structure of aluminosilicate glasses.

[0042] For example, alkaline earth metal oxides may include MgO. MgO can significantly improve the melting properties of glass by lowering the density, lowering the high-temperature viscosity without lowering the strain point, and reducing the atomic number of Mg compared to other alkaline earth metals. However, Mg 2+ is Ca 2+ , Sr 2+ , Ba 2+ Compared to Al2O3, it has a high ionic field strength and facilitates the formation of 5- and 6-coordinated aluminum. In the aluminosilicate composition, Al2O3 functions as a glass network former or an intermediate oxide to form a strong network structure of the glass, but when it has 5- and 6-coordination numbers, it causes crystallization of the glass. Therefore, when MgO is included, it causes a violation of the Al-avoidance law of the internal structure of the aluminosilicate glass, inducing Si-O-Si and Al-O-Al bonds, so if it is included in large quantities, it can cause crystal precipitation of Mg-Si-O series. In addition, the high ionic field strength reduces the free volume in the glass, resulting in the formation of Na inside the glass. + K has a larger atomic radius than + It becomes difficult for ions to penetrate into the glass, so the substituted K + This can cause a phenomenon in which the compressive stress caused by ions is lowered or the ion exchange depth is lowered. On the other hand, when CaO, SrO, or BaO is included, the internal structure of aluminosilicate glass may have more Si-O-Al bonds than Al-O-Al or Si-O-Si bonds.

[0043] Vickers hardness is correlated with the ionic radius of alkaline earth metals, and Vickers hardness can increase in the order of Mg > Ca > Sr > Ba depending on the ionic radius of alkaline earth metals. In particular, MgO is known as a component that increases Young's modulus, Vickers hardness, and fracture toughness.

[0044] The glass article may contain 0 to 10 mol%, for example 0 to 8 mol%, of an alkaline earth metal oxide relative to the total content of the glass article. For example, the glass article may contain 0 to 10 mol%, for example 0 to 8 mol%, of MgO relative to the total content of the glass article. If the content of MgO is less than the aforementioned range, melting of the glass material may become difficult, and if it exceeds the aforementioned range, the free volume within the glass may be reduced, making chemical toughening difficult.

[0045] For example, the glass article of the present invention comprises, based on the total content of the glass article, 40 to 80 mol% of SiO2, 5 to 25 mol% of Al2O3, 8 to 20 mol% of Na2O, 0 to 10 mol% of K2O, and 0 to 10 mol% of MgO.

[0046] The glass article of the present invention may further include ZnO, SnO2, CaO, SrO, BaO, and mixtures thereof.

[0047] ZnO has the same electric field strength as MgO, and when ZnO is included, a large number of Si-O-Al bonds can exist in the internal structure of the aluminosilicate glass. The glass article may include 0 to 10 mol% of ZnO, for example, 0 to 8 mol%, based on the total content of the glass article. When the content of ZnO is less than the aforementioned range, melting of the glass material may become difficult, and when it exceeds the aforementioned range, crystallization may occur.

[0048] For example, the glass article of the present invention may include MgO, ZnO, or a mixture thereof. As another example, the glass article of the present invention may include MgO and ZnO. ZnO has the same tensile strength as MgO and a similar glass structure, and thus plays a similar role in the expression of glass properties. However, as the ZnO content increases, a devitrification phenomenon may occur during glass manufacturing, and therefore, the ZnO content included in the glass article is preferably 50 mol% or less of the MgO content, for example, 25 mol% or less, or in another example, 10 mol% or less.

[0049] For example, the glass article may include 0 to 10 mol% of ZnO, for example 0 to 8 mol%, 0 to 0.5 mol% of SnO, for example 0 to 0.3 mol%, 0 to 10 mol% of CaO, for example 0 to 8 mol%, 0 to 10 mol% of SrO, for example 0 to 5 mol%, and 0 to 10 mol% of BaO, for example 0 to 8 mol%, based on the total content of the glass article.

[0050] For example, the glass article of the present invention satisfies the following equation (2).

[0051] (2) [ZnO] + [Y2O3] + [TiO2] + [ZrO2] + [Nb2O5] ≤ [MgO] / 2

[0052] In the above formula,

[0053] [ZnO] is the content of ZnO (mol%) relative to the total content of the glass article,

[0054] [Y2O3] is the content of Y2O3 (mol%) relative to the total content of the glass article,

[0055] [TiO2] is the content of TiO2 (mol%) relative to the total content of the glass article,

[0056] [ZrO2] is the content of ZrO2 (mol%) relative to the total content of the glass article,

[0057] [Nb2O5] is the content of Nb2O5 (mol%) relative to the total content of the glass article,

[0058] [MgO] is the content of MgO (mol%) relative to the total content of the glass article.

[0059] For example, the glass article of the present invention satisfies the following equation (3).

[0060] (3) [Al2O3] / [R2O] < 1

[0061] In the above formula,

[0062] [Al2O3] is the content of Al2O3 (mol%) relative to the total content of the glass article,

[0063] [R2O] is the content of R2O (mol%) relative to the total content of the glass article,

[0064] R is one or more elements selected from the group consisting of Li, Na, and K.

[0065] Al2O3 and alkali metal oxide R2O(R=Li + , Na + , K + ) content affects the structure and properties of aluminosilicate glasses. When Al2O3 is included in the glass composition in excess of R2O, Al2O3 no longer acts as a Si 4+ Not substituted for, Al 5+ , Al 6+ The shape of the glass changes, and the liquid fragility index (m) increases, which can induce crystallization of the glass. In addition, the melting temperature increases as the content of Al2O3 increases, which can hinder the formability of the glass. On the other hand, when there is an excess of R2O than Al2O3, Al ions are substituted for Si, forming AlO4. - , and Li, Na, and K ions are added to AlO4 to play a charge compensation role. -In combination with, alkali metals that do not participate in chemical toughening can break the Si-O bonds of SiO2, which is a glass network former, resulting in a decrease in free volume inside the glass, which can result in a decrease in ion exchange depth. When [Al2O3] / [R2O] ≤ 1 is satisfied, excellent hardness can be secured. In particular, when [Al2O3] / [R2O] < 0.8, or for example, 0.5 < [Al2O3] / [R2O] < 0.7 is satisfied, excellent compressive stress and hardness as well as high formability can be secured.

[0066] For example, the glass article of the present invention satisfies the following equation (4).

[0067] (4) [GNI] / [SiO2] < 0.5

[0068] In the above formula,

[0069] R is one or more elements selected from the group consisting of Li, Na, and K,

[0070] [GNI] is the content (mol%) of GNI (glass network intermediate) relative to the total content of the glass article, GNI is an intermediate oxide with an e value of 60 to 80, e=E / n, and E is the content of 1 mole of oxide (MO y / x ) is the dissociation energy required to completely decompose, and n is the oxygen coordination number of the M atom. For example, GNI may contain oxides of Al, Zn, Ti, Nb, Mn, Fe, Zr, Mo, W, and Ta.

[0071] The GNI and SiO2 contents affect the structure and properties of aluminosilicate glasses. As the [GNI] / [SiO2] ratio increases, the number of bridging oxygens decreases and the non-bridging oxygens increase. An increase in non-bridging oxygen can lead to a decrease in free volume within the glass, resulting in reduced hardness. When the [GNI] / [SiO2] ratio ≤ 0.5 is satisfied, excellent compressive stress can be ensured.

[0072] For example, the glass article of the present invention satisfies the following equation (5).

[0073] (5) [ZnO] < [MgO] / 2

[0074] In the above formula,

[0075] [ZnO] is the content of ZnO (mol%) relative to the total content of the glass article,

[0076] [MgO] is the content of MgO relative to the total content of the glass article.

[0077] The hardness (y) of the glass article of the present invention is equal to the Vickers hardness, and the hardness (y) may be 300 to 1,000 Hv, for example, 500 to 800 Hv. If the hardness (y) is less than the above-mentioned range, the hardness may be insufficient, making it difficult to apply to ultra-thin glass, and if it exceeds the above-mentioned range, the internal structure of the glass may become excessively dense, making chemical toughening through ion exchange difficult.

[0078] The ion exchange depth of the glass article of the present invention is 50% or less, for example, 45% or less, of the total glass thickness, the thickness is 500 μm or less, for example, 30 to 300 μm, the thermal expansion coefficient is 4.0 ppm / C or more, for example, 6 to 20 ppm / C, and the pencil hardness is 3H or more. In addition, the minimum radius of curvature of the glass article of the present invention is 3 mm or less, for example, 1.5 mm or less, another example is 0.3 to 3 mm, and another example is 0.3 to 1.5 mm. When the minimum radius of curvature of the glass article satisfies the above-mentioned range, it is suitable for application to a flexible display according to the development of form factors.

[0079]

[0080] Hereinafter, the present invention will be described in more detail through experimental examples. However, the following examples are intended only to aid understanding of the present invention and are not intended to limit the scope of the present invention in any way.

[0081]

[0082] [Experimental Example 1-9]

[0083] Glass compositions for each experimental example were prepared according to Table 1 below. Glass articles prepared using the glass compositions for each experimental example were heat-treated in an electric oven (100-150°C) for 30 minutes, and then the Vickers hardness was measured according to ASTM E 92, and the results are shown in Table 1 below.

[0084]

[0085]

[0086] y(maximum): maximum value of longitude (y) calculated according to equation (1)

[0087] y(minimum): minimum value of longitude (y) calculated according to equation (1)

[0088]

[0089] As shown in Table 1 above, the hardness (y) of the glass article of Experimental Example 1-9 is consistent with the Vickers hardness. Therefore, according to the present invention, even if the glass article is manufactured and the hardness is not measured by a destructive measurement method, the Vickers hardness of the glass article can be predicted using the hardness value calculated according to Equation (1).

[0090]

[0091] The present invention provides a glass article with excellent mechanical strength. In particular, the present invention reduces the time and cost of fracture measurement by enabling prediction of the hardness of a glass article based on its composition, while minimizing variables caused by the measurer or measurement environment, thereby providing a glass article with excellent reliability.

Claims

1. A glass article whose hardness (y) satisfies the following equation (1): (1) y = k[MgO] + b In the above formula, k is 6.2842±2.5616, b is c[Al2O3] / [SiO2] + d, c is 932.5265±139.825, d is 408.87664±23.87966, [MgO] is the content of MgO (mol%) relative to the total content of the glass article, [Al2O3] is the content of Al2O3 (mol%) relative to the total content of the glass article, [SiO2] is the content of SiO2 (mol%) relative to the total content of the glass article.

2. In paragraph 1, a glass article satisfying the following formula (2): (2) [ZnO] + [Y2O3] + [TiO2] + [ZrO2] + [Nb2O5] ≤ [MgO] / 2 In the above formula, [ZnO] is the content of ZnO (mol%) relative to the total content of the glass article, [Y2O3] is the content of Y2O3 (mol%) relative to the total content of the glass article, [TiO2] is the content of TiO2 (mol%) relative to the total content of the glass article, [ZrO2] is the content of ZrO2 (mol%) relative to the total content of the glass article, [Nb2O5] is the content of Nb2O5 (mol%) relative to the total content of the glass article, [MgO] is the content of MgO (mol%) relative to the total content of the glass article.

3. In paragraph 1, a glass article satisfying the following formula (3): (3) [Al2O3] / [R2O] ≤ 1 In the above formula, [Al2O3] is the content of Al2O3 (mol%) relative to the total content of the glass article, [R2O] is the content of R2O (mol%) relative to the total content of the glass article, R is one or more elements selected from the group consisting of Li, Na, and K.

4. In paragraph 1, a glass article satisfying the following formula (4): (4) [GNI] / [SiO2] < 0.5 In the above formula, [GNI] is the content (mol%) of GNI (glass network intermediate) relative to the total content of the glass article, GNI is an intermediate oxide with an e value of 60 to 80, e = E / n, and E is the content of 1 mole of oxide (MO y / x ) is the dissociation energy required to completely decompose, n is the oxygen coordination number of the M atom, [SiO2] is the content of SiO2 (mol%) relative to the total content of the glass article.

5. In paragraph 1, a glass article satisfying the following formula (5): (5) [ZnO] < [MgO] / 2 In the above formula, [ZnO] is the content of ZnO (mol%) relative to the total content of the glass article, [MgO] is the content of MgO relative to the total content of the glass article.

6. A glass article comprising, in the first paragraph, 40 to 80 mol% of SiO2, 5 to 25 mol% of Al2O3, 8 to 20 mol% of Na2O, 0 to 10 mol% of K2O, and 0 to 10 mol% of MgO with respect to the total content of the glass article.

7. In paragraph 6, a glass article further comprising 0 to 10 mol% of ZnO, 0 to 0.5 mol% of SnO, 0 to 10 mol% of CaO, 0 to 10 mol% of SrO, and 0 to 10 mol% of BaO with respect to the total content of the glass article.

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