CN116969683A - Microcrystalline glass capable of being chemically strengthened and strengthening method and application thereof - Google Patents
Microcrystalline glass capable of being chemically strengthened and strengthening method and application thereof Download PDFInfo
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- CN116969683A CN116969683A CN202310762062.5A CN202310762062A CN116969683A CN 116969683 A CN116969683 A CN 116969683A CN 202310762062 A CN202310762062 A CN 202310762062A CN 116969683 A CN116969683 A CN 116969683A
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- 239000011521 glass Substances 0.000 title claims abstract description 87
- 238000000034 method Methods 0.000 title claims abstract description 35
- 238000005728 strengthening Methods 0.000 title claims abstract description 27
- 239000002241 glass-ceramic Substances 0.000 claims abstract description 55
- 150000003839 salts Chemical class 0.000 claims abstract description 30
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 claims abstract description 28
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 claims abstract description 26
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims abstract description 21
- 239000000919 ceramic Substances 0.000 claims abstract description 20
- 239000011734 sodium Substances 0.000 claims abstract description 19
- 235000010333 potassium nitrate Nutrition 0.000 claims abstract description 14
- 239000004323 potassium nitrate Substances 0.000 claims abstract description 14
- 229910052708 sodium Inorganic materials 0.000 claims abstract description 13
- 235000010344 sodium nitrate Nutrition 0.000 claims abstract description 13
- 239000004317 sodium nitrate Substances 0.000 claims abstract description 13
- 239000005345 chemically strengthened glass Substances 0.000 claims abstract description 12
- 238000004321 preservation Methods 0.000 claims abstract description 9
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Chemical compound [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 claims abstract description 8
- 238000003426 chemical strengthening reaction Methods 0.000 claims description 28
- 229910018068 Li 2 O Inorganic materials 0.000 claims description 15
- 230000008569 process Effects 0.000 claims description 15
- HEHRHMRHPUNLIR-UHFFFAOYSA-N aluminum;hydroxy-[hydroxy(oxo)silyl]oxy-oxosilane;lithium Chemical compound [Li].[Al].O[Si](=O)O[Si](O)=O.O[Si](=O)O[Si](O)=O HEHRHMRHPUNLIR-UHFFFAOYSA-N 0.000 claims description 13
- 229910052670 petalite Inorganic materials 0.000 claims description 13
- 239000006104 solid solution Substances 0.000 claims description 13
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 10
- 229910052760 oxygen Inorganic materials 0.000 claims description 10
- 239000006058 strengthened glass Substances 0.000 claims description 9
- WVMPCBWWBLZKPD-UHFFFAOYSA-N dilithium oxido-[oxido(oxo)silyl]oxy-oxosilane Chemical compound [Li+].[Li+].[O-][Si](=O)O[Si]([O-])=O WVMPCBWWBLZKPD-UHFFFAOYSA-N 0.000 claims description 8
- PAZHGORSDKKUPI-UHFFFAOYSA-N lithium metasilicate Chemical compound [Li+].[Li+].[O-][Si]([O-])=O PAZHGORSDKKUPI-UHFFFAOYSA-N 0.000 claims description 5
- 229910052912 lithium silicate Inorganic materials 0.000 claims description 5
- CNLWCVNCHLKFHK-UHFFFAOYSA-N aluminum;lithium;dioxido(oxo)silane Chemical compound [Li+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O CNLWCVNCHLKFHK-UHFFFAOYSA-N 0.000 claims description 3
- 229910000500 β-quartz Inorganic materials 0.000 claims description 3
- 229910052644 β-spodumene Inorganic materials 0.000 claims description 3
- 238000002425 crystallisation Methods 0.000 description 16
- 230000008025 crystallization Effects 0.000 description 16
- 239000013078 crystal Substances 0.000 description 15
- 238000005342 ion exchange Methods 0.000 description 14
- 238000009826 distribution Methods 0.000 description 7
- 239000000126 substance Substances 0.000 description 7
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- 229910052744 lithium Inorganic materials 0.000 description 5
- 244000137852 Petrea volubilis Species 0.000 description 4
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 230000003287 optical effect Effects 0.000 description 4
- 229910052700 potassium Inorganic materials 0.000 description 4
- 239000011591 potassium Substances 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 210000003127 knee Anatomy 0.000 description 3
- 239000006064 precursor glass Substances 0.000 description 3
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 239000006059 cover glass Substances 0.000 description 2
- 238000004031 devitrification Methods 0.000 description 2
- 238000007496 glass forming Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 2
- 238000005191 phase separation Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- NPYPAHLBTDXSSS-UHFFFAOYSA-N Potassium ion Chemical compound [K+] NPYPAHLBTDXSSS-UHFFFAOYSA-N 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- JFBZPFYRPYOZCQ-UHFFFAOYSA-N [Li].[Al] Chemical compound [Li].[Al] JFBZPFYRPYOZCQ-UHFFFAOYSA-N 0.000 description 1
- OBNDGIHQAIXEAO-UHFFFAOYSA-N [O].[Si] Chemical compound [O].[Si] OBNDGIHQAIXEAO-UHFFFAOYSA-N 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910000272 alkali metal oxide Inorganic materials 0.000 description 1
- 239000005354 aluminosilicate glass Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 238000004453 electron probe microanalysis Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000005357 flat glass Substances 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 230000009477 glass transition Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000007373 indentation Methods 0.000 description 1
- 239000013081 microcrystal Substances 0.000 description 1
- 238000000386 microscopy Methods 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 229910001414 potassium ion Inorganic materials 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 239000006017 silicate glass-ceramic Substances 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000004017 vitrification Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C10/00—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
- C03C10/0018—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition containing SiO2, Al2O3 and monovalent metal oxide as main constituents
- C03C10/0027—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition containing SiO2, Al2O3 and monovalent metal oxide as main constituents containing SiO2, Al2O3, Li2O as main constituents
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C21/00—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface
- C03C21/001—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface in liquid phase, e.g. molten salts, solutions
- C03C21/002—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface in liquid phase, e.g. molten salts, solutions to perform ion-exchange between alkali ions
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K5/00—Casings, cabinets or drawers for electric apparatus
- H05K5/02—Details
- H05K5/0217—Mechanical details of casings
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Dispersion Chemistry (AREA)
- Ceramic Engineering (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Surface Treatment Of Glass (AREA)
- Glass Compositions (AREA)
Abstract
The invention relates to a chemically strengthened glass ceramic, a strengthening method and application thereof, wherein the glass ceramic comprises the following components in percentage by mole 2 55‑78％；Al 2 O 3 2‑15％；Li 2 O16‑30％；P 2 O 5 0.6‑2％；ZrO 2 1‑4％；K 2 O 0‑1％，Na 2 O0-4%. The glass is subjected to heat preservation at 520-560 ℃ and 620-660 ℃ during strengthening, and the obtained microcrystalline glass is subjected to primary strengthening at 420-520 ℃ or secondary strengthening (480-520 ℃ and 490-510 ℃) and can be applied to electronic equipment shells: the primary strengthening salt bath comprises 0-95% of potassium nitrate, 5-100% of sodium nitrate and 0-0.5% of lithium nitrate, and the secondary salt bath comprises 50-100% of sodium nitrate and 0-50% of potassium nitrate, 0-10% of sodium nitrate and 90-100% of potassium nitrate.
Description
Technical Field
The invention belongs to the field of glass ceramics manufacturing, and particularly relates to chemically strengthened glass ceramics, and a strengthening method and application thereof.
Technical Field
With the development and popularization of intelligent mobile electronic devices, consumers put forward higher requirements on anti-drop performance of a housing of the electronic device, and the housing is generally made of cover glass. The cover glass is generally chemically strengthened glass, and the glass can be subjected to ion exchange in a high-concentration potassium nitrate solution or a mixed solution of potassium nitrate and sodium nitrate, so that the strength of the glass is improved, and the purpose of protecting a display screen is achieved.
The glass ceramics have high crack extension resistance, drop resistance and other mechanical properties, high chemical stability and excellent thermal properties. Based on the advantages, the glass ceramics are already applied to the field of cover plate glass of display equipment with high strength requirements.
Since a large number of crystal phases exist in the microcrystalline glass, ion exchange in the crystal phases is difficult to carry out, a certain difficulty is brought to chemical strengthening of the microcrystalline glass, and the strength performance is difficult to meet the requirements of users due to the shallower ion exchange depth, so that the microcrystalline glass cannot be well applied to the shells of electronic equipment.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides the chemically strengthened glass ceramic, the strengthening method and the application thereof, and the anti-falling performance of the strengthened glass ceramic obtained after strengthening is obviously improved, so that the glass ceramic can be well applied to the shell of electronic equipment.
The invention is realized by the following technical scheme:
the glass ceramics capable of being chemically strengthened comprises the following components in percentage by mole: siO (SiO) 2 55％-78％；Al 2 O 3 2％-15％；Li 2 O 16％-30％；P 2 O 5 0.6％-2％；ZrO 2 1％-4％；K 2 O 0-1％，Na 2 O 0-4％。
Preferably, the SiO 2 、Li 2 O and Al 2 O 3 The following relationship is satisfied:
(SiO 2 +Li 2 O)/Al 2 O 3 ＝18-25。
preferably, the glass ceramic comprises 1% -20% of glass phase and 80% -99% of crystalline phase, wherein the crystalline phase is one or more of lithium disilicate, lithium silicate, beta-quartz solid solution, petalite solid solution and beta-spodumene.
Preferably, the Al 2 O 3 5% -8%, P 2 O 5 0.8% -2%, zrO 2 1% -2%.
The method for strengthening chemically strengthened glass ceramics according to any one of the above, comprising the steps of:
s1, siO with the proportion 2 、Al 2 O 3 、Li 2 O、P 2 O 5 、ZrO 2 、K 2 O and Na 2 O is melted and formed into plain glass;
s2, firstly carrying out first heat preservation on plain glass at 520-560 ℃, and then carrying out second heat preservation at 620-660 ℃ to obtain microcrystalline glass;
s3, carrying out chemical strengthening on the glass ceramics for the first time or the second time according to the following process to obtain the strengthened glass ceramics:
the salt bath for primary chemical strengthening comprises, by mass, 0-95% of potassium nitrate, 5-100% of sodium nitrate and 0-0.5% of lithium nitrate, wherein the salt bath temperature is 420-520 ℃;
the secondary chemical strengthening process uses a first salt bath and a second salt bath, wherein the salt bath temperatures are 480-520 ℃ and 490-510 ℃ respectively, the first salt bath comprises 50-100% of sodium nitrate and 0-50% of potassium nitrate according to mass percent, and the second salt bath comprises 0-10% of sodium nitrate and 90-100% of potassium nitrate.
Preferably, in S2, the first heat preservation time is 3-5h, and the second heat preservation time is 1.5-2.5h.
Preferably, in S3, the time for one chemical strengthening is 5-18 hours.
Preferably, in S3, during the secondary chemical strengthening, the glass ceramics are strengthened in the first salt bath for 6-10h.
Preferably, in S3, during the secondary chemical strengthening, the microcrystalline glass is strengthened in the second salt bath for 0.5-1.5h.
Use of the strengthened glass ceramic obtained by the strengthening method of any one of the above-mentioned chemically strengthened glass ceramic in an electronic equipment housing.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention provides a glass ceramics, siO which can be chemically strengthened 2 The network structure for stabilizing the glass is one of components for forming a solid solution of crystalline phase lithium disilicate and petalite, and the concentration of the network structure is too small, so that the content and the grain size of the formed crystalline phase are influenced, and the optical performance is influenced; the concentration should be high enough to form a solid solution phase of petalite, but too high a temperature of melting of the glass would result in difficult formation; al (Al) 2 O 3 The aluminum oxide tetrahedron and the silicon oxide tetrahedron can be interpenetrating into a network structure, the crystallization tendency of glass can be reduced by increasing the content, the thermal stability, the chemical stability, the mechanical strength and the hardness are improved, the depth of an ion exchange layer of microcrystalline glass and the surface stress are increased, but the content of lithium silicate can be reduced by too high, the degree of an interlocking structure can not be reached, and the viscosity of a melt can be increased; li (Li) 2 Insufficient O content affects crystallization effect and strengthening performance; too high a content may decrease the chemical stability of the glass and may decrease the optical properties of the glass-ceramic; k (K) 2 O and Na 2 O tends to reduce the content of crystalline phases, forming a glassy phase, which can lead to deformation or unfavorable thermal expansion during crystallization, an appropriate amount of K 2 O and Na 2 O helps to improve the low temperature meltability and formability of the glass, but too much K 2 O reduces the chemical stability of the glass and excessive Na 2 O can change the types of precipitated crystal phases in the crystallization process and increase the crystal grain size; p (P) 2 O 5 The crystallization nucleus can be formed in the crystallization process of the glass, the formation of crystals is promoted, the crystallinity of the microcrystalline glass is improved, and if the concentration is too low, the precursor glass is not crystallized; too high a concentration, it can be difficult to control devitrification when cooling during precursor glass formation; zrO (ZrO) 2 Can reduce P 2 O 5 The phase separation during glass forming, the crystallization temperature is increased during crystallization, the integrity degree of crystalline phases in the glass ceramics is ensured, the haze of the glass ceramics is reduced, and the ZrO is 1% -4% at high temperature 2 The liquidus viscosity can be obviously reduced, the grain size of the petalite solid solution is reduced, and the transparent microcrystalline glass is formed.
Further, (SiO) 2 +Li 2 O)/Al 2 O 3 The numerical value of (2) can influence the haze and grain size of the glass ceramics, and the number range of (18) to (25) can obtain smaller grains, so that the mechanical strength of the glass ceramics is improved.
The invention provides a strengthening method of glass ceramics capable of being chemically strengthened, and glass ceramics can be obtained by microcrystallizing heat treatment of plain glass. The ion exchange rate is low due to the fact that the temperature is too low during primary chemical strengthening, the glass strength cannot meet the requirement, the temperature is too high, the ion exchange rate is accelerated, the vitrification phenomenon on the surface of glass ceramics is aggravated, a crystalline phase layer is damaged, and the stress relaxation phenomenon of the glass is aggravated due to the fact that the temperature is too high. Compared with the primary strengthening, the secondary chemical strengthening has larger surface compressive stress and deeper ion exchange depth, so that the dropping performance of the glass complete machine after the secondary strengthening is better. The reinforced glass ceramic has higher compressive stress and obvious knee stress, has excellent anti-falling performance, has the depth of a compressive stress layer not smaller than 20% of the thickness of the glass, has the maximum central tensile stress of 58MPa-155.31MPa, and can form a shell of electronic equipment.
The strengthened glass ceramics of the invention ranges from the surface of the glass to 5% of the thicknessIn the stress distribution curve, a peak exists, the slope of all points of the stress distribution is not more than-5 MPa/mu m, and the fracture toughness is not less than 1.2MPa m 1/2 . The surface of the glass generates uniform compressive stress, uniform tensile stress is formed inside the glass, and cracks are prevented from further expanding to a tensile stress area, so that the strength of the glass is improved. The high knee stress enhances the crack propagation resistance of the glass, and effectively prevents further propagation of cracks.
Drawings
FIG. 1 is a graph showing the concentration distribution of sodium element in glass thickness direction of glass ceramics after chemical strengthening of glass ceramics according to the present invention.
FIG. 2 is a graph showing the concentration distribution of potassium element in the glass thickness direction of the glass-ceramic after chemical strengthening.
FIG. 3 is a graph showing the stress of the chemically strengthened glass ceramic of example 4 according to the present invention.
Detailed Description
The invention will now be described in further detail with reference to specific examples, which are intended to illustrate, but not to limit, the invention.
Glasses and glass ceramics (i.e., glass ceramics) can be generally described as lithium-containing aluminosilicate glasses and include SiO 2 、Al 2 O 3 And Li (lithium) 2 O. In addition to SiO 2 、Al 2 O 3 And Li (lithium) 2 In addition to O, the glass and glass-ceramic embodied may further contain two other alkali metal oxides, denoted R 2 O, i.e. K 2 O and Na 2 O. The invention relates to a chemically strengthened microcrystalline glass, which comprises the following components in percentage by mole: siO (SiO) 2 ：55％-78％；Al 2 O 3 ：2％-15％；Li 2 O：16％-30％；P 2 O 5 ：0.6％-2％；ZrO 2 ：1％-4％；K 2 O：0-1％，Na 2 O：0-4％。
Further, (SiO) 2 +Li 2 O)/Al 2 O 3 The numerical range of (2) is 18-25.
OptimizationIn the range of SiO 2 ：65％-75％；Al 2 O 3 ：5％-8％；Li 2 O：18％-30％；P 2 O 5 ：0.8％-2％；ZrO 2 ：1％-2％。
The glass ceramic comprises 1% -20% of glass phase and 80% -99% of crystalline phase, wherein the crystalline phase is one or more of lithium disilicate, lithium silicate, beta-quartz solid solution, petalite solid solution and beta-spodumene, and all crystalline phases of the lithium aluminum silicate glass ceramic are included, and the petalite solid solution and the lithium disilicate serve as main crystalline phases.
Petalite solid solution (liaalsi) 4 O 10 ) Is monoclinic crystal, has smaller grain size, can be used as a lithium source for ion exchange, and is used as a low expansion phase to improve the heat shock resistance of microcrystalline glass. Furthermore, the petalite solid solution may be chemically strengthened in a salt bath, wherein Na + (and/or K) + ) Substitution of Li in petalite solid solution structure + So that the surface of the glass ceramics generates a compressive stress layer and the strength is improved.
Lithium disilicate (Li) 2 Si 2 O 5 ) Is based on { Si 2 O 5 The rhombohedral of the corrugated sheet of the tetrahedral array, lithium disilicate crystals are generally flat or plate-like and have distinct dissociation planes. Because of the microcrystalline structure of the randomly oriented interlocking crystals, crack deflection and crack tip passivation are caused, thereby preventing crack propagation and improving inherent mechanical strength and fracture toughness of the glass-ceramic.
SiO 2 The glass ceramic is a basic component of the glass ceramic, is used for stabilizing a network structure of the glass, and is one of components for forming crystalline phase lithium disilicate and petalite solid solution. Too small a concentration thereof may affect the content of the formed crystal phase and the crystal grain size, thereby affecting the optical properties; the concentration should be high enough to form a solid solution phase of petalite, but SiO 2 Too high a concentration can result in a high glass melting temperature and difficulty in shaping. Thus, siO 2 The content of (2) is 55% to 78%, more preferably 65% to 75%.
Al 2 O 3 Is to form a glass network structureThe components of the glass are formed into a network structure by interpenetrating aluminum oxide tetrahedron and silicon oxygen tetrahedron, and the content is increased, so that the crystallization tendency of the glass can be reduced, the thermal stability, the chemical stability, the mechanical strength and the hardness are improved, and the depth of an ion exchange layer and the surface stress of the microcrystalline glass are increased. However, the content is too high, which can reduce the content of lithium silicate, cannot reach the degree of the interlocking structure, and can increase the viscosity of the melt. Thus, al 2 O 3 In the range of 2% to 15%, more preferably 5% to 8%.
Li 2 O is an essential component of the crystal phase composition and is also an essential component for chemical strengthening. The insufficient content can affect crystallization effect and strengthening performance; too high a content may decrease the chemical stability of the glass and may decrease the optical properties of the glass-ceramic. Thus Li 2 O is in the range of 16% to 30%, more preferably 18% to 30%.
It is found through experiments that SiO 2 、Al 2 O 3 And Li (lithium) 2 The proportional relationship between O has a certain influence on the crystallization of glass ceramics, specifically, (SiO) 2 +Li 2 O)/Al 2 O 3 The value of (2) affects the haze and grain size of the glass-ceramic, (SiO) 2 +Li 2 O)/Al 2 O 3 The numerical range of (2) is 18-25, so that smaller grains can be obtained, and the mechanical strength of the glass ceramics is improved.
K 2 O and Na 2 O tends to reduce the content of crystalline phases, forming a glassy phase, which can lead to distortion or unfavorable thermal expansion of the crystallization process. Thus, a proper amount of K 2 O and Na 2 O contributes to improvement of low-temperature meltability and formability of glass. But too much K 2 O reduces the chemical stability of the glass and excessive Na 2 O can change the types of precipitated crystal phases in the crystallization process and increase the grain size. Thus, K is 2 O and Na 2 O ranges from 0 to 1% and 0 to 4%, respectively.
P 2 O 5 Can form crystal nucleus in the crystallization process of glass, promote the formation of crystal and improve the crystallinity of microcrystalline glass. If the concentration is too low, the precursor glass does not crystallize; too high a concentration, too high a formation of precursor glassDuring cooling, it can be difficult to control devitrification. Thus, P 2 O 5 The addition range of (2) is 0.6% to 2%, more preferably 0.8% to 2%.
ZrO 2 Can reduce P 2 O 5 The phase separation during glass forming and crystallization raise the crystallization temperature, ensure the integrity of crystal phase in glass ceramics and reduce the haze of glass ceramics. At high temperature, 1% -4% ZrO 2 The liquidus viscosity can be obviously reduced, the grain size of the petalite solid solution is reduced, the transparent microcrystalline glass is formed, and more preferably, the grain size is 1% -2%.
The strengthening method of the invention comprises the following steps: the raw materials are firstly melted and formed into glass, the forming process comprises fusion forming, slot drawing, float and other forming processes known to those skilled in the art, the glass is subjected to microcrystal heat treatment (firstly, the temperature is raised to 520-560 ℃ from room temperature, the temperature is kept for 3-5h, then the temperature is raised to 620-660 ℃ continuously, the temperature is kept for 1.5-2.5 h) to obtain microcrystalline glass with the thickness generally below 1.1mm, and the microcrystalline glass is reinforced to obtain the reinforced microcrystalline glass.
Specifically, the microcrystalline glass is subjected to one-time chemical strengthening or two-time chemical strengthening. The glass is placed in a salt bath with the temperature of 420-520 ℃ and the concentration of 0-95wt% of potassium nitrate, 5-100wt% of sodium nitrate and 0-0.5wt% of lithium nitrate for chemical strengthening, the ion exchange rate is low when the temperature is too low, the glass strength cannot meet the requirements, the temperature is too high, the ion exchange rate is accelerated, the glass transition phenomenon on the surface of microcrystalline glass is aggravated, a crystalline phase layer is damaged, the stress relaxation phenomenon of the glass is aggravated when the temperature is too high, and the chemical strengthening time is 5-18h.
Two salt baths, a first salt bath and a second salt bath, are used for the secondary chemical strengthening, and the first salt bath comprises: 50-100% of sodium nitrate and 0-50% of potassium nitrate, wherein the second salt bath comprises 0-10% of sodium nitrate and 90-100% of potassium nitrate, and the temperature is 480-520 ℃ and the chemical strengthening time is 6-10h when the first chemical strengthening is performed. In the second chemical strengthening, the temperature is 490-510 ℃ and the chemical strengthening time is 0.5-1.5h. Compared with the primary strengthening, the secondary strengthening glass has larger surface compressive stress and deeper ion exchange depth, so that the whole glass after the secondary strengthening has better falling performance.
The reinforced glass ceramic has higher compressive stress and excellent anti-falling performance, can form glass products, and has the most wide application in manufacturing shells of electronic equipment.
The fracture toughness of the strengthened glass ceramics is measured using a known method, for example, using the vickers hardness indentation method, according to GB/T37900-2019.
It should be noted that, when the technical scheme of the present invention is popularized and applied in a large scale, some impurities are inevitably contained in the above raw materials due to the production equipment, but the exertion of the above functions and the realization of the performance are not affected.
The strengthened glass ceramic is transparent and has a suitable thickness, typically 0.3-1.1mm, and a depth of layer under compressive stress (DOL) of not less than 20% of the glass thickness, e.g., DOL can be 100-300 μm, 120-280 μm, 150-250 μm. And in various embodiments has a maximum compressive stress of 200-400 MPa. The maximum compressive force may also be 210 to 400MPa, 230 to 380MPa, 250 to 350MPa. The maximum central tensile stress is 58MPa to 155.31MPa.
The concentration profile of the various components in the glass was measured by electron probe microscopy. For example, EPMA can be used to measure the value of glass after compressive stress increases due to alkali ion exchange into the glass, so that Na in the glass-ceramic thickness direction can be measured 2 O and K 2 O content. The glass ceramics of the present invention are subjected to a temperature of 500 ℃ and contain 90% nano 3 、10％KNO 3 Is treated by salt bath for 8 hours; then contain 93% KNO at 500 DEG C 3 、7％NaNO 3 The law of the change of the sodium and potassium ion concentration of the obtained strengthened microcrystalline glass along the thickness direction from the surface of the glass to the center of the glass after the glass is treated for 45min is shown in figures 1 and 2. As shown in FIG. 1, na at the surface of glass-ceramic + The concentration is not less than 2wt%, and the chemically strengthened ion exchange depth reaches 50% of the glass thickness, and the concentration is Na from the glass surface to the glass center + The concentration gradually decreases. As shown in FIG. 2, K + The potassium element is firstly increased and then reduced to the minimum value, the potassium element is increased to the maximum value at the position 20-30 mu m away from the surface of the glass ceramics, the maximum value is 12wt percent, and the potassium element is spiked at the position 20 mu m away from the surface of the glass ceramics.
Stress curves for strengthened glass ceramics are shown in FIG. 3 as measured by the Refractive Near Field (RNF) method and FSM-6000LE and SLP-2000 combination described in U.S. Pat. No. 8,854,623 to System and method for measuring profile characteristics of glass samples. Glass ceramics subjected to a temperature of 500 ℃ containing 90% NaNO 3 、10％KNO 3 Is treated by salt bath for 8 hours; then contain 93% KNO at 500 DEG C 3 、7％NaNO 3 And (3) treating the glass in a salt bath for 45min to obtain the strengthened microcrystalline glass. The stress distribution curve of FIG. 3 contains significant knee stress CS K 150MPa, larger CS K The method can meet the requirements of manufacturing the shell of the electronic equipment, can increase the falling performance of the complete machine simulated by the reinforced glass ceramics in the rough sand paper, particularly the medium rough sand paper, and adopts the medium rough sand paper with the numerical value of 0.7-1.4m in the data acquisition process of the following embodiment. As can be seen from FIG. 3, there is a peak in the stress distribution curve from the glass surface to 5% of the glass thickness (0.6 mm), the slope of all points of the stress distribution is not more than-5 MPa/. Mu.m, the fracture toughness and the stress are positively correlated, and not less than 1.2 MPa.m 1/2 . After chemical strengthening, the surface of the glass ceramics can generate uniform compressive stress, uniform tensile stress is formed in the glass ceramics, and cracks can be prevented from further expanding to a tensile stress area, so that the strength of the glass is improved. High CS K The crack propagation resistance of the glass is enhanced, and further propagation of cracks is effectively prevented, so that when the rough sand paper falls, cracks are generated by sharp object impact, but the cracks are difficult to further propagate.
Examples
For easier and easier understanding of the various embodiments, the present invention describes the relevant process and parameters, performance data in the form of tables plus data, with the thickness of the sample in each example being 0.6mm.
Table 1a relevant process and parameter, performance data for examples 1-4
TABLE 1b relevant process and parameter, performance data for examples 5-8
Claims (10)
1. The glass ceramics capable of being chemically strengthened is characterized by comprising the following components in percentage by mole: siO (SiO) 2 55％-78％；Al 2 O 3 2％-15％；Li 2 O16％-30％；P 2 O 5 0.6％-2％；ZrO 2 1％-4％；K 2 O 0-1％，Na 2 O 0-4％。
2. The chemically strengthened glass ceramic of claim 1 wherein the SiO 2 、Li 2 O and Al 2 O 3 The following relationship is satisfied:
(SiO 2 +Li 2 O)/Al 2 O 3 ＝18-25。
3. the chemically strengthened glass ceramic of claim 1, wherein the glass ceramic comprises 1% -20% glass phase and 80% -99% crystalline phase, the crystalline phase being one or more of lithium disilicate, lithium silicate, beta-quartz solid solution, petalite solid solution, and beta-spodumene.
4. The chemically strengthened glass ceramic according to claim 1, wherein the Al 2 O 3 5% -8%, P 2 O 5 0.8% -2%, zrO 2 1% -2%.
5. The method for strengthening chemically strengthened glass ceramics according to any one of claims 1 to 4, comprising the steps of:
s1, siO with the proportion 2 、Al 2 O 3 、Li 2 O、P 2 O 5 、ZrO 2 、K 2 O and Na 2 O is melted and formed into plain glass;
s2, firstly carrying out first heat preservation on plain glass at 520-560 ℃, and then carrying out second heat preservation at 620-660 ℃ to obtain microcrystalline glass;
s3, carrying out chemical strengthening on the glass ceramics for the first time or the second time according to the following process to obtain the strengthened glass ceramics:
the salt bath for primary chemical strengthening comprises, by mass, 0-95% of potassium nitrate, 5-100% of sodium nitrate and 0-0.5% of lithium nitrate, wherein the salt bath temperature is 420-520 ℃;
the secondary chemical strengthening process uses a first salt bath and a second salt bath, wherein the salt bath temperatures are 480-520 ℃ and 490-510 ℃ respectively, the first salt bath comprises 50-100% of sodium nitrate and 0-50% of potassium nitrate according to mass percent, and the second salt bath comprises 0-10% of sodium nitrate and 90-100% of potassium nitrate.
6. The method for strengthening glass ceramics capable of being chemically strengthened according to claim 5, wherein in S2, the time for the first heat preservation is 3-5 hours, and the time for the second heat preservation is 1.5-2.5 hours.
7. The method for strengthening glass ceramics according to claim 5, wherein in S3, the time for one chemical strengthening is 5 to 18 hours.
8. The method for strengthening glass ceramics according to claim 5, wherein in S3, the glass ceramics is strengthened in the first salt bath for 6 to 10 hours during the secondary chemical strengthening.
9. The method for strengthening glass ceramics according to claim 5, wherein in S3, the glass ceramics is strengthened in the second salt bath for 0.5 to 1.5 hours during the secondary chemical strengthening.
10. Use of a strengthened glass ceramic obtained by the strengthening method of a chemically strengthened glass ceramic according to any one of claims 5 to 9 in an electronic equipment enclosure.
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