KR20170077480A - Li2O-Al2O3-SiO2 transparent crystallized glass and the manufacturing method of the same - Google Patents

Abstract

The invention LAS having an _{Li 2 O-Al 2 O 3} -SiO 2 transparent crystallized glass-based, and as it relates to a process for the preparation, more specifically as the glass composition of _{Li 2 O, Al 2 O 3} , SiO 2 into a basic composition In the glass-based glass, TiO ₂ and ZrO ₂ are further added to the LAS-based glass, and the beta- phase spudumin is the main crystal phase, and the crystal size of the beta-spondumin exceeds the lower limit of the wavelength of the visible light region Wherein the glass transition temperature of the Li ₂ O-Al ₂ O ₃ -SiO ₂ -based transparent crystallized glass is in the range of 100 to ₂₀₀ ° C.
According to the present invention, by using the lithium aluminosilicate glass, the optimal crystal growth temperature is set according to the nucleation temperature through the thermal parallax analysis to suppress the growth of the crystal growth, and Li ₂ O-Al ₂ O ₃ -SiO ₂ -based transparent crystallized glass can be expected.

Description

Li2O-Al2O3-SiO2 transparent crystallized glass and production method thereof [0002] Li2O-Al2O3-SiO2 transparent crystallized glass and the manufacturing method of the same [

The present invention relates to a transparent crystallized glass of Li ₂ O-Al ₂ O ₃ -SiO ₂ system and a method for producing the same, and more particularly, to a LAS system glass having a basic composition of Li ₂ O, Al ₂ O ₃ and SiO ₂ In the LAS-based glass, TiO ₂ and ZrO ₂ are further added, and the beta- state spodumin is the main crystal phase. The crystal size of the beta- state spodumin does not exceed the lower limit of the wavelength of the visible light region to provide _{Li 2 O-Al 2 O 3} -SiO 2 based transparent crystallized glass as set.

Although the glass material has the largest transparency, it has a low brittleness and low mechanical properties. In order to compensate for these disadvantages, the thermal and mechanical properties are improved through crystallization. In this case, the transmittance is lowered due to the interfacial scattering between the precipitated crystal phase and the glass phase or the refractive index difference. However, when the characteristics such as the type, size and refractive index of the crystal phase are well controlled, a transparent crystallized glass can be obtained. Since the crystallized glass is transparent and utilizes excellent thermal / mechanical properties, And the application to the substrate glass is being developed.

Crystallized glass has been transformed into a fine, homogeneous aggregate of crystals by reheating glass of suitable composition. Since the glass is formed in a glassy state, a complicated shape can be obtained and the mechanical properties can be improved by adjusting the crystal grain size according to the heat treatment method And the coefficient of thermal expansion can be controlled.

In addition, since the crystallized glass can be mass-produced by a general glass manufacturing process, it can be applied to a chemical container or a heat-resistant table requiring high thermal shock resistance and high strength, and a high-temperature lamp requiring thermal stability.

Therefore, LAS (SiO ₂ -Al ₂ O ₃ -Li ₂ O) -based glass which has a coefficient of thermal expansion close to zero and a high transmittance in the crystallized glass has been actively studied.

The crystallization of the glass is divided into two stages, nucleation and crystal growth, and the main crystal phase is formed in the nucleation stage and the grain size of the main crystal phase is determined in the crystal growth stage. In order to make the crystallized glass transparent, the size of the nucleated particles should be less than 100 nm smaller than the visible light region (400 to 800 nm), or the refractive index difference between the crystalline phase and the residual glass phase should be small and optically isotropic.

According to the conventional patents of WO2013124373, WO2008065167, JP1020030055689 and the like, β-quartz is prone to have transparency mainly in the production of transparent crystallized glass, and thus many studies have been made as the main crystalline phase of transparent crystallized glass. The crystallized glass having the β-spodumene crystal phase as another main crystal phase of the lithium aluminosilicate crystallized glass has advantages of having high mechanical strength and low thermal expansion coefficient, but it is opaque and whitening (WO2012016724, WO2014132005, WO200304429).

DISCLOSURE OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to adjust the size of crystal grains of crystallized glass having β-spodumene as a main crystal phase, A1 A Li ₂ O-Al ₂ O ₃ -SiO ₂ transparent crystallized glass capable of increasing transparency despite the use of β-spodumene and a process for producing the same are provided.

Crystallization glasses having β-spodumene as a main crystal phase were crystallized by controlling the degree of crystal growth by setting heat treatment conditions such as the temperature at which crystal growth was minimized by thermal parallax analysis. The size of the crystal grains was smaller than 400 nm and optically isotropic Thereby obtaining a transparent crystallized glass. Therefore, the β-spodumene phase is formed through heat treatment for the lithium aluminosilicate glass of the present invention and the temperature and the crystal growth temperature at which nucleation can be maximized through the thermal parallax analysis are set, To minimize crystallization of the glass.

In order to achieve the above object, the present invention provides an LAS-based glass having a basic composition of Li ₂ O, Al ₂ O ₃ and SiO ₂ , wherein TiO ₂ and ZrO ₂ are further added to the LAS- And the crystal size of the beta-spondumin does not exceed the lower limit value of the wavelength of the visible light region, and a transparent crystallized glass of Li ₂ O-Al ₂ O ₃ -SiO ₂ system is provided do.

It is preferable that Na ₂ O and BaO are further added to the LAS-based glass in order to lower the melting point.

It is preferable that ZnO is further added to the LAS-based glass for spheroidizing the nucleus.

It is preferable that P ₂ O ₅ is further added to the LAS-based glass in order to increase the solubility of ZrO ₂ .

It is preferable that MgO and CaO are further added to the LAS-based glass.

The crystallized glass may be SiO ₂ 20 to 25 parts by weight of Al ₂ O ₃ , 2 to 5 parts by weight of Li ₂ O 2, 1 to 2 parts by weight of Na ₂ O, 1 to 2 parts by weight of MgO, 1 to 2 parts by weight of CaO, To 2 parts by weight, ZnO 1 to 2 parts by weight, ZrO ₂ 1 to 5 parts by weight, TiO ₂ 1 to 5 parts by weight, Sb ₂ O ₃ 0.5 to 1 part by weight, and P ₂ O ₅ 5 to 10 parts by weight.

The particle size of the beta-form spodumene contained in the crystallized glass is preferably 15 to 150 nm.

The crystallized glass preferably has a coefficient of thermal expansion of 1.6 to 3.0 10 ^-6 / ° C in the range of 0 to 300 ° C.

The crystallized glass preferably has a transmittance to visible light of at least 75%.

(A) analyzing a crystal growth peak according to a nucleation temperature through thermal parallax analysis for the mother liquor for producing the crystallized glass of claim 1; (b) identifying a nucleation temperature for growing the crystal according to the size of the crystal growth peak; And (c) determining the size of the crystal by growing the crystal at the identified nucleation temperature. The crystallized glass of Li ₂ O-Al ₂ O ₃ -SiO ₂ based clear crystal glass Provides a method for setting nucleation conditions.

It is preferable to set the nucleation temperature so that the size of the crystal grows smaller than the lower limit of the wavelength of the visible light region.

It is preferable that the temperature is in the range of 740 캜 to 770 캜.

It is preferable that the holding time for crystallization at this temperature is 1 to 4 hours.

The present invention also relates to a process for producing a glass raw material mixture comprising the steps of: preparing a glass raw material mixture containing a starting material for producing Li ₂ O, Al ₂ O ₃ , SiO ₂ based glass; Heating and melting the glass raw material mixture; Molding the molten glass raw material mixture in a mold and slowly cooling the glass raw material mixture to produce a glass molded body; Heating the glass compact to a plurality of temperatures and performing thermal parallax analysis to derive respective nucleation temperatures according to respective crystal growth peaks; And a step of producing a crystallized glass, by deriving the nucleation temperature of the temperature at which the formation of the crystal grains that are smaller than the visible light wavelength of growing a sports dyumin crystal phase on the beta at this temperature; Li ₂ O, characterized in that it comprises a -Al ₂ O ₃ -SiO ₂ based transparent crystallized glass.

It is preferable that the temperature is in the range of 740 캜 to 770 캜.

It is preferable that the holding time for crystallization at this temperature is 1 to 4 hours.

According to the present invention, by using the lithium aluminosilicate glass, the optimum crystal growth temperature is set according to the nucleation temperature through the thermal parallax analysis to suppress the growth of the crystal growth, so that the high thermal expansion coefficient -spodumene phase as a main crystal phase is expected to produce a transparent crystallized glass with lithium aluminosilicate.

It is expected that the crystallization glass can be manufactured by applying the above-mentioned composition in addition to the nucleation and crystal growth temperature conditions in which the particle size is minimized through thermal parallax analysis.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagram showing the thermal parallax analysis of the parent glass of the present invention.
FIG. 2 is a graph showing the results of analysis of the area and the temperature change of the crystal growth peak according to the nucleation temperature according to an embodiment of the present invention through thermal parallax analysis. FIG.
3 is a graph showing a change in transmittance according to a set heat treatment condition according to an embodiment of the present invention.
4 is a photograph showing a SEM surface observation result for confirming the grain size of a crystal phase, according to an embodiment of the present invention.
FIG. 5 is a graph showing the XRD analysis results for the main crystal phase analysis of the crystallized glass according to an embodiment of the present invention.
FIG. 6 is a graph showing a change in thermal expansion coefficient according to a predetermined heat treatment condition of a crystallized glass according to an embodiment of the present invention. FIG.

Hereinafter, the present invention will be described in more detail based on the accompanying drawings and preferred embodiments.

The crystallized glass containing β-spodumene solid solution as the main crystal phase of the present invention is represented by wt%, the total weight of β-spodumene is at least 98 wt%, and the main nucleating agent is a composition based on TiO ₂ and ZrO ₂ .

<Production Example>

For the production of the glass, batches were mixed in a ball mill for 8 hours, then placed in an alumina crucible, heated to 1650 ° C. and maintained at the same temperature for 4 hours or longer. The molten glass was molded into a graphite mold and annealed at 600 ° C for 2 hours. In order to analyze the crystal growth peaks according to the nucleation temperature by performing the thermal parallax analysis on the molded glass, the powder obtained by pulverizing the produced glass into 400 to 600 μm was prepared and the nucleation temperature was 700, 720, 740 and 760 ℃, and the crystal growth peaks were analyzed by thermal parallax analysis.

The peak change according to the nucleation temperature is shown in FIG.

As shown in the figure, the area of the first exothermic peak decreases as the nucleation temperature increases and the temperature of the peak of crystallization decreases as the nucleation temperature increases.

This phenomenon means a decrease in the energy required for crystallization as the nucleation temperature increases, indicating that the degree of crystal growth is reduced. Therefore, it is estimated that nucleation is increased and crystal growth is decreased when nucleation temperature is increased.

When the nucleation temperature is higher than 770 ° C., the nucleation temperature is set from 700 ° C. to 760 ° C. since the first exothermic peak disappears and becomes white. Therefore, as shown in Table 1, the optimum temperature was set according to the increase of the nucleation temperature, and the heat treatment was performed for 4 hours to maximize nucleation and crystal growth in each heat treatment.

However, the time required for the crystallization can be determined within a range of 1 to 4 hours. If the nucleation and crystallization time are less than 1 hour, it is confirmed that the nucleation occurs during the reheating treatment, The time required for crystallization was set to 4 hours or less because there was no significant difference in properties between the case of 4 hours treatment and the case of the case of abnormal heat treatment.

Nucleation temperature (° C) Nucleation time (hr) Crystallization temperature (캜) Crystallization time (hr) HT1 700 4 855 4 HT2 720 4 850 4 HT3 740 4 840 4 HT4 760 4 810 4

<Measurement example>

For the permeability analysis, a UV spectrophotometer V570 from Jasco was used. The specimen was 4 mm thick and polished to 400 ~ 2000 mesh. The analysis area was the visible light area (380 ~ 780nm) and the average of the measured values in the area was obtained. This is because the transparency can be higher when the grain size of the visible region is smaller than the wavelength of the visible region. By analyzing the transmittance in the visible region, it is possible to derive the growth conditions of the crystal grains having the desired grain size.

The present invention relates to a transparent glass which is produced in accordance with a condition for growing crystal grains so as to have a crystal grain size not exceeding the wavelength of a visible light region and a condition thereof.

JEOL's JSM-7610F FE-SEM was used to analyze the particle size. The specimens were surface-polished after the crystallization. The specimens were etched in a 3% HF solution for 15 seconds and then coated with Pt. The surface of the crystallized specimen was observed.

For crystallization analysis, XRDD / Max-3C from Rigaku was used and analyzed in the region of 10 ~ 80 ° using CuKα (= 1.5418nm) line at 40KV 30mA. The program used for phase analysis was PANalytical's Highscore plus and XRD analysis was analyzed with ICDS database.

The thermal expansion coefficient was measured in the range of 30 to 300 ° C. TMA Q400 of TA Instrument Korea was used as the measuring device. The sample was prepared at 10 × 10 × 4 mm and the rate of temperature rise was measured at 300 ° C. at a rate of 10 ° C./min.

&Lt; Evaluation example &

The results of the comparison of transmittance according to each heat treatment temperature are shown in FIG. HT4 with a nucleation temperature of 760 ° C and a crystal growth temperature of 810 ° C showed the highest transmittance at 76% in the visible region, HT1 and HT2 showed low transmittance and HT2 showed the lowest value at 45%.

FIG. 4 shows SEM analysis results of each specimen in order to grasp the correlation between the transmittance and the average particle size. HT1 had an average particle size of 30 nm and a maximum particle size of 120 nm. HT2 had the largest particle size range of 55 ~ 270 nm. The mean particle size of HT3 and H4 was 25 nm and 15 nm, respectively, and homogeneous particles were produced. The average particle size of all the samples is less than 100 nm. However, the reason why the transmittance of HT1 and HT2 is sharply decreased is because HT1 and HT2 have uneven growth of particles and residual glass phase, do.

When the amount of nucleation is small, the non-uniform growth of the crystal grains is increased by increasing the crystal growth of the nucleus formed through the space where the nucleus is not formed during the crystal growth, and when the nucleation amount is large, It is difficult to secure a necessary space, so crystal growth is suppressed and the particle size is reduced. For this reason, if the nucleation is insufficient, the distance between the crystal grains increases, and the residual glass phase increases. Therefore, it is necessary to ensure sufficient nucleation.

FIG. 5 shows the results of XRD analysis according to the heat treatment. It was confirmed that the same β-spodumene phase existed as the predominant crystal phase under the pre-heat treatment condition. The measurement results of the thermal expansion coefficient of each specimen are shown in Fig. The highest thermal expansion coefficient in HT2 was 3.18 × 10 ^-6 / ℃ and 1.66 × 10 ^-6 / ℃ in HT4.

In the present invention, a crystallized glass was prepared by crystallizing and growing the optimal crystal growth temperature according to the nucleation temperature through the thermal parallax analysis using the lithium aluminosilicate glass, and the main crystalline phase was analyzed as β-spodumene. Through the thermal parallax analysis, it was confirmed that the optimal crystal growth temperature was lowered and the area of the crystal growth peak was decreased with increasing the nucleation temperature. Therefore, in order to reduce the average particle size, the average grain size was 15 nm, which is the lowest value obtained by heat treatment in HT4, which is the condition that crystal growth is minimized. As a result, it was possible to obtain a low-expansion transparent crystallized glass having a transparency of 76% and a thermal expansion coefficient of 1.66 × 10 ^-6 / ° C.

The features of the present invention are summarized as follows.

When ZrO ₂ is added to the lithium aluminosilicate glass as a nucleating agent, β-styrene is formed as a main crystal phase. When TiO ₂ is added to the solution, β-spodumene phase is formed. β-spodumene crystallized glass has the advantage of having a relatively low coefficient of thermal expansion from room temperature to about 700 ° C. and has been usefully used because of its clear milky white color. However, it is not suitable for maintaining transparency which is an advantage of basic glass. Therefore, as a method for producing a crystallized glass having a transparent and low thermal expansion coefficient, a condition of crystal grain size is established through thermal parallax analysis, Transparent crystallized glass having β-spodumene as the main crystal phase was prepared by controlling the particle size.

Claims (16)

In an LAS-based glass having a basic composition of Li ₂ O, Al ₂ O ₃ and SiO ₂ ,
TiO ₂ and ZrO ₂ are further added to the LAS-based glass, and the beta- state spudumin is the main crystal phase, and the crystal size of the beta- state spodumin does not exceed the lower limit value of the wavelength of the visible light region Li ₂ O-Al ₂ O ₃ -SiO ₂ based transparent crystallized glass. The method according to claim 1,
Wherein the LAS-based glass is further doped with Na ₂ O and BaO in order to lower the melting point of the Li ₂ O-Al ₂ O ₃ -SiO ₂ based transparent crystallized glass. The method according to claim 1,
The LAS-based glass is _{Li 2 O-Al 2 O 3} -SiO 2 transparent crystallized glass-based, characterized in that the ZnO is further added to the sphering of the nucleus. The method according to claim 1,
The LAS-based glass is _{Li 2 O-Al 2 O 3} -SiO 2 transparent crystallized glass-based, characterized in that the P ₂ O ₅ is further added in order to increase the solubility of the ZrO _2. The method according to claim 1,
And Li ₂ O-Al ₂ O ₃ -SiO ₂ based transparent crystallized glass characterized in that MgO and CaO are further added to the LAS-based glass. The method according to claim 1,
The crystallized glass is a SiO ₂ 50 ~ 60 parts by weight, Al ₂ O ₃ 20 ~ 25 parts by weight, Li ₂ O ₂ ~ 5 parts by weight, Na ₂ O 1 ~ ₂ parts by weight, MgO 1 ~ 2 parts by weight, CaO 1 ~ 2 parts by weight, BaO 1 ~ 2 parts by weight, ZnO 1 ~ 2 parts by weight, ZrO ₂ 1 ~ 5 parts by weight, TiO ₂ 1 ~ 5 parts by weight, Sb ₂ O ₃ 0.5 ~ 1 parts by weight, P ₂ O _{5 5} ~ Li ₂ O-Al ₂ O ₃ -SiO ₂ based transparent crystallized glass. The method according to claim 6,
Particle size is 15 ~ 150nm the _{Li 2 O-Al 2 O 3} -SiO 2 transparent crystallized glass-based, characterized in that the spokes dyumin (spodumene) on the beta contained in the crystallized glass. The method according to claim 6,
The crystallized glass is _{0 ~ Li 2 O-Al 2} O 3 -SiO 2 transparent crystallized glass-based in which characterized in that a thermal expansion coefficient of 1.6 ~ 3.0 10 ^-6 / ℃ area of 300 ℃. The method according to claim 6,
The crystallized glass is _{Li 2 O-Al 2 O 3} -SiO 2 transparent crystallized glass-based, characterized in that the transmittance to visible light of at least 75%. (a) analyzing the crystal growth peak according to the nucleation temperature through thermal parallax analysis of the mother liquor for producing the crystallized glass of claim 1;
(b) identifying a nucleation temperature for growing the crystal according to the size of the crystal growth peak; And
(c) determining the size of the crystal by growing the crystal at the identified nucleation temperature;
Wherein the crystallization conditions of the Li ₂ O-Al ₂ O ₃ -SiO ₂ based transparent crystallized glass are determined according to the crystal size. 11. The method of claim 10,
The nucleation temperature is set so that the size of the crystal grows smaller than the lower limit value of the wavelength of the visible light region, and the nucleation conditions are set according to the crystal size of the Li ₂ O-Al ₂ O ₃ -SiO ₂ based transparent crystallized glass . 12. The method of claim 11,
Wherein the temperature is in the range of 740 ° C to less than 770 ° C. The method of setting the nucleation temperature according to the crystal size of the Li ₂ O-Al ₂ O ₃ -SiO ₂ transparent crystallized glass. 13. The method of claim 12,
Wherein the time for crystallization at the temperature is 1 to 4 hours. A method for setting a nucleation temperature according to a crystal size of a crystallized glass of Li ₂ O-Al ₂ O ₃ -SiO ₂ system. Preparing a glass raw material mixture comprising a starting material for producing Li ₂ O, Al ₂ O ₃ , SiO ₂ based glass;
Heating and melting the glass raw material mixture;
Molding the molten glass raw material mixture in a mold and slowly cooling the glass raw material mixture to produce a glass molded body;
Heating the glass compact to a plurality of temperatures and performing thermal parallax analysis to derive respective nucleation temperatures according to respective crystal growth peaks;
A step of producing a crystallized glass, by deriving the nucleation temperature is the temperature at which the formed crystal grains that are smaller than the wavelength of visible light of growing a crystal phase on the spokes dyumin beta at the temperature; characterized in that it comprises a Li ₂ O- Al ₂ O ₃ -SiO ₂ based transparent crystallized glass. 15. The method of claim 14,
Wherein the temperature is in the range of 740 ° C to less than 770 ° C. The method of setting the nucleation temperature according to the crystal size of the Li ₂ O-Al ₂ O ₃ -SiO ₂ transparent crystallized glass. 16. The method of claim 15,
Wherein the time for crystallization at the temperature is 1 to 4 hours. A method for setting a nucleation temperature according to a crystal size of a crystallized glass of Li ₂ O-Al ₂ O ₃ -SiO ₂ system.

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