High-transparency high-fracture-toughness complex- phase alkali earth silicate aluminate transparent glass ceramic and preparation method thereof

Abstract

The application discloses a kind of high-transparency high-fracture toughness complex-phase alkali earth silicate-aluminate transparent glass ceramic and its preparation method.Using glass crystallization method, a controlled degree of chemical disorder is used in the structure to obtain optical isotropy of micron length scale, CaAl2Si2O8 crystal form is rod-shaped structure, which is beneficial to increase the crack toughness of the material, and can inhibit the growth of SrAl2Si2O8 crystal grain.CaAl2Si2O8 crystal grain can effectively inhibit the grain growth of SrAl2Si2O8, and the grain boundary is relatively thin, the particle size is 0.1-30 μm, the crystal phase forms a dense structure, and the addition of nucleating agent can effectively reduce the melting temperature and crystallization temperature of the glass, which is beneficial to the formation of crystal phase and can improve the stability of the glass.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic material preparation, in particular to a high-transparency high-fracture-toughness composite alkali earth silicate aluminate transparent glass ceramic and a preparation method thereof. BACKGROUND

[0002] Transparent ceramics are polycrystalline materials that allow incident photons to pass through without significant absorption and internal scattering, and have broad application prospects in the fields of illumination, transparent armor, medical treatment, communication, infrared detection, space science, national defense, etc. Traditional ceramic materials are generally opaque due to the influence of potential extinction factors such as anisotropy, low-symmetry crystal structure, grain boundary, pores and impurities. At present, the preparation process of classical transparent ceramics generally follows the same technical route, and the basic steps include powder preparation, molding, sintering, annealing, grinding and polishing. Most solid-state preparation techniques of transparent ceramics are considered to be expensive because they often involve high-purity, high-dispersion, high-sintering-activity nanometer powder synthesis technology and long-period high-temperature and high-pressure densification sintering technology. SUMMARY

[0003] The purpose of the present application is to provide a preparation method of high-transparency high-fracture-toughness composite alkali earth silicate aluminate transparent glass ceramic.

[0004] Another purpose of the present application is to provide a high-transparency high-fracture-toughness composite alkali earth silicate aluminate transparent glass ceramic prepared by the above preparation method.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0006] On the one hand, the present application provides a preparation method of high-transparency high-fracture-toughness composite alkali earth silicate aluminate transparent glass ceramic, comprising the following steps:

[0007] (1) A glass powder raw material is weighed and placed in a ball mill tank, anhydrous ethanol is added for ball milling to obtain a mixed slurry, and then the mixed slurry is dried, and the dried powder is melted at 1450-1850℃ for 30-120min to obtain a glass liquid; wherein the glass powder raw material is composed of the following molar percentage of components: SrCO320-40%, CaCO3 3-10%, SiO230-50%, Al2O315-45%, crystal nucleus agent 2-10% and Sb2O30.03%, the crystal nucleus agent is selected from one or more of P2O5, ZrO2 and TiO2;

[0008] (2) The glass liquid is poured into a copper mold to obtain a transparent glass block;

[0009] (3) The glass block is annealed at 600-800℃ for 10-60h to obtain a precursor glass;

[0010] (4) placing the precursor glass in turn at crystallization temperatures of 700-850℃ and 900-1050℃ for 1-10h, and taking out after cooling to room temperature, to obtain the multiphase transparent ceramic, and annealing in air.

[0011] Preferably, the rotation speed of the ball milling in step (1) is 160-210r / min, and the ball milling time is 10-20h.

[0012] Preferably, the drying temperature of the mixed slurry in step (1) is 70℃, and the drying time is 6-12h.

[0013] Preferably, in step (1), an induction melting furnace is used for heating, and the heating rate is 5-20℃ / min.

[0014] Preferably, in step (4), the temperature is kept at 700-850℃ for 0.5-1.5h, and then the temperature is raised to 900-1050℃, and kept for 1-10h.

[0015] Preferably, in step (4), the multiphase transparent ceramic is annealed in air at 650-850℃ for 15h.

[0016] In another aspect, the present application also provides a high-transparency high-fracture-toughness multiphase alkali earth silicate aluminate transparent glass ceramic prepared by the above preparation method.

[0017] The multiphase alkali earth silicate aluminate transparent glass ceramic is composed of multiple crystal phases, wherein the main crystal phases are SrAl2Si2O8 and CaAl2Si2O8. Controlled degree of chemical disorder is used in the structure to obtain optical isotropy at micron length scale, the SrAl2Si2O8 has low crystallization activation energy, and the glass is easy to obtain high-transparency ceramic after crystallization, the CaAl2Si2O8 has rod-like structure, which is beneficial to increase the crack toughness of the material, and can inhibit the grain growth of SrAl2Si2O8. The CaAl2Si2O8 grain can effectively inhibit the grain growth of SrAl2Si2O8, and the grain boundary is thin, the particle size is 1-30μm, the crystal phases form a dense structure, the addition of P2O5, ZrO2 and TiO2 nucleating agents can effectively reduce the melting temperature and crystallization temperature of the glass, which is beneficial to the formation of crystal phases, and can improve the stability of the glass, and Sb2O3 is additionally introduced as a fining agent.

[0018] The average grain size of the ceramic prepared by the present application is 0.1-30μm, the visible light transmittance of the ceramic can reach more than 88%, and the fracture toughness can reach 2-10MPa·m 1 / 2 .

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] (1) The transparent ceramic prepared by the present application realizes controllable crystallization by controlling the crystallization time and temperature through two-step crystallization method, and preferentially generates CaAl2Si2O8 crystal phase, which does not cause light scattering to the main crystal phase of SrAl2Si2O8;

[0021] (2) The ceramic preparation method provided by the present application generates CaAl2Si2O8 crystal phase, which limits the growth of SrAl2Si2O8 crystal grains through pinning effect, effectively controls the grain growth, and the grain size is uniform, and the controlled degree of chemical disorder is used in the structure to obtain optical isotropy of micron length scale, which has good optical quality and transmittance, and the transmittance of the ceramic at 800 nm is 90.1%;

[0022] (3) The ceramic preparation method provided by the present application adopts a melting method to further control the growth of ceramic grains, and the prepared ceramic has small grain size, and the generated SrAl2Si2O8 crystal phase has a rod-shaped structure, which effectively improves the mechanical properties of the transparent ceramic;

[0023] (4) Based on mature glass forming technology, the transparent ceramic can be obtained after heat treatment of the precursor glass, and the process is simple, efficient, high in crystallinity, and large-size transparent ceramic can be prepared by this method. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The transmittance graph of the transparent ceramic prepared in Example 1 of the present application;

[0025] Figure 2 The optical micrograph of the multiphase transparent ceramic prepared in Example 1 after crystallization at 800 DEG C;

[0026] Figure 3 The optical micrograph of the multiphase transparent ceramic prepared in Example 1 after crystallization at 1020 DEG C;

[0027] Figure 4 The actual picture of the multiphase transparent ceramic prepared in Examples 1-3 of the present application. DETAILED DESCRIPTION

[0028] The present application will be further described in detail below in combination with the drawings and specific examples.

[0029] The raw material powders used in the following examples are all commercially available products, and the purity is greater than 99.9%.

[0030] (1) The following components were weighed according to the following molar percentage: 24% SrCO3, 27% Al2O3, 43.5% SiO2, 3% CaCO3, and 2.47% P2O5, 2% ZrO2 and 0.03% Sb2O3 powder were placed in a ball mill tank, 70 mL of anhydrous ethanol was configured into a slurry, a planetary ball mill was used, the ball mill speed was 200 r / min, the ball milling time was 16 h, and the mixed slurry obtained after ball milling was dried.

[0031] (2) The powder prepared in step (1) was poured into a crucible, an induction melting furnace was used to raise the temperature from room temperature to 1200°C at a rate of 10°C / min, and then the temperature was kept at 1200°C for 1 h, and then the temperature was raised to 1760°C at a rate of 5°C / min, and then the temperature was kept at 1760°C for 1 h, and then a glass liquid was obtained;

[0032] (3) The glass liquid was poured into a preheated copper plate mold at 600°C, the mold size was φ22*3 mm, and the temperature was lowered with the preheated platform at a rate of 10°C / min, and a transparent glass block was obtained;

[0033] (4) The glass block was annealed at 700°C for 30 h to obtain a precursor glass;

[0034] (5) The precursor glass was placed at a crystallization temperature of 800°C for 0.5 h, then the temperature was raised to 1020°C, and then the temperature was kept at 1020°C for 4 h, and then the temperature was cooled to room temperature, and then the multi-phase transparent ceramic was obtained, and then the ceramic was annealed in air at 750°C for 15 h.

[0035] Figure 1 The transmittance curve of the aluminum oxide transparent ceramic prepared in this example showed that the transmittance of the ceramic at 800 nm was 90.1%, indicating that the ceramic had high transmittance.

[0036] Figure 2 The SEM image of the CaAl2Si2O8 phase formed by crystallization of the multi-phase alkaline earth silicate aluminate transparent ceramic prepared in this example at 800°C showed that the CaAl2Si2O8 phase grew into a strip shape, and the grain size was very small.

[0037] Figure 3 The SEM image of the multi-phase alkaline earth silicate aluminate transparent ceramic prepared in this example crystallized at 1020°C showed that the two phases grew densely, and the ceramic had excellent mechanical properties.

[0038] Figure 4 The actual image of the aluminum oxide transparent ceramic prepared in this example showed that the ceramic sample had excellent light transmission performance, and the image below the ceramic could be clearly seen.

[0039] Example 2

[0040] (1) The following components were weighed according to the following molar percentage: 21.5% SrCO3, 26.5% Al2O3, 42.5% SiO2, 5% CaCO3, and 2.47% P2O5, 2% ZrO2 and 0.03% Sb2O3 powder were placed in a ball mill tank, 70 mL of anhydrous ethanol was added to prepare a slurry, a planetary ball mill was used, the ball mill speed was 180 r / min, the ball mill time was 15 h, and the mixed slurry obtained after ball milling was dried.

[0041] (2) The slurry prepared in step (1) was poured into a crucible, an induction melting furnace was used, the temperature was raised to 1600°C from room temperature at a rate of 10°C / min, and the temperature was kept for 0.5 h, then the temperature was raised to 1750°C at a rate of 5°C / min, and the temperature was kept for 1.5 h, to obtain a glass liquid;

[0042] (3) The glass liquid was poured into a copper plate mold preheated at 580°C, the mold size was φ22*3 mm, and the transparent glass block was obtained by cooling with the preheated platform;

[0043] (4) The glass block was annealed at 800°C for 15 h to obtain a precursor glass;

[0044] (5) The precursor glass was placed at a crystallization temperature of 820°C for 0.5 h, then the temperature was raised to 1130°C, and the temperature was kept for 2.5 h, and then the temperature was cooled to room temperature to obtain a multiphase transparent ceramic, which was annealed in air at 850°C for 15 h.

[0045] The surface SEM image, transmittance curve and actual object of the multiphase transparent ceramic prepared in this example are similar to those of Example 1.

[0046] Example 3

[0047] (1) The following components were weighed according to the following molar percentage: 21.5% SrCO3, 26.5% Al2O3, 42.5% SiO2, 5% CaCO3, and 2.47% P2O5, 2% ZrO2 and 0.03% Sb2O3 powder were placed in a ball mill tank, 70 mL of anhydrous ethanol was added to prepare a slurry, a planetary ball mill was used, the ball mill speed was 180 r / min, the ball mill time was 15 h, and the mixed slurry obtained after ball milling was dried.

[0048] (2) The powder prepared in step (1) was poured into a crucible, an induction melting furnace was used, the temperature was raised to 1700°C from room temperature at a rate of 15°C / min, and the temperature was kept for 1 h, then the temperature was raised to the melting temperature 1760°C at a rate of 5°C / min, and the temperature was kept for 1 h, to obtain a glass liquid;

[0049] (3) The glass liquid was poured into a copper plate mold preheated at 580°C, the mold size was φ22*3 mm, and the transparent glass block was obtained by cooling with the preheated platform;

[0050] (4) annealing the glass block at 720℃ for 15h to obtain a precursor glass;

[0051] (5) the precursor glass is placed at a crystallization temperature of 800℃ for 0.5h, then heated to 1010℃ and kept for 3h, and then removed after cooling to room temperature, to obtain a multiphase transparent ceramic, which is annealed at 800℃ for 15h in air.

[0052] The multiphase transparent ceramic prepared in this example has a similar surface SEM image, transmittance curve and actual object image as those of Example 1.

[0053] The Vickers hardness, bending strength and fracture toughness of the ceramic samples of Examples 1, 2 and 3 are detected, and the data are shown in Table 1.

[0054] The bending strength of the sample is determined by a three-point bending method using a WDW-200 electronic universal testing machine, with a loading speed of 0.5mm / min and a span of 16mm, and the fracture toughness of the sample is determined by a single edge notched beam (SENB) method using the same equipment,

[0055] Table 1: Mechanical properties of ceramic materials

[0056] Example 1 Example 2 Example 3 Vickers Hardness (GPa) 12.4 11.9 12.1 Bending Strength (MPa) 538 552±18 530±15 Fracture toughness (MPa-m 1 / 2 )]]> 8.9 9.5 9.1

[0057] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any modification, equivalent replacement and improvement within the technical range disclosed by the present application and within the spirit and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A method of making a high transparency high fracture toughness multiphasic alkali earth silioaluminate transparent glass-ceramic, characterized in that, The method comprises the following steps: (1) a glass powder raw material is weighed and placed in a ball mill tank, anhydrous ethanol is added for ball milling to obtain a mixed slurry, the mixed slurry is dried, and the dried powder is placed in a furnace at 1450-1850°C for 30-120 min for melting to obtain a glass liquid; the glass powder raw material is composed of the following components in terms of molar percentage: SrCO320-40%, CaCO33-10%, SiO230-50%, Al2O315-45%, a crystal nucleus agent 2-10%, and Sb2O30.03%, the crystal nucleus agent is selected from one or more of P2O5, ZrO2, and TiO2; (2) the glass liquid is poured into a copper mold to obtain a transparent glass block; (3) the glass block is annealed at 600-800°C for 10-60 h to obtain a precursor glass; (4) the precursor glass is heated at 700-850°C for 0.5-1.5 h, then heated to 900-1050°C, and heated for 1-10 h, and then removed after cooling to room temperature, to obtain a composite alkaline earth silicate aluminate transparent glass ceramic, which is annealed in air; The main crystal phase of the complex-phase alkali earth silicate-aluminate transparent glass ceramic is SrAl2Si2O8 and CaAl2Si2O8, the visible light transmittance of the glass ceramic is above 88%, and the fracture toughness is 2-10 MPa·m 1 / 2 .

2. The method of making a high transparency high fracture toughness multiphasic alkali earth sil aluminate transparent glass-ceramic according to claim 1, characterized in that, In step (1), the ball milling speed is 160-210 r / min, and the ball milling time is 10-20 h.

3. The method of claim 1, wherein the method further comprises: heating the glass to a temperature of 1000-1200 °C for 1-10 hours; and annealing the glass at a temperature of 500-700 °C for 1-10 hours. In step (1), the mixed slurry is dried at a temperature of 70°C for 6-12 h.

4. The method of claim 1, wherein the method further comprises: heating the glass to a temperature of 1000-1200 °C for 1-10 hours; and annealing the glass at a temperature of 500-700 °C for 1-10 hours. In step (1), an induction melting furnace is used for heating, and the heating rate is 5-20°C / min.

5. The method of making a high transparency high fracture toughness multiphasic alkaline earth silico-aluminate transparent glass-ceramic according to claim 1, characterized in that, In step (4), the composite alkaline earth silicate aluminate transparent glass ceramic is annealed in air at 650-850°C for 15 h.

6. A high-transparency high-fracture-toughness composite alkaline earth silicate aluminate transparent glass ceramic prepared by the method of any one of claims 1-5.

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