Preparation method of transparent magnesia-alumina spinel ceramic

Abstract

The invention provides a preparation method of transparent magnesia-alumina spinel ceramic MgO.nAl2O3, wherein n is larger than or equal to 1 and smaller than or equal to 2. The method specifically comprises the steps as follows: 1) MgO powder and alpha-Al2O3 are mixed and ball-milled, a solvent is removed, sieving is performed, and magnesia-alumina spinel powder is obtained after a high-temperature solid-phase reaction and sieving; 2) the magnesia-alumina spinel powder is placed in a graphite mold, the graphite mold is placed in spark plasma sintering equipment for forming and pre-sintering,and a pre-sintered body is obtained; 3) the pre-sintered body is placed in a muffle furnace to be sintered again, natural cooling is performed, and a pore-closed sintered body is obtained; 4) the pore-closed sintered body is subjected to hot isostatic pressing sintering treatment, a sintered sample is polished, and the transparent magnesia-alumina spinel ceramic is obtained. By means of the method, the sample composition can be controlled, high compactness can be obtained without addition of a sintering aid, large-scale industrial production can be performed through sintering in non-pressure air, and the production cost can be reduced.

Description

technical field [0001] The invention belongs to the field of preparation of transparent ceramic materials, in particular to a magnesium aluminum spinel MgO·nAl 2 o 3 (1≤n≤2) Preparation method of transparent ceramics. Background technique [0002] Magnesium-aluminum spinel transparent ceramic material has high temperature resistance, chemical corrosion resistance, excellent electrical insulation and mechanical properties, and has good optical transmittance in the wavelength range of 0.20-6.5 μm. As a solid solution, the properties of magnesium aluminum spinel change with the stoichiometry, which provides a technical basis for regulating the properties of materials by controlling the composition. The solid solution of alumina into the spinel lattice reduces the lattice constant and improves its mechanical properties, which makes spinel transparent ceramics meet the performance requirements of different application fields. For example, it is used as a transparent armor and ...

AI Technical Summary

Problems solved by technology

Krell et al. used a special MgAl particle size of 53nm 2 o 4 The powder is formed by cold isostatic pressing at 350MPa, sintered at 1240-1260°C under pressure-free conditions, and hot isostatically pressed below 1300°C to obtain magnesium-aluminum spinel transparent ceramics with an average grain size of 0.2-0.3μm ( Krell A, Hutzler T, Klimke J, et al., Fine-Grained Transparent Spinel Windows by the Processing of Different Nanopowders[J].Journal of the American Ceramic Society,2010,93(9):2656-2666.), sample When the thickness is 4-10mm, the transmittance in the visible light area reaches 80%. This method has high requirements on the particle size of the raw material powder, and the cost is high

Morita et al. (Morita K, Kim B N, Yoshida H, et al., Effect of loading schedule ondensification of MgAl 2 o 4 spinel during spark plasma sintering (SPS) processing[J].Journal of the European Ceramic Society,2012,32(10):2303-2309.) using commercial powder with a particle size of 100-300nm, using spark plasma vacuum sintering to Heating rate of 10-100°C / min When the temperature rises to 1000-1400°C, quickly pressurize to 80MPa within 10-300s and sinter for 20min to obtain MgAl 2 o 4 The grain size of the ceramic samples is about 0.4 μm, but the transmittance is not ideal. The sample with the best transmittance is prepared at 100°C / min to 1300°C and pressurized. The linear transmittance at 550nm is about 35 %, 74% at 2000nm

Dericioglu et al. combined reaction sintering and hot-pressing sintering, sintered at 1400 °C, 50 MPa for 1 h and hot isostatic pressing at 1900 °C, 189 MPa, obtained spinel transparent ceramics with n values ​​of 1, 1.5 and 2, but chemical The visible light transmittance of measured spinel is only 20-40%, and the aluminum-rich spinel does not exceed 60% (Dericioglu F, Boccaccini AR, Dlouhy I, et al., Effect of Chemical Composition on the Optical Properties and Fracture Toughness of Transparent Magnesium Aluminate Spinel Ceramics[J].Materials Transactions,2005,46(5):996-1003)

[0004] From the above, it can be seen that the magnesia-alumina spinel ceramics obtained by hot-pressing sintering with additives in the prior art generally have poor uniformity in grain size distribution, poor mechanical properties of transparent ceramics, and the added sintering aids are enriched. The formation of the second phase reduces the transmittance and mechanical properties; the magnesia-alumina spinel grains obtained by spark plasma sintering are small, but the carbon pollution reduces the optical properties due to the use of graphite molds; and the application requirements of magnesia-alumina spinel transparent ceramics It combines excellent optical properties with mechanical properties such as strength and hardness

Although the traditional pressureless sintering method is successful in preparing fine-grained transparent ceramics, it has high requirements for the raw material powder, and the particle size of the powder is required to be less than 50nm, and the preparation cost also increases accordingly. Therefore, the prepared composition is simple and excellent. Magnesium aluminum spinel ceramics with mechanical and optical properties have become an urgent problem to be solved in current research

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