General ceramics are opaque. The reason for opacity is that there are impurities and pores in the interior. The impurities can absorb light. The pores can scatter light, so it is opaque. If high-purity raw materials are selected and pores are eliminated through technological means, transparent ceramics as transparent as glass can be obtained.
The key to preparing transparent ceramics is: firstly, to improve the purity and fineness of the ceramics, and to make the particles uniform, such as using alumina with a particle size of 0.3 μm as the raw material; The slow movement of the grain boundary eliminates the micro pores. The third is to reduce the air content in the kiln during the firing process and try to make it reach a vacuum state.
The key process factors for making transparent ceramics are as follows:
Selection of ceramic powder
The characteristics of the ceramic powder directly affect the densification sintering and the microstructure inside the ceramic, thereby significantly affecting the light transmission properties of the ceramic after the final sintering.
Suitable sintering additives
The amount of additives is generally small. In principle, the additives used should be evenly distributed in the material, that is, they can be completely solid-dissolved in the main crystalline phase without precipitating in the form of a new solid phase. New secondary phase scattering will form.
Densification sintering process
A reasonable and effective sintering process can fully eliminate pores and make the porosity close to zero, so as to achieve full densification and obtain transparent ceramics with good light transmission; therefore, whether the sintering process selection is reasonable will directly determine the ceramic transparency. Sex.
Surface finish
The surface finish of sanding and polishing is generally 11 ~ 13.