Messi Biology said, in the preparation and production of advanced ceramics, magnesium oxide is a common additive, what is its role? In the sintering process, what changes it will bring to the ceramics? Here we understand through several cases.
The effect of magnesium oxide on alumina ceramics
1, magnesium oxide on alumina ceramic sintering temperature and densification of the impact
First of all, magnesium oxide as a common sintering aid, is able to effectively reduce the sintering temperature of alumina ceramics. With high-purity a-Al2O3 powder as raw material and magnesium oxide as sintering aid, alumina ceramics were prepared by discharge plasma sintering technology (SPS), and the effects of magnesium oxide addition and sintering temperature on the densification process and microstructure of alumina ceramics were studied, and the diffusion and evolution of pores during the sintering process were analyzed. The results showed that the addition of appropriate amount of MgO can reduce the sintering temperature, inhibit the grain growth and improve the densification of alumina ceramics, and 0.25% (mass fraction) is the best addition amount of MgO.
2, magnesium oxide on alumina ceramics mechanical properties and grain growth of the impact
Using alumina powder as raw material, magnesium oxide as additives, two-step sintering process to prepare alumina ceramics, and analyze the changes in additives on alumina ceramics density, mechanical properties and microstructure of the influence of the law.
It was found that the relative density, flexural strength and hardness of the sintered alumina ceramics showed a tendency to increase and then slightly decrease with the increase of magnesium oxide addition. When the content of magnesium oxide is lower than the solid solution limit, magnesium accelerates the diffusion of grain boundaries and has a certain refining effect on the grains, and the density and mechanical properties are better; when the content of magnesium oxide exceeds the solid solution limit, although the refining effect on the grains is enhanced, but the formation of magnesium-aluminum spinel at the grain boundaries will prevent the pore discharge.
In terms of grain growth, with the increase of MgO addition, the grain size and homogeneity of the...
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