During the processing of zirconia ceramics, some zirconia ceramics have a lot of pores on their surfaces, while some zirconia ceramics have a very smooth surface with almost no pores. Do you know what is the reason for pores on the surface of zirconia ceramics?
Reasons for pores on the surface of zirconia ceramics:
1. Grain growth in zirconia ceramics is not affected by the properties of the molded body.
2. Higher dihedral angles, molding density, narrower particle and pore size distribution are conducive to the movement of the grain density relationship trajectory of zirconia ceramics toward high density and small grains.
3. The linear relationship between grain size and density is affected by the properties of the molded body, because grain growth is driven by the chemical potential of the size difference between grains, while densification is driven by the sintering compressive stress acting on the pores of zirconia ceramics.
4. The growth of pores is controlled by both grain growth and densification. The former causes pore growth to be synchronized with grain growth, while the latter causes pore shrinkage and a decrease in pore R value, which also makes the pore growth of zirconia ceramics affected by the properties of the mold body.
5. Zirconia ceramics are almost negligible in the initial stage of ultrafine powder sintering, and grain growth and densification occur simultaneously. From the beginning of sintering to the end of the intermediate stage, the grain size and density are linearly related. This linear relationship can be explained by the fact that grain growth and densification occur in the same diffusion and mass transfer mechanism, and the dependence of grain growth and density on time during the isothermal process.
In summary, this is the reason why pores appear on the surface of zirconia ceramics. When we encounter pores on the surface, we can check these aspects and analyze the reasons, and then solve the problem according to the reasons.
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