What is the roughness of the unpolished surface of zirconia?

The roughness requires Ra not to exceed 0.25 μ m. In the precision machining of engineering ceramics, scholars at home and abroad have also done a lot of research work, but there is little research on the reasonable control of grinding surface roughness. Taking zirconia ceramic parts in a machine tool as an example, the working surface is flat, and the roughness Ra should not exceed 0.25 micron. ..