Optimization and quantification of the liquid immersion method for characterization of ceramics green bodies and comparison of the method with comventional tools.

点击翻译按钮获取中文摘要

The objective of this study is to examine the relationship between the optical image of microscope and the true structure of green body. Ceramics specimens with known size and concentration of pores were prepared by first pressing the mixture of polystylene particles of spherical shape and ceramic powders, and then burning out of the particles. Powders of alumina, silicon nitride and zirconia were used.The characteristics of pores in the green bodies were consistent to those of polystylene particles used for the sample preparation. This result clearly shows that the present characterization method can successfully evaluate the shape, size and concentration of pores in the green bodies. The maximum specimen thickness for accurate evaluation decreased with decreasing size of pore. For pores of the size 40 microns located in alumina with the average particles size 200nm, the maximum thickness for accurate evaluation is approximately 0.5mm. With increasing mismatching between the specimen and the immersion liquid, the optical contrast increased. However, this reduced the transparency of the specimen, reducing the maximum thickness for evaluation. Overlapped pores can be evaluated separately by adjusting the position of focus at adequate position. The similar results were obtained for silcon nitride and zirconia green bodies.