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

本研究的目的是考察显微镜光学图像与绿体真实结构之间的关系。将球形聚乙烯颗粒与陶瓷粉混合压制，然后烧出颗粒，制得了孔洞大小和浓度已知的陶瓷样品。使用了氧化铝、氮化硅和氧化锆粉，坯体中的气孔特征与用于样品制备的聚苯乙烯颗粒的气孔特征一致。这一结果清楚地表明，该表征方法可以成功地评价生坯中气孔的形状、大小和浓度。准确评价的最大试件厚度随着孔径的减小而减小。对于平均颗粒尺寸为200 nm的氧化铝中40微米大小的孔，准确评估的最大厚度约为0.5 mm。随着样品与浸泡液失配程度的增加，光学对比度增大。然而，这降低了样品的透明度，减少了用于评估的最大厚度。通过在适当的位置调整焦点的位置，可以单独评估重叠的孔。氮化硅和氧化锆生坯体也得到了类似的结果。

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.