Published online by Cambridge University Press: 06 March 2019
Accurate measurement of the electrical and mechanical properties of polycrystalline oxide ceramics has revealed anisotropy in a number of properties. The source of this anisotropy may be attributed to a number of causes, however, with oxides having anisotropic crystals, preferred orientation of the crystallites may be suspected. Aluminum oxide and beryllium oxide ceramics samples of high purity and density were formed by slip casting, dry pressing, isostatic pressing, and extrusion. Pole figures for the (113), (110) and (030) planes in aluminum oxide and (100) and (103) planes in beryllium oxide were prepared by using a Siemens automatic pale figure goniometer.
It was found that both slip-cast oxide samples and dry-pressed aluminum oxide samples and dry-pressed beryllium oxide samples showed sufficient preferred orientation to prepare a pole figure from the data. The actual preferential orientation of the crystallites in these two oxides is discussed and the pole figure information presented. The effect of furnace atmosphere and surface contaminants on re crystallization at an exposed surface is covered briefly.