CHARACTERIZATION OF TEXTURED CERAMICS BY ELECTRON-PARAMAGNETIC RESONANCE SPECTROSCOPY .2. FORMATION AND PROPERTIES OF TEXTURED MGO

A method for the formation of macroscopic quantities of faceted, nanophase MgO precursor powders has been developed that permits a degree of control over the particulate size distribution. By employing powders of this type it was possible to form textured MgO ceramics by means of cold‐pressing and sintering. The theoretical basis for the application of EPR techniques to texture analysis as developed in Part I of this work was used to establish the nature of the preferred orientation in these MgO ceramics. Both EPR and X‐ray analyses showed that preferred orientations of the 〈111〉 axes of the MgO microstructural grains occur along or near the direction of force used to compact the green body. EPR results also show that this texture develops during the sintering process and that no preferred orientation effects are present in the unsintered body formed by cold‐pressing the faceted, nanophase MgO powder. Effects of parametric variations such as sintering temperature, compaction force, and faceted particle size on the degree of preferred orientation in these sintered MgO ceramics were investigated using EPR techniques. The results show that the amount of texturing increases with increasing compaction force or temperature up to a limiting value and that it also increases with decreasing faceted particle size. Copyright © 1990, Wiley Blackwell. All rights reserved