TEXTURE FORMATION IN AL2O3 SUBSTRATES

The formation of textures (preferred crystal orientation) in Al2O3 substrates by green forming and subsequent sintering was studied. The observed texture type was always characterized by the basal plane parallel to the substrate plane. Crystal orientation within this plane was nearly axially symmetric. The c-axis pole distribution was obtained by an indirect method from several (hkil) pole distribution functions measured by X-ray diffraction. Texture formation starts in the very first stages of green forming, the essential process being rigid particle rotation. Small texture changes were observed also in the initial stages of sintering. The strongest increase of texture, however, took place during grain coarsening at high sintering temperatures. The texture strength factor can be expressed quantitatively in terms of the green texture as well as the sintering time and temperature.