The effects of holding time on grain size, orientation degree and properties of h-BN matrix textured ceramics

Abstract

Hexagonal boron nitride (h-BN) matrix textured ceramics were prepared by hot pressing sintering assisted with grain rearrangement during Digital Light Processing (DLP), using CaO-Y2O3-Al2O3 as a sintering additive. The effects of holding time on h-BN grain size, texture degree, mechanical and thermophysical properties were investigated. Under liquid phase sintering, the C-axis of the flaky h-BN grains was preferentially arranged in the direction parallel to the sintering pressure. With the increase of holding time, the texture degree of the material was gradually improved, and the mechanical and thermal physical properties of anisotropy were gradually enhanced. When the holding time was 4 h, the material had the most typical anisotropic characteristic and properties. Grain size and grain orientation degree were the main factors affecting the anisotropic properties.