Microstructure of ZrB2/Ni composite ceramics prepared by hot-pressing

Four kinds of zirconium diboride (ZrB2) powders were sintered at the same technical condition of 1950/50 MPa/1 h by hot-pressing. They were coarse monolithic ZrB2powders, high energy milled powders with and without the sintering additive of metal nickel, respectively. The archimedes method was used to measure the density of the as-sintered ceramic samples. The microstructure observation and element distribution mapping were performed by using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS), respectively. The results indicated that: the density process can be described as spherical surface contact and matter diffusion when the coarse monolithic ZrB2powders were sintered at the condition of high temperature and high press. The density behavior was profited from the augmentation of surface area and sinter active when the powder was deal with high energy mill. The sintering additive of metal nickel was contributive to the sinter density for both thick ZrB2powders and milled super-thin powders, but different density action between them. The Ni element was distributed at the boundary of thick granules or rudimental cavity, and it had the operation to augment the contact area of thick ZrB2grain and accelerate the matter diffuse between the contacted ZrB2granules. Ni element was distributed at the common boundary of ZrB2grain, and which had the contribution for the diffusion between ZrB2grain and the reduction of superfine cavity. ©, 2014, Journal of Functional Materials. All right reserved.