Papers by Author: Jian Rong Song

Abstract: In this work, ZrB2 powder coated with ZrO2 (ZrB2 @ ZrO2) were applied to promote the densification of ZrB2 prepared by pulsed electric current sintering (PECS). The coating process and sintering behavior were investigated. While the pH value was about 9, the ZrB2 particles were successfully coated with ZrO2 by co-precipitation methods. The thickness of ZrO2 layer was about 3-5nm. The coated powder was sintered at 1600°C ~1950°C by PECS in vacuum. For comparison, the pure ZrB2 powder was sintered at the same conditions. The relative density of the sample coated with ZrO2 was 97.8% at PECS 1950°C, which was higher than that of sample without coating. The densification process can be divided into three stages. The ZrO2 coating layer plays an important role on the densification of ZrB2.

Abstract: The purpose of this study was to investigate the oxidation of ZrB2/ZrO2 (ZZ) and ZrB2/ZrO2/SiC (ZZS) ceramics. The ceramics were fabricated by spark plasma sintering (SPS) at 1900°C and exposed to ten-minute oxidation cycles in stagnant air at 1200°C in a box furnace with molybdenum disilicide heating elements. Results of relative density, surface phase change and the rate of weight growth show that the addition of ZrO2 improved the sintering properties of ZrB2 ceramics. While the resistance to oxidation declined with the increase content of ZrO2. And the addition of SiC improved the resistance to oxidation of ZrB2/ZrO2 composites significantly.