Spark Plasma Sintering of Zirconium Diborides

Abstract

The densification behavior and grain growth of single‐phase ZrB 2 ceramics by a spark plasma sintering (SPS) process were systematically investigated. The sintering was conducted at temperatures ranging from 1800° and 1950°C in vacuum under a pressure of 50 MPa. The heating rate and the soaking time varied from 50° to 430°C/min and from 0 to 20 min, respectively. The microstructure was observed by field emission scanning electron microscopy. A near‐fully dense ZrB 2 ceramic can be obtained at a lower temperature, within a much shorter time, than those used in conventional hot‐pressing process. The density of the sintered ceramics increases with increase in sintering temperature, heating rate, and holding time. On the other hand, microstructural examination shows a strong dependence of grain growth on sintering temperature, heating rate, and holding time. The fully dense ZrB 2 ceramic with fine grain and homogeneous structure could be achieved by the processing conditions as follows: sintering temperature of 1900°C, holding time of 3 min, and heating rate of 200°–300°C/min.