Preparation of porous YB4 ceramics using a combination of in-situ borothermal reaction and high temperature partial sintering

A novel method for preparing high porosity and high strength porous YB4 ceramics was developed combining the in-situ borothermal reaction synthesis and high temperature partial sintering. Since pores could be produced by gasses such as B2O3 and CO generated in the reaction between Y2O3 and B4C, high porosity porous YB4 ceramics were obtained after synthesis at 1650 °C and sintering at 1780 °C for 2 h in vacuum, respectively. Using this new and simple method, porous YB4 with controllable porosities of 60–70% and compressive strengths of 7.4–19.9 MPa were obtained depending on the green density. The phase composition, porosity, pore size distribution and compressive behavior of the porous YB4 ceramics were systematically investigated. The effects of vacuum on synthesis of YB4 and pore forming mechanism were also discussed in detail.