Preparation and characterization of high temperature SiCN/ZrB2 ceramic composite

The SiCN/ZrB2 ceramic composite was prepared from a liquid polyvinylsilazane with addition of ZrB2 powders, subsequently crosslinked at 300 °C and pyrolysed at 1000 °C in flowing Ar. Scanning electron microscopy (SEM) and X-ray diffractometry (XRD) showed that SiCN/ZrB2 consists of dense amorphous SiCN matrix with dispersed micron ZrB2 crystals. Thermal gravimetric analysis (TGA) showed SiCN/ZrB2 was stable up to 1550 °C in Ar with 5.4% weight loss, 6.4% lower than the pure SiCN ceramic. Heat treatment from 1100 °C to 1500 °C was performed to initiate crystallization. XRD showed thata SiCN matrix of SiCN/ZrB2 remained amorphous up to 1400 °C in Ar and indicated new crystals formed such as ZrO2 at 1100 °C, ZrC/ZrN at 1200 °C and Zr2CN at 1500 °C, which account for the improved high-temperature stability of the material.