Preparation, properties, and structural evolution of a novel polyborosilazane adhesive, temperature-resistant to 1600 °C for joining SiC ceramics

A liquid polyborosilazane was synthesised by modifying polymethylsilane with borazine, and a novel organic adhesive resistant to temperature of 1600 °C was prepared using polyborosilazane matrix with aluminium powder as filler. The properties and structural evolution of the obtained adhesives were investigated by shear strength test, thermogravimetry–differential scanning calorimetry, Fourier-transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The results show that polyborosilazane was synthesised via dehydrogenation between polymethylsilane and borazine. The ceramic yield of the obtained polyborosilazane treated up to 1200 °C reached 82.6 wt%. By adding aluminium powder as active filler, yield increased to 93.0 wt%. In addition, polyborosilazane adhesive exhibits good bonding strength and excellent temperature resistance. At room temperature, SiC ceramic joints bonded by the adhesive treated at 1600 °C showed shear strength of 7.9 MPa. The high ceramic yield and outstanding heat-resistance of polyborosilazane, and its modification by aluminium powder, facilitate ideal high-temperature bonding properties of the prepared adhesive.