Study on the microstructural evolution of high temperature adhesives for graphite bonding Original Research Article

Development of high-temperature adhesives (HTAs) can provide a way to produce carbon materials with a large size or a complex shape. Some HTAs were developed for joining graphite materials. These HTAs were prepared using phenol formaldehyde (PF) resin as matrix and B4C powders as fillers. The results showed that these HTAs had satisfactory adhesive properties for graphite bonding even though the bonded graphite components were heat-treated at temperatures up to 1500 °C. In order to clarify the effects of the microstructure of HTAs on adhesive strength, the bonded graphite parts were heat-treated at high temperatures ranging from 400 to 1500 °C. The microstructural evolution of HTAs was investigated using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Analyses of the HTAs at the interface revealed that during microstructural evolution, carbonization of PF resin and complex interactions between PE and B4C powders occurred. A high chemical bonding force was introduced at the interface through interactions between the glassy carbon from the PF resin and B4C fillers, and the B4C fillers restrained the volume shrinkage of PF resin during carbonization, which can be responsible for the good adhesive properties of HTAs for graphite bonding.