Joining and machining of (ZrB2-SiC) and (Cf-SiC) based composites

Filler materials of (ZrB2-SiC-B4C-YAG) composite were developed for gas tungsten arc welding (GTAW) of the ZrB2-SiC and Cf-SiC based composites to themselves and to each other. Reaction with filler material, porosity and cracks were not observed at weld interfaces of all the joints. Penetration of filler material in to voids and pores existing in the Cf-SiC composites was observed. Average shear strength of 25.7 MPa was achieved for joints of Cf-SiC composites. By incorporation of Cf-SiC (CVD) ground short fibre reinforcement the (ZrB2-SiC-B4C-YAG) composite was machinable with tungsten carbide tool. The joint and machined composites were resistance to oxidation and thermal shock when exposed to the oxy-propane flame at 2300 °C for 300 s. The combination of (ZrB2-SiC-B4C-YAG) and Cf-SiC based composites can be used for making parts like thermal protection system or nozzles for high temperature applications.