13th International Conference on Advanced Materials and Nanotechnology
Yeungnam University, Republic of Korea
Title: Joining Of Sicf/Sic Using Preceramic Polymers
Biography: Dong Hyuk Jeong
SiCf/SiC possesses great potential for applications in severe conditions, including high temperatures and structural components for future fusion reactors. Various fabrication techniques have been developed to fabricate SiCf/SiC, which generally produce simple shape, such as plates and tubes. However, their practical utility can only be realized by integrating simple shapes into complex geometries. Therefore, considerable research efforts are being directed to develop filler materials, which can be employed to join SiCf/SiC. However, SiC-based fillers being similar to the SiCf/SiC joining body are a natural choice to preserve the outstanding properties of SiCf/SiC. Taking this into consideration, we tried to obtain pure SiC joining filler by pyrolyzing the preceramic polymers, such as polycarbosilane(PCS) and polysilazane(PSZ). Both of PCS and PSZ were applied in a paste form followed by thermal treatment, where SiC was the main porducts along with the presence of small amount of Si3N4, depending on the starting material. Because cracks and pores might be generated by the vaporization of gaseous products, which can hamper the overall joining properties, careful optimization for the polymeric composition, choice of filler, heating rate, joining temperature and pressure was performed. A slow heating rate of 2°C/min was employed for the temperatures of 1600-1700°C to obtain sound and crack-free joints, while the pressure of 3.5 and 20 MPa was applied. The joining strength was estimated by 3-point bending test and correlated with the interfacial microstructure, mode of failure as well as the joint thickness.