Silicon carbide (SiC) is an important structural ceramic material that finds applications in many industries including nuclear industry, aerospace industry, automotive industry, heat exchangers, ball valves and many other fields of science and technologies. These widespread applications of SiC are due to its superior properties in corrosive atmosphere and in severe conditions at elevated temperatures. Moreover, SiC materials show high value of hardness and conductivity. The joining of SiC based components for assembling complex structures is a scientific and engineering challenge as they cannot be joined using conventional welding processes due to their non-wetting nature. There are different processes that are being used in industry for joining of SiC components such as diffusion bonding, reaction bonding and brazing with metals etc. In the present study a laser based joining process was applies using rare-earth aluminosilicate glasses as solders.
The high-temperature stability of rare-earth aluminosilicate glasses combined with their low coefficient of thermal expansion make them interesting to be used as solders for the joining of structural ceramic materials. Different rare-earth aluminosilicate glasses were prepared using melt-quench technique. Their structural and thermal characterizations were carried out using XRF, In-situ and ex-situ XRD, Raman and IR spectroscopic techniques and DTA/DSC etc. These prepared glassy solders were used for joining of SiC components via optimized laser process parameters. The characterizations of the joints were performed using helium leakage tests, 4-point bending tests and electron micro-probe analyses. Moreover, heat-treatments of the joint samples were carried out at different temperatures to evaluate the resultant microstructure in the joint layers and joints properties.
This study showed the promising potential of these high-temperature resistant glass/glass-ceramics for application as hermetic sealing of SiC components produced by short-time laser process.
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