Helium gas permeability of SiC tubes produced using cotton fabric

Tubular ceramic heat exchangers are increasingly used in many nuclear power plants. Silicon carbide has been considered as a promising material for heat exchanger application since it has good thermal conductivity and high temperature corrosion resistance. In this work, SiC ceramic tubes were prepared by liquid silicon infiltration of carbon preform made from cotton fabric/phenolic resin composite. Microstructure shows the presence of three distinct phases i.e. silicon carbide, silicon and carbon. Further densification of the tubes was carried out by chemical vapor infiltration of SiC. The leak tightness of the tubes was determined with the help of helium gas leak detector. The effect of chemical vapor infiltration on the leak tightness has been studied for the tubes infiltrated for 50 h and 100 h. The SiC tube treated for 100 h has the leak tightness of the order of 0.8×10−9 mbar l/s.