| 摘要 |
PURPOSE:To provide a heat exchanger which stands for long use up to the heat- resistant temperature which silicon carbide originally has, by using a molded silicon carbide body, of which pores are packed with silicon, and of which content of Fe, Al and Na converted into the metallic condition is less than the specified value. CONSTITUTION:Pores of a molded body made of recrystallized silicon carbide are filled with silicon. Material of high purity, silicon-made of silicon carbide, of which impurity is less than 500ppm in regard to Fe, less than 1,000ppm in regard to Al, and less than 100ppm in regard to Na, is to be used for the filler. The molded body of recrystallized silicon carbide has a gas permeability because its porosity is high, so that silicon is filled up with the pores to turn it into a gas impermeable body. On the other hand, if impurity such as Fe2O3, Al2O3 and the like is contained much in the body, an SiO2 film formed on the surface of silicon carbide is converted into composition which is thermally unstable, and it causes the SiO2 film to come off. |
