(188v) Corrosion Behavior and Microstructure Changes of RBSC in Boiling Sulfuric Acid Solutions

SI process is the candidate processes for being used of a very high temperature gas cooled reactor (VHTR) due to its high temperature energy in the nuclear power industries. The SI process is efficient and promising for hydrogen production, however, the highly corrosive environment of this overall process limits an application of this process for H2 production. The corrosion behavior and microstructure changes of reaction-bonded SiC in boiling 98wt% H2SO4 solutions is studied using the mass-loss technique. A weight gain of which the amount was increased with the immersion time up to 100 days was observed. Nevertheless, the corrosion rate diminishes initially with time and tends to stabilize for long exposure times. After 120 days exposure time, the weight gain was saturated and decreased with time, while the rate was constant during the initial exposure time. It means that an oxide film is formed on the surface of a specimen during an immersion and the formed oxide thickness increases with the immersion time up to 100 days. After 120 days, there is no weight gain in the samples, therefore it means that a dense oxide layer (about 25um thickness) was formed on the surface. The surface morphologies were examined by using SEM-EDS. A passive silicon oxide layer on a Si/SiC surface is attributable to the corrosion resistance for RBSC in boiling 98wt% sulfuric acid.