R and D results of carbon and titanium carbide coating on molybdenum substrate for JT-60 first wall

This report describes R D results of carbon and titanium carbide coating on molybdenum for JT-60 first wall done in FY 1980. The reactive glow discharge method for carbon coating and the hollow-cathode-type physical vapor deposition (HCD-PVD) method for titanium carbide coating were adopted, respectively. Coating thickness was 20μm in both cases. In the case of carbon coating, stable layer of 20μm was obtained at temperature less than 3000C, but not above 4000C. Therefore, the carbon coating of 20μm was performed at room temperature, 1000C, 2000C and 3000C. Average deposition rate, uniformity of deposition, crystal orientation, surface and cross section morphologies, contained gas species, and chemical composition of coated layer were measured for both carbon and TiC coating. Thermal cycles test was also performed. The coated substrates were heated by infra-red lamp from an initial temperature of 1000C to a highest temperature of 11000C for 10 sec. The carbon layer peeled off after only one cycle. The titanium carbide layer partially peeled off with 10--100 cycles. These results show that titanium carbide coated with the HCD-PVD method is promising as a surface material for molybdenum first wall. The improvement of adhesion characteristics, however, is still left for a future research. (author)