Flat-Plate Solar Array Project: Task I. Silicon Material. Investigation of the Hydrochlorintion of SiCl sub 4 . Third Quarterly Report, January 9-April 8, 1982

摘要

A research and development program on the hydrochlorination of silicon tetrachloride and metallurgical grade silicon metal to trichlorosilane was carried out as scheduled. Effects of pressure and temperature on this reaction were last reported. The presence of HCl in the reaction product mixture was successfully analyzed. Experiments on the corrosion study were carried out to evaluate a variety of metals and alloys as the material of construction for the hydrochlorination reactor. Material includes carbon steel, nickel, copper, Alloy 400 (Monel), stainless steel (Type 304), Incoloy 800H and Hastelloy B-2. The corrosion test was carried out at reaction temperature of 500 exp 0 C, pressure of 300 psig and H sub 2 /SiCl sub 4 feed ratio of 2.0 for a total of 87 hours. Results of the corrosion test show that all the test samples achieved a weight gain. As previously observed, the weight gain is due to the deposition of silicon on the metal surface to form a silicide protective film. Interestingly, the amount of Si deposition differs greatly between the different metals and alloys. Pure metals such as nickel and copper show a much larger silicon deposition than that of their alloys. Type 304 stainless steel, Incoloy 800H and Hastelloy B-2 show the least amount of silicon deposition. The silicide films on the nickel and Incoloy 800H test samples were analyzed by Scanning Electron Microscopy (SEM). The composition of the silicide film was analyzed by the x-ray microprobe and the EDAX analyzer. A plausible mechanism on the formation of this silicide film is discussed. Based on the corrosion test results, the most suitable material of construction for the hydrochlorination reactor is the type of alloys which contain a high level of Ni, Cr and Mo. (ERA citation 07:042802)