Abstract
In order to prepare titanium carbide powders of high purity and fine grain size, purification of crude titanium carbide powder containing free carbon or sometimes oxygen was examined. The mixture of crude titanium carbide powder prepared by vacuum carburizing of TiO2 and Ca metal tips (sometimes CaCl2 was used as flux) was charged in an iron crucible and heated to 950-1000°C in an argon atmosphere. Then the reaction product which was cooled to room temperature was washed in water and hydrochloric acid.
By this treatment, free carbon contained in crude titanium carbide was almost completely removed even free carbon content in crude titanium carbide was as high as 10%. Ca was not detected by chemical analysis in the purified product, and high purity titanium carbide powder was obtained from highly carburized crude titanium carbide powder. But, in the case of Ca treatment of low-carburized powder (low combined carbon and high oxygen content), although oxygen decreased and combined carbon increased, these decreasing and increasing rates were both considerably low.
Obvious surlace oxidation of flu powder was detected by holding wet powder cake in a hot air bath at 120°C. Vacuum dring was effective for prevention the surface oxidation. "Flushing" seemed to also be effective for this purpose.
