SYNTHESIS OF ZRB2 BY CVD AT LOW-TEMPERATU RE AND PRESSURE - CHARACTERIZATION OF THE DEPOSITS

An experimental study of the ZrB2 synthesis at low temperature and low pressure was performed by CVD from a mixture of ZrCl4, BCl3 and H-2. It was shown that the reduction of boron chloride by hydrogen is of gr eat Importance in the heterogeneous chemical mechanisms. Different fil m microstructures have been observed, depending on the experimental de position conditions. Moderate helium dilution lowered the growth rate and roughness of the deposits and, in some cases, lead to specific ori entations growth.