J. Phys. IV France 02 (1991) C2-579-C2-586
INFLUENCE OF ETCHING THE TiC UNDERLAYER WITH CH4/AlCl3/H2 ON THE CVD FORMATION OF KAPPA-Al2O3M. DANZINGER, R. HAUBNER and B. LUX
Institute for Chemical Technology of Inorganic Materials, Technical University Vienna, A-1060 Vienna, Austria
Al2O3 coatings deposited by CVD on cemented carbide inserts precoated with TiC did not lead to kappa-Al2O3 formation under laboratory conditions. An "etching treatment" with CH4/AlCl3/H2 gas mixtures prior to Al2O3 deposition did however promote kappa-Al2O3 growth. A pronounced dependence of the amount of kappa-Al2O3 on the etching time and on the CH4 concentration during the etching procedure was observed. A decrease in the deposition temperature increased the amount of the kappa-Al2O3. The alpha:kappa-Al2O3 ratio was also influenced by the Co content in the cementea carbide inserts. Higher percentages of kappa-Al2O3 were observed for inserts with the lower Co concentrations than with the higher Co concentrations. However, no kappa-Al2O3 was deposited when CH4 was added during Al2O3 deposition. Only the pure and undoped AlCl3/CO2/H2 system led to the kappa-Al2O3 formation.
© EDP Sciences 1991