SiC-TiSi2 materials codeposited by CVD

SiC - TiSi2 composites were prepared by CVD under atmospheric pressure at 850 C using the TiCl4 - SiH2Cl2 - C4H10 - H2 gas system. Thermodynamical calculation trends, dealing with the influence of the initial gas phase composition on the amount of TiSi2 were compared with the experiments. Codeposits were texture-free. Apparent crystallite size was ranging between 20 to 50nm. Intrinsic hardness deduced from the extrapolation at infinite load of measured values, fitted well with that given by a rule mixture:H∞=VTiSi2.HTiSi2+(1-VTiSi2).HSiC. Using indentation technique, median-radial crack system was observed. Values of toughness were about 35 to 50 % greater than for a pure SiC-CVD depending on the amount of TiSi2. (orig.)