(SiC/Ti3SiC2)n Multi-Layered Coatings Deposited by CVD
Thin (SiC/Ti3SiC2)n multi-layered coatings were deposited at 1100°C on ceramic substrates by chemical vapour deposition (CVD) methods. Each SiC sub-layer was classically processed from H2/CH3SiCl3. Each Ti3SiC2 sub-layer was obtained by reactive CVD (RCVD) from a H2/TiCl4 gaseous mixture reacting on each SiC solid sub-layer that was previously deposited. The growth of Ti3SiC2 by RCVD involves partial or total SiC consumption. The H2/TiCl4 ratio was chosen on the basis of a thermodynamic study. Using a sufficiently high H2/TiCl4 ratio and limiting the sub-layer thickness allowed the formation of TiC or binary titanium silicides to be avoided. By using a constant low gas pressure in the CVD reactor, it was possible to obtain nearly pure Ti3SiC2 sub-layers as thin as 0.8 μm. In that case, the ternary compound exhibits basal planes oriented perpendicular to the substrate surface. A way to obtain thinner sub-layers was the use of a pressurepulsed CVD method. In addition, the pressure-pulsed method allowed the preferential orientation to be prevented in the Ti3SiC2 coating.
S. Jacques and H. Fakih, "(SiC/Ti3SiC2)n Multi-Layered Coatings Deposited by CVD ", Advances in Science and Technology, Vol. 45, pp. 1085-1090, 2006