Abstract

Plasma spraying is known to be one of the main promising processes for the manufacturing of Ti/SiC long fiber composites. However, some improvements remain to be done for this process to be applied in a routine industrial route. These include : oxygen contamination of the sprayed material through that of Ti particles before and during spraying ; damaging of fibers due to a high level of thermal stresses induced at the spraying stage; adequate deposition of Ti-based powder to achieve a low-porosity matrix and good impregnation of the fiber array. This contribution deals with work in the 3 previously mentioned fields, which resulted in a whole 3-fold study of the process. Oxidation was studied using electron microprobe analysis of elementary particles quenched and trapped into a closed box at various given flight distances. Oxygen diffusion phenomena within the particles are discussed from a preliminary theoretical approach coupled with experimental data. Isothermal and thermo-mechanical calculations were made using ABAQUS® code to determine stresses arising from contact of a liquid Ti-6A1-4V particle onto a SiC fiber. On a higher scale, i.e. that of the sprayed powder flow, a 2-dimensional original model simulating the deposition of droplets onto a substrate was developed. This model is based on a lattice-gas automaton which reproduces the hydrodynamical behavior of fluids.

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