Continuous fiber-reinforced composite and composite coating production using plasma spray method

The number of studies related to ceramics coatings is enormous that indicates not only its importance but also shows the problems dealing with them. The ceramic coatings have some advantages like high wear resistance, chemical stability, corrosion and high temperature oxidation resistance, low friction coefficient, low thermal expansion coefficient and high hardness. However, they have some disadvantages like brittleness, adhesion difficulty and low thermal shock resistance. The aim of this study is to obtain the similar advantages of continuous fiber reinforcement in composite materials by using plasma spray technique in ceramic coatings. Thermal barrier MgZrO3 coating was selected as application area and reinforcement material was also chosen appropriate to this coating (i.e. continuous or thin wire to obtain high temperature resistance). Thin Mo wire has high melting point, low thermal expansion coefficient and high susceptibility on substrate. In this study, cylindrical and flat, mono-layer and multi-layer specimens were produced and these were exposed to thermal shock and thermal fatigue tests to investigate the effect of wire reinforcement on coating. Application of Mo fibre which forms compressive stress instead of tensile stress on the ceramic matrix with increasing temperature improves thermo-mechanical properties of the coating. Non fibre reinforcement MgZrO3 coatings spall off due to thermal expansion mismatch effect between coating and substrate at production stage. Fibre reinforcement samples exhibited a very good stability during thermal fatigue experiments and did not form any damage. However, microcracks formed during thermal shock experiments at 1000oC. As a result of this study, it was observed that continuous thin Mo fibre reinforcement has been increased the thermal shock resistance and improved mechanical properties of coatings. Mo fibers oxidized and delamination from the matrix has started above 1000 oC.