SYNTHESIS AND DEPOSITION OF TIC-FE COATINGS BY PLASMA SPRAYING

TiC possesses a hardness so great that it has been considered for the development of wear-resistant coating materials. However, its brittleness and the difficulty in dispersing it homogeneously and finely in large volume proportions within a tough metal matrix have so far limited its application in the hard surfacing industry. Because the plasma spraying of premixed powder blends or composite powders containing TiC and metallic elements does not give coatings with homogeneous microstructures, a new method was developed for producing TiC composite coatings. It consists of the simultaneous synthesis and deposition of TiC-Fe materials by plasma spraying. Solid reagents bound together to form a single particle are injected into the plasma where a reaction occurs. The reaction products are propelled onto a substrate to form a coating. Microstructural analyses comprising X-ray diffraction analysis revealed that TiC was synthesized during spraying. Dense and thick coatings containing submicron TiC particles dispersed in an iron matrix were compared with those obtained by spraying composite powders comprising TiC and iron. With their unusual microstructure, these plasma spray-synthesized (PSS) coatings may be suitable for wear resistant applications. The low cost of starting materials makes these PSS TiC-Fe coatings very attractive as substitutes for strategic materials.