Tungsten Inert Gas (TIG) Assisted TiC-NiCoating on AISI 304 Stainless Steel

Abstract

Metal components very often lose their functionality through wear by various modes such as abrasion, impact or corrosion. To counteract such problems, and there by to extend the service life, modification of surfaces are frequently done. This surface engineering approach finds application across many sectors namely defense, mining, steel, power, cement, petrochemical sugarcane and food. Generally the base material of the component is selected on the ground of strength and cost involved, while the details of the surface properties are adopted for local tribological conditions to which the vulnerable section will be subjected during its service period. There have been wide range advancement in surface engineering technology to square up surface failure in steels. But each technology that evolved has its own limitations. Deposition of thin hard coatings of 0.5 mm can improve tribological properties in terms of low friction and wear resistance. But in case of light metal alloys, when the load is high, the coating may fail by deformation. In such cases reinforcement of metals with ceramics can increase the physical and surface properties like strength, stiffness, wear resistance, high temperature strength and a reduction in weight. Over the years, modification of the matrix close to the surface, as well as reinforcement, has been introduced. The addition of ceramic particles into the molten metal surfaces to form a metal matrix composite (MMC) is a very popular one and is widely used worldwide. The formation of MMC meets the specifications required for specific applications. Tungsten Inert Gas (TIG) welding method produces a small modified hemispherical surface which has a width of few millimeters. It also incorporates less cost compared to laser treatment, so widely in practice. TiC is used as a reinforcement material as it has received some attention being a wear resistance substrate. Ni is used as it is a very good binder that produces a well-mixed Tic-Ni mixture. TIG process was used to melt the TiCNi MMC on an AISI 304 stainless steel. This achieved an approximate micro hardness value of 800HV.