Optimization of hvof coating process parameters to improve the wear resistance of titanium alloy

Abstract

Recently, titanium alloys have received considerable attention due to their excellent corrosion resistance, high strength-to-weight ratio, high strength at elevated temperatures, and biological compatibility. Hence, these alloys are used in a wide range of applications in aerospace, automotive, chemical, and medical industries. Titanium alloys have outstanding physical-mechanical properties, but they are difficult-to-machine because of their high chemical reactivity, poor heat conductivity, low modulus of elasticity, which lead to lower production rates and increased wear. Improving the wear resistance of titanium alloys has become an important area of research nowadays, and for enhancing the wear resistance of the Ti-6Al-4V alloy, some surface modification is required. It has been evaluated by earlier researchers that, ceramic could be plasma sprayed, but results have not been illustrated with proper correlation between coating properties and interfacial bonding characteristics and also, sufficient data were not available on specific wear rate of thermal sprayed coatings. In conjunction with this, High Velocity Oxygen Fuel (HVOF) technique was chosen, which is widely accepted and presently used in many advanced industrial applications. In this research work, heat treatment and HVOF based thermal spraying of silicon carbide (SiC) powders were carried out and experiments were conducted to evaluate the mechanical and tribological properties. Based on the outcomes, suggestions have been made for their efficient usage at applications where high wear resistance is warranted in aerospace, defence and automotive fields. iv In the first case, the Ti-6Al-4V alloy material was subjected to heat treatment above its transformation temperature (950and#61616;C) followed by cooling in furnace. These specimens were further aged at 550and#61616;C for 3 hours and then water quenched. The property of poor wear resistance can be improved by changing the microstructure of the alloy with the formation of martensitic structure (acicular and#945; or retained