Oxidation Resistance HVOF Sprayed Coating 25% (Cr3C2- 25(Ni20Cr)) + 75%NiCrAlY on Titanium Alloy

The titanium alloys posses good affinity towards oxygen at elevated temperature in air and thereby leading to oxidation. The current paper presents the oxidation behaviour of titanium alloy, Ti-6Al-4 V at elevated temperature. The degradation of the alloy oxidation mechanism is described in detail. Rapid degradation or the inability to repair these complex material results in excessively high operating costs. A suitable protective HVOF coating 25% (Cr3C2-25(Ni20Cr)) + 75% NiCrAlY was sprayed on Ti-31 alloy to combat oxidation to improve the life and efficiency of components. Thermogravimetric technique was used to study the high temperature oxidation behaviour of bare and coated alloy at 800 °C for 50 cycles, 1 hr heating in tube furnace and 20 minutes colloing in atmospheric temperature. The oxidized products are analyzed using XRD and SEM/EDX. It is observed that a coating has less porosity and semi melted powder particles in the structure. Also the coating has imparted necessary oxidation resistance by formation of chromium and nickels oxides.