Oxidation and Hot Corrosion Performance of Al2O3-40%TiO2 Coating on Nickel Based Superalloys at 800 °C

Abstract

The properties of good oxidation and corrosion resistance Nickel based Superalloys are mostly common in used at high temperature. The major degradation mechanism of failure of boiler and gas turbine components are due Oxidation and Hot corrosion. Most of the failures occur just because of the frequent uses of broad range of fuels such as oil and coal at the very higher temperature range. Superalloys as like Nickel based having extraordinary mechanical properties such as creep resistance and mechanical strength at very high temperature is used under such environment but they have small resistance. To avoiding these problems, in present research investigation Al2O3-40%TiO2 powder has been deposited on two materials Superni718 and Superni600 superalloys by using Detonation spray gun method. The coated Al2O3-40%TiO2 as well as uncoated Superni718 and superni600 alloys performance regarding Oxidation and hot corrosion, has been evaluated in air and Na2SO4-82%Fe2(SO4)3 in an aggressive environment, under cyclic conditions at a very high temperature of 800 °C. The kinetics of the oxidation and hot corrosion is approximated by weight change measurements made after each cycle for total duration of 50 cycles. Each cycle consists of keeping the samples for 1 h duration in Kanthol wire tube furnace at 800 °C followed by 20 min cooling in ambient air repeatedly. Thermogravimetric technique was used to approximate the kinetics of oxidation and hot corrosion. Technique like scanning electron microscopy was used to characterize the oxidation and hot corrosion products. The coating was deposited on both Ni based superalloys imparted better oxidation and hot corrosion resistance than the uncoated one. The Superni600 superalloy have shown better resistance to oxidation in comparison to Superni718 and Superni718 superalloy performed better than Superni600 in case of hot corrosion in the given environment.