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Research Paper | Mechanical Engineering | India | Volume 7 Issue 6, June 2018
Cyclic Corrosion and Oxidation of Inconel-600 in Molten Salty Environment at 8000C by D-Gun Sprayed Coating
Sumit Kumar Pandey | Shiv Kumar Tripathi 
Abstract: Deterioration is the main cause of failure in Metals and alloys due to high temperature oxidation in the boiler, gas turbine, and other power generating units. Alloys are employed due to higher mechanical properties and creep resistance for air and salty environment. In current studies, Al2O3 - 40 %TiO2 coating has been sprayed on Inconel-600 alloys at 800oC by Detonation Gun (D-Gun) sprayed technique. The elevated temperature oxidation behavior of uncoated and coated alloy has been estimated by exposing the specimens at 800oC for 50 cycles of 60 Minuets heating followed by 20 minutes cooling in each cycle at ambient condition. At temperature below 650oC corrosion attack is relatively insignificant and significant above the750oC since contaminants are in the solid phase. The oxidation kinetics and hot corrosion kinetics of coated and uncoated alloys have been fixed with the help of weight change measurements. The D-Gun sprayed coating has shown good contaminants to the substrate metal and lower weight gain in coated sample as compared to bare alloy Inconel-600. The oxidation behavior of Inconel-600 in salt of 50 % Na2SO4 + 50 %NaCl has been studied under isothermal conditions at a temperature of 800C in a cyclic manner. Squalor of components of boilers, gas turbine, metallurgical furnaces, petrochemical installations are mainly due to the high temperature oxidation and hot corrosion. Superalloys find their wide applications in the gas turbine and marine engineering due to their good mechanical properties at elevated temperature. It was observed that all the coated and uncoated Inconel mapping techniques were used to analyze the oxidation products of the coated and uncoated Inconel. The uncoated Inconel and hot corrosion in the form of its oxide scale, which was perhaps due to the formation of unproductive oxide scale. The coating showed better resistance to the air oxidation as compared to the uncoated Inconel. The coating Al2O3 - 40 %TiO2 was found to be more protective. The formation of oxides and spinals of aluminum and titanium may be contributing to the development of air oxidation resistance in the coatings. The high temperature oxidation and hot corrosion behavior of Al2O3 - 40 %TiO2 coatings on inconel-600 has been investigated at 800oC in air and molten salt 50 % Na2SO4+ 50 % NaCl under cyclic heating and cooling conditions for 50 cycles. The kinetics of oxidation of coated and bare boiler steel has been established with the help of weight change measurements. The kinetics of oxidation may be define by evaluation by parabolic rate constant value KP, which was found by the following rate equation (/) 2/t = KP where (/) was the weight change measurement per unit surface area and Kp the parabolic oxidation rate constant, t the cooling time. It was observed that all the coated and bare steels obeyed parabolic rate law of oxidation (KP). The oxidation and hot corrosion of the coated and uncoated Inconel. The uncoated Inconel-600 are hot corrosion in the form of intense spelling and peeling of its oxide scale, which was perhaps due to the formation of unproductive oxide scale. The coatings showed better resistance to the air oxidation as compared to the uncoated Inconel-600. The Al2O3 - 40 %TiO2 coating was found to be more protective. The formation of oxides and spinals of nickel and chromium may be contributing to the development of air oxidation resistance in the coating.
Keywords: Deterioration of metal and alloys, preventing of metals from hot corrosion, detonation spray coating of metal, D-spray
Edition: Volume 7 Issue 6, June 2018,
Pages: 1556 - 1562