Experimental and fe simulation studies on mechanical degradation of coatings in high temperature applications

Abstract

Metals and alloys used in high temperature application like boilers, internal combustion engines, gas turbines, fluidized bed combustion, industrial waste incinerators, etc., experience accelerated oxidation as their surfaces are covered by a thin film of fused salt in an oxidizing atmosphere at elevated temperatures which results in degradation of the material surface. This mode of attack is called hot corrosion. It has been found that no alloy or metal is immune to hot corrosion. Some alloy composition are highly resistant to hot corrosion and require a long initiation time at which the hot corrosion process moves from the initiation stage to the propagation stage. Despite the development of alloys for high temperature applications, the problem arises with these alloys in their ability to meet both the high temperature strength and the high temperature corrosion resistance to go in parallel. However, the need for protection from corrosion to a high temperature withstanding system have to overcome several criteria like adequate environmental resistance, that are chemically and mechanically compatible with the substrate; but applicable, reliable and economically viable; in practice compromising equally on all the criteria the coatings on high temperature metals and alloys that find a suitable solution. The focus of the present work is an arriving at the optimum coating thickness of wear for high temperature applications where super alloys are used. This research is broadly divided into the following four parts:Study of Coated SS-316 used as ultrasonic cavitation probe.Thermal barrier coatings for Super alloys.etals and alloys used in high temperature application like boilers, internal combustion engines, gas turbines, fluidized bed combustion, industrial waste incinerators, etc., experience accelerated oxidation as their surfaces are covered by a thin film of fused salt in an oxidizing atmosphere at elevated temperatures which results in degradation of the material surface. This mode of attack is called hot corro