Simultaneous Erosion and Oxidation of Nickel at High Temperatures

Abstract

Structural alloys and coating alloys have been developed that successfully resist high temperature oxidation and, to a lesser extent, hot corrosion — depending on conditions. Such protection depends upon the maintenance of a surface layer of oxide that effectively separates the metal from the reactive environment.

The oxide protective coatings may however be damaged by erosion by solid particles in the gas flow, the effect being worse when the velocity of the gas flow is high. Unfortunately the detailed mechanisms by which the processes of erosion and oxidation interact at high temperatures are not understood. Much of the work carried out so far has involved studies of the erosion of metals and oxidized metals at room temperature under controlled conditions, or has involved tests at high temperature under conditions designed to simulate those in gas turbines or coal combustors. The data obtained from such tests are well suited to producing reliable comparisons of the behavior of different materials but do not readily lead to analysis of the mechanisms by which erosion and corrosion interact at high temperature.

This paper is concerned with the erosion-oxidation of nickel. An apparatus is described in which specimens can be exposed to well defined and controlled conditions. Results are then presented on the erosion-oxidation of nickel and models are developed to describe the observed interaction between these two processes.