Rolls-Royce Corporation

The Chancellor, Masters and Scholars of the University of Cambridge

Siavash Pahlavanyali

Stephen Moray Bagnall

Julian Charles Mason-Flucke

Catherine M F Rae

Catherine Mary Fiona Rae

A method of testing the oxidation resistance of an alloy includes applying a layer of salt on the alloy's surface and placing the alloy in a furnace at a temperature of at least 1000&#xb0; C. and containing an oxygen containing gas. The alloy is maintained in the furnace at the predetermined temperature for a period of time then the alloy is removed from the furnace and the alloy is to cool to ambient temperature or other suitable temperature. These steps are repeated for a number of times to maintain the salt on the alloy's surface at a level of 0.5 to 30 &#x3bc;g cmh. The alloy is weighed periodically to determine oxidation resistance. The addition of salt reduces the time to test the oxidation resistance of the alloy and the addition of the salt mimics the degradation of the alloy in a real working environment in a gas turbine engine.

Method of testing the oxidation resistance of an alloy

A method of assessing the degradation of an oxide-forming coating on a component after a period of operational use of the component, said degradation of the coating being caused by depletion of the oxide-forming element within a remnant coating layer due to inter-diffusion of said element between the remnant coating and both an outer oxide layer and an inner, secondary diffusion layer, wherein a depletion parameter indicative of the depletion of the oxide-forming element in the remnant coating layer varies as a function of the surface roughness of the coated component, the method comprising the steps of: carrying out a non-destructive, quantitative measurement of the surface roughness of the component after said period of operational use; and, based on an estimation of the functional relationship between the surface roughness and the depletion parameter, using the result of said measurement of surface roughness to quantitatively assess the degradation of the coating.

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Epsom, United Kingdom

Siavash Pahlavanyali