Method for assessing degradation of a coating on a component by measuring its surface roughness
Patent 8056407 Issued on November 15, 2011. Estimated Expiration Date: September 16, 2028. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
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.