Patent ID: 7175720
Filing Date: 2007-02-13
Classification: G01N

Abstract:
1. A method of determining the depletion of Al and Cr of a γ/γ′ MCrAlY-coating of a component after use in a high temperature environment, the method comprising: (a) using a component having a γ/γ′ MCrAlY-coating in a high-temperature environment in which the γ/γ′ MCrAlY-coating exhibits an equilibrium γ/γ′-microstructure, (b) cooling the component to a temperature lower than the operation temperature such that the γ/γ′ MCrAlY-coating exhibits a non-equilibrium γ/γ′-microstructure at room temperature. (c) applying a defined annealing heat treatment to the γ/γ′ MCrAlY-coated component to transform the non-equilibrium high temperature γ/γ′-microstructure into the equilibrium room temperature microstructure with a α-Cr phase, (d) measuring qualitatively impedance curves or the electrical conductivity and magnetic permeability of the MCrAlY-coating by means of a multi-frequency eddy current system, and (e) determining the Al and/or Cr depletion of the coating from the measured impedance curves or coating conductivity and permeability.