Patent ID: 6040694
Filing Date: 2000-03-21
Classification: G01B

Abstract:
A method for determining a thickness of a protective layer of a component, which comprises:providing a component having a protective layer with an electrical conductivity .kappa..sub.1 and a base material with an electrical conductivity .kappa..sub.2, the protective layer disposed on the base material and the electrical conductivity .kappa..sub.1 and the electrical conductivity .kappa..sub.2 being different from each other;applying a high-frequency electric current to an excitation coil, the excitation coil being coupled to a probe coil;moving the excitation coil near to the protective layer to produce an electric eddy current in at least the protective layer;determining a parameter related to an impedance of the probe coil, using the determined parameter, according to an eddy-current testing principle, as a basis for determining a thickness of the protective layer; andselecting a frequency of the high-frequency electric current, based on the eddy-current testing principle, to unambiguously determine the thickness of the protective layer where a ratio .kappa..sub.2 /.kappa..sub.1 of the electrical conductivities is between 0.7 and 1.5.