Non-destructive metal coating thickness measurement - uses electrodes in contact with surface, local layer, carrier resistance differences

摘要

An arrangement for non-destructive measurement of the thickness of a metallic surface layer (2) on a carrier body (1) is applicable where the layer and carrier body electrical conductivities are significantly different. It operates irrespective of the atomic wts. of the carrier body and the surface layer material. Two electrodes (3,4), which are connected to a voltage source via an adjustable series resistor, are placed on the surface layer (2) at a defined separation distance (1) and with a defined application pressure. The thickness of the layer is determined from the locally different electrical resistance values of the carrier body and the surface layer at the measurement point. The electrodes are rectangular, and in partic. square, with a contact area small compared to the electrode separation.