Eddy-current testing of the hardness,wear resistance,and thickness of coatings prepared by gas-powder laser cladding

The possibility of applying the eddy-current method to estimate the composition, hardness, abrasive wear-resistance, and wear resistance under sliding friction conditions of chromium-nickel and chromium-nickel-cobalt coatings prepared by gas-powder laser cladding was studied. Variations in the readings of an eddy-current instrument along the depth of the surface cladding layer and with changing thickness of coatings, which are due to the distribution of structural components in coatings and large differences between the electromagnetic characteristics of cladding layers and the ferromagnetic steel base of specimens, were determined. A technique of the eddy-current testing of the thickness of Cr-Ni and Cr-Ni-Co cladding coatings on a ferromagnetic steel base is proposed. It allows one to estimate the quality of the strengthening laser cladding and subsequent grinding, monitor the state of coatings under service conditions, and forecast the residual life of cladding elements subjected to intense wear.