A Novel NDT Method for Measuring Thickness of Brush-Electroplated Nickel Coating on Ferrous Metal Sueface

Brush-electroplated nickel coating has been widely applied to repair and remanufacture ferrous metal component. Generally, the nickel coating has thickness from 0.05 mm to 0.2 mm, and it is also ferromagnetic like iorn metals. Therefore, the traditional supersonic thickness tester and eddy current thickness tester are not competent to measure the nickel coating thickness on iron or steel metal surface, and the brush-electropalted nickel coatings are still lack of NDT method to measure its thickness. In this paper, a novel NDT method for the brush-electroplated nickel coating thickness measuring was investigated on eddy current mechanism. A series of brush-electroplated nickel coatings with various thickness were prepared on SUS1045 steel, whose thickness was confirmed on cross-section with SEM or optical microscope. Then Eddy signals of the coatings was tested, and a fitted relationship between the eddy signal phase and the thickness was found for the nickel coatings. Based on this results, a novel NDT method to measure the nickel coating thickness was set up, which could give precise resuts and be operated simply. Therefore, the method shows wide application in engineering.