For conductive plates with tens of micrometres of metallic coating, a novel approach is proposed to simultaneously measure the coating thickness, coating conductivity and substrate conductivity by analogizing eddy current testing to the parameter measurement process using the apparent conductivity in the field of magnetotelluric sounding. A normalisation method is presented for both coil impedance and plane wave impedance and the approximation relationship between them is theoretically deduced under a certain condition. Comparing the experimental curve of the equivalent conductivity of coil impedance measured by swept-frequency eddy current testing and theoretical curves of normalised apparent conductivity of plane wave impedance, all parameters of the coated plate can be measured. Two measurement experiments were performed on a 304 stainless steel plate with titanium coating, and the results show that all relative measurement errors are less than 3% for the plate with 32 μm-titanium coating and 5% for the plate with 23 μm-titanium coating. The effect of the difference between the coating and substrate conductivity values on the measurement error, and the selection of measurement frequency range were discussed.

对于具有数十微米金属涂层的导电板，提出了一种新颖的方法，该方法通过将涡流测试与大地电磁测深领域中的视在电导率相类似的参数测量过程，来同时测量涂层厚度，涂层电导率和基体电导率。提出了针对线圈阻抗和平面波阻抗的归一化方法，在一定条件下理论推导了两者之间的近似关系。将扫频涡流试验测得的线圈阻抗等效电导率实验曲线与平面波阻抗归一化视在电导率理论曲线进行比较，可以测得镀层板的所有参数。在具有钛涂层的304不锈钢板上进行了两次测量实验，结果表明，对于32μm钛涂层的钢板，所有相对测量误差均小于3％，对于23μm钛涂层的钢板，其相对测量误差均小于5％。 。讨论了涂层和基体电导率值之间的差异对测量误差的影响，以及测量频率范围的选择。