Development of the High-Precision Intelligent Coating Thickness Gauge

An intelligent and high-precision eddy current thickness measuring gauge for thin nonmagnetic coating thickness measurement on magnetic substrate was researched and developed. The system included the special probe with magnetostatic shielding, the signal generator with high stability and low-drift, low noise and high precision amplifier, the system software with the function of multiple calibration and compensation. The measuring result for the zinc coating on magnetic substrate using the gauge showed that the measuring range was from 0 to 30 μm, the measuring precision could meet 0.5 μm±3%(measurement value) and the diameter of the minimal measurement area was  5 mm2, which was satisfactory for the measurement of high-precision coating thickness. The application prospect of this gauge was bright.