Estimating Ti-6Al-4V coating thickness over SS304 substrate using simulated single-frequency apparent eddy current conductivity

摘要

Eddy current technology brings forward many advantages which can offer attractive solutions to assess metallic coating thicknesses over nonmagnetic metals. Available single and multi-frequency based impedance models are sensitive to lift-off deviations from those measured over the calibration blocks as well as different combinations of metallic coatings over nonmagnetic metal substrates. Apparent eddy current conductivity (AECC) spectroscopy has proven to overcome these drawbacks and offer a one order of magnitude improvement in estimating coating thickness in the lift-off range of ±25.4 μm. However, this technique at its present state is highly impractical due the requirement of a large coil diameter to meet the plane-wave approximation. This study simplifies the previous AECC technology to operate at a single frequency, which is validated using COMSOL simulations in agreement with the plane-wave approximation to estimate coating thicknesses, thus making this technique more practical.