A Quick and Accurate Method to Determine Submicron Size Coating Thickness Using Micro-Indentation along with a Mathematical Model

Abstract

Hard and adherent wear-resistant thin surface coatings are synthesized on an aerospace alloy AA2219-T6 alloy using plasma-assisted physical vapor deposition. Submicron size TiN coatings with Ti interlayers are deposited and evaluated as a function of different deposition temperatures varying from 100 °C to 200 °C. Features of deposited surface layers are evaluated using different techniques; these include field emission scanning electron microscopy equipped with energy dispersive spectroscopy and X-ray diffraction. Mathematical models developed by Yu. A. Bykov and S. Hogmark are considered to estimate the coating thickness using the Composite Hardness measurements. The values predicted by Bykov’s model grossly underestimated the thickness values and thus a correction factor is proposed. The actual coating thickness is measured by sandwiching the thin coating between the substrate and electrolytically deposited nickel layer; the observations are made using field emission scanning electron microscope. The present study successfully used corrected Bykov’s Model along with micro-indentation proved to be an easy, quick and accurate method to estimate the coating thicknesses of thin hard coatings on the soft substrate over a wide range coating thicknesses.