Comparative study of three methods for measuring thickness of PVD hard coatings

摘要

This study presents a comparison between three methods that are widely employed for measuring thickness of PVD hard coatings, namely: the calotte grinding method (CGM), glow discharge optical emission spectroscopy (GDOES) and metallographic micro polishing (MMP). Thickness measurements were performed in several coating structures deposited on steel substrates. Based on the results, a discussion of their main advantages and disadvantages is presented, focusing on the complementarities between the three methods. Each method provided results at various levels of cost, accuracy and time. The high precision of MMP is the main advantage of this method; however sample preparation is time consuming. GDOES provides quick results but the equipment and testing costs are high. The CGM is the quickest and less expensive, but not the most accurate. It was concluded from this study that no method is better than the others; instead, each method should be regarded as complementary to one another.