The Metallographic Characterization of Thermal Spray Coating Microstructures

Thermal spray coatings from several different coating families have been metallographically prepared using traditional and modern metallographic techniques. The different recipes used were intended to demonstrate the effect of abrasive on coating appearance. Traditional metallographic recipes, which rely heavily on the use of silicon carbide (SiC) abrasive papers, were found to produce a notably different appearance than those prepared using modern recipes. Modern recipes, which incorporate extended diamond grinding and polishing steps, were found to produce what appears to be a more representative coating structure. Other variables, including mounting media and use of vacuum impregnation, were also found to influence coating appearance.