T. Suhonen, T. Varis, E. Turunen, VTT Technical Research Centre of Finland, Espoo, Finland; X. Liu, S. P. Hannula, Helsinki University of Technology, Espoo, Finland
Instrumented indentation tests are shown to be easy and suitable way to test mechanical properties of thermal sprayed coatings. The linkage between these properties and coating performance under real life wear conditions were studied. Different low and high load abrasive wear tests, fine particle slurry abrasion test and solid particle erosion test were conducted to oxide and carbide coatings.Higher load range indentations were used to measure cross-sectional and surface hardness, elastic modulus, fracture toughness and critical crack initiation load. Mechanical properties of different areas and individual phases of coatings were studied by nanoindentation. Clear relationships between properties and wear were found. The new parameter called critical crack initiation load Pcr is used to evaluate how much load the surface of the coating can withstand without cracking. Components where crack-free surface is preferred Pcr play a significant role when choosing the suitable coating, for example, for wear and/or corrosion protection.
Summary: Different wear protection properties of HVOF oxide and carbide coatings were studied and linked to different mechanical properties measured with nanoindentation and higher load instrumented indentation equipment. Clear correlation between different wear conditions and mechanical properties like fracture toughness and critical crack initiation load were found.
