High-temperature tribological investigation of APS and HVOF sprayed NiCrBSiFe coatings on SS 316L

ABSTRACT In numerous high-temperature applications like hot forming, power generation and aerospace, many components are coated by thermal spraying to counter wear and high-temperature oxidation. In this paper, the unidirectional dry sliding wear and friction behaviour of APS (atmospheric plasma spray) and HVOF (high velocity oxy-fuel) sprayed NiCrBSiFe coatings have been investigated at 300, 500, and 700°C temperature. The high-temperature dry sliding wear tests were performed at 18 m/min sliding velocity, 10 N normal load, and silicon nitride (1580 HV0.3) as counter material on the pin on disc tribometer, as per ASTM G99 standard. The specific wear rate and the coefficient of friction were compared to assess the behaviour of APS and HVOF coatings. For both coatings, the specific wear rates increased with the temperature. As compared to the APS coating, the HVOF coating had enhanced wear resistance at high-temperature, due to the close packed partially melted particles, low oxide inclusion, low porosity and high hardness. GRAPHICAL ABSTRACT