High temperature sliding wear behavior of detonation sprayed Ni-5wt%Al coating

Abstract

The tribological behavior of detonation (DSC) sprayed Ni-5%wtAl coatings at room temperature (25 °C) and elevated temperature (850 °C) has been studied in this work. Dry sliding wear experiments were done by using alumina (Al2O3) ball-on-disc tribometer. FESEM-EDS and a non-contact 3D profilometer microanalysis were used to evaluate the worn scar and wear rate and identify the wear mechanism. X-ray diffraction (XRD) investigation indicated that the Ni-5wt%Al coating predominantly consists of γ-Ni phases at 25 °C and 850 °C conditions. The phase evolution, thermal expansion, crystallite size, and lattice strain were evaluated using in-situ high-temperature X-ray diffraction (HT-XRD). The crystallite size (D) and lattice strain (ε) were determined by Williamson-Hall analysis using a uniform deformation model (UDM), employing X-ray peak profile analysis (XPPA). In high-temperature conditions, the thermal expansion mismatch between the coating and substrate is negligible, with reduced spallation and cracking at the interface. The findings of the wear tests revealed that as the temperature increased, the coefficient of friction (CoF) and wear rate (ω) significantly decreased as the wear mechanism changed from abrasive to adhesive. The improvement of wear resistance of Ni-5wt%Al coating at high temperatures has been evaluated and discussed from the perspective of thermal expansion and tribo-layer formation.