Effect of addition of Al2O3 on the high-temperature solid particle erosion behaviour of HVOF sprayed Inconel-718 coatings

Abstract

In the present study, three different coatings Inconel718 + 10 wt%Al2O3, Inconel718 + 20 wt%Al2O3 and Inconel718 + 30 wt%Al2O3, were deposited by using a high-velocity oxy-fuel (HVOF) spray process. The effect of adding Al2O3 content in the Inconel-718 matrix was analyzed for the mechanical and microstructural properties. Using an 800 °C high-temperature air-jet erosion test apparatus, the erosion behaviour of the bare and coated specimens was examined at various impact angles. The XRD (x-ray diffraction) technique for determining the phases prevalent in the powders and coatings. Scanning electron microscopy (SEM) and energy dispersive spectroscopy were used to examine the surface morphology and elemental analysis of coatings (EDS). The composite coatings with maximum alumina content (30 wt%) exhibited maximum erosion resistance with a maximum microhardness of about 801 ± 40 HV0.2. However, the coating with 20 wt% alumina showed the highest fracture toughness. The inclusion of alumina reinforcement has improved the coating’s mechanical properties as well as their erosive wear resistance.The removal of splats and micro-cracking wereidentified as theprimary material removal mechanisms at a 90° impact angle. The ploughing and micro-cutting were identified as the dominant material removal mechanisms at 30° impact angle.