Erosion Behavior of Cold-Sprayed Coatings Made of CoCrFeMnNi HEA and Tungsten Carbide Nanoparticles in a Nickel Matrix

The study investigated the performance of CoCrFeMnNi high entropy alloy and tungsten carbide–nickel coatings under alumina particle impingement. The coatings were applied to 2205 duplex stainless steel substrates by cold spray using nitrogen. For the composite coatings, the amount of WC nanoparticles entrapped in the Ni matrix was estimated as 42.5 ± 8 vol.%. A cold-sprayed interlayer of 316 stainless steel promoted CoCrFeMnNi HEA deposition. Post-process annealing was performed on the coatings. After 3 hours of holding time, x-ray diffraction examination revealed no tungsten decarburization in the WC/Ni-Ni coating. Annealing peak temperatures for the WC/Ni–Ni and high entropy alloy coatings were 600 and 550 °C, respectively. The effect of SS316 annealing on subsequent HEA deposition and coating’s erosion behavior was also investigated. Microhardness tests showed the HEA coating outperforming the WC/Ni-Ni. The coatings were subjected to impact erosion using alumina particles at three different approach angles: 30°, 60°, and 90°. To compare the different materials, average erosion values were calculated expressed in volume loss per grams of erodent. The as-sprayed WC/Ni–Ni was the most effective against 60° impingement angle, while HEA coatings demonstrated promising under impacts at 30° and 90°. Overall, the 30° impact orientation was identified as the most critical condition. Eroded surfaces were examined using optical microscopy (OM) and scanning electron microscopy (SEM).