A Comparative Study of Erosion Wear Performance of Thermally Sprayed Ni-Based Composite Coatings

The present study examines the erosion wear performance of Ni-15%Al2O3-5%TiO2 (Ni-Al-Ti) and Ni-15%Cr2O3-5%TiO2 (Ni-Cr-Ti) composite coatings thermally sprayed on the pump impeller material i.e., SS-420. High-Velocity Oxy-Fuel (HVOF) system was used for the deposition of these composite coatings. The erosion wear performance was analyzed by using slurry pot tester at the rotational speed of 750-1500 rpm for the time duration of 30-120 min. Fly ash was used as an erodent medium and the concentration varied from 35 to 50% with the particle size of < 53-250 µm. Taguchi method was used to optimize the influence of these operating parameters on the erosion wear performance of coatings. From the results, it was found that the erosion wear performance of uncoated SS-420 has been improved by using Ni-Al-Ti and Ni-Cr-Ti coatings. The order of effect of process parameters on erosion wear performance is found as Particle size > Time > Solid concentration (wt.%) > Rotational speed. Ni-Cr-Ti coating is considered to be superior to Ni-Al-Ti coating. From the results, particle size was observed as the most predominating factor for both coatings. This study explains that both the coatings show various erosion mechanisms, such as craters, lip formation, smear and cracks and have better erosion wear performance as compared to the uncoated SS-420.