Optimization of mechanical and corrosion properties of plasma sprayed low-chromium containing Fe-based amorphous/nanocrystalline composite coating

By Kumar, Anil; Nayak, Sapan K.; Bijalwan, Pavan; Dutta, Monojit; Banerjee, Atanu; Laha, Tapas
Published in Surface and Coatings Technology 2019


In this work, iron (Fe)-based amorphous/nanocrystalline composite coatings were synthesized using low-chromium containing amorphous powder (Fe73Cr2Si11B11C3, at. %) via atmospheric plasma spraying (APS) at different plasma spraying parameters. Coatings were deposited with 2 and 3 numbers of torch pass to get different coating thickness, along with the plasma power range was varied from 25 kW to 35 kW to alter the degree of powder melting. Microstructural studies demonstrated that porosity content and fraction of crystalline phase formation in the coatings were highly sensitive to spraying parameters. Increase in both the plasma power and coating thickness led to reduction in the porosity content and higher devitrification. Nanohardness of the coatings increased at elevated plasma power which was ascribed to the formation of denser coatings and precipitation of nano-sized Fe-borides, and therefore wear resistance of the coatings also improved. However, decrease in corrosion resistance was observed in the coatings deposited at the highest spraying power of 35 kW. Corrosion resistance improved with increasing coating thickness because of reduction in pore content, while formation of larger grains in thicker coatings caused decrease in nanohardness. Spraying power of 30 kW with three numbers of torch passes was found to be the optimum spraying parameters, and coating deposited at these parameters showed nanohardness value of 11 GPa, wear resistance coefficient of 49.9

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