Wear Behavior of Plasma Sprayed Nanostructured Al-SiCp Composite Coatings: A Comparative Study

Powders of AlSi, 2024Al and 6061Al were separately ball milled with 15 wt% SiC reinforcement in a high-energy attrition ball mill using stainless steel balls for 8 h. The ball milled powders were plasma sprayed on the weathering steel (Cor-Ten) substrates to get Al-SiC composite coating with as much high volume fraction as possible of SiC. The microstructure characteristics of coatings were examined by SEM, XRD and image analyzer. XRD studies showed SiCp embedment in the Al matrix after ball milling, and nano grains in the ball milled powder and coatings. The thickness of coating and hardness were measured. The high adhesion-strength of the coatings observed might be attributed to higher degree of diffusion at the interface. The wear behaviors of the coatings were carried out under pin-on-disc wear test machine for 50 N load. Results showed that hardness and wear resistance of coatings depended on SiCp fraction and crystallite size in the matrix. The results of mechanical and wear tests also indicated that high-energy attrition ball milling and addition of SiC particles increased the strength, hardness and wear resistance of the coatings.