Wear resistance of plasma sprayed Al–Si binary alloy coatings on A6063 Al alloy substrate

To improve the wear resistance of the aluminum (Al) alloy low pressure, plasma spraying was employed to form a hyper eutectic Al–Si binary alloy coating on A6063 aluminum alloy substrate by using tentatively made powders with different Si contents from 20 to 70 mass%. Dense coatings with approximately 200 μm in thickness were made on a substrate for each powder and no cracking and peeling occurred in the coatings. Hardness of the coatings increased with increasing Si content and reached approximately 570 HV at approximately 70 mass% Si. Wear resistance of the coatings evaluated by ball-on-disc wear test increased with increasing Si content to one third of that of the substrate at more than 50 mass% Si. Friction coefficient of the coating was approximately 0.4 at more than approximately 30 mass% Si and lower than that of the substrate, approximately 0.6. Estimated bond strength of the coating is at least approximately 20 MPa or higher irrespective of Si content.