Wear studies on plasma-sprayed Al2O3 and 8mole% of Yttrium-stabilized ZrO2 composite coating on biomedical Ti-6Al-4V alloy for orthopedic joint application

Abstract

Perumal Ganapathy,1 Geetha Manivasagam,2 Asokamani Rajamanickam,3 Alagumurthi Natarajan4 1Department of Mechanical Engineering, VRS College of Engineering and Technology, Arasur, Villupuram, Tamil Nadu, India; 2Centre for Biomaterials Science and Technology, SMBS, VIT University, Vellore, Tamil Nadu, India; 3Department of Physics, Dhanalakshmi Engineering College, Anna University, Chennai, Tamil Nadu, India; 4Department of Mechanical Engineering, Pondicherry Engineering College, Pondicherry, Puducherry, India Abstract: This paper presents the wear characteristics of the composite ceramic coating made with Al2O3-40wt%8YSZ on the biomedical grade Ti-6Al-4V alloy (grade 5) used for total joint prosthetic components, with the aim of improving their tribological behavior. The coatings were deposited using a plasma spraying technique, and optimization of plasma parameters was performed using response surface methodology to obtain dense coating. The tribological behaviors of the coated and uncoated substrates were evaluated using a ball-on-plate sliding wear tester at 37°C in simulated body-fluid conditions. The microstructure of both the titanium alloy and coated specimen were examined using an optical microscope and scanning electron microscope. The hardness of the plasma-sprayed alumina–zirconia composite coatings was 2.5 times higher than that of the Ti-6Al-4V alloy, while the wear rate of Ti-6Al-4V alloy was 253 times higher than that of the composite-coated Ti-6Al-4V alloy. The superior wear resistance of the alumina–zirconia coated alloy is attributed to its enhanced hardness and intersplat bonding strength. Wear-track examination showed that the predominant wear mechanism of Ti-6Al-4V alloy was abrasive and adhesive wear, whereas, in the case of alumina–zirconia composite coated alloy, the wear was dominated by microchipping and microcracking. Keywords: Ti-6Al-4V alloy, alumina–zirconia, wear, Hank’s solution, titanium