EFFECT OF MULTI-WALLED CARBON NANOTUBES IN REINFORCED HYDROXYAPATITE COMPOSITE COATINGS FOR ORTHOPEDIC APPLICATIONS

Abstract

Hydroxyapatite (HA)-coated metallic substrates are commonly used for load-bearing orthopedic implants. In this work, Titanium grade 2 and Titanium grade 5 substrates were coated with hydroxyapatite and hydroxyapatite reinforced with 5% (by wt.) multiwalled carbon nanotubes (MCNT) separately using plasma spray coating. The wear behavior of these coated substrates was studied with the simulated body fluid (SBF) having a pH between 7.20 and 7.40. Fracture toughness and wear resistance of HA reinforced with 5% (by wt.) MCNT composite coating was found to be higher as compared to pure HA coating. This improvement is by virtue of inherent mechanical properties and the crack bridging effect offered by MCNT. The addition of MCNT also helped in restricting crack propagation in the coatings. As evident from SEM images, abrasive and adhesive wear mechanisms were observed which reduce greatly with the reinforcement of MCNT.