Scratch resistance and in-vitro biocompatibility of plasma-sprayed baghdadite coatings reinforced with carbon nanotubes

Abstract

Hydroxyapatite (HA, Ca10(PO4)6(OH)2) coatings, commonly used for metallic implants, have limitations such as excessive brittleness, low fracture toughness, inadequate wear resistance, and slow osseointegration properties. In contrast, baghdadite (BAG, Ca3ZrSi2O9), a calcium zirconium silicate-based bioceramic, exhibits outstanding biological properties, to promote cell proliferation and differentiation of human osteoblasts along with adequate mechanical strength. In this study, plasma-sprayed HA, BAG, and carbon nanotubes (CNT, 1 wt%, and 2 wt%) reinforced BAG coatings are deposited on titanium (Ti) substrate to enhance its mechanical as well as biological properties. The microhardness values of CNT-reinforced BAG coatings increase due to a decrease in porosity and the retention of CNT inside the BAG matrix. Progressive loading scratch tests are performed, revealing a reduction in wear volume loss from 15.051 mm3 to 12.574 mm3 and scratch rate from 43.262 mm3N−1 m−1 to 36.172 mm3N−1 m−1 with the addition of 2 wt% CNT in BAG coatings. The scratch hardness test results demonstrated that introducing CNT into BAG coating significantly enhances its performance, showing a remarkable 38.7 % improvement. In-vitro cell culture studies indicate excellent cell adhesion, growth, and proliferation of MC3T3-E1 osteoblast cells on the surfaces of the CNT-reinforced BAG coatings.