Corrosion behaviour of plasma-sprayed baghdadite bioceramic coatings reinforced with carbon nanotubes

Bioceramics have been extensively used for the restoration and replacement of hard tissues, such as bones and teeth due to their physicochemical resemblance to these tissues. This study focuses on enhancing the properties of plasma-sprayed bioceramic coatings with the addition of carbon nanotubes. The coatings deposited include hydroxyapatite, baghdadite, and baghdadite with carbon nanotube reinforcement. The effect of incorporating carbon nanotubes into baghdadite coatings is thoroughly investigated in terms of microstructural, mechanical, and electrochemical properties. Multiple characterization techniques such as scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry, and Raman spectroscopy have been employed to reveal microstructural details, elemental composition, and phase constituents of the deposited coatings. The results indicate that baghdadite coatings exhibit higher porosity compared to hydroxyapatite coatings. However, the addition of carbon nanotubes as reinforcement into baghdadite coatings effectively reduces porosity by integrating carbon nanotubes within the inter-lamellae structure and filling voids within the inter-splat regions. This integration also mitigates common post plasma spray defects including porosity, voids, and microcracks. The incorporation of 2 wt% carbon nanotubes into the baghdadite matrix results in a substantial 80% reduction in corrosion current density(Icorr). This reduction is attributed to the combined effects of reduced porosity, and improved structural integrity due to carbon nanotubes. Furthermore, the carbon nanotubes reinforced baghdadite coatings have indicated the healthy development of the MC3T3-E1 osteoblast cell line.