In situ synthesized TiB–TiN reinforced Ti6Al4V alloy composite coatings: Microstructure, tribological and in-vitro biocompatibility

• Published in: Journal of the mechanical behavior of biomedical materials 2014-01, Vol.29, p.259-271
• Main Authors: Das, Mitun, Bhattacharya, Kaushik, Dittrick, Stanley A., Mandal, Chitra, Balla, Vamsi Krishna, Sampath Kumar, T.S., Bandyopadhyay, Amit, Manna, Indranil
• Format: Article
• Language: English
• Subjects: Alloys - chemistry; Biocompatibility; Biocompatible Materials - chemistry; Biocompatible Materials - pharmacology; Boron Compounds - chemistry; Boron nitride; Cell Line; Composite coatings; Humans; In vitro testing; Laser processing; Load-bearing implants; Materials Testing; Mechanical Phenomena; Osteoblasts - cytology; Osteoblasts - drug effects; Particulate composites; Surface Properties; Titanium - chemistry; Titanium base alloys; Titanium boride; Titanium nitride; Tribology; Wear; Wear resistance
• ISSN: 1751-6161; 1878-0180
• DOI: 10.1016/j.jmbbm.2013.09.006

Wear resistant TiB–TiN reinforced Ti6Al4V alloy composite coatings were deposited on Ti substrate using laser based additive manufacturing technology. Ti6Al4V alloy powder premixed with 5wt% and 15wt% of boron nitride (BN) powder was used to synthesize TiB–TiN reinforcements in situ during laser deposition. Influences of laser power, scanning speed and concentration of BN on the microstructure, mechanical, in vitro tribological and biological properties of the coatings were investigated. Microstructural analysis of the composite coatings showed that the high temperature generated due to laser interaction with Ti6Al4V alloy and BN results in situ formation of TiB and TiN phases. With increasing BN concentration, from 5wt% to 15wt%, the Young's modulus of the composite coatings, measured by nanoindentation, increased from 170±5GPa to 204±14GPa. In vitro tribological tests showed significant increase in the wear resistance with increasing BN concentration. Under identical test conditions TiB–TiN composite coatings with 15wt% BN exhibited an order of magnitude less wear rate than CoCrMo alloy—a common material for articulating surfaces of orthopedic implants. Average top surface hardness of the composite coatings increased from 543±21HV to 877±75HV with increase in the BN concentration. In vitro biocompatibility and flow cytometry study showed that these composite coatings were non-toxic, exhibit similar cell–materials interactions and biocompatibility as that of commercially pure titanium (CP-Ti) samples. In summary, excellent in vitro wear resistance, high stiffness and suitable biocompatibility make these composite coatings as a potential material for load-bearing articulating surfaces towards orthopaedic implants. [Display omitted] •In situ synthesized TiB+TiN reinforced Ti6Al4V alloy composite coatings were laser deposited on Ti.•Young's modulus of the coatings was between 170GPa and 204GPa.•In vitro wear resistance of the coatings containing 15wt% BN are found superior than CoCrMo alloy.•Composite coatings exhibited similar cell–material interactions as titanium.