title: Integrated experimental and theoretical approach for corrosion and wear evaluation of laser surface nitrided, Ti-6Al-4V biomaterial in physiological solution.
abstract: A laser based surface nitriding process was adopted to further enhance the osseo-integration, corrosion resistance, and tribological properties of the commonly used bioimplant alloy, Ti-6Al-4V. Earlier preliminary osteoblast, electrochemical, and corrosive wear studies of laser nitrided titanium in simulated body fluid clearly revealed improvement of cell adhesion as well as enhancement in corrosion and wear resistance but mostly lacked the in-depth fundamental understanding behind these improvements. Therefore, a novel integrated experimental and theoretical approach were implemented to understand the physical phenomena behind the improvements and establish the property-structure-processing correlation of nitrided surface. The first principle and thermodynamic calculations were employed to understand the thermodynamic, electronic, and elastic properties of TiN for enthalpy of formation, Gibbs free energy, density of states, and elastic properties of TiN were investigated. Additionally, open circuit potential and cyclic potentio-dynamic polarization tests were carried out in simulated body fluid to evaluate the corrosion resistance that in turn linked with the experimentally measured and computationally predicted surface energies of TiN. From these results, it is concluded that the enhancement in the corrosion resistance after laser nitriding is mainly attributed to the presence of covalent bonding via hybridization among Ti (p) and N (d) orbitals. Furthermore, mechanical properties, such as, Poisson׳s ratio, stiffness, Pugh׳s ductility criteria, and Vicker׳s hardness, predicted from first principle calculations were also correlated to the increase in wear resistance of TiN. All the above factors together seem to have contributed to significant improvement in both wear and corrosion performance of nitride surface compared to the bare Ti-6Al-4V in physiological environment indicating its suitability for bioimplant applications.
authors.affiliation: Laboratory of Laser Materials Processing & Synthesis, Center for Advanced Research & Technology (CART), USA; Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203-5017, USA.
authors.forename: Hitesh D
authors.initials: HD
authors.lastname: Vora
authors.affiliation: Laboratory of Laser Materials Processing & Synthesis, Center for Advanced Research & Technology (CART), USA; Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203-5017, USA.
authors.forename: Ravi
authors.initials: R
authors.lastname: Shanker Rajamure
authors.affiliation: Laboratory of Laser Materials Processing & Synthesis, Center for Advanced Research & Technology (CART), USA; Texas Academy of Mathematics and Science (TAMS), University of North Texas, Denton, TX 76203-5017, USA.
authors.forename: Sanket N
authors.initials: SN
authors.lastname: Dahotre
authors.affiliation: Laboratory of Laser Materials Processing & Synthesis, Center for Advanced Research & Technology (CART), USA; Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203-5017, USA.
authors.forename: Yee-Hsien
authors.initials: YH
authors.lastname: Ho
authors.affiliation: Laboratory of Laser Materials Processing & Synthesis, Center for Advanced Research & Technology (CART), USA; Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203-5017, USA.
authors.forename: Rajarshi
authors.initials: R
authors.lastname: Banerjee
authors.affiliation: Laboratory of Laser Materials Processing & Synthesis, Center for Advanced Research & Technology (CART), USA; Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203-5017, USA. Electronic address: Narendra.Dahotre@unt.edu.
authors.forename: Narendra B
authors.initials: NB
authors.lastname: Dahotre
mesh_terms: D000497:Alloys; D001672:Biocompatible Materials / Q000737:chemistry* / Q000378:metabolism; D001826:Body Fluids / Q000378:metabolism; D003343:Corrosion; D004548:Elasticity; D004563:Electrochemistry; D007834:Lasers; D055595:Mechanical Phenomena; D008958:Models, Molecular; D009584:Nitrogen / Q000737:chemistry*; D011789:Quantum Theory; D012996:Solutions; D013499:Surface Properties; D013816:Thermodynamics; D014025:Titanium / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000497:Alloys; D001672:Biocompatible Materials; D012996:Solutions; C031462:titanium alloy (TiAl6V4); D014025:Titanium; D009584:Nitrogen
keywords: Corrosion; DFT; First-principles calculations; Laser gas alloying; Laser surface nitriding; Wear