Surface Modification of Ti-6Al-4V Alloy by Electrical Discharge Coating Process Using Partially Sintered Ti-Nb Electrode

• Published in: Materials Vol. 12; no. 7; p. 1006
• Main Authors: Prakash, Chander, Singh, Sunpreet, Pruncu, Catalin Iulian, Mishra, Vinod, Królczyk, Grzegorz, Pimenov, Danil Yurievich, Pramanik, Alokesh
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 27.03.2019; MDPI
• Subjects: Adhesive strength; Biocompatibility; Biological activity; Coated electrodes; Corrosion resistance; Corrosive wear; Electric discharges; Electrodes; Machining; Mechanical properties; Microcracks; Microhardness; Morphology; Niobium carbide; Niobium oxides; Orthopaedic implants; Orthopedics; Plasma sintering; Scanning electron microscopy; Sintering (powder metallurgy); Spectrum analysis; Surface hardness; Surface properties; Thickness; Titanium base alloys; Titanium carbide; Titanium dioxide; Transplants & implants; Wear resistance; Workpieces; United States > US; India; alloy; microhardness; adhesion strength; EDC; Ti-6Al-4V; microcracks
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma12071006

In the present research, a composite layer of TiO2-TiC-NbO-NbC was coated on the Ti-64 alloy using two different methods (i.e., the electric discharge coating (EDC) and electric discharge machining processes) while the Nb powder were mixed in dielectric fluid. The effect produced on the machined surfaces by both processes was reported. The influence of Nb-concentration along with the EDC key parameters (Ip and Ton) on the coated surface integrity such as surface topography, micro-cracks, coating layer thickness, coating deposition, micro-hardness has been evaluated as well. It has been noticed that in the EDC process the high peak current and high Nb-powder concentration allow improvement in the material migration, and a crack-free thick layer (215 μm) on the workpiece surface is deposited. The presence of various oxides and carbides on the coated surface further enhanced the mechanical properties, especially, the wear resistance, corrosion resistance and bioactivity. The surface hardness of the coated layer is increased from 365 HV to 1465 HV. Furthermore, the coated layer reveals a higher adhesion strength (~118 N), which permits to enhance the wear resistance of the Ti-64 alloy. This proposed technology allows modification of the mechanical properties and surface characteristics according to an orthopedic implant’s requirements.