Tribo-corrosion characterization of NiTiCu alloy for bio-implant applications

In the current scenario of medical research, NiTi based smart alloys gaining importance due to the pioneer quality of biocompatibility, wear and corrosion resistance. In the present research, copper particles were blended with the nickel and titanium powder for 8 hours in high energy ball mill for uniform mixing. Specimens were fabricated using powder metallurgy at different compaction pressures. During the sintering process, the binder gets evaporated which makes it porous and suitable for biomedical implants. The testing was carried out to improve the corrosion and wear resistance of NiTi alloy under load-bearing biomedical applications. The addition of copper increases the wear and corrosion resistance of NiTi alloy. The experiments were conducted on pin-on-disk tribometer in the presence of simulated body fluid (SBF) at the temperature of 37 +/- 1 degrees C. The test conditions were maintained according to the simulated hip joint. It was observed that the wear resistance of NiTi alloy increases slightly with the addition of copper particles up to certain percentage. The behaviour of the material changes after copper addition in the presence of SBF. Furthermore, the copper particles were blended with other particles to investigate the consequences on the tribological and corrosion characteristics of the developed materials. The corrosion rate increases when the copper contents were more than 5% due to decrease in the E-corrosion (-0.19), but after increase the copper content from 5% an increase in E-corrosion (-0.17) was observed. The copper content should be less than 5% to avoid pitting in the material; otherwise, it decreases the anti-pitting ability of NiTi alloy. The size of wear debris also decreases with the addition of copper up to 5%. After that, an increase in the size of wear debris was observed which makes it unsuitable for biomedical implants.