Tribological Behavior of Direct Metal Laser Sintering–Manufactured Ti6Al4V Alloy in Different Biofluids for Orthopedic Implants

Abstract

Ti6Al4V alloy is widely used in several engineering applications, especially in the biomedical field, because of its excellent biocompatibility, mechanical strength, and corrosion resistance. However, the Ti6Al4V alloy possesses poor tribological properties, which may lead to premature failure of the implants. From the available literature, it has been found that the wear properties of direct metal laser sintering (DMLS)-produced Ti6Al4V alloy in different lubrications have not been explored in detail. The present study tries to evaluate the tribological behavior of DMLS-manufactured Ti6Al4V alloy in different biofluid conditions, such as physiologic saline solution, simulated body fluid, and phosphate-buffered saline against an Al2O3 ball. Apart from the fluids, the effect of different load conditions like 5 N, 10 N, and 20 N at 0.157 m/s (500 rpm @ 6 mm track dia.) was also evaluated on the ball-on-disk tribometer. The experimental results have shown that the DMLS-produced Ti6AL4V alloy yields a 23% lower coefficient of friction and a 68% lower wear rate as compared to the cast Ti6Al4V. Additionally, cast and DMLS-produced Ti6Al4V alloys have followed the same wear trend for biofluids phosphate-buffered saline > simulated body fluid > physiologic saline solution. Analysis of variance (on the obtained results), field emission scanning electron microscopy, and electron dispersive spectroscopy were performed to investigate the reason behind the obtained wear behavior. The results have confirmed that the lesser wear of DMLS-produced Ti6Al4V is mainly due to its hydrophilic nature and higher hardness. Additionally, adhesion, abrasion, and oxidation were found to be the dominant wear mechanisms in both types of samples.