Wear resistance enhancement of the titanium alloy Ti–6Al–4V via a novel co-incident microblasting process

Abstract

In this study a room temperature coating deposition technology was investigated as a means of enhancing wear resistance of the titanium alloy Ti–6Al–4V. This process, termed CoBlast™, consists of co-incident particle streams of abrasive and coating materials which impact a substrate to create a modified surface. Al 2O 3 powder was chosen as the abrasive, while Teflon, SiC and B 4C powders were investigated as coating precursors. Ti–6Al–4V surfaces modified via CoBlast using either Al 2O 3–SiC or Al 2O 3–B 4C powder mixtures both demonstrated increased hardness compared with the unmodified alloy, however, wear testing performed using a pin-on-disc tribometer revealed that this did not translate to an appreciable improvement in wear resistance performance. In contrast, under the same wear test conditions, Al 2O 3–Teflon CoBlast modified Ti–6Al–4V demonstrated a significantly reduced friction coefficient and average pin-on-disc wear track widths and depths of 68 and 90% less than those which formed on the unmodified alloy. Through the deposition of either SiC or B 4C coatings in combination with a Teflon top layer a further improvement in wear resistance was confirmed by a 81/97% reduction in wear track width/depth. In conclusion, the deposition of Teflon coatings onto unmodified, SiC modified or B 4C modified Ti–6Al–4V using the CoBlast process yielded surfaces with significantly enhanced wear performance.