The dry sliding wear behaviour of titanium (Grade 5) alloy has been investigated in order to highlight the mechanisms responsible for the poor wear resistance under different applied normal load, sliding speed, and sliding distance conditions. Design of experimental technique, that is, response surface methodology (RSM), has been used to accomplish the objective of the experimental study. The experimental plan for three factors at three levels using face-centre central composite design (CCD) has been employed. The results indicated that the specific wear rate increases with an increase in the applied normal load and sliding speed. However, it decreases with an increase in the sliding distance and a decrease in the sliding speed. The worn surfaces of the titanium alloy specimens were analyzed with the help of scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) techniques. The predicted result also shows the close agreement with the experimental results and hence the developed models could be used for prediction of wear behaviour satisfactorily. 1. Introduction Titanium and its alloys exhibit a unique combination of mechanical, physical, and corrosion resistance properties which have made them desirable for critical application in aerospace industries and chemical and energy industries. In comparison to light weight alloys based on aluminum, magnesium and titanium alloys present interesting possibilities as tribomaterials, but they have not been widely investigated as bearing materials [1]. The tribological concerns for titanium alloy in aerospace components have focused mainly on their fretting behavior, leading to research on surface treatments like ion implantation and solid film lubrication [2, 3]. However, titanium and titanium alloys generally exhibit poor fretting, wear resistance, and tribological properties even when sliding against softer materials. One of the main reasons behind poor tribological properties of titanium alloys is the low thermal conductivity of these alloys [4]. This is due to the disruption of extremely thin, low shear strength, oxide film, consisting mainly of titanium dioxide (TiO2) which results in both depassivation and subsequent accelerated wear of the metallic surface due to the displaced particles of oxide giving rise to three-body abrasive wear [5–10]. The use of titanium alloys in sliding applications is limited because of their poor wear resistance [11]. This is due to low resistance of titanium alloys to plastic shearing as well as low protection by surface oxide
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