Tribological Behaviour of Pure Ti with a Nanocrystalline Surface Layer Under Different Loads

Abstract

Surface mechanical attrition treatment (SMAT), a novel surface severe plastic deformation method, was carried out for titanium (Ti) to create a gradient-structured Ti (SMAT Ti). The tribological behaviour was studied under different loads and dry sliding conditions. The results showed that the deformation layer of SMAT Ti was about 160 lm. The friction and wear results showed that the wear resistance of SMAT Ti was enhanced compared to the coarse-grained (CG) counterpart. SMAT Ti showed abrasive wear under 1 and 5 N, and exhibited abrasive and adhesive wear under 2 N. While CG Ti showed abrasive and adhesive wear under 1-2 N, and exhibited abrasive wear under 5 N for the work hardening effects.

Oxide dependent wear mechanisms of titanium against a steel counterface: Influence of SMAT nanostructured surface

“…The top surface curvature with a shallow valley is due to a ball impact occurring during the SMAT process. Consistently with several previous investigations of SMATed surfaces, and in particular with studies carried out on commercially pure Ti [21,22,25], a layer containing sub-micrometer or even nanosize grains is detected at the top surface within a few tens of μm. In our case, these sub-micrometer grains -as illustrated in the higher magnification image Fig.…”

“…After the break-in, the coefficient of friction reached values of around 0.5 corresponding to stage I. Similar results were previously reported by Wen et al [25] and by Alikhani Chamgordani et al [22] respectively for nanostructured and coarse grained commercially pure Ti surfaces. The coefficient of friction remained in a steady-state for at least several hundreds of cycles independently of the surface condition.…”

“…SMAT resulted in a 20 times increase of both Ra and Rz values when compared to the polished initial surfaces. It is interesting to stress here that the Rz value is comparable to the typical depth of wear tracks measured after the tribology tests in several other studies [22,25]. As will be discussed and 5 N on commercially pure titanium treated by SMAT on a limited 30 m total sliding distance.…”

“…The tests were conducted at a relatively high speed of 230 mm/s with a 3 N load and a 275 m total sliding distance. Wen et al [25] also noted a reduction in wear loss for tests conducted at 50 mm/s with loads of 1, 2 i. The initial coarse grained samples after the 2000 grit polishing procedure ii.…”

“…The aim of this work is to gain new insights in the understanding of the tribological properties of Ti and investigate in details the potential of SMATed commercially pure titanium at room temperature under unlubricated condition and at relatively low sliding speed. Thus, compared to previous works [22,25], this paper proposes a deep understanding of the wear mechanisms and their origin for the titanium-steel contact by the determination of the nature of the oxides formed, where and when they appeared and how they affected the friction. Potential industrial applications of this titanium-steel contact are in the manufacturing of steels parts when titanium friction pads are used to guide the work piece during processing as well as for aeronautical applications where titanium is widely used.…”