Wear mechanism and tribological characteristics of porous NiTi shape memory alloy for bone scaffold

Abstract

The abraded debris might cause osteocytic osteolysis on the interface between implants and bone tissues, thus inducing the subsequent mobilization of implants gradually and finally resulting in the failure of bone implants, which imposes restrictions on the applications of porous NiTi shape memory alloys (SMAs) scaffolds for bone tissue engineering. In this work, the effects of the annealing temperature, applied load, and porosity on the tribological behavior and wear resistance of three-dimensional porous NiTi SMA are investigated systematically. The porous structure and phase transformation during the exothermic process affect the tribological properties and wear mechanism significantly. In general, a larger porosity leads to better tribological resistance but sometimes, SMAs with small porosity possess better wear resistance than ones with higher porosity during the initial sliding stage. It can be ascribed to the better superelasticity of the former at the test temperature. The porous NiTi phase during the exothermic reaction also plays an important role in the wear resistance. Generally, porous NiTi has smaller friction coefficients under high loads due to stress-induced superelasticity. The wear mechanism is discussed based on plastic deformation and microcrack propagation.

Is Graphene a Promising Nano-Material for Promoting Surface Modification of Implants or Scaffold Materials in Bone Tissue Engineering?

“…74,75 However, its metal nature results in metal leaching, lack of cell adhesion, and proliferation and thrombosis when in contact with flowing blood, which limits its application. An ideal surface coating is expected to have high adhesion strength, be chemically inert, and show hemo-and biocompatibility.…”

Fabrication of nickel-titanium-iron shape memory alloys by powder metallurgy route and analyses of their physical and mechanical behaviour

“…But as the Ti content decreases (below 33%) and the temperature increases, Ni 3 Ti formation is favourable. This elemental fluctuation usually arises from insufficient mixing [45]. The superelastic behaviour of NiTi-based SMAs is caused by the stress-induced or temperature-induced transformation between both the austenite and martensite phases.…”

“…The superelastic behaviour of NiTi-based SMAs is caused by the stress-induced or temperature-induced transformation between both the austenite and martensite phases. The NiTi intermetallic phase shows the superelastic behaviour, whereas the secondary phases do not show the superelastic behaviour but contribute to the hardness and tribological behaviour in the NiTiFe samples [45].

Figure 4 XRD analysis of samples with different Fe contents.

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A mechanical contact model for superelastic shape memory alloys

“…Neupane (2014) conducted a series of experiments on Nitinol and examined the effects of load and sliding distance on the wear of this alloy. Parametric studies on the effect of working temperature (Wu et al, 2013; Yan et al, 2013) as well as the influence of normal load and sliding speed (Zhang and Farhat, 2009) have been frequently reported. There are also other studies on the comparison of wear in an SMA and other metals (Gialanella et al, 2008; Li, 2000; Liang et al, 1996; Wang et al, 2003).…”