Preliminary study of micro-scale abrasive wear of a NiTi shape memory alloy

Nitinol (NiTi), a nearly equiatomic nickel–titanium alloy is known for its unique shape memory and superelastic properties, which result from martensitic transformations. It is the material of choice for numerous biomedical applications such as endovascular stents, vena cava filters, dental files and guidewires for non-invasive surgery, etc. Micro-scale abrasion tests (MSATs) have been performed on the NiTi shape memory alloy, so as to evaluate the influence of different commercial abrasives such as silicon carbide, alumina and glass on the wear behaviour. The aim of the work was the selection of the most effective abrasive for cleaning the inner surface of laser-cut cardiovascular stents. Abrasive particles have been characterised by X-ray diffraction, SEM and EDS before and after MSATs. Worn surfaces have been studied by stylus profilometry, SEM and atomic force microscopy. The effect of abrasive particle hardness, size and angularity on the wear behaviour has been evaluated and discussed.