ToF-SIMS Characterization of Nanostructured ZrO2 Coatings Applied to Near Equiatomic Ni-Ti Alloy

Abstract

The ToF-SIMS technique was applied to analyze thin ZrO 2 coatings deposited on the surface of a Ni-Ti alloy. Due to its nanostructured nature, these films are difficult to characterize by conventional techniques. ZrO 2 coatings were deposited on near equiatomic Ni-Ti wires by pulse electrodeposition. Part of the samples was electrolytically polished before the coating process. The coated samples were then analyzed by ToF-SIMS to evaluate the influence of the deposition time and previous surface electropolishing on the structure of the deposited coating. The results indicate that thicker coatings were produced on the electropolished samples, in comparison with the as-received ones. The best uniformity in thickness was achieved when Ni-Ti samples were previously electropolished followed by ZrO 2 electrodeposition for 1200 seconds. Moreover, it was possible to observe by this technique that the inclusions in the Ni-Ti matrix were not entirely covered by the coating.

Nanoscale Polishing Technique of Biomedical Grade NiTi Wire by Advanced MAF Process: Relationship between Surface Roughness and Bacterial Adhesion

“…As reported by Solheid et al [43], during the laser polishing process, high temperatures occur on the polishing zone at the surface of the workpiece and can create extended areas of heat-affected tissue with resulting microstructural changes that significantly influence the biocompatibility of a thin stent wire. Lopes et al [44] have found problems with ZrO 2 coatings, particularly that the production of ZrO 2 nano-coatings is difficult due to their reduced dimensions. Moreover, this process requires long processing for up to 1200 s to achieve NiTi stent wires with smooth surfaces, greatly increasing the costs to produce these products.…”