Investigation of coating ability, characterization and corrosion properties of NiTi shape memory alloys by thermal evaporation method

Some disadvantages of NiTi biocompatible alloys have been noticed in the long term and scientific studies have been started to minimize this disadvantageous situation. In this thesis, two different types of NiTi alloys were chosen as substrates and coating with silver, copper and selenium elements was carried out. Thermal evaporation method (TEM) under high vacuum was chosen for the coating process. Alloys were coated by TEM method and the effects of coatings on corrosion resistance were investigated by performing detailed characterization analyzes after coating. After coating, SEM-EDS measurement was taken to determine the surface morphology of the alloys and successful surface coatings were obtained in all sample groups. The presence of coatings on the surfaces was confirmed by EDS and XRD analysis. To examine the effect of coatings on surface roughness, atomic force microscopy measurements were made and it was seen that the coatings reduced the roughness of the NiTi alloy. In order to examine the effects of coatings on corrosion resistance, in-vitro corrosion tests were performed in artificial body fluid using three electrode techniques, and it was determined that silver and selenium coatings made a significant contribution to corrosion resistance. In addition, the changes in the surface morphology after corrosion were extensively investigated by SEM-EDS analyses.