Nickel titanium alloys are known for their good corrosion resistance. NiTi alloy is due to its shape memory properties particularly used in biomedical application. Their corrosion properties are satisfactory (sufficient), but in some circumstances they suffer from pitting and crevice corrosion. Since dental NiTi archwires experience severe failures in applications it is assumed that their performance is affected also by microstructure. Beside corrosion the wear resistance of this alloy is of critical concern in many applications. In the present work, two types of NiTi alloy samples were investigated, NiTi plate and NiTi dental wire with and without surface oxide. The electrochemical investigation was conducted in artificial saliva and was proved by the use of tribocorrosimeter. Microstructural characteristics were studied in cross section and longitudinal direction. The wear scare was investigated by the use of SEM/EDS analysis and profilometer. The hardness of the wear scar was followed as well. The results of electrochemical investigation showed that the dental alloy and NiTi plate without surface oxide exhibit very similar corrosion properties. The variation in corrosion performance in artificial saliva was bigger at specimens covered with surface oxide films. Tribocorrosion studies showed that the total wear of the NiTi alloy is greater when corrosion is combined by the wear. The bigger wear loads lead to greater changes in passive film and wear scar. Greater loads resulted in bigger inclusions in the wear. Also, the hardness in the wear scar is increased after applying the load. It can be concluded that microstructure of the investigated NiTi sample has effect on electrochemical and tribocorrosion properties of the samples as well.
Different NiTi samples with different morphological properties have also different electrochemical properties. Dental NiTi wires with oxide film exhibits worse electrochemical behaviour. Tribochemical experiments have shown that the wear regime varies at different applied loads. Corrosion potential is decreased the most at the higher applied force. Wear track after tribolelectrochemical wear has lower number of inclusions whereas the wear rate is higher then after dry tribological wear.
COBISS.SI-ID: 1808231