Effect of Cu and Co Additions on Corrosion Behavior of NiTi Alloys for Orthodontic Applications

Abstract

The aim of this study is to investigate effect of Cu and Co additions on corrosion behavior of NiTi shape memory alloys for orthodontic application. Ni50.6Ti49.4, Ti49Ni46Cu5 and Ti50Ni47Co3 (at%) alloys were prepared. The specimens were melted by arc-melting furnace and homogenized at 800oC for 3.6 ks. Transformation temperatures were analyzed by differential scanning calorimeter (DSC). The corrosion behavior was assessed electrochemically in artificial saliva (pH 5.35) at 37oC. Open circuit potential (OCP) was monitored 3.6 ks followed by potentiodynamic techniques. The results show that all of specimens revealed transformation temperature close to oral temperature which may be utilized as orthodontic wire. Surface roughness was measured in order to ensure that there is no significant difference which might affect corrosion resistance. It is seen that by adding Co and Cu into NiTi alloys, the corrosion potential (Ecorr) and pitting corrosion potential (Ebreak) increase resulting in lower corrosion rate. Conceivably, Co and Cu additions considerable affect the corrosion behavior of NiTi alloys by improving corrosion resistance in artificial saliva.