Salt Heat Treatment and Passivation to Improve the Corrosion Resistance of Nitinol (Ni-Ti)

Materials

Ik-Bu Sohn¹  Inho Bae²  Byung-Hoon Kim²  Seong-Won Yang³  Dong-Gon Kim⁴ 

[1] Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-Gu, Gwangju 61005, Korea;Department of Dental Materials, School of Dentistry, Chosun University, 309 Pilmun-Daero, Dong-Gu, Gwangju 61452, Korea;Department of Ophthalmology, College of Medicine, Chosun University Hospital, 365 Philmun-Daero, Dong-Gu, Gwangju 61453, Korea;Department of Polymer Science and Engineering, Sunchon National University, Suncheon 57922, Korea;

关键词: nitinol;    corrosion resistance;    implantable materials;    passivation;    salt furnace;   

DOI  :  10.3390/ma14247789

来源: DOAJ

【 摘 要 】

Corrosion of nitinol (NiTi) is a major factor in the failure of implantable materials. Recently, as the importance of corrosion of metals has increased, testing according to international guidelines is essential. The purpose of this study was to evaluate the corrosion resistance of NiTi wire through heat treatment and passivation process. In this study, NiTi wire used two commercially available products and a self-manufactured stent. Experimental consideration was carried out according to ASTM standards. Heat treatment was carried out in an air or a salt furnace, and the corrosion was measured after additional process, such as passivation and scratch tests. As a result, the metal potential was rapidly decreased in the air furnace group. On the other hand, the potential of wires was dramatically increased in the salt furnace group compared to the air furnace group. The dislocation decreased below the acceptance criteria (>600 mV) within 60 s of heat treatment time in the air furnace. Moreover, the potential was dramatically improved, even after only 20 min of passivation treatment (1076 mV, 442% compared to the non-passivated group), and it continued to rise until 180 min. This phenomenon was similarly observed in the group of self-manufactured stents. The potential slightly decreased by the scratch process (93.1%) was significantly reduced by the air furnace process (315 mV, 24.4% of the nontreated group). In the passivated group of the air furnace sample with reduced potential, the potential was restored to the level before the air furnace (scratch stage) (1032 mV). In conclusion, the heat treatment is preferably carried out in a salt furnace rather than an air furnace, and the passivation process can be an advantageous tool to improve corrosion resistance by suppressing the oxidation process.

【 授权许可】

Unknown