Electrolytic plasma polishing of NiTi alloy

Abstract

. Nitinol is widely used in the production of medical devices, especially the ones that are designed for minimally invasive treatment, such as stents to restore vascular patency, stent grafts to eliminate aneurysms, and cava filters to trap blood clots. One of the most important characteristics that determines the reliability of the functioning of such products in the human body is the state of the surface layer. The higher the surface quality, the less negative impact is on the circulatory system, the walls of blood vessels and the higher the biological compatibility of the product. Electrochemical polishing methods are mainly used to improve the surface quality of nitinol products. The disadvantage of the applied electrochemical methods is the need to use aggressive electrolytes that contain toxic components, such as hydrofluoric acid, sulfuric acid, perchloric acid, nitric acid, methanol. As an alternative to the existing methods of electrochemical polishing, we have developed electrolytic-plasma polishing (EPP), a new highly efficient process for improving the surface quality of nitinol products. The most important advantage of the method over traditional electrochemical polishing is the use of aqueous salt solutions with a concentration of 4 % as electrolytes. Based on the results of the studies performed, the most rational EPP mode was established, the use of which during polishing of nitinol provides surface cleaning from scale, polishing with a decrease in the roughness parameter Ra by 0.344 µm and an increase in pitting potential by 33 %. test of polishing of metal products, development of medical products and technologies for their production, research of the method of thermal relaxation differential spectrometry to study the total thermal resistance in products of power semiconductor and optoelectronics. In this paper was responsible for the metal removal during EPP was found to be proportional to the amount of stress passed through the treated sample and was largely dependent on the electrolyte temperature, voltage, and immersion depth. of removal, radial pitting potential for the analysis of the surface chemical composition of the investigated samples was performed, the ratio of the main alloy components of EPP was determined, and the participants of the endovascular implantable stent-graft for abdominal aortic stent element were studied.