Efeito da nitretação por plasma na dureza e na resistência à corrosão do aço inoxidável cirúrgico ASTM 420F

Abstract

Martensitics stainless steels are used in biomedical applications because of that yours excellent corrosion resistance and good mechanical properties. However, in applications such as drills for implant their performance has been unsatisfactory. This application is usually used how DLC coatings to improve corrosion resistance, wear resistance and to decrease the coefficient of drill bone friction. Several studies in the literature show that nitriding at low temperatures produce surface layers of high hardness and high resistance to corrosion. It is also known that increasing the hardness of the substrate it improves the adhesion of the coating as DLC. These treatments are known as duplex. In this work were studied the effect of low temperature nitriding on the corrosion resistance and hardness of martensitic stainless steel type ASTM 420F, as well as the influence on the hardness and corrosion resistance of nitriding and DLC duplex treatment. Five parameters of nitriding at low temperature, at different times to evaluate the behavior in the hardness and corrosion resistance were chosen. The parameter that had the best performance providing a higher hardness and better corrosion resistance was at 380°C for 6 hours. The average hardness of the drill top was 894 HV (1 Kgf) and not showed corrosion in duplex layer. It can be expected to apply these conditions in a surgical drill, in the tool wear will be less, since the surface has a higher hardness than usually marketed and the drill maintained the resistance to corrosion in aggressive environment that they are exposited.