A novel low temperature and green salt bath nitriding of titanium alloy

Abstract

A novel low temperature and green salt bath nitriding of TC4 titanium alloy was developed by adding a certain amount of K 2 SO 4 in the KNO 3 and NaNO 3 salt bath. The results show that compared with as-received TC4 alloy, the surface hardness and tribological properties of the nitrided titanium alloy were greatly improved. Furthermore, based on the theoretical and experimental analysis of the effects of the K 2 SO 4 on the inhibition of the cyanide in the nitriding salt bath and tribological properties of the nitrided samples, wonderful discoveries were obtained. The tribological properties of the nitrided samples were dominated by not only the surface hardness but also the subsurface hardness. Moreover, there exists an optimum value for K 2 SO 4 addition (about 1 wt-%): K 2 SO 4 can not only effectively inhibit cyanide production but also cause the hardness in the nitride layer subsurface to further be improved, resulting in the further enhancement of the tribological properties.

Impact of the Amount of the Gold Layer on the Tribological Performance of the Ceramic Conversion Treated CP-Titanium

“…However, titanium has a high and unstable coefficient of friction, strong adhesive tendency and high wear rate [2], thus making it difficult for high-stress and long-term applications like long-spanned fixed prostheses and the frameworks of removable partial dentures [3,4]. Different surface engineering methods like PVD (physical vapour deposition) [5], CVD (chemical vapour deposition) [6], plasma treatment [7], nitriding [8] and anodization [9] have been used to modify titanium alloys. Among them, ceramic conversion treatment (CCT) can generate a ceramic hard layer supported by a hardened diffusion zone on the surface of the titanium alloys which can greatly improve the tribological performance of titanium alloys [10,11].…”