UNDERSTANDING WEAR/CORROSION INTERACTIONS IN TRIBO-CORROSION OF TITANIUM AND ITS ALLOYS

摘要

Today, titanium is no longer considered to be an exotic material. Previously, it was thought that titanium and its alloys imposed such high costs that their use was not viable. This is not the case now and there are many titanium components in service in marine environments, such as Ti valves, impellers and heat exchanger tubes. Designers and engineers are increasingly seeing titanium and its alloys as a viable alternative to other high-grade alloys for applications in marine environments, where erosion and corrosion resistance are important. This paper reports on studies of tribo-corrosion performance of commercially pure titanium (CP-Ti) and three alloys in two situations (1) erosion-corrosion conditions and (2) cavitation-corrosion conditions. As titanium relies on a passive film for its corrosion resistance, under any tribological application it may be expected that the passive film will be breached. If so, parallels to work on stainless steel under such conditions may be expected. A series of experiments was conducted to determine the electrochemical corrosion characteristics and resistance to cavitation-corrosion at 18 deg C and 50 deg C and erosion-corrosion at 18 deg C, both in 3.5 percent NaCl. The performance of Ti and its alloys under tribo-corrosion conditions, with emphasis on the role of corrosion and cavitation/corrosion and erosion/corrosion interactions in the overall material degradation is discussed.