Development of Advanced Ceramic Conversion Treatment for Titanium Alloys to Combat Wear– An Overview

Ceramic conversion treatment (CCT or C2T) was developed to improve the tribological performance by in-situ converting the titanium alloy surface into a wear-resistant TiO2 ceramic layer via thermal oxidation in a controlled atmosphere, which is supported by an oxygen diffusion hardened subsurface. This cost-effective and environmentally friendly technology has been successfully applied for motor sports, general engineering, and biomedical applications. In the past decades, we have endeavored to advance the technology by duplex treatment such as combining with laser texturing technique or accelerating the conversion process via incorporating catalytic metal elements to make it more efficient. This work is a summary of our efforts in using different metallic elements on a variety of titanium alloys in the catalytic ceramic conversion (C3T) process. A thin gold layer pre-deposited on the surface can accelerate the oxidation of a variety of titanium alloys (CP-Ti, Ti6Al4V, Ti6Al7Nb etc.) significantly, while the gold particles embedded in the oxide layer reduces the friction and increases the wear resistance. A silver layer pre-deposited on the surface of Ti6Al4V can speed up the oxidation up to 50 times and produce a thick oxide layer in a short period i.e 3-hour which is equivalent to a normal 80-hour treatment at 620°C. In addition, if palladium is predeposited with silver, a much thick and compact oxide layer can be formed which greatly improves the performance of the titanium pin in the inserting test. Other elements, like vanadium, have also been used in the C3T process.