A novel slurry for ultra-smooth chemical mechanical polishing of TC4 titanium alloy

Abstract

TiC4 titanium alloy has become one of the most important materials for aerospace and medical device applications due to its advantages such as good biocompatibility and high specific strength. However, the high hardness and low thermal conductivity of TiC4 make it challenging to machine. Therefore, a novel chemical mechanical polishing (CMP) slurry for TC4 titanium alloy was developed to achieve its ultra-smooth surface polishing. Firstly, five slurries with different compositions were prepared, and the polishing effect of each slurry was analyzed. The results demonstrate that the slurry containing 2-aminobenzoic acid (2-ANA) as a chelating agent exhibits the best polishing performance with Ra of 0.661 nm and material removal rate of 173.9 nm/min. Subsequently, the influence laws of different slurry on the polishing effect of TC4 were explored by electrochemical tests. Finally, based on XPS and infrared test characterisation, the CMP mechanism of TC4 was revealed as follows: hydrogen peroxide oxidises the Ti element into high-valent oxides, the −N–H and −O–H groups in 2-ANA combine with metal ions in solution to form complexes, and this chemical process reaches a dynamic equilibrium with the mechanical action of abrasive grains to ultimately achieve the ultra-smooth polishing of TC4.