Effect of heat treatment on cohesion of films on alkali-treated titanium

Abstract

The cohesiveness of films on titanium was evaluated by a scratch test. The films were formed on titanium by immersion in an aqueous solution of NaOH (hereafter referred as "alkali-treated") followed by heating at 500-700°C for 3.6ks. The cohesion of the alkali-treated film was increased by the heat treatment, and the maximum cohesion was obtained by heating at 500°C. The film on alkali- and heat-treated titanium consisted of both microporous films and dense films. The microporous film furthest from the titanium surface was barely cohesive, whereas the dense film showed cohesion with titanium. The cohesion of film formed by alkali-treatment was increased on heating, but the formation of TiO 2 (rutile) at the film-titanium interface on heating at and above 600°C caused a deterioration in the cohesion. © 2005 The Japan Institute of Metals.