An investigation of plasma processes in titanium(iv) isobutoxide: the formation of films on Ti and Si

Surfaces have been modified by means of gaseous plasma reactions with the intent of developing novel surface chemistry for adhesive bonding or other applications. Materials exhibiting the benefits of traditional sol/gel thin films were sought via a gaseous plasma reaction process to enhance the adhesion of polymer to Ti–6Al–4 V and silicon. The chemical, mechanical, and adhesion-promoting properties of thin films deposited via the vapor plasma processes for titanium(IV) isobutoxide (TiiB) were investigated. X-ray photoelectron spectroscopy (XPS) was used to assess the chemical nature of the plasma prepared (PP) films, while nanomechanical properties (modulus, hardness and adhesion) were studied by means of atomic force microscopy, nanoindentation, and nanoscratch testing. alysis revealed that deposited films were principally organic in nature. Carbon 1s, O 1s, and Ti 2p photopeaks suggested that titanium was incorporated into the film as TiO2 dispersed in an organic matrix. The nanomechanical properties of PP TiiB films deposited on polished Ti–6Al–4V and silicon were measured. The hardness and reduced Youngʹs modulus of PP TiiB on polished Ti–6Al–4V were 3.4 GPa and 75.1 GPa, respectively, while the values for PP TiiB on a silicon wafer were 1.2 GPa and 32.3 GPa, respectively. The findings indicate that the substrate had an effect on the film composition and on film properties. Scratch tests were performed on the PP TiiB films on Ti–6Al–4V and Si, but the films were too soft to obtain a critical load at debond. ngle lap shear (SLS) strengths for plasma-reacted TiiB—titanium alloy specimens bonded with a polyimide adhesive were compared with titanium substrates that had been cleaned with acetone and bonded with the same adhesive. The best SLS strength of 30.3±3.5 MPa (4390±510 psi) was obtained from samples coated with a PP TiiB film deposited at 10 W with argon as the carrier gas. Further, the failure mode for all samples pretreated with PP TiiB was interfacial at the PP film/substrate interface.