Preparation of TiO₂ coating on dental metal materials by plasma CVD

In this study, TiO₂ films were prepared on Ag-Pd alloys by Plasma-enhanced Chemical Vapor Deposition (PECVD) using Ti(O-i-Pr) ₂(dpm)₂ precursor. Ag-Pd alloys are widely used as a substrate material of a resin-veneered dental crown. Since an adhesion of a dental resin to the Ag-Pd alloy substrate is poor, protuberances are usually formed on the substrate surface to sustain the mechanical retention. One of the weak points in the resin-veneered dental crown is that a mechanical retention should be indispensable to fix the resin onto the metal frame. Instead of mechanical retention, TiO₂ films were prepared on the substrates. The effects of the deposition conditions on the crystalline phases, microstructures, and color of the deposited films were investigated. As a result, at a substrate pre-heating temperature T_dep=500 °C, microwave power P_M = 2 kW, deposition pressure P_tot,=0.4 or 0.7 kPa, the film color changed from black to white, and crystalline phase was anatase. And the microstructure of the film was granular. The grain size was a diameter of about 100nm. These are optimum deposition conditions.