Surface modifications to improve Ti–porcelain bonding

Investigations of surface modifications on cast titanium surfaces and titanium-ceramic adhesion were performed. Cast pure titanium was subjected to surface modification by preoxidation and introduction of an intermediate layer of SnOx by sol–gel process. Surfaces only sandblasted with alumina were used as controls. Specimen surfaces were characterized by XRD and SEM/EDS. The adhesion between the titanium and porcelain was evaluated by three-point flexure bond test. Failure of the titanium–porcelain with preoxidation treatment predominantly occurred at the titanium-oxide interface. Preoxidation treatment did not affect the fracture mode of the titanium–ceramic system and did not increase the bonding strength of Ti–porcelain. However, a thin and coherent SnOx film with small spherical pores obtained at 300 °C served as an effective oxygen diffusion barrier and improved titanium–ceramic adhesion. The SnOx film changed the fracture mode of the titanium–ceramic system and improved the mechanical and chemical bonding between porcelain and titanium, resulting in the increased bonding strength of titanium–porcelain.