Abstract
Cross-sectional microstructure observation of the titanium firing porcelain inserted ion-coated gold layer was performed by SEM-EDX that can analyze light elements from boron. Two gold-coated samples applied to mirror finished titanium surface were prepared; one was applied only degassing treatment, and the other was applied firing after degassing treatment. In addition, in order to investigate effect of the gold coating, titanium/porcelain samples without coating were also observed. From SEM-EDX observation of the specimen, approximately 2.5 μm thickness titanium oxide layer appeared across the gold film in the first sample. In the titanium firing porcelain after degassing treatment, two obvious reaction layers appeared across the gold coating. One included mainly titanium and oxygen, and another included titanium, gold and aluminum. Thickness of the reaction layers was approximately 2.5—3 μm. From the results, it is suggested titanium was diffused into porcelain through a gold coating, and titanium oxide was formed at an interface. Titanium/porcelain without gold coating had two reaction layers at the interface, however, many cracks and crevices were exhibited in the layer and between the layers. Effect of gold coating on interfacial layer formation was discussed by the comparison with titanium/porcelain interface without gold coating. Thickness of the reaction layers decreased by gold coating, and cracks and crevices in the layer disappeared. The results suggested that oxygen diffusion became lower due to existence of the coating, and titanium-gold reaction changed layer's microstructure. It is also suggested that gold diffusion into the reaction layer and restriction of oxygen diffusion contribute to the reaction layer formation, consequently gold coating on titanium substrate contributes to improvement of adhesion between titanium and porcelain.
