The Effect Of Co-Cr Alloy Coating By EB-PVD On The Bonding Strength Of Titanium To Porcelain

Objective:To investigate the effect of the deposited Co-Cr coatings on the bonding strength of titanium-porcelain restoration,Co-Cr coatings with different thickness were deposited onto the pure titanium substrate by EB-PVD.Methods:Sixty pure titanium specimens were randomly divided into five groups.Four Co-Cr coatings with different thickness,including 20 nm,40nm,60 nm and 80 nm,were deposited onto the specimens(Abbreviated by group A,B,C and D,respectively).Sandblasting treatment was selected as a control group(group E).After porcelain fusion,bonding strengths of titanium-porcelain restoration were measured by three-point bending test according to ISO 9693.Scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS)were employed to evaluate the morphology and elemental composition of both Co-Cr coatings and interfaces of the titanium-porcelain restorationResults:The surface morphology of the coated specimens was observed under scanning electron microscope,and the surface of the titanium sheet in the sandblasted control group showed a concave and convex sharp structure with holes between the bumps.Under electron microscope,the surface of titanium sheets of each experimental group presented concave-convex structure without obvious pore structure,and the pores were well covered.Among them,the edges of concave-convex structure on the surface of titanium sheets of group B became round and blunt without obvious sharp structure.Cobalt and Chromium elements were detected on the surface of each titanium sheet in the experimental group.With the increase of coating thickness,the content of cobalt and chromium elements increased correspondingly.The bond strengths of the control group and the test groups were(30.23±1.94),(36.11±1.17),(43.33±1.17),(39.95±2.22),(38.85±1.10)MPa,respectively.In contrast to control group,the Co-Cr coatings would significantly improve the bonding strength between titanium and porcelain.Moreover,some cracks and pores were found at the titanium-porcelain interface of control group,while the titanium-porcelain interface of group B were tight and compact.Meanwhile,comparing to control group,more residual porcelains could be found on the substrate of group B.Conclusion :Co-Cr coating with appreciate thickness using EB-PVD could significantly improve bonding strength between titanium and porcelain.