The Effect Of Preoxidation Technique On The Metal-Porcelain Bond Strength Of Co-Cr Ceramic Alloy

Objective: To investigate the effect of preoxidation technique on the metal-porcelain bond strength of the Cobalt-Chromium (Co-Cr) Alloys porcelain, and weather the metal-porcelain bond strength of the Co-Cr Alloys porcelain is depend on the time of preoxidation. Then provide reference for raising the rehabilitation achievement ratio.Methods: Co-Cr ceramic alloy and VMK95 porcelain powder were used in this study. The 6 different technique were used for metal surface: (1)no preoxidation(control group)(2) preoxidation for 1 minute (3) preoxidation for 2 minutes (4) preoxidation for 5 minutes (5) preoxidation for 10 minutes (6) preoxidation for 15 minutes;60 pull-rod samples were made and divided into 6 groups according to different technique for metal-porcelain bond strength measurement; 6 metal-porcelain compounds were made and also divided into 6 groups according to different technique for SEM observation and X-ray element energy analysis.Results: Six groups'bonding strength was significant difference by analysis of variance(P <0.01);Compared with bonding strength of the normal control group (group 1), there are no significant differentce in neither the group preoxided for 1 minute (group 2) nor in the group preoxided for 2 minutes (group 3) (P >0.05), while the bonding strength in group 4, group 5 and group 6 increased significantly , compared to group 1,group 2 and group 3 (P <0.01). Compared with the group 4, group 5 and group 6 each other,there are no significant difference (P >0.05).These results show that with the preoxidation time more increased, the metal-porcelain bond strength increased, and reached the top at 5 minutes, since then, the metal-porcelain bond strength will not change significantly with the increase of preodxided time. Observes through the electron microscope, In the melt area, the metal-porcelain contact surface appearance is clear, micro-analysis on metal-porcelain interface shows that combination between metal and ceramic are tight and simonized in each other without any crack and bubble. And there is a continuous thin reaction layer.Conclusion: The preoxidation increased the metal-porcelain bond strength of the Cobalt-Chromium (Co-Cr) Alloys porcelain, and achieved the chemical compound at the Metal-porcelain interface the bonding strength meets the standards of ISO, the 5 minutes preoxidation form a well-distributed oxide film on the surface of the metal, and it's bonding strength reached the top. The longer of the preoxidation time can not increase the metal-porcelain bond strength of the Cobalt-Chromium Alloys.