[Effect of different heat treatment on the bonding strength of porcelain and Co-Cr alloy].

PURPOSE:To investigate and compare the effect of different heat treatment on the metal-ceramic bonding strength and the interfacial microstructure of the Co-Cr alloy.METHODS: Thirty specimens were made according to ISO 9693,and then divided into 3 groups(n=10) through the measurements.Group A(degassed 60s):degassed and then maintained 60s in 980℃;Group B(degassed 60s and preoxidation 60s): degassed and maintained 60s in 980℃,then were maintained continuously for 60s in 980℃ after re-gassed;Group C(degassed 120s): degassed and maintained 120s in 980℃.The bonding strengths of the three groups were evaluated through three point bending test.Six specimens divided into 3 group were made in the same method to observe the metal-ceramic interface through scanning electronic microscope(SEM) and energy dispersive spectrum(EDS).The bonding strength data were analyzed using ANOVA and Bonferroni's test by SPSS13.0 software package.RESULTS: The mean value of bonding strength was(39.03±2.70)MPa for group A,(34.43±2.36)MPa for group B,(31.65±1.49)MPa for group C,respectively.There were significant difference between every two groups(P0.05).SEM demonstrated that the width of interfacial transition layer was 12.3-16.4μm in group A,15.2-21.8μm in group B and 26.3-32.2μm in group C.CONCLUSIONS: Higher metal-ceramic bonding strength for Co-Cr alloy will be formed under the situation of degassed,and maintained 60s in 980℃;while extending degassed time,prolonging the heat maintained time and preoxidation after degassing will reduce metal-ceramic bonding strength.Supported by Guangdong Provincial Science and Technology Research Project(2006B36006016) and Guangzhou Municipal Science and Technology Research Project(2005Z3-E0531).