Study On The Effects Of The Energy Parameter Of Microarc Oxidation On The Bonding Strength Of Titanium-porcelain

Titanium has strong reactivity to non-metallic elements in surrounding environment, such as oxygen, hydrogen, and nitrogen, at high temperatures. Some titanium-ceramic systems appear to be susceptible to oxidized film, loosed construction and low bonding strength between abutment and oxidized layer, which can cause weaker bonding strength of titanium- porcelain. The micro-arc oxidation(MAO) is a new technique which causes ceramic film growing on the surface of abutment. The oxidized film, having high bonding strength with abutment, is porus on surface and compact in internum. In addition, element can be changed in the film, so the oxidized film could be functional layer between titanium and porcelain, chemical bonding and mechanical bonding can be strengthened. The constitutive properties of the oxidized film on surface of titanium are determined by the energy parameter of MAO. Therefore, this study is about microarc oxide treatment on the titanium surface and to invent the effect of microarc oxide pretreatment on the bonding strength of titanium porcelain. And the effect on titanium-ceramic bonding strength by changing MAO parameter was studied, so the optimal energy parameter of MAO was selected. Objective : To study the effects of microarc oxide treatment on the titanium-ceramic bonding strength. At the different parameter of MAO, to study the effects of microarc oxide treatment on the oxidized film surface structure and on bonding strength of titanium-porcelain.Method:Titanium samples were prepared with smooth surface,rough surface, and half of each group were drawn randomly by microarc oxide treatment.The electrolytic solution was prepared with Na2SiO3 and deionized water. The surface microstructure of the samples were observed by scanning electron micro-scope (SEM) and energy dispersive spectrometry analysis(EDS).The samples were bonded to porcelain.The bonding strength of the samples was measured by a three-point bending test according to ISO9693.The mechanism was be analysised about the effects of microarc oxide treatment on the titanium-ceramic bonding strength. The effects of different parameter of MAO on the oxidized film of titanium by changing the duty cycle , frequency, voltage and time were invented. The surface microstructure of the samples was observed by SEM.The samples were bonded to porcelain.The bonding strength of the samples was measured by a three point bending test.In the end, the optimal energy parameter of MAO was selected according to the titanium-ceramic bonding strength. And by analysising interface microstructure, the mechanism was analysised about the effect of different parameter on bonding strength of titanium–porcelain.Results:After the abrator and MAO treatment, the results showed: SEM indicated microarc oxide treated surface was rough and porous,and there was no obvious terminal line in films or between film and porcelain in the group of MAO treatment.There was about 5μm leakage between titanium and porcelain in smooth group and only a few pore in rough group. The bonding strength(MPa) of the samples to porcelain indicated that the bonding strength of the samples of MAO group was 1.45 times higher than no MAO group's, and rough group's bonding strength was 1.25 times higher than smooth group's.According to different energy parameter of MAO, the results showed: the higher the frequency was, the smaller holes on surface was and the more holes in the number was, and the thicker the oxidized layer was,and the lower the bonding strength of titanium-porcelain was. The higher the duty cycle was, the similar holes on surface was, the higher the surface roughness was and the lower the bonding strength of titanium-porcelain was. According to different voltage, The higher the voltage was, the rougher and porouser the microarc oxide treated surface was, the larger the pore diameter was and the fewer in the number was. The thickness of oxidized layer was increased from 5μm to 10μm, but the bonding strength of titanium-porcelain was decreased. According to different time, The longer the time was, the rougher and porouser the microarc oxide treated surface was, the larger the pore diameter was and the fewer in the number was. The thickness of oxidized layer was increased from 5μm to 12μm, but the bonding strength of titanium- porcelain was decreased.Conclusions:The microarc oxide treatment on titanium can increase the titanium—ceramic bonding strength. At the same time, abrator method on surface of titanium test piece also increases the titanium-ceramic bonding strength. It has different effect on the titanium-ceramic bonding strength at the different of treated parameter during the microarc oxide treatment. The optimal bonding strength of titanium–porcelain can be achieved at the duty cycle 0.04, frequency 500Hz, voltage 300V and the time 3min in this study.