Effects Of Low-temperature Plasma Treatment On The Bonding Strength Between Titanium And Porcelain After Micro-arc Oxidation

Objective:To prove that low temperature plasma treatment can increase the bonding strength between titanium and porcelain.Method:55 pieces of titanium（25mm X3mm X0.5mm）were sandblasted and treated with20g/L Na₂Si O₃ electrolyte for micro-arc oxidation,and then randomly divided into 5 groups.Group A was the control group and group B was treated with oxygen low-temperature plasma,group C was treated with 95%argon+5%oxygen plasma,group D was treated with nitrogen plasma,and group E was treated with argon plasma.Then,randomly select 2titanium sheets in each group to observe the surface topography with a scanning electron microscope（SEM）,and use X-ray photoelectron spectroscopy（XPS）to detect the surface element composition.Then another 3 samples were selected to measure the contact angle.After above all,porcelain was fused on the remaining titanium specimens.Choose 4 pieces from each group for a three-point bending test to test the bonding strength,and perform SEM observation of the porcelain exfoliation surface morphology and energy dispersive spectroscopy（EDS）to analysis surface element.The remaining two samples were embedded with epoxy resin,and the cross-section of the titanium-porcelain was observed by SEM.Results:The bonding strength is as follows:the group A is 39.57±0.61 MPa,the group B is 49.17±1.03 MPa,the group C is 51.97±2.84 MPa,the group D is 49.20±1.31 MPa,and the group E is 47.90±2.34 MPa.The bonding strength of group B-E is higher than that of group A（P<0.05）.Scanning electron microscopy shows that the surface of each group of titanium sheets has relatively uniform porous structure.After plasma treatment,the pore size and shape has not changed significantly.XPS results shows that the content of carbon element in group B-E is significantly reduced,the content of oxygen element increased,and the content of silicon element increased.The measurement result of the contact angle is:31.60±5.22°in group A,8.56±2.84°in group B,5.73±2.71°in group C,6.54±4.51°in group D,and 6.93±1.22°in group E.It is confirmed that each group of titanium after plasma treatment shows super hydrophilicity.After the porcelain layer is peeled off,EDS measures the characteristic elements of porcelain such as Si,F,Na and K on the titanium sheet surface.Conclusion:Low-temperature plasma can increas titanium porcelain bonding strength.This may be related to the fact that low-temperature plasma can introduce new functional groups on the titanium surface,clean the surface of the titanium,thereby increasing the surface wettability and surface energy of titanium.