| B279 optical glass has good light transmittance,refractive effect,hardness and texture,and it is heavily used in the field of optical coating.Titanium alloy has a wide range of application used in various fields for the excellent specific strength,corrosion resistance and heat resistance.Therefore,the composite structure composed by optical glass and titanium alloy can be a great way to improve the glass's ductility and impact toughness,which can be widely used in the field of microelectronics and optics.At present,the proven technology has been generally applied to glass/metal,glass/aluminum in the industrial field with less research on glass/titanium in the scientific research field.In order to realize the stable bonding and good air tightness of the TC4 titanium alloy/glass,we mainly studied two connection methods of TC4 titanium alloy/glass with vacuum heat pressing and anodic bonding.Firstly,we studied the influence of surface treatments on the joint of glass/TC4 titanium alloy during heat pressing process,including surface roughing treatments and surface oxidation.We observed the interface morphology and determined the distribution of interface elements.The influence of different particle sizes on the surface morphology of the titanium alloy were compared to determine the most suitable surface treatment process as well as the advantages and disadvantages of the surface roughing treatments on the titanium alloy.Secondly we studied the influence of vacuum heat pressing parameters(heat pressing temperature,pressing time,pressure),we also discussed the causes leading to residual stress and the method to release it.The results indicated that the titanium alloy surface area was enlarged by surface roughing treatments,and it was enhanced of the bonding strength between the oxide film and the metal substrate,glass and titanium alloy.Not only did the oxidation treatment improve the wettability of the glass,but it achieved a firm joint of the glass and titanium alloy.The shear strength is 11 MPa,and the rate of combination can reach more than 95%.The best vacuum heat pressing parameters were:T=750?,t=2h,P=0.5MPa.Finally we studied the anodic bonding process by analyzing the process characteristics with different bonding process parameters(T and V).Basing on the analysis of the structure and elements of the bonding interface,we compared the differences between the vacuum heat pressing and anodic bonding process,and discussed the mechanism of the anodic bonding process.TC4 titanium alloy/glass can achieve the great joint When the bonding temperature was at the range of 350-550 ? and the voltage was 500-700V.The analysis of bonding interface structure indicates that the whole bonding region is composed by glass-intermediate transition layer-titanium alloy,the intermediate transition layer and the chemical element on both sides of the interface indicate a gradient distribution.The shear strength is 15MPa,and the rate of combination can reach 100%.Titanium alloy and glass bonding process is divided into three stages:interface polarization resulting in migration of alkali metal ions,close contact phase by formation of EMF,and the formation of the final transition layer by oxidation reaction with the inter-migration of metal ions and oxygen ions in glass.The migration of alkali metal ions by the action of electric field and temperature is the prerequisite for the interface bonding,and the generation of the internal electrostatic force and the difference of the chemical concentration provide the driving force to form the transition layer. |
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