Effects of anodizing temperature on the microstructure of Ti6Al4V and its apparent shear strength bonded with epoxy

摘要

In this paper, the effects of anodizing temperature on the microstructure, chemical and phasecomposition and surface profile of the oxide layer produced on Ti6Al4V were systematically investigated.In addition, single lap shear strengths of the anodized alloy bonded with epoxy adhesive werecompared and the fracture mechanisms were investigated. With increase in anodizing temperaturefrom 0C to 40C, thickness of the oxide layer showed a decreasing trend from 1000nm1500nm to200nm, which was attributed to the accelerated oxide dissolution due to increased ionic mobilityat high temperature. After anodization at 40C, a honeycomb-like porous oxide layer with porediameter of 100200nm was uniformly developed on Ti6Al4V surface. The oxide layers behavedamorphous structure with surface roughness (Sq) from 657.0nm to 817.2nm. The apparent shearstrength of the specimens anodized at 0C, 25C and 40C was improved by 217.7％, 225.0％, and317.2％ in comparison with that of the specimen without anodization. In addition, work of fractureshowed a similar trend. From SEM fractomicrographic analysis, specimen without anodizationshowed adhesive failure in between epoxy-alloy interface; while mixed fracture modes, i.e., oxidelayer failure, epoxy-alloy interface adhesive failure, and epoxy cohesive failure, were observed forspecimens anodized at 0C and 25C. With increasing anodizing temperature up to 40C, nooxide layer failure area was observed, and epoxy cohesive failure area increased greatly whichwas due to the increased mechanical interlock between epoxy and oxide layer for the existence ofhoneycomb-like porous structure.