材料期刊网

为改善铝合金表面润湿性与胶接强度,采用常压空气射流等离子体对5052铝合金进行表面处理.通过接触角测试,表面自由能计算和胶接接头剪切强度测试表明处理时间对铝合金表面改性效果影响不大,随着处理距离减短,铝合金表面自由能、胶接接头强度均逐步提升.处理距离为5 mm时等离子处理铝合金获得最佳表面改性效果,铝合金胶接接头剪切强度由10.6 MPa提升至19.3 MPa,失效模式由界面失效转变为内聚失效.利用SEM,XPS,傅立叶变换红外光谱等检测手段分析不同处理距离对应表面理化特性的变化,结果表明:处理距离较远时,等离子体并未改变铝合金表面物理形貌,其主要改性效果体现为表面清洗;处理距离较近时,铝合金表面高温熔融产生复杂微结构的粗糙氧化层,同时氧化层表面吸附羟基等极性官能团,显著提升了其表面自由能与胶接强度.

To improve the wettability and bonding properties of aluminum alloy,atmospheric pressure air plasma surface treatment was performed on aluminum alloy 5052 substrates.Contact angle measurement,surface free energy calculation and lap-shear test were conducted to evaluate surface wettability and static strength of adhesive-bonded aluminum alloy.It is found that plasma treatment time has little effect on the modification performance of the aluminum samples,while the surface free energy and adhesive bond strength of aluminum samples gradually increase with the decrease of treatment distance.The plasma treatment greatly improve the joint strength of adhesive-bonded aluminum alloy from 10.6 MPa to 19.3 MPa when treatment distance is 5 mm.The failure mode is changed from adhesive to cohesive.Surface morphologies and chemical composition of the plasma treated substrates were investigated by SEM,XPS and Fourier transform infrared spectroscopy (FTIR),respectively.Results show that the plasma treatment can't change the physical topography,which only removes the residual carbon contamination of the aluminum alloy surface at the far distance.As a consequence of high temperature effect,a rougher oxide layer with adsorption of polar groups is emerged after the treatment at a short distance,which considerably modifies the surface wettability and improves the adhesive bonding strength of aluminum alloy.