【摘要】 在低碳钢表面电镀一定厚度的Cr层,再利用光纤激光连接低碳钢与碳纤维增强树脂基复合材料(CFRP),研究镀Cr层对低碳钢/CFRP搭接接头剪切强度及界面结合特征的影响.结果表明,低碳钢表面镀Cr层大大提高了接头的剪切力和剪切强度,剪切力由2237.37 N增加到6127.81 N,剪切强度由9.32 MPa增加到22.14 MPa;未镀Cr的低碳钢/CFRP接头的剪切破坏主要发生在搭接接头的连接界面上,镀Cr后改善了界面结合质量,剪切破坏发生在靠近搭接接头连接界面的CFRP上,断裂位置与CFRP中的气孔区相吻合.激光连接过程中,镀Cr层与CFRP在连接界面处发生反应,形成了Cr—O—PA6T化学键合,是接头界面强度得以提高的重要原因.更多还原

【Abstract】 The carbon fiber reinforced polymer(CFRP) has been widely used in aerospace and military fields,whereas it is still at its initial stage in the field of automobile manufacturing,wind power generation and so on.One of the main reasons to restrict its wide application is that the strength of metal/CFRP joint is very low and cannot meet the industrial requirements.In this study, an investigation of the laser joining between CFRP and mild steel with Cr electroplating was presented. The influence of Cr plating layer on shear strength of mild steel/CFRP lap joint was studied and the bonding characteristics of the joint interface were analyzed by SEM and XPS.The results show that Cr plating layer can greatly improve the shear force and shear strength of mild steel/CFRP joint.The shear force increases from 2237.37 N to 6127.81 N and the shear strength increases from 9.32 MPa to 22.14 MPa.For the mild steel/CFRP joint without Cr plating,the shear failure happens at the interface.However,for the mild steel/CFRP joint with Cr plating,the shear failure happens at the porosities zone in the CFRP.It means that the Cr plating can improve the interfacial bonding strength. The results of SEM observation and XPS analyses show that the mechanical bonding represented as the "anchoring effect" is achieved at the mild steel/CFRP interface both with and without Cr plating. But the chemical bonding is detected only at the mild steel/CFRP interface with Cr plating,which is considered as an important reason that the Cr plating can improve the bonding strength of the mild steel/CFRP joint.更多还原