表面处理工艺对单组分聚氨酯密封胶与不锈钢粘接的影响

Influence of surface treatment processes on the bonding of monocomponent PU sealing strip to stainless steel

为了研究不同表面处理工艺对单组分聚氨酯密封胶与不锈钢粘接的影响规律,依据DVS 1618《轨道机车车辆中的弹性厚膜粘接》标准对胶条试样进行剥离试验和GB/T 7124标准对胶粘接头剪切强度进行评估,利用SEM、水接触角测定仪、红外光谱分析仪、原子力显微镜(AFM)等试验方法表征了粘接表面的表面能、化学分子结构及断口显微形貌。结果表明,在不锈钢表面施加活化剂+溶剂型环氧底涂剂有效提高了单组分聚氨酯密封胶对其的粘接效果,胶条剥离形貌从界面失效改善为内聚失效,粘接接头拉剪强度从1.0 MPa提升为1.7 MPa;此外,施加活化+底涂剂有效改善了胶条剥离试样的抗高温高湿耦合老化的剥离形貌,从完全界面失效转变为完全内聚失效。SEM断口分析表明,无底涂粘接接头断口形貌为界面平滑失效,施加活化剂+底涂剂后的粘接接头断口为胶黏剂填充料撕裂的内聚破坏形貌。水接触角测试结果表明,施加活化剂+底涂剂后表面能增加不明显。红外光谱结果显示,施加活化剂+底涂剂表面存在大量环氧基团(C-O),这可能对增加被粘表面的活性具有重要影响。

In order to study the influence law of different surface treatment processes on the bonding of monocomponent PU sealing strip to stainless steel,a peeling test of the strip sample is carried out as per DVS 1618“Elastic Thick Film Bonding in Rail Rolling Stock”and the shear strength of the bonding joint is evaluated following the GB/T 7124,meanwhile SEM,water contact angle determinator,infrared spectrometric analyzer,atomic force microscope(AFM),etc.is used to express the interface energy of the bonded surface,chemical molecular structure and the microstructure of the fracture.Test results indicate that the application of activating agent on the stainless steel surface and solvent-based epoxy primer coat can effectively improve the bonding effect of the monocomponent sealing strip on the surface,and the peeling morphology of the sealing strip can be improved from interface failure to cohesion failure,with the shear strength of the adhesive joint increasing from 1.0 MPa to 1.7 MPa;in addition,the application of activating agent and primer coat can effectively improve the coupling aged peeling morphology of the high-temperature-humidity-resistant sealing strip sample for peeling test,with the complete interface failure changing into complete cohesion failure.SEM fracture analysis shows that the fracture morphology of the adhesive joint without primer coat presents interface smooth failure,while the fracture of the adhesive joint applied with activating agent and primer coat demonstrates cohesion failure with tearing adhesive filling materials.The water contact angle test result indicates unconspicuous surface energy increase after the application of activating agent and primer coating.The infrared spectroscopic test shows that there are a large number of epoxy groups(C-O)on the surface with activating agent and primer coating,which might be of significance to the increase of the activity of the bonded surface.