Effect Of High Welding Temperature On Properties Of Adhesives

Nowadays taking high speed trains has become more indispensable for people to travel,with the development of lightweight and high-speed progress of locomotive,we use aluminum alloy structures to replace steel structures,and use elastic bonding method to replace mechanical connection.Elastic bonding can not only reduce the weight of the trains’parts greatly,but also make it more beautiful and reliable compared with the mechanical connection.However,the elastic bonding method is not perfect,when we weld and modify the train’s parts,the stability of the bonding system might be affected by the welding temperature,be aged and cracked quickly,even be fractured and damaged,this phenomenon will endanger the safety of the train and its personnel seriously.In this thesis the influence of high temperature on the properties of adhesives of different types and distances in the welding process were explored.We tested the properties of adhesives with different surface treatments and different welding forms through Fourier transform infrared spectroscopy(FTIR),X ray diffraction(XRD),scanning electron microscopy(SEM),DVS 1618 peeling test,tensile strength,elongation at break and elastic modulus.The results of the study are as follows:For Sika 265 polyurethane adhesive,FTIR and XRD results showed that the influence distance on the Sika 265 bonding surface of aluminum alloy plate coated with finishing coat in the form of T joint is at least 200mm,the effect distance of Sika 265 bonding surface on aluminum alloy plate coated with finishing coat in the form of butt joint are between 50mm and 100mm,the reason is that the stick component reduced,and the crystallization increased.The mechanical test results showed that the welding high temperature has little effect on the mechanical properties of the samples.For Sika 221 polyurethane adhesive,FTIR and XRD results showed that the influence distances of welding high temperature influence on the Sika 221 bonding surface of aluminum alloy plate coated or uncoated with primer in the form of T joint and butt joint are both at least 200mm,the reason is that the curing reacting further on the bonding surface,and the phase changed.The mechanical test results showed that the welding high temperature had little effect on the mechanical properties of the samples.For Caropur 166 polyurethane adhesive,FTIR and XRD results showed that the influence distances of welding high temperature influence on the Caropur 166 bonding surface of carbon steel coated with primer in the form of T joint,butt joint and lap joint are at least 200mm,the reason is that the curing reaction further on the bonding surface,and the crystallization increased.The mechanical test results showed that the welding high temperature has little effect on the mechanical properties of the samples.