Copper and aluminium alloy could be welded by friction stir welding (FSW) but it is quite difficult to achieve a defect-free welding joint for welding dissimilar materials because of the enormous difference of their thermo-physical performances. In this paper, another friction stir tool was applied as a heating source to preheat the copper side to 150~200°C in the welding direction. Preheating temperature can make up the lost heat, improve the temperature of copper plate before the FSW process, achieve the refining grains, and then obtain a high quality welding joint. We concentrated on hybrid heat-source equipments design and procedure optimization in our studies. The microstructure, mechanical properties and phase constituents of FSW joints were studied through mechanical test and metallographic analysis. The results indicated that the hybrid FSW technology with preheating for copper T2/aluminium 5A06 dissimilar materials can not only improve the welding efficiency, but also obtain the high quality welding joint. This special welding technology could solve the welding problems of Al-Cu dissimilar materials and had a good potential for application in aerospace manufacturing.
Four kinds of polymer emulsions were coated on the surface of coal pitch carbon fiber using atomized flow static coating method. The surface morphology of the carbon fiber after modification was analyzed by fluorescence microscope.The tensile strength of coated carbon fiber in the cement mortar and the mechanical property of the coated carbon fiber reinforced concrete were tested. The results showed that all the polymer emulsions were coated successfully on the surface of carbon fiber. The tensile strength of the coated carbon fiber in the cement mortar increased obviously, specially for the carbon fiber coated by meta chloride copolymer emulsion, whose tensile strength improved by 61%. The tensile strength of the coated carbon fiber reinforced concrete increased by 11%, the fracture energy increased by 47% and the max crack width increased by 18.5% when the content of the carbon fiber coated by meta chloride copolymer was 1.7 kg/m3.
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