Developing chemical interaction and achieving mechanical interlock to manufacture high-reliability Polypropylene/A6061-T6 aluminum alloy FAW joints

Abstract

Polypropylene (PP) is wildly used to light the weight of advanced cars and vehicles due to its good resistance to abrasion and wear, high flexibility, and excellent impact strength. However, PP macromolecules consist of long chains of carbon atoms attached to hydrogen atoms. The non-functional surfaces of PP make it hard to achieve stable hybrid structures with metals. Current work reported an interfacial design strategy to manufacture high-reliability PP/A6061-T6 aluminum alloy (6061) hybrid structures by friction assisted welding (FAW). To achieve this, carboxy group (COOH) was grafted on PP while the surficial microstructure was built on 6061. The introducing carboxy group reacted with 6061 to develop interfacial covalent and hydrogen bonds. The built surface microstructures of 6061 not only realized the mechanical interlock at PP/6061 interfaces but also improved the compatibility between PP and 6061. The surface microstructures enabled the good wetting and fast spread of melt PP to provide sufficient reaction area and time for the development of interfacial chemical interaction. Compared with other developed methods, our interfacial design strategy enhances the reliability of metal-thermoplastic hybrid structures with low equipment, process, materials, and environmental costs, making it a promising candidate for industrial applications. Current work provides a simple yet attractive strategy for achieving high-reliability joints between dissimilar metals and thermoplastics.