Influence Of Surface Micro-nano Morphology On The Injection Bonding Characteristics Of Aluminum-plastic Heterogeneous Structure

The application of light-weight and high-strength polymer-metal composite structure was one of the effective ways to solve the excessive consumption of energy.It was a big challenge to quickly and effectively obtain composite structure with high interface bonding strength.The surface micro-nano morphology of aluminum alloy(Al)has an important influence on the interface bonding of lightweight aluminum-plastic heterogeneous structure.First,the surface of Al was modified by anodic oxidation,sandblasting and pure water treatment.Then,light-weight and high-strength aluminum-plastic heterogeneous structure was obtained through injection molding technology.The interface strength meet the needs of engineering applications,and has certain application value in the aerospace and automotive fields.The main research contents are as follows:1.Glass fiber-reinforced polyphenylene sulfide(PPS)and aluminum alloy(Al 6061)were joined via flexible injection molding technology.With pretreatments of anodizing and the coupling agent,the maximal lap shear strength between the polymer and aluminum alloy were significantly enhanced,which was almost eight-fold compared with the untreated case.The scanning electron microscope(SEM)and X-ray photoelectron spectrometer(XPS)investigations proved that the micro cracks with widths of nanometer scale and chemical Si-O-Al bonds were formed on the aluminum alloy substrate,which contribute significantly to the interface bonding strength.According to Fourier transform infrared(FTIR)investigations,the existing C-N bonds in the coupling-agent layer on the aluminum alloy surface also have a crucial effect on the bonding strength of the two dissimilar materials.2.The effect of the nanostructure size and porosity on the bonding performance of the PPS-Al composite parts were discussed.It reveals that when the diameter of the nanostructure increases to 160 nm and the porosity reaches 0.281,the bonding strength and fracture work of the PPS-Al composite parts reach the highest.Furthermore,the effect of chemical bond(-OH)amount on the aluminum alloy surface wettability and bonding strength was first analyzed.After plasma treatment,the relative contents of chemical bond(-OH)obtained on Al surface were calculated.When the-OH bond content reaches 0.431,the largest bonding strength and fracture work of the composite structure were found to be24.8 MPa and 20.1 KJ/m~2 respectively,improving by 16%and 17%compared with non-plasma treated sample.These results proved that the nanostructure and chemical functional group formed on the Al surface played vital role on the bonding strength of the PPS-Al composite structures.3.The surface of Al was modified by the synergistic treatment of sandblasting and deionized water.The influence of sandblasting parameters on the surface roughness of Al was discussed,and the influence of surface roughness on the interface bonding strength of injection molded PPS-Al composite parts was quantitatively discussed.The Al OOH structure on the Al surface was analyzed by SEM and XPS,and the influence of the relative content of Al OOH and its wettability on the interface bonding properties were discussed.When the deionized water treatment time was 30 min,the relative content of Al OOH was0.236,and the bonding strength was 32.3 MPa,which was 2.3 times higher than the bonding strength before deionized water treatment.The composite structure was further annealed,and the influence of the crystallinity of PPS on the interface bonding strength was discussed.When the crystallinity of PPS reached 51.9%,the bonding strength of composite structure was increased by 10.2% to 35.6 MPa.