Effect Of The Surface Pretreatments Of Aluminum Alloys On The Mechanical Properties Of Glass Fiber-aluminum Laminates

Glass fiber reinforced polymer-aluminum laminates which has been widely used inaerospace,3C products and automotive industries owing to its low manufacture costsand lighter density. Using the composite structure can greatly improve the fracture,impact, damping and corrosion of the material. Glass fiber reinforcedpolymer-aluminum laminates can be obtained by the processes, including theprocedures of pretreating the aluminum surface, laying the glass fiber fabric,impregnating the epoxy resin, standing and curing. The performance of laminates arerelated to multiple factors, such as aluminum material, laminates thickness, fiberorientation, surface preparation and so on.This paper with the background of developing the high performance glass fiberreinforced polymer-aluminum laminates and expanding its application scope. On thebasis of the present status, the author began researching from the surface pretreatmentof aluminum alloys through untreated, mechanical treatment, chemical treatment andanodizing methods in order to improve interface strength of aluminum/glass fiber resinand mechanical properties of the laminates.At first, the thesis has studied different surface pretreatment which responded tosurface microscopic morphology and microscopic outline of the aluminum alloys, andthe micro mechanism of the variation of the aluminum alloys under different surfacepretreatment were also revealed. Next, the writer researched the dynamic contact angle(DCAA) between epoxy resin and aluminum alloys which had been processed bydifferent surface pretreatment, the wettability about aluminum alloys and epoxy resinwas also discussed. Then glass fiber reinforced polymer-aluminum laminates wereprepared by vacuum infusion molding process innovatively, and the static mechanicalproperties of laminates which were disposed by different surface pretreatment werecomprehensive studied. Finally, the improvement about interface of aluminum alloys/glass fiber resin in laminates which were processed by different surface pretreatmentwere researched. The main conclusions were as follows:1) In comparison with the microstructure of the aluminum surface that was treatedby untreated, mechanical treatment, chemical treatment and anodizing methodsrespectively, the diameter and number of micropore on the aluminum surface bothincreased orderly, and the distribution of micropore was also much more homogeneoussuccessively. 2) The advancing dynamic contact angle (DCAA) between epoxy resin andaluminum alloys decreased with different surface pretreatment, the value of the DCAAwere56.8°,51.8°,46.5°and40.0°. The advancing dynamic contact angle (DCAA)between epoxy resin and glass fiber was55.1°. And retreating dynamic contact angle(DCAA) were both0°. The value of the advancing DCAA were connected with manyfactors, such as testing velocity and immersing depth, which means the value of theadvancing DCAA increased with increasing testing velocity and decreased withimmersing depth.3) Glass fiber reinforced polymer-aluminum laminates were prepared by vacuuminfusion molding process, the results about static mechanical property of laminateswhich was processed by untreated, mechanical treatment, chemical treatment andanodizing methods respectively showed that the0°and90°direction of tensile strengthand bending strength were elevated one by one with, the value of tensile strength andbending strength direction about0°direction were272.24、359.70、408.17、436.39MPaand295.59、320.35、384、410.68MPa, and the value of tensile strength and bendingstrength direction about90°direction were210.53、304.14、384.69、390.62MPa and291.42、308.45、333.15、380.70MPa. The results showed that the tensile and bendingproperty improved with improving of surface roughness and activity of aluminum alloy.The compressive strength of laminates were almost the same when the compressdeformation were conducted in the same direction. The0°and45°directioncompressive strength of laminates which processed by untreated, mechanical treatment,chemical treatment and anodizing methods respectively were98.24、102.46、107.08、114.22MPa and51.48、53.86、61.00、75.26MPa, this was due to the density of glassfiber in45°direction less than0°direction, so the laminates bore less paylad in theprocess of compression. In addition, not only had the elasticity modulus and fracturestrain of laminates which were processed by different surface pretreatment similar value，but also both lower than aluminum alloys, and the compressive modulus is similarity.Because of the modulus and elongation of epoxy resin and glass fiber were lower thanaluminum alloys.4) The interfacial gap of laminates which was processed by untreated, mechanicaltreatment, chemical treatment and anodizing methods respectively reduced in turn. Theinterfaces of aluminum alloys/epoxy resin/glass fiber of laminates which wereprocessed by anodizing methods had no defects, such as bubbles, inclusions and so on.