Research On Bond Strength And Mechanism Of Metal-Rubber Impact Bar Surface/Interface Under Sandblasting Process

In this paper,the bonding strength of 6063-T5 aluminum alloy substrate and rubber layer in the metal-rubber impact bar was investigated.The sandblasting process was used to pretreat the surface of aluminum alloy substrate.Based on the combination of theoretical analysis and experimental research,the formation mechanism of substrate surface roughness was studied.The influence of surface roughness and different sandblasting process parameters on the interfacial bonding strength of aluminum alloy-rubber layer was also systematically studied.The main research contents and conclusions of this paper are as follows:Based on Hertz contact theory,the dynamic contact between the blasted abrasive and the surface of metal substrate was analyzed,deducing the theoretical formula of the depth of the pit surface and obtaining the influencing factors of sandblasting on the surface roughness.The influence of sandblasting abrasive grain size,working pressure,and angle of incidence on surface roughness of the substrate was investigated.The results show that when the other blasting conditions are fixed,under smaller abrasive grain size,higher working pressure and greater incident angle,surface roughness of the substrate is greater.The influence of these factors on surface roughness of the substrate is : working pressure> abrasive particle size>incidence angle.Although the incident angle has the least influence on the surface roughness,it has a great influence on the surface quality of the substrate.When the incident angle is smaller,the scratches and furrow on the surface of substrate are more obvious.The influence of surface roughness of the aluminum alloy matrix after sandblasting and process parameters on the bond strength of the rubber layer was analyzed by orthogonal test.The results show that the interfacial bonding strength of aluminum alloy-rubber layer is affected by the surface roughness,surface morphology and surface residual stress of the substrate,where surface roughness of the substrate is the most important influencing factor.The results show that there is an optimal relationship between the bonding strength and the roughness.When the surface roughness Rz is close to 30.2μm,the interfacial bonding strength of aluminum alloy matrix-rubber layer reaches the largest value.When the substrate surfaceroughness Rz is close(ie,the fluctuation of Rz is less than 5 μm),the aluminum alloy substrate after sandblasting with the 80-mesh abrasive is more conducive to the bonding of the rubber layer;the surface of substrate after sandblasting at an incidence angle of 60° has a better bonding strength with the rubber layer.Based on the orthogonal test,it is found that when the blasting time is 10 s,the sandblasting distance is 40 mm,the abrasive grain size is 80 mesh,the working pressure is0.7MPa,and the incident angle is 60°,the interfacial bonding strength of the aluminum alloy matrix-rubber layer is the best.When adhesive is not added to the interface,the bonding strength is 29.7 times than that of the unblasted one.The final results show that the optimal combination of process parameters corresponding with the actual production is that sandblasting time is 10 s,sandblasting distance is 40 mm,abrasive particle size is 60 mesh,working pressure is 0.7MPa,and incidence angle is 60°.The microstructure of aluminum alloy substrate before and after sandblasting was compared using SEM.It was found that the reason why the interfacial bond strength of aluminum alloy-rubber layer after sandblasting is significantly improved is as follows: the contact area between the substrate and the rubber layer increases;the removal of oxide coating of the substrate surface improves infiltration of the interface;the tiny pits,scratches and furrows formed in the substrate surface play the role of the mechanical bite,anchoring and pinning.