Friction And Wear Characteristics Of In-Situ Al₂O₃/6063 Aluminum Matrix Composites

Friction is one of the main forms of material failure.According to incomplete statistics,about 30%-50%of energy consumption and 70%-80%of equipment damage in our country is caused by various forms of wear and tear every year.Particle reinforced aluminum matrix composites have the advantages of high specific strength,high specific stiffness,high wear resistance etc,and are widely used in many fields such as aerospace.In this paper,X%Al₂O₃/6063（X=0,2,4,6）composites were prepared by in-situ reaction near liquidus casting with 6063 aluminum alloy as matrix and Al₂O₃ particles as reinforcement phase.Using in situ reaction near liquidus casting method,preparation of Al₂O₃/6063 X%（X=0,2,4,6）composite materials.By optical microscope,X-ray diffractometer and scanning electron microscope analysis of composite materials is studied in as-cast organization,reaction products,wear surface topography.Friction and wear tests were carried out on MMW-1 vertical universal friction and wear testing machine.The dry friction and wear properties of Al₂O₃/6063 composite and 6063 aluminum alloy under different external loads（20N,30N,40N,50N）at room temperature were co MPared and analyzed.The relationships among microstructure,friction and wear mechanism and wear resistance of the materials were studied.The research results are as follows:Under the conditions of molar ratio of reactants Al:Cu O=4:1,mixing time of 60min,forming pressure of prefabricated block 10MPa and melt preheating temperature of nearly1000℃,in-situ reaction was carried out in 6063 aluminum alloy melt to generate in-situ particles,and then Al₂O₃/6063 composite material was prepared by near liquidus casting method.with the increase of Al₂O₃ particle content,its microstructure gradually changes from rose-like to equiaxed crystal.When the addition amount of Al₂O₃particles is 6%,the microstructure is almost all equiaxed grains.The results show that the in-situ particle nucleation and near liquidus casting can produce equiaxed grain composites.There are two interfacial relationships between the in-situ reaction productθ-Al₂O₃ and Al matrix:（1）theθ-Al₂O₃（600）crystal plane is semi-coherent with the Al（111）crystal plane;The crystal plane of（2）θ-Al₂O₃（311）//Al（111）is coherent.The second phase Mg₂Si（02^—2）crystal faces and Al（111）crystal faces of 6063 aluminum alloy also form a coherent interface structure.These particles belong to the in-situ particles,the interface is clean and pollution-free,the interface bonding strength is high,which helps to improve the hardness and wear resistance of the composite material.The reinforcement particles Al₂O₃ in the Al₂O₃/6063 composite material play a decisive role in the wear resistance of the material.In the prepared X%Al₂O₃/6063（X=0,2,4,6）composite material,The wear of 6%Al₂O₃/6063 composite is the least,and the wear of the composite can reach 1/5 of the wear of the matrix.With the increase of load,the wear amount of composite materials gradually increases,and this increasing trend gradually decreases with the addition of Al₂O₃ particles.According to the wear mechanism,Al₂O₃/6063 composites can be divided into three wear stages of different degrees:abrasive wear,adhesive wear and delamination wear.The larger the applied load,the earlier the stage of adhesive wear and delamination wear will appear.The larger the content of reinforced particles Al₂O₃ is,the later the stage of adhesive wear and delamination wear appears,and even the last stage of delamination wear may not appear.