Research On Aluminum Composite Production Process And Performance

With the rapid development of modern automobile industry, the traditional pistonsmanufacturing methods cannot meet the requirement of high power engine gradually.Powder metallurgy method reduces defects such as segregation and coarse grains inthe traditional casting method widely used in the production of automobile parts for itshigh utilization, strong designability and low processing temperature as a net-shapeforming method. One of the piston material aluminum composite was prepared by theusing of powder metallurgy techniques, and the organization, tensile fracture and wearperformance was studied in this work.The powder metallurgy process used in this work contains: mix powder, pressing,sintering and extrusion, heat treatment,and the powder metallurgy process on theinfluence of material properties was studied.First different pressure was chose toproduce the powder body, the density law with change of pressure was analyzed andproper pressure was determined. The appropriate sintering process was got byanalyzing the influence of temperature and time on sinter density and hardness. Theinfluence of different extrusion temperature on the material strength and hardness, thechanges of material performance in different heat treatment process were studied in afollow-up processing.Finally,the optimal powder metallurgy parameters of aluminumcomposite were obtained:press power of50t, sintering system for570℃x2h,extrusion temperature of390℃, heat treatment process for510℃×3.5quenching,175℃×10h aging.The SEM, EDAX equipment were used to observe and analyze aluminum compositeorganization, tensile fracture and wear morphology.The results indicate: the size ofsilicon particle is larger and the shape is the plate polygon cut apart organizationcontinuity seriously. Silicon phase is small and equality dispersoid distribution, thephenomenon such as holes and loose are improved and the density enhanced obviouslyafter plastic deformation. The tensile fracture of materials were observed before and after extrusion.Low strength appeared in the materials before extrusion, metallurgicalcombination and mechanical bite coexist among the powder. The fracture mechanismwas brittle rupture. Bond strength was improved obviously between the particles, gapsin the organization were filled,and the fracture mechanism was brittle rupture coexistwith ductile rupture.The strength and hardness of aluminum composite reached amaximum after solid solution, increased by87.9%and24%than the aluminumcomposite before extrusion respectively,were266MPa and HBS89.7.Friction and wear test results show that, the wear rate change tendency of sintering,extrusion and heat treatment of aluminum composite are the first rise,then to drop,then reached a plateau all.The specimens has a low wear rate,good abrasionperformance after heat treatment. Wear mechanism formed by adhesion wear, particleattrition and oxidative wear to three kinds of condition for aluminum composite.Different wear mechanism plays a leading role in different state for the aluminumcomposite wear.