Structures And Properties Of Pistons Of SiC Particle Reinforced Aluminum Composite Formed By Centrifugal Casting

This paper focuses on the manufacturing process of ZL104/ZL109 alloy composites reinforced by SiC particles, and the centrifugal casting process of composites. The microstructure, composition and properties of composites are also studies deeply. The result indicates that the equipment and process are feasible. The particle is dispersive and well combined with the matrix alloy. The part formed by centrifugal casting has integrated figuration, dense microstructure and fine properties. The main parts of the thesis are as following:The fabrication of SiC particle reinforced ZL104/ZL109 composites which weigh 18kg is researched deeply, whose volume fraction of SiC particles is 20 percent, average diameter is 15μm, 30μm,and 50μm. The pretreatment process of SiC particles and the manufacturing parameter of composite are confirmed.Three-dimensional software (UG) is used to design a piston which is machined later.Piston core is made in the wooden core box.According to the different matrix materials , two different pouring technologies are adopted to manufacture composite material pistons parts. According to the cross section of the block cast , clearly the piston parts has three parts: top reinforced zone,free particle zone and inner reinforced zone. After the comparison between the microstructure and capability of the cylinder parts, the result shows as following: the combination of the part formed by centrifugal casting is nice, and structure is dense; the percentage of the SiC volume fraction is more; the hardness of sample located in the reinforced zone is about 70HRB/80, while in the free particle zone it is 50HRB/60, from which we can see obviously that the reinforced zone is harder than the free particle zone.The heat treatment processing of the SiCp/Al composites located in the reinforced zone and particle free zone of cylinder have also been studied, and the hardness, CET and wear resistance have been also discussed during heat treatment. The results are: the reinforced zone is harder than the free particle zone, because after the heat treatment, the hardness of reinforced zone rises to 49% while the particle free zone 22%; after heat treatment, the wear resistance of the reinforced zone and particle free zone increase separately by 23% and 42%。The CET is 15×10-6·K-1 under 300℃, more than common piston alloy in the present level.