Study Of The Process Optimization And Performance Of The SICP/Al Composites Fabricated By Stir Cast Method

The SiCp/Al composites with different weight fraction were fabricated by lowcost stir cast method. Micro-topography/microstructures of the particulate and thecomposites were investigated using Scanning Electron Microscope(SEM) and OpticalMicroscope(OM). Also, they were deeply studied by X-rd and Differential ThermalAnalysis(DTA), especially, chemical reaction products. Archimedes principle,Electronic universal testing machine and Brinell testing machine were selected thataimed at the compactness, tensile properties in room temperature and hardness of allthe materials. The SEM can be also used in analyzing the micrographs of tensilefracture. Moreover, fracture mechanism was obtained simultaneously. Thermalexpansion properties of the composites were investigated by DIL402C thermaldilatometer, and the tribology and wear behavior were also studied for the6%(wt.%)SiCp/Al composites under dry sliding condition, the wear mechanism were alsoanalyzed, the creep properity of the composites under high temperature were alsostudied.Composite process optimization results through orthogonal experiment can beget the optimizing technological parameter, and the parameter is as follows:mechanical stirring speed (400r/min), mechanical and ultrasonic stirring temperature(650°C~670°C), mechanical and ultrasonic stirring time (20min) and the weightfraction of the reinforcement is6%. In this condition, the micrographs revealreasonably uniform distribution of the SiC particulates in the matrix. At the sametime, tensile strength, modulus, hardness and elongation of the composites withdifferent weight fraction are improved significantly. It can be also concluded that theeffect on fracture mechanism of the composites are plastic cracking of the matrix, the fracture of the SiC particulates and the chemical reaction at the interface between Aland SiC.According to the experiment of the thermal expansion, coefficients of thermalexpansion (CTEs) of the composites are decreasing with the increasing of the weightfraction of the SiC particulates. The cumulative residual strain of the composite isdeclining obviously relative to the pure aluminum. It can be noticed that thetheoretical CTEs are very closer than the experiment CTEs when CTEs of theSiCp/Al composites were described by Kerner model.In addition, the tribology and wear behavior were also studied for the SiCp/Alcomposite with different sliding speed and different applied loads under dry slidingcondition. The variation of weight wear rate is not monotonous, but presents a trendthat firstly increases and then descends with the increasing of the sliding speed andapplied loads. Otherwise, the most friction coefficient stability and the smallest wearrate of materials were noticed when sliding speed is0.8059m/s and applied load is18N. Under dry sliding condition, friction and wear mechanism is changed fromadhesive wear to abrasive wear, even severely peeling wear in the end. Sometime,two or three mechanisms were found to the dominant for the SiCp/Al composites.The creep properties under high temperature of the SiCp/Al compositesindicated high temperature creep resistant properties of composite materials are betterthan base material.