| Si Cp/Al composites as an important part in materials with its low weigth, high hardness and strength, low expansibility, wear resistance and other excellent performances. so many experts and investigators took great interest on it, and it has been commonly used in many fields. The composite in this paper means that 6061 aluminum being as the matrix, Si C particles at different sizes as the reinforcement, adopting cold pressing and sintering methods which was in powder metallurgy.We added 20%, 25%, 30% volume frictions of Si C particles into aluminum matrix, through isostatic cold pressing methods shaped composite powder into body, then being sintered; We compared the macro morphology and micro microstructure under SEM, the results shows that particles combination were more compactness, and intensity were more high after sintered. From the XRD spectrum of 30% Si Cp/6061 Al composites, we found that main phases were Al and Si C, indicating that there were no reactions or could be negligible in the interface, the combination of particles belonged to metallurgical bonding.We knew that Si C volume frictions and particle sizes could have great impacts on properties from the results of experiment and microstructures of SEM. With the increasing of Si C contents in the matrix, the uniformity in organization varies differently. While the coefficient of thermal expansion increased, this owing to reinforcement have an inhibitory action on the matrix. With Si C particle sizes became bigger, the tensile strength increased firstly, and then decreased. The fracture mechanism changing from tearing of matrix and cracking of interface to the fracture of particle reinforcement.Though after being sintered, the microstructure and properties of composites were not the best yet, so we need improve them through hot extrusion. We compared the microstructure of composites before and after hot extrusion, the results shows that, the Si C particles distributed in the matrix from disorganized to streamlined uniform distribution, furthermore, the grain sizes become smaller and the number rose; We carried the solution treatment on composites under the temperature from 470℃ to 530℃, the second phase in the matrix supersaturated in organization gradually. Then being aging treatment under the temperature from 180℃ to 210℃, this lead to the second phase deposited in smaller particles in the treatment, so it could play the reinforcement role. We also calibrated and calculated through the diffraction pattern, knew that the precipitated material was Al2 Cu Mg, which corresponded to the phenomenon in analysis of XRD spectrum.Lastly, we investigated the friction and wear properties of Si Cp/6061 Al composites with the same Si C particle sizes but different Si C volume contents, we analysed wear loss, wear rate, microstructure and element components of wore interface, the experiment results showed that, the wear loss of composites increased with wear time became longer in the time of 0~120s, furthermore, the more Si C contents, the more wear loss; In the analysis of wore interface morphology, the more load and wear time on the material, the more deeper scratches or even furrows. Besides, the more Si C volume contents in composites, the bigger hardness of it and less abrasive dust; During the process of wearing, oxygen element contents rose in the interface, which may demonstrate aluminum matrix was oxidized. |
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