Microstructural Evolution and Wear Behavior of SiCp/7085 Composites Manufactured by Ultrasonic Stirring Casting

Abstract

In this work, SiCp/7085 composites with a volume fraction of 10% were fabricated by ultrasonic stirring casting. The evolution of the microstructure and wear properties of SiCp/7085 composites, as well as the mechanism of ultrasonic action in the process of preparation, when the ultrasonic treatments last for 0 min, 5 min, 10 min, and 15 min, respectively, were studied using the optical effects (OM), scanning electron microscope (SEM), and X-ray diffraction (XRD). The experimental results show that the high temperature and high pressure formed by the cavitation of ultrasound can effectively eliminate the cluster of particles, improve the distribution of SiC particles, increase the interfacial wettability of the composites, and form MgAl2O4 and MgO on the particle surface, thereby ultimately improving the wear resistance of the composites. Because the particles in the melt are affected by the segregation effect of ultrasonic standing wave field, there exists an optimal value for the ultrasonic treatment time. When the melt is treated with the ultrasonic wave with an amplitude of 12 μm and a treatment duration of 10 min in the test conditions given in this paper, the composites have the most uniform distribution of particles, the best wear resistance, a large and stable friction coefficient, and the minimum weight loss of sample wear: 12 mg. The change of wear resistance is consistent with the variation of solidification structure and interface properties.