Bifunctional nano-SiO2 additive for reinforcing the SiC/Al composites fabricated via a novel hybrid additive manufacturing

Abstract

In this work, a novel hybrid additive manufacturing technique is used to prepare the SiC/Al composites. The effect of silica sol concentration on the microstructure and property of SiC preforms and SiC/Al composites were investigated. Silica sol infiltration proved to be an efficient strategy to address the troublesome issue of strength decrease for the SiC preforms after preoxidation. With an increase in silica sol concentration from 0 to 30 %, the strength of the pre-oxidised SiC preforms increased from 0 to 2.77 ± 0.21 MPa, which well satisfied the processing requirements of the subsequent vacuum-pressure infiltration process. Interestingly, the nano-SiO2 in the silica sol not only is favorable for the SiC–Al interface of SiC/Al composite, but also has a significant grain refinement effect on the aluminium matrix. As a result, the strength of the samples treated with preoxidation and silica sol infiltration reached a maximum value of 411.41 MPa, which was 88.38 % higher than 218.4 MPa of the control group. Meanwhile, a notable enhancement in fracture strain was observed from 0.125 to 0.156 % for the optimized SiC/Al composite. More importantly, the large-size and high-performance SiC/Al composite parts with complex structures have been successfully prepared by this hybrid additive manufacturing technique. The results of this work show that the hybrid additive manufacturing technology has great potential for application in aerospace, automotive industry and other fields.