Low-cost and rapid preparation of high-performance carbon fiber reinforced ceramic matrix composites by molding-in situ densification

Carbon fiber reinforced ceramic matrix composites (CFCMCs), demonstrated huge demand of braking and transmission systems for heavy-loading equipment. However, high production cost, cumbersome preparation process and long preparation cycle severely limited its application and industrialization in the defense industry. In this work, a molding-in situ densification process was proposed to prepare AlN-modified CFCMCs under the synergistic effects of Al and Al₂O₃ fillers, facilitating a significant reduction in the preparation steps and treating temperature. The existence of active Al fillers was conducive to inducing the formation of Al-Si alloy melt and increasing contact area between Si and C to reduce the temperature of the Si-C reaction and promote the densification of composite materials. Meanwhile, the addition of Al₂O₃ effectively limited long-range flow of the alloy melt, further inhibiting severe volume deformation of the composites and the generation of large pores. When the maximum heat treatment temperature reached 1300 °C, the preparation cycle of AlN-modified CFCMCs reduced as low as 23–28 h after the molding-in situ densification process, which was roughly decreased by a 50 % drop. The compressive and flexural strength of AlN-modified CFCMCs achieved 308.51 MPa and 115.68 MPa, respectively. This molding-in situ densification strategy provided a pathway toward to achieve low-cost and rapid preparation of high-performance CFCMCs for the scale-up application in the fields of defense and military industry.