Thermal shock resistant 3D printed ceramics reinforced with MgAl2O4 shell structure

Abstract

The demand for the swirl nozzle with enhanced temperature resistance and lightweight properties is increasing as the thrust-to-weight ratio of aero-engines rises. The Al2O3 ceramic swirl nozzle can maintain high strength in a hostile environment of high temperature and severe corrosion, while also meeting the requirements of aircraft to enhance efficiency and decrease weight. However, Al2O3 ceramics are limited in their application for aerospace components due to their poor thermal shock resistance (TSR) stemming from their inherent brittleness. This work reported an innovative design and fabrication strategy based on photopolymerization 3D printing technology to realize the three-dimensional shell structure through element interdiffusion and nanoscale stacking of the reinforced phase. With this strategy, a novel type of the new dual-structure Al2O3 ceramic composed of MgAl2O4 shell structure and matrix could be constructed in situ. The nano-sized MgAl2O4 caused a crack passivation effect after the thermal shock, which could improve the strength and TSR of 3D-printed Al2O3 ceramic. In addition, the effects of MgO content and sintering temperature on sintering behavior, flexural strength, porosity, and TSR of Al2O3 ceramics manufactured by digital light processing (DLP) processing were systematically studied. The optimum overall performance of Al2O3 ceramics was obtained at the sintering temperature of 1550 °C and the MgO content of 1.0 wt.%, with a maximum flexural strength of 111.929 MPa and a critical temperature difference of 374.24 °C for TSR. Based on the above research, an aero-engine swirl nozzle with high thermal shock resistance has been successfully prepared by ceramic 3D printing technology, which enhances high-temperature resistance and promotes lightweight design in aero-engine.