(A) study on the characterization of high-performance silicon nitride ceramics and carbon fiber composites for extreme environments

Abstract

In modern times, researches on improving the performance of various transportation is being actively conducted. On the ground, the importance and interest in eco-friendly electric vehicles and various military equipment for national defense in developed countries are increasing. Recently, a lot of attention is being paid to aerospace field due to the actions of Korea’s Nuri(KSLV-II) and America’s SpaceX. What each field has in common is that extreme materials serve as the basis to bring out the best performance. Power modules, which are key parts of electric vehicles, and thrusters of rocket missiles require special materials suitable for their extreme environments. Therefore, it is important to find the optimal material to improve the durability and performance of each system and to improve the thermal and mechanical properties. In this study, alpha-beta phase control and pressureless sintering were introduced to improve the mechanical strength and thermal conductivity of silicon nitride ceramics, which is a substrate material for power modules. In addition, to improve the ultra-high temperature properties of C/SiC composites for extreme environments, a C/SiC composite with zirconium boride, an ultra-high temperature ceramic, was designed, and ablation and oxidation resistance was evaluated using an oxy-acetylene torch set up. In order to improve the structural ratio of aerospace components, a diffusion-bonding was conducted using a titanium intermediate layer between a tungsten-rhenium alloy, a very high temperature refractory metal, and a lightweight carbon-carbon composite. Furthermore, studies on enhancing mechanical properties through nitriding of C/SiC composites and diffusion-bonding of tungsten-rhenium alloys and C/SiC composites were also discussed to strength the connectivity between each material.