Robocasting entropy stabilised ultra-high temperature ceramic composites for hypersonic applications.

在高超声速飞行中，锋利的前缘和前锥体对飞行控制是有利的，但要承受比钝体高得多的温度。因此，加强高超声速状态下的飞行控制要求材料能够在2000摄氏度以上运行，并具有最小的侵蚀/氧化，同时还具有良好的导热性和抗热震性。超高温陶瓷基复合材料(UHTCMCs)是少数几种能够长期耐受这种环境的材料之一，克服了单片式UHTCs韧性低的缺点。然而，生产高质量UHTCMCs的传统方法，如液体熔体渗透或化学蒸气渗透，时间和成本都很高。机器人浇注是一种添加剂制造形式，在这种制造中，陶瓷浆料/墨水被沉积并固化为净形状组件或预浸层，然后进行热处理以使粘结剂材料交联，这是CASC团队正在开发的一种新颖且更负担得起的组件生产方法。高熵或熵稳定的UHTCs是一种新的陶瓷类型，其中通常存在于UHTC中的多种过渡金属结合成单相结晶溶液。早期的研究表明，高熵UHTCs的潜在性能比单个组分更高，熔化温度和抗氧化性都有所提高。这项博士提案提供了一个令人兴奋的机会，将机器人预测和熵稳定的UHTCS的进步结合起来，以回答两个关键问题。1.将3D打印的过渡金属粉末在酚醛/碳化树脂中转化为致密的UHTCMC基质是否可行？2.如果将多个过渡金属粉末组合在同一工艺中，能否制备出比单一二元过渡金属粉末具有更好的热机械性能的熵稳定的UHTCMC？

Sharp leading edges and nose cones are advantageous for flight control in hypersonic flight but suffer much higher temperatures than blunt ones. Hence enhanced flight control in the hypersonic regime requires materials capable of operating above 2000 C with minimal erosion/oxidation while also showing good thermal conductivity and thermal shock resistance. Ultra-high temperature ceramic matrix composites (UHTCMCs) are one of the few materials able to withstand this environment for prolonged periods overcoming the low toughness of monolithic UHTCs. Traditional methods of producing high-quality UHTCMCs such as liquid melt infiltration or chemical vapour infiltration are however time and cost-intensive. Robocasting, a form of additive manufacture in which a ceramic slurry/ink is deposited and cured as a net shape component, or pre-preg ply, prior to heat treatment to cross-link the binder material, is a novel and more affordable method of producing components that is under development by the CASC team. High entropy or entropy stabilised UHTCs are a new class of ceramic in which multiple transition metals typically found in UHTCs are combined into a single-phase crystalline solution. Early research has shown the potential performance of high entropy UHTCs to be greater than individual components with increased melting temperatures and oxidation resistance. This PhD proposal provides an exciting opportunity to combine the advances in robocasting and entropy-stabilised UHTCs to answer two key questions. 1. Is it feasible to convert 3D printed transition metal powders within a phenolic / carbon yielding resin into a densified UHTCMC matrix? And, 2. If multiple transition metal powders are combined in the same process can an entropy stabilised UHTCMC be produced with better thermo-mechanical properties than binary transition metal powders alone?