SBIR Phase I: Novel, Robust Process for Thin, Dense Ceramic Coatings

这个小企业创新研究第一阶段项目旨在开发一种新型的低成本工艺，用于制造航空燃气轮机中陶瓷基复合材料（cmc）的环境屏障涂层（EBCs）。CMC采用的一个关键限制是没有廉价的、真正不透气的ebc来提供所需的CMC发动机使用寿命。虽然已经确定了新的EBC组合物，但用这些组合物沉积薄而致密的气体不透水涂层的方法主要是基于蒸汽的工艺，这些工艺昂贵，效率低（非视线）且速度慢（沉积速率低）。努力利用低成本、快速的等离子喷涂工艺，涡轮机行业熟悉，已经取得了一些成功，但仍需要重大改进。作为将CMC应用于航空燃气轮机的一项使能技术，提出的EBC处理技术——溶液前驱体等离子喷涂技术，有可能推动CMC更广泛地应用于航空燃气轮机。在cmc广泛采用的推动下，EBC市场本身到2025年将增长到3亿美元以上。cmc的广泛采用所带来的效率提升可以大大降低新飞机的燃油消耗和温室气体排放，最高可降低15%。该项目的智力价值体现在它是溶液前驱体等离子体喷雾（SPPS）用于EBC处理的第一次演示。SPPS工艺实现非常薄、高密度涂层的独特能力，是由相对于粉末工艺的溶液衍生颗粒的非常小的碎片尺寸驱动的。SPPS工艺提供了一种与蒸汽基工艺相似的涂层方法，但涂层速度更快，成本更低。在SPPS方法中，含有所需阳离子的液体化学前体被雾化到等离子体射流中。注入的溶液蒸发，产生的化学物质被热解，随后是目标氧化物的熔化和沉积，形成尺寸小于5微米的片状物，而传统的空气等离子体喷涂工艺的尺寸为30-125微米。这使得薄而致密的涂层的沉积成为可能。在第一阶段，将展示在碳化硅衬底上沉积薄而致密的最先进的EBC组合物的可行性，并展示涂层的初步耐久性。厚度小于50微米，密度大于95%的EBCs的沉积将被证明。

This Small Business Innovation Research Phase I project is aimed at development of a novel, low-cost process for manufacturing environmental barrier coatings (EBCs) for ceramic matrix composites (CMCs) in aviation gas turbines. A key limitation for CMC adoption is the unavailability of inexpensive, truly gas impervious EBCs to provide required CMC engine service life. While novel EBC compositions have been identified, methods of depositing thin, dense gas impervious coatings with these compositions have largely been vapor-based processes that are expensive, inefficient (non-line-of-sight) and slow (low deposition rates). Efforts to utilize low-cost, and fast plasma spray processes, familiar to the turbine industry, have had some success, but still need major improvements. As an enabling technology for CMC adoption into aircraft gas turbines, the proposed EBC processing technology, solution precursor plasma spray, has the potential to fuel wider adoption of CMCs into aviation gas turbines. The EBC market itself, driven by such a wider adoption of CMCs, can grow to over $300 Million by 2025. The efficiency gains due to such wider adoption of CMCs can substantially lower fuel consumption and greenhouse gas emissions by up to 15% in new aircraft.The intellectual merit of this project is illustrated by the fact that it is the first demonstration of solution precursor plasma spray (SPPS) for EBC processing. The unique ability of the SPPS process to achieve very thin, high-density coatings is driven by the very small splat sizes of the solution-derived particles relative to powder-based processes. The SPPS process offers a route to get coatings similar to what is feasible with vapor based processes, but at much faster coating rates and lower cost. In the SPPS approach, a liquid chemical precursor, containing the desired cations, is atomized into the plasma jet. The injected solution evaporates and the resulting chemicals are pyrolyzed, followed by melting and deposition of targeted oxides as splat of sizes less than 5 microns compared to 30-125 microns with the conventional air plasma spray process. This makes the deposition of thin, dense coatings possible. In Phase I, the feasibility of depositing thin, dense state-of-the art EBC compositions on silicon carbide substrates will be demonstrated, and preliminary durability of the coatings will be demonstrated. The deposition of EBCs with thickness less than 50 micron and with density greater than 95% will be demonstrated.