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

该小型企业创新研究第一阶段项目旨在开发一种新型、低成本的工艺，用于制造航空燃气轮机中陶瓷基复合材料（CMC）的环境阻隔涂层（EBC）。CMC采用的一个关键限制是无法获得廉价的、真正不透气的EBC来提供所需的CMC发动机使用寿命。虽然已经鉴定了新颖的EBC组合物，但是用这些组合物沉积薄的、致密的不透气涂层的方法主要是基于蒸气的方法，其昂贵、低效（非视线）且缓慢（低沉积速率）。努力利用涡轮机工业所熟悉的低成本和快速等离子体喷涂工艺已经取得了一些成功，但仍需要重大改进。作为CMC采用飞机燃气轮机的一种使能技术，所提出的EBC处理技术，溶液前体等离子喷涂，有可能推动CMC更广泛地应用于航空燃气轮机。在CMC更广泛采用的推动下，EBC市场本身到2025年可能会增长到3亿美元以上。由于更广泛地采用CMC而带来的效率提高可以使新飞机的燃料消耗和温室气体排放量大幅降低15%。该项目的智力优势体现在以下事实上：它是EBC处理的溶液前驱体等离子喷涂（SPPS）的首次演示。SPPS工艺实现非常薄、高密度涂层的独特能力是由溶液衍生颗粒相对于粉末基工艺的非常小的飞溅尺寸驱动的。SPPS工艺提供了一种获得类似于基于蒸汽的工艺可行的涂层的途径，但具有更快的涂覆速率和更低的成本。在SPPS方法中，将含有所需阳离子的液体化学前体雾化到等离子体射流中。注入的溶液蒸发，所得的化学品热解，然后熔化并沉积目标氧化物，其尺寸小于5微米，而常规空气等离子喷涂工艺为30-125微米。这使得沉积薄而致密的涂层成为可能。在第一阶段，将证明在碳化硅基底上沉积薄、致密的最先进的EBC组合物的可行性，并证明涂层的初步耐久性。将展示厚度小于50微米且密度大于95%的EBC的沉积。

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.