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

这个小型企业创新研究第一阶段项目旨在开发一种新的、低成本的工艺，用于制造航空燃气轮机陶瓷基复合材料(CMC)的环境屏障涂层(EBCs)。CMC采用的一个关键限制是无法获得廉价、真正不透气的EBCs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，但使用这些组合物沉积薄而致密的气体防渗涂层的方法主要是基于蒸汽的过程，这些过程昂贵、低效(非视线)和缓慢(低沉积速率)。利用涡轮机行业熟悉的低成本、快速等离子喷涂工艺的努力取得了一些成功，但仍需要重大改进。作为航空燃气轮机采用CMC的一项使能技术，拟议的EBC处理技术--溶液前体等离子喷涂--有可能推动航空燃气轮机更广泛地采用CMC。在CMCS如此广泛采用的推动下，EBC市场本身到2025年可以增长到超过3亿美元。由于更广泛地采用CMCS，效率的提高可以显著降低新飞机的燃油消耗和温室气体排放高达15%。该项目的智能优势体现在它是第一个用于EBC加工的溶液前体等离子喷涂(SPPS)的演示。SPPS工艺获得非常薄、高密度涂层的独特能力是由溶液衍生颗粒相对于粉末工艺非常小的飞片尺寸驱动的。SPPS工艺提供了一种获得涂层的方法，与基于蒸汽的工艺类似，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，然后熔化和沉积目标氧化物，其尺寸小于5微米，而传统的空气等离子喷涂工艺的尺寸为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，将论证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，并初步证明涂层的耐用性。将展示厚度小于50微米、密度大于95%的EBCs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.