STTR Phase I: Additive manufacturing of ceramic composites for next generation gas turbines

该项目更广泛的影响/商业潜力在于下一代燃气轮机，其中发动机的心脏，燃烧室和叶片由陶瓷基复合材料（CMC）构成。这些发展将使航空运输进入一个新的阶段，超越目前依靠镍基高温合金的发动机，这些发动机已经达到了最大能力。陶瓷发动机的效率最终有望提高25%。CMC由碳化硅纤维制成，这些纤维被纺成网状，然后用同样坚固的高温基质渗透，该基质也由碳化硅基陶瓷制成。纤维复合材料克服了整体陶瓷固有的脆性，同时在侵蚀性环境中保持其机械和耐腐蚀性。这些复合材料的应用范围将超越燃气轮机。它们可以成为聚光太阳能发电系统太阳能集热器的关键突破，并有可能用作核燃料的包层，以提高安全性和事故容忍度。第一阶段项目的关键创新是开发一种增材制造工艺，用于从转化为碳化硅基陶瓷的聚合物前体中创建致密无缺陷的基质。 这个小企业技术转移研究（STTR）第一阶段项目采用增材制造技术来制造陶瓷基复合材料（CMC）的致密无缺陷基体。这些复合材料由碳化硅（SiC）纤维构成。该项目的创新在于从聚合物前体构建基质，其中纳米级层快速连续沉积以创建基质。这些硅基聚合物前体在加热至约800 oC时转化为陶瓷。标称处理，也称为聚合物渗透和热解，尽管有24小时的固化周期，仍会在基质中产生裂纹。这些裂纹降低了复合材料的强度。在这个项目中，纳米涂层以液体薄层的形式沉积，然后在一两秒钟内热解成陶瓷。涂层无缺陷且致密。短的固化时间允许层的快速沉积。CMC可以在约4小时内由SiC纤维预制件制备。该工艺的可行性已经在NSF陶瓷计划的资助下用碳纤维进行了证明。在这个SBIR项目中，美国制造有限责任公司试图展示由碳化硅纤维制成的CMC的制造，并展示其在高温应用中的可行性。

The broader impact/commercial potential of this project lies in next generation gas turbines where the heart of the engine, the combustor and the blade, are constructed from ceramic matrix composites (CMCs). These developments will spell a new phase of air transportation beyond the current engines that rely upon nickel-base superalloys, which have reached their maximum capability. The ceramic engines are eventually expected to be 25% more efficient. The CMCs are constructed from fibers of silicon-carbide that are spun into net shape and then infiltrated with an equally robust high temperature matrix, also made from silicon carbide-based ceramics. The fiber composites overcome the inherent brittleness of monolithic ceramics while retaining their mechanical and corrosion resistance in aggressive environments. These composites will have applications beyond gas turbines. They can become the critical breakthrough for the solar collector on Concentrated Solar Power systems, and have the potential to be used as cladding for nuclear fuels for greater safety and accident tolerance. The key innovation in this Phase I project is the development of an additive manufacturing process for creating a dense and defect free matrix from polymer precursors that convert into silicon carbide-based ceramics. This Small Business Technology Transfer Research (STTR) Phase I project employs additive manufacturing to fabricate dense and defect free matrices for ceramic matrix composites (CMCs). These composites are constructed from fibers of silicon carbide (SiC). The innovation in this project lies in constructing the matrix from polymer precursors where nanoscale layers are deposited in quick succession to create the matrix. These silicon-based polymer precursors convert into ceramics when heated to ~800 oC. Nominal processing, also known as polymer-infiltration-and-pyrolysis, produces cracks in the matrix despite 24 hour curing cycles. These cracks degrade the strength of the composite. In this project nanoscale coatings are deposited in the form of thin layers of liquid and then pyrolyzed into the ceramic in just one or two seconds. The coatings are defect free and dense. The short curing time allows rapid deposition of layers. The CMC can be prepared from SiC fiber preforms in about four hours. The feasibility of the process has been demonstrated with carbon fibers under a grant from Ceramics Program at NSF. In this SBIR project, American Manufacturing LLC seeks to demonstrate the fabrication of CMCs made from silicon-carbide fibers, and demonstrate their viability for high temperature applications.