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，其中发动机的核心，燃烧室和叶片由陶瓷基复合材料（cmc）构成。这些发展将标志着航空运输的一个新阶段，而不是目前依赖镍基高温合金的发动机，这种发动机已经达到了最大的性能。陶瓷发动机的效率最终有望提高25%。cmc由碳化硅纤维构成，这些碳化硅纤维纺成网状，然后渗透到同样坚固的高温基体中，该基体也由碳化硅基陶瓷制成。纤维复合材料克服了单片陶瓷固有的脆性，同时在侵略性环境中保持其机械和耐腐蚀性。这些复合材料的应用将超越燃气轮机。它们可以成为聚光太阳能发电系统中太阳能集热器的关键突破，并有可能被用作核燃料的包层，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，用于将聚合物前体转化为碳化硅基陶瓷，从而创造致密且无缺陷的基体。这个小型企业技术转移研究（STTR）第一阶段项目采用增材制造技术为陶瓷基复合材料（cmc）制造致密和无缺陷的基体。这些复合材料由碳化硅（SiC）纤维构成。这个项目的创新之处在于用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。当加热到~800℃时，这些硅基聚合物前体转化为陶瓷。标称处理，也称为聚合物渗透和热解，即使在24小时的固化循环中，也会在基体中产生裂缝。这些裂纹降低了复合材料的强度。在这个项目中，纳米级涂层以薄层液体的形式沉积，然后在一到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快速沉积。由SiC纤维预制体在4小时左右即可制备CMC。在美国国家科学基金会陶瓷项目的资助下，该工艺的可行性已经用碳纤维进行了验证。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.