SBIR Phase I: Novel Environmental Barrier Coatings for High-Temperature Metals and Ceramic Matrix Composites

这个小企业创新研究第一阶段项目提出了两种方法来开发一种薄的、低成本的保护涂层，用于sic基陶瓷复合材料和耐火材料和其他高温金属合金，达到1200摄氏度。金属和陶瓷需要保护涂层，以防止氧化和腐蚀加速疲劳。通过金属掺杂热固性聚硅氮烷制备新型SiCN涂层，具有体积收缩率低、结合强度高和优异的赫敏性。Zr/Ti和Zr/Al掺杂的聚硅氮烷将被粉末包覆，从而通过限制挥发分来提高陶瓷收率。掺杂的SiCN涂层具有较低的杨氏模量和可定制的热膨胀系数（TCEs）和表面化学成分，提高了涂层在热循环中的耐久性。第二种建议的涂层系统包括溶胶-凝胶或聚合物衍生的ZrSiO4氧屏障，其顶部有一层用于防潮的溶胶-玻璃层。锆石起着保护Y-Zr-Al-Si-O的结合涂层的作用。锆石相可以通过标准溶胶合成或Zr和Si热固性聚合物的缩合而成。本文提出的新型涂层的应用不仅限于保护sic基陶瓷复合材料，还可以用于氮化硅、硅基整体陶瓷和高温金属合金。该项目的更广泛影响/商业潜力涉及创新材料解决方案，以提高推进和发电热机中的金属、陶瓷和复合部件的性能、耐久性和预期寿命。热循环和加速腐蚀大大降低了高温材料的使用寿命，这些材料正在经历越来越苛刻的操作条件。在高温环境下保护陶瓷和金属部件已被确定为21世纪材料科学的首要任务。目前用于金属和陶瓷的保护涂层由不同成分的厚层（100微米）材料组成，这增加了用于长寿命应用的高温材料的生产复杂性和成本。通过创新的化学方法，以低成本、易于加工的材料实现这一目标，将降低过高的腐蚀成本。正在开发的涂层方法通过重新应用涂层系统提供了快速检测和维修的潜力。陶瓷、金属和复合结构材料在腐蚀性或氧化环境下在高热机械负荷下工作将受益于低成本涂层系统的开发。

This Small Business Innovation Research Phase I project proposes two approaches to develop a thin, low cost, protective coating for SiC-based ceramic composites and refractory and other high-temperature metal alloys reaching 1200 C. Protective coatings are required for metals and ceramics to prevent accelerated fatigue from oxidation and corrosion. A novel SiCN coating will be synthesized via metal doping of thermoset polysilazanes, exhibiting low volumetric shrinkage, high bond strength, and excellent hermiticity. Zr/Ti and Zr/Al doped polysilazanes will be powder coated, thereby increasing ceramic yield by limiting volatile content. Doped SiCN coatings offer lower Young's modulus and tailorable coefficients of thermal expansion (TCEs) and surface chemistries, increasing the coatings' durability during thermal cycling. The second proposed coating system involves a sol-gel or polymer derived ZrSiO4 oxygen barrier with a sol-glass top layer for moisture protection. Zircon functions as a bond coat for the protective Y-Zr-Al-Si-O. The zircon phase will either be spin/dip cast via a standard sol synthesis or derived from the condensation of Zr and Si thermoset polymers. The applications of the novel coatings in this proposal are not limited to protecting SiC-based ceramic composites, but also can be used for silicon nitride, silicon-based monolithic ceramics, and high-temperature metal alloys. The broader impact/commercial potential of this program involves innovative material solutions to improve the performance, durability, and life expectancy of metal, ceramic, and composite components within propulsion and power generation heat engines. Thermal cycling and accelerated corrosion dramatically reduce the lifetime of high-temperature materials, which are experiencing increasingly harsh operating conditions. Protecting ceramic and metal components during service in elevated temperature regimes has been identified as a 21st century materials science priority. Current protective coatings for both metals and ceramics consist of thick layers (100s of microns) of materials of varying composition, increasing the complexity and cost of production of high-temperature materials intended for long-lifetime applications. Achieving this with low-cost, easily processable materials through innovative chemistry will reduce the exorbitant costs of corrosion. The coating approaches being developed offer the potential for quick inspection and servicing through reapplication of the coating system. Ceramic, metal, and composite structural materials operating under high thermo-mechanical loads in corrosive or oxidative environments would benefit from the low-cost coating systems to be developed.