SBIR Phase I: Microwave Heating of Reaction-Bonded Silicon Carbide Ceramics

这个小型企业创新研究第一阶段项目解决了对低成本陶瓷材料的需求，特别是反应结合碳化硅(RBSC)产品。RBSC用于从窑具到防弹衣嵌件再到超高纯度半导体元件的多种应用中。降低成本将使陶瓷材料可用于更广泛的用途。目前，由于与昂贵的原材料和高温加工要求相关的高成本，这些产品的应用受到限制。该项目通过使用低成本的预制件材料和创新的热加工技术来解决这些问题。在前人的工作中，开发了一种新的制备RBSC的方法，即通过直接微波加热熔融硅液来制备RBSC。这一创新工艺允许使用微波完全渗透多孔预制件，而不需要高真空环境。然而，一个长期存在的技术问题是在RBSC中形成不受欢迎的硅脉。这可能部分是由于渗透过程中的显著放热反应造成的。静脉可能有害地影响最终RBSC的物理性能。这项工作的预期技术成果是确定硅脉形成的来源，并开发缓解这一问题的方法。该项目的更广泛的影响/商业潜力是降低RBSC陶瓷的成本，使其在当前应用中更经济可行，并增加它们在以前不可行的应用中的使用，在RBSC可以提供优异性能特性的应用中。低成本、高强度、高纯度的RSBC的成功开发将为陶瓷元件制造商和最终用户带来巨大的好处。目前RBSC的一些应用包括窑具和用于燃烧的各种燃烧器部件。扩大用途的目标领域是：耐磨部件(例如滑环密封件)、士兵防弹衣、喷砂喷嘴和半导体工业的扩散部件。半导体行业尤其令人感兴趣。随着设备继续变得越来越小，扩散元件的纯度正成为一个关键问题。将这种RBSC用于高纯度晶片载体将是有利的，因为处于绿色状态的预制件可以被加热和提纯。最后，这项工作将增进对高温放热反应的科学和技术认识，探索控制反应放热速度的方法，并量化微波处理相对于传统方法的能量效益。

This Small Business Innovation Research Phase I project addresses the need for lower cost ceramic materials, specifically for reaction-bonded silicon carbide (RBSC) products. RBSC is used in a multitude of applications ranging from kiln furniture to body armor inserts to ultra-high purity semiconductor components. Lowering costs would make ceramic materials available for more wide-spread use. Currently, these products are limited in applications due to the high costs associated with expensive raw materials and high-temperature processing requirements. This project addresses these issues though the use of low cost preform materials and an innovative thermal processing technique. In prior work, a new method for producing RBSC was developed, through liquid infiltration of molten silicon by direct microwave heating. This innovative process allows for complete infiltration of porous preforms using microwaves, without the need for a high vacuum environment. However, one of the persistent technical issues is the formation of undesirable silicon veins in the RBSC. This may be caused by in part by a significant exothermic reaction during the infiltration. The veins can detrimentally affect the physical properties of the final RBSC. The anticipated technical results of this work are to identify the origin of silicon vein formation, and to develop methods to mitigate this issue. The broader impact/commercial potential of this project is to lower the cost of RBSC ceramics, making them more economically viable in current applications, and increasing their use in previously unfeasible applications where RBSC could provide superior performance characteristics. The successful development of low-cost, higher strength, and higher purity RSBC would provide significant benefits to ceramic component manufacturers and end users. Some of the current applications for RBSC include kiln furniture and various burner parts for combustion. Areas targeted for expanded use are: wear resistant components (e.g., slip ring seals), body armor for soldiers, sand blasting nozzles, and diffusion components for the semiconductor industry. The semiconductor industry is of particular interest. As devices continue to get smaller, the purity of diffusion components is becoming a critical issue. The use of this RBSC for high-purity wafer carriers would be advantageous, as preforms in the green state can be heated and purified. Finally, this work will enhance scientific and technological understanding of high temperature exothermic reactions, explore methods to control exothermic rates of reaction, and quantify the energy benefit of microwave processing versus conventional methods.