SGER/GOALI: Electrostatic-Force-Assisted Cold Gas Dynamic Spray of Nanoparticles-A New Low Temperature Process for Producing Nanostructured Coatings and Bulk Materials

纳米结构涂层和块体材料在开发新的结构表面和块体部件方面变得越来越重要。例如，使用纳米金属不锈钢粉末喷涂的涂层显示出比传统涂层更高的硬度，而纳米结构铝基块体合金的抗拉强度大约是商业涂层的两倍。实验室中已经开发了各种方法，如激光沉积、热喷涂和等离子喷涂，以获得纳米结构涂层。然而，到目前为止，还没有用于工业应用的纳米粉末涂料技术商业化。这项研究的重点是一种新型的、创新的静电辅助冷气动力喷涂(ECGDS)技术，用于低成本、高产量地低温制备纳米结构涂层。这项工作的智慧价值包括将传统的微米级颗粒CGDS系统扩展到纳米级颗粒尺寸谱。它将静电场与超音速气粒两相动态流场相结合，为纳米粒子穿透弓形激波提供足够的动量，并以足够的动能沉积在靶面上。研究的目的是通过大量的数值模拟和实验研究，研究ECGDS的可行性，了解纳米颗粒在超音速流动中的传输过程，并将纳米颗粒尺寸、载气、气体压力和气体温度等喷雾参数与所得涂层的密度和结构进行关联。该提案的创新包括使用静电力帮助纳米颗粒加速穿过弓形冲击波，防止纳米颗粒团聚的技术，以及将纳米颗粒充电到高水平的新充电器。这一SGER-GOALI项目预计将对密尔沃基大学和大密尔沃基地区的研究和教育产生重大而广泛的影响。ECGDS系统是开发新的低温涂层技术的重要工具，它将直接影响许多工业应用，如燃料电池。纳米粒子的生产、分散和充电方面的研究成果将对纳米粒子制造和纳米制造的总体领域做出重大贡献。该Goali项目将与国际热力系统公司(ITS，Goali合作伙伴)共同开发，如果成功，这项技术将直接转移到工业中。该项目通过本科生、毕业生和K-12教师的参与，特别是代表人数不足的少数族裔的参与，促进了UWM的进一步教育努力。这项工作也影响到了威斯康星大学的课程。

Nanostructured coatings and bulk materials have become increasingly important in developing new structural surfaces and bulk components. For instance, sprayed coatings using nanocrystalline metallic stainless steel powders exhibit superior hardness compared to conventional coatings, and nanostructured Al-based bulk alloy exhibits tensile strength about twice that of the commercial counterparts. Various methods, such as laser deposition, thermal spray, and plasma spray, have been developed in the laboratory to obtain nanostructured coatings. However, to date no nanoscale powder coating technologies for industrial applications are commercially available yet. The research being conducted is focused on a new and innovative electrostatic-force-assisted cold gas dynamic spray (ECGDS) technique for producing nanostructured coatings at low temperature with low cost and high throughput. The intellectual merit of the work involves the extension of the conventional CGDS system for micro-sized particles to the nanoscale particle size spectrum. It combines the electrostatic field with the supersonic gas-particle two-phase dynamic flow field to provide sufficient momentum for nanoparticles to penetrate through the bow shock and then deposit on the target surface with sufficient kinetic energy. The objectives of the research effort are to investigate the feasibility of the ECGDS, to understand the transport process of nanoparticles in the supersonic flow, and to correlate the spray parameters, including nanoparticle size, carrier gas, gas pressure, and gas temperature, with the density and the structure of the resulted coating through intensive numerical simulations and experimental studies. Innovations of the proposal include use of electrostatic force to assist nanoparticle acceleration to penetrate the bow shocks, techniques to prevent agglomeration of nanoparticles, and a new charger to charge nanoparticles to high levels. This SGER-GOALI project is expected to have a significant and broad impact on research and education at UWM as well as in the Great Milwaukee Area. The ECGDS system is an essential tool for the development of new low temperature coating technology, which will directly impact many industrial applications, such as fuel cells. Results on the nanoparticle production, dispersion, and charging will significantly contribute to the general area of nanoparticle-based nanomanufacturing and nanofabrication. This GOALI project will be co-developed with International Thermal Systems (ITS, GOALI partner), and this technology, if successful, will be transferred directly to industry. The project promotes further educational efforts at UWM through the participation of undergraduates, graduates and K-12 teachers, particularly underrepresented minorities. The work is also impacting the curriculum at UWM.