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

纳米结构涂层和散装材料在开发新的结构表面和散装部件方面变得越来越重要。例如，与传统涂层相比，使用纳米晶金属不锈钢粉末的喷涂涂层表现出优异的硬度，而纳米结构铝基合金的拉伸强度约为商业同类产品的两倍。实验室已开发出多种方法来获得纳米结构涂层，例如激光沉积、热喷涂和等离子喷涂。然而，迄今为止，还没有用于工业应用的纳米级粉末涂料技术商业化。正在进行的研究重点是一种新型创新静电力辅助冷气动态喷涂（ECGDS）技术，用于在低温下以低成本和高产量生产纳米结构涂层。这项工作的智力价值涉及将微米级颗粒的传统 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，为纳米粒子提供足够的动量，使其穿透弓激波，然后以足够的动能沉积在目标表面上。研究工作的目标是调查 ECGDS 的可行性，了解纳米颗粒在超音速流中的传输过程，并通过深入的数值模拟和实验研究将纳米颗粒尺寸、载气、气压和气体温度等喷涂参数与所得涂层的密度和结构相关联。该提案的创新包括使用静电力协助纳米颗粒加速穿透​​弓形冲击、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。该 SGER-GOALI 项目预计将对 UWM 以及大密尔沃基地区的研究和教育产生重大而广泛的影响。 ECGDS系统是开发新型低温涂层技术的重要工具，它将直接影响燃料电池等许多工业应用。纳米颗粒生产、分散和充电的结果将对基于纳米颗粒的纳米制造和纳米加工的一般领域做出重大贡献。该GOALI项目将与International Thermal Systems（ITS，GOALI合作伙伴）共同开发，如果成功，该技术将直接转移到行业。该项目通过本科生、研究生和 K-12 教师，特别是代表性不足的少数族裔的参与，促进 UWM 进一步的教育工作。这项工作也影响了 UWM 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.