GOALI: Continuous Spatial Particle Atomic Layer Deposition Processing

原子层沉积（ALD）是制造保形连续薄膜涂层的最精确方法。ALD处理在光学、微电子和生物医学应用的许多制造过程中是重要的，尽管它可能缓慢且昂贵。ALD使用连续的气固反应，其中通过将前驱体单独送入反应室并与粘合在表面的官能团反应来防止气相反应。拟议中的GOALI项目是科罗拉多大学博尔德分校的一个学术团队与工业合作伙伴ALD NanoSolutions的合作项目。本研究的目的是提高对粒子空间原子层沉积（即空间粒子ALD）的基本认识，从而实现高效、低成本的连续粒子ALD。拟议的项目将包括计算流体动力学（CFD）模型开发和综合实验，旨在开发可扩展的ALD工艺，在该工艺中，初级颗粒被均匀包裹，昂贵的前驱气体被有效利用。连续尺度模型将考虑团聚体的形成和破裂，以及化学反应，流体动力学，热/质量传递，以及在细颗粒搅拌过程中使用振动的所有相关多相相互作用。待测试的假设包括：(1)连续尺度模型将充分描述所提出的搅拌颗粒系统；(2)可以在连续振动的粒子ALD反应器中涂覆单个纳米颗粒而不损失活性表面积；(3)在连续振动的颗粒ALD反应器中进行颗粒ALD处理可以优化到几乎完全利用前驱体气体；(4)修改后的内部实验室系统将提供CFD模型实验验证所需的数据；(5)在相同的ALD循环次数下，连续空间颗粒ALD涂层的基底颗粒将优于使用间歇流化床工艺合成的颗粒。在ALD NanoSolutions进行的实验将侧重于验证模型预测和学术团队的发现，并扩大这一过程。该项目的最终目标是大大提高对颗粒ALD如何使包括纳米颗粒在内的初级细颗粒在搅拌颗粒床反应器中被涂覆的基本理解，并使工艺规模扩大到商业生产。研究生将与工业伙伴密切合作进行培训，本科生将从事研究。该项目也将作为一个顶点设计项目，供本科生团队进行工艺设计和技术经济分析。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Atomic layer deposition (ALD) is the most precise method for manufacturing conformal, continuous thin film coatings. ALD processing is important in many manufacturing processes for optics, microelectronics, and biomedical applications, though it can be slow and costly. ALD uses sequential gas-solid reactions where gas-phase reactions are prevented by having precursors fed separately into the reaction chamber and react with functional groups bonded to the surface. The proposed GOALI project is a collaboration between an academic team from the University of Colorado at Boulder and an industrial partner, ALD NanoSolutions. The objective of the proposed research is to develop an improved fundamental understanding of spatial atomic layer deposition on particles (i.e. spatial Particle ALD), so that high-efficiency and low-cost continuous Particle ALD can be achieved.The proposed project will involve Computational Fluid Dynamics (CFD) model development and integrated experiments aimed at developing a scalable ALD process in which primary particles are coated uniformly and expensive precursor gases are effectively utilized. A continuum-scale model will account for agglomerate formation and breakup as well as chemical reactions, fluid dynamics, heat/mass transport, and all relevant multiphase interactions during fine particle agitation using vibration. The hypotheses to be tested include: (1) that a continuum-scale model will adequately describe the proposed agitated particle system; (2) that it is possible to coat individual nanoparticles in a continuous vibrating Particle ALD reactor without loss of active surface area; (3) that Particle ALD processing in a continuous vibrating Particle ALD reactor can be optimized to utilize the precursor gases nearly completely; (4) that the modified in-house lab system will provide data needed for experimental validation of the CFD model; and (5) that substrate particles coated by continuous spatial particle ALD will compare favorably with particles synthesized using a batch fluidized bed process - for the identical number of ALD cycles. Experiments carried out at ALD NanoSolutions will focus on validating the model predictions and findings of the academic team and scaling up the process. The ultimate objective of the project is to substantially improve the fundaental understanding of how Particle ALD enables primary fine particles, including nanoparticles, to be coated in an agitated particle bed reactor and enable process scale up for commercial production. A graduate student will be trained in close collaboration with the industrial partner and undergraduate students will be engaged in research. The project will also be used as a capstone design project for undergraduate student teams to perform process design and techno-economic analysis.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.