Glosse Philipp, Denneler Stefan, Stier Oliver, Moos Ralf
Department of Functional Materials, University of Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany.
Siemens AG, Otto Hahn Ring 6, 81739 München, Germany.
Materials (Basel). 2021 May 12;14(10):2502. doi: 10.3390/ma14102502.
The powder aerosol deposition method (PAD) is a vacuum-based spray coating technology. It allows for production of highly dense coatings at room temperature, especially of brittle-breaking materials. This yields new options for coating substrate materials that even melt at low temperatures. The film formation mechanism is called room temperature impact consolidation (RTIC). The occurrence of this mechanism is strongly linked to the gas jet used in the process. The velocity and direction of the particles in the gas jet forming between the nozzle orifice and the substrate are the main factors influencing the quality of the coating. This dependency aimed to be elaborated with a measurement setup and coating experiments and is shown in this work. We investigated the gas jet formation using a shadow optical imaging system. Regions of different gas density are visualized by this technique. Several parameter sets, in particular gas flow rates and chamber pressures, were investigated. In addition, coatings were produced on glass substrates with the same parameters. As a coating material, the superconducting ceramic-like magnesium diboride (MgB) was chosen. A correlation between shadow images and thickness profiles of the coatings shows how the gas jet formation affects the uniformity of thickness. Shadow optical images provide valuable information on the flight direction of the particles and allow validation of simulation results.
粉末气溶胶沉积法（PAD）是一种基于真空的喷涂技术。它能够在室温下制备高密度涂层，特别是对于易碎材料。这为甚至在低温下会熔化的基底材料涂层提供了新的选择。成膜机制被称为室温冲击固结（RTIC）。这种机制的出现与该过程中使用的气体射流密切相关。在喷嘴孔口和基底之间形成的气体射流中颗粒的速度和方向是影响涂层质量的主要因素。这种相关性旨在通过测量装置和涂层实验进行阐述，并在本工作中展示。我们使用阴影光学成像系统研究气体射流的形成。通过该技术可以可视化不同气体密度的区域。研究了几个参数集，特别是气体流速和腔室压力。此外，使用相同参数在玻璃基底上制备涂层。作为涂层材料，选择了类似超导陶瓷的二硼化镁（MgB₂）。阴影图像与涂层厚度轮廓之间的相关性表明气体射流的形成如何影响厚度的均匀性。阴影光学图像提供了关于颗粒飞行方向的有价值信息，并允许对模拟结果进行验证。
