New Opportunities for the Aerosol Deposition Method by Substrate by Cryogenics

采用气溶胶沉积法(ADM)在几乎任何衬底材料上都可以直接从陶瓷粉末涂覆1至300微米的致密陶瓷涂层，无需高温处理，这种方法在德语中称为“Aerosolbasierte Kaltabscheidung(室温冲击固结)”。即使是含有低熔点金属、玻璃或非常硬的聚合物的陶瓷涂层也可以涂覆。因此，沉积层的材料性能与源材料相似。在ADM领域，人们反复观察到，衬底和涂层材料之间的硬度差异以及衬底的机械性能是影响ADM沉积成功的关键因素。自己的观察表明，与较硬的陶瓷相比，较软的材料更容易沉积在陶瓷上，并且厚度要大得多。在这个项目中，我们希望通过改变温度来改变基片和涂层材料的力学性能，特别是通过在77K以下的大温度范围内冷却基片或粉末来研究机械性能对形成高质量薄膜的能力的影响。到目前为止，只有解释衬底温度升高的(负面)影响的工作是已知的。该项目计划为期两个月(所需资金仅为18个人月)。它首先对椅子的ADM涂布机之一进行改造，使粉末和基材冷却成为可能。为了确定温度对涂层行为的影响，然后以测试矩阵的形式对五种基材和四种粉末在不同温度下进行了实际涂层测试，其方式是根据基材和粉末材料的温度变化来调整沉积窗口。在项目结束时，应提供概念性证据，表明低温ADM改善了层形成(更高的沉积速率或更高的层质量)或允许延长工艺窗口(沉积否则不能通过ADM沉积的材料)。

Dense ceramic coatings in the range from 1 to 300 µm can be applied directly from ceramic powders without high temperature processes on almost any substrate materials using the aerosol deposition method (ADM), which is known in German as "aerosolbasierte Kaltabscheidung (room temperature impact consolidation)". Even ceramic coatings with low melting metals, glasses or very hard polymers can coated. The material properties of the deposited layer are thereby similar to the source material.In the ADM community it is repeatedly observed that the hardness difference between substrate and coating material as well as the mechanical properties of the substrate are key influencing factors for the ADM deposition success. Own observations suggest that softer materials can be deposited more easily and with much larger thicknesses on ceramics as harder ceramics. It seems that a certain minimum substrate hardness and substrate toughness must exist to deposit the powder as a dense adhesive film.In this project, we want to vary the mechanical properties of the substrate and the coating material by temperature variation, especially by cooling of the substrate or the powder over a large temperature range down to 77 K to investigate the effect of the mechanical properties on the ability to form high quality films. So far, only works are known, which explain the (negative) impact of an increase in substrate temperature.The project is planned for a period of two months (with required funding for only 18 person month). It starts with the modification of one of the chair's ADM coating machines so that powder and substrate cooling is possible. In order to determine the effect of temperature on the coating behavior, the actual coating tests are then carried out in the form of a test matrix at different temperatures for five substrate materials and four powders in a way that by temperature variations of substrate and powder material the deposition window is adjusted. For that purpose, materials that exhibit a large change in the mechanical properties in the low-temperature range are used.At the end of the project, a conceptual proof should have been provided showing that the cryogenics ADM improves the layer formation (higher deposition rates or higher layer quality) or allows an extension of the process window (deposition of materials that can otherwise not be deposited by ADM).