Optimization of dielectric interfaces using nano structured surfaces

在这项研究应用中，具有电位分离的接头、套管和终端(例如，中压到超高压技术中的电缆套管和终端)的电气强度将得到改进。发生在基于不同材料特性的界面处的电绝缘布置的电性能的变化是已知的。除了对这一行为的预期影响外，表面粗糙度和装配误差还会导致空洞的形成，超过一定的尺寸，会导致局部放电，导致绝缘材料和界面的损坏。因此，这些空洞的设计应尽可能小于10微米的临界尺寸。目前的技术水平是使用透气材料或其他辅助材料(如浆料)来封闭这些潜在的空洞。相应地选择了表面硬度和合适的接触压力。此外，初步研究表明，特定的表面结构，例如通过三角形结构(100微米)，增加了界面长度。目的：在本项目提案中，使用等离子体改性有针对性地使用褶皱结构(褶皱)是为了在纵向界面材料的表面产生所需的结构尺寸(导致10微米以下的空洞)。这将导致电界面强度的增加和附加材料的使用的减少以及组件尺寸的减小。为此，拉伸弹性衬底，同时施加或产生薄的固体薄膜。随后的松弛导致了薄的固体薄膜和弹性衬底之间的应力妥协。这会导致薄膜在表面的局部变形，导致周期性的正弦褶皱结构。在单轴变形的情况下，皱纹垂直于伸长方向形成。特征参数是皱纹的波长和结构高度，可以通过不同的等离子体工艺参数进行精确的调节。其他结构化方法，如光刻或激光结构化，也允许结构在所需的尺寸范围内，但速度太慢或太昂贵，或者无法缩放到大区域或3D几何形状。通过压花或印刷进行结构化不允许所需的大小范围。另一方面，起皱结构可以通过制造参数进行灵活控制，并且可以大面积、资源高效地实施。此外，目前的项目提案旨在构建有机硅，这就是为什么原位等离子体改性结合衬底的可控变形来形成皱纹是最有前途的。

In this research application, joints, bushing, and terminations with electrical potential separation (e.g. cable sleeves and terminations in medium to extra-high voltage technology) are to be improved concerning their electrical strength. Changes in the electrical behaviour of electrical insulation arrangements, which occur at interfaces based on different material properties, are known. In addition to the intended influence on this behaviour, surface roughness and assembly inaccuracies can cause cavities to form which, above a certain size, allows partial discharges, leading to damage in the insulating material and the interface. For this reason, these cavities should be designed to be as small as possible below the critical size of 10 µm. State of the art is gas permeable materials or other auxiliary materials such as pastes to close these potential cavities. The surface hardness as well as a suitable contact pressure are selected accordingly. Furthermore, preliminary investigations show that a specific surface structuring, e.g., by a triangular structure (100 µm), increases the interface length. The extension of this resulted in an expected increase in electrical strength.Objective: In the present project proposal, the targeted use of wrinkle structuring (wrinkling) using plasma modification is intended to generate required structural sizes (resulting in cavities below 10 µm) on the surface of longitudinal interface materials. This will be lead to an increase in the electrical interface strength and a reduce in the use of additional materials as well as a decrease in the component size.For this purpose, an elastic substrate is stretched and at the same time, a thin, solid film is applied or generated. The subsequent relaxation leads to a stress compromise between the thin, solid film and the elastic substrate. This causes local deformations of the film at the surface, resulting in a periodically sinusoidal wrinkle structure. In the case of uniaxial deformation, the wrinkles form perpendicular to the direction of elongation. The characteristic parameters are the wavelength and the structure height of the wrinkles, which can be precisely adjusted by the different plasma process parameters. Other structuring methods like lithography or laser structuring, which also allow structures in the desired size range, are too slow or too expensive or cannot be scaled to large areas or 3D geometries. Structuring by embossing or printing does not allow the desired size range. Wrinkle structuring, on the other hand, can be flexibly controlled via the manufacturing parameters and can be implemented in a large area and resource-efficiently. Also, the present project proposal aims to structure silicones, which is why in-situ plasma modification combined with controlled deformation of substrates for wrinkle formation is most promising.