Development of martensitic support layers for hard coatings for optimized properties of surface layers by local electron beam (EB) hardening

PVD层的优良特性，如高硬度和耐磨性，只能在具有足够承载能力的衬底上开发，例如在工具钢上。在由软钢(51CrV 4)制成的摩擦应力部件上使用PVD层，需要进行额外的表面硬化。由于其独特的工艺特性，如高功率密度、灵活和高度动态的能量调制以及真空处理，电子束硬化(EBH)非常适合确保钢的局部应力优化承载能力的提高。本课题的研究主题是PVD涂层与后续EBH的创新结合。该项目的研究方法有两个方面：一方面，通过电子束溅射显著提高磁控溅射Ti1-xAlxN层下衬底表面层的支撑作用；另一方面，深入研究热输入对PVD层结构成分和性能的影响。在项目的第一阶段，关于Ti1-xAlxN的化学成分和层厚度对其在EBH过程中的行为的影响取得了重要的发现。在项目第二阶段，科学原理将在有前景的涂层/EB处理变化领域进一步深化，并应得到扩展，以发展对此类表面-层组合的微观结构和磨损行为的新的重要见解。在一期工程中，开裂、剥落、分层等层状缺陷的发生得到了遏制，但还没有完全消除。伴随着内部应力的数学模拟，应推导出这种损伤的原因，并生成定制的多层和分级层系统，以最大限度地减少相对于后续EBH的损伤潜力。此外，还应生产具有与应用相关的厚度的无裂缝表层组合。此外，对Ti1-xAlxN层的电子束处理所带来的不被充分理解的现象，特别是PVD和EBH层界面上的局部限制扩散和微熔化，还有待于研究。在这方面，必须澄清有针对性地利用这些效应在多大程度上与改善层间附着力有关。第二个项目期的重点将进一步研究EBH过程中非均匀吸收层吸收能量的机制，以及Ti1-xAlxN中热诱导相变的检查。这些转变使内应力的Eb作用局部修正成为可能，从而使涂层硬度的局部修正成为可能。EBH处理也应使用闪光技术，而不是迄今使用的EB硬度场(CI技术)。因此，对于定义的样品，可以实现定向的一维散热。

The excellent characteristics of PVD layers, as high hardness and wear resistance, can only be exploited on substrates with sufficient load-bearing capacity, e.g., on tool steels. The use of PVD layers on tribologically stressed components made of softer steels (51CrV 4) makes additional surface hardening necessary. Due to its unique process-specific characteristics - as high power density, flexible and highly dynamic energy modulation, and treatment under vacuum - Electron Beam Hardening (EBH) is eminently suitable to ensure local, stress-optimized improvement of the load-bearing capacity of the steel. The subject of the research project is the innovative combination of PVD coating with subsequent EBH. The research approach of the project is twofold: On the one hand, to increase considerably by means of EBH the supportive function of the substrate surface layer under Ti1-xAlxN layers deposited by magnetron sputtering and, on the other hand, to research in depth the effects of that thermal input on the structural composition and properties of the PVD layer. During phase 1 of the project, significant findings were made regarding the influence of the chemical composition and layer thickness of the Ti1-xAlxN on its behavior during EBH. In the projects 2nd phase, the scientific principles shall be deepened further in the area of promising layer/EB-treatment variations, and shall be expanded to develop new and important insights into the microstructure and wear behavior of such surface-layer combinations. In the 1st project period, the occurrence of layer defects such as cracking, flaking, and delamination could be contained, but not completely eliminated. Accompanied by a mathematical simulation of the internal stresses, the causes of such damage shall be derived, and tailor-made multilayer and graded layer systems generated to minimize damage potential with respect to the subsequent EBH. Moreover, crack-free surface layer combinations with application-relevant thicknesses shall be produced. Furthermore, insufficiently understood phenomena brought about by the EB treatment of the Ti1-xAlxN layers shall be researched, especially locally restricted diffusion and micro-melting at the interface between the PVD and EBH layers. In this context, the extent to which targeted utilization of these effects is relevant for the improvement of layer adhesion must be clarified. Key concerns of the 2nd project period further shall be the research of the mechanism of energy absorption by inhomogeneous absorption layers during EBH, as well as the examination of thermally induced phase transformations in Ti1-xAlxN. These transformations make possible the local modification by EB action of internal stresses and, therefore, of the layer hardness. The EBH treatment shall also be realized using the Flash technique, as opposed to the EB hardness field (CI Technique) used to date. Targeted one-dimensional heat dissipation can thus be realized for defined samples.