Investigation of the influence of the manufacturing conditions and the design on the tribo-mechanical properties and residual stresses of PVD multilayer systems

PVD涂层多层体系中存在的残余应力对其最终的摩擦机械行为有很大的影响。在用DCMS沉积不同的Ti/TiAlN多层膜系的实验中，已经证明了高的残余压应力的集中促进了涂层的裂纹和层裂的产生。此外，随着DCMS沉积金属中间层厚度的增加，残余压应力增大，从而影响多层/衬底复合材料的摩擦学和力学性能。在此基础上，利用HIPIMS技术对Ti/TiAlN多层膜的组织结构进行了选择性的改变。将这些涂层与上述涂层进行了比较，揭示了不同的微观结构和生长机制对PVD多层涂层残余应力的影响。为此，用X射线衍射仪对Ti/TiAlN HiPIMS涂层的设计进行了评价，并通过横截面X射线纳米束衍射分析得到了涂层的残余应力深度分布。此外，由于DCMS沉积的Ti/TiAlN涂层的残余应力较高，摩擦机械响应性能较差，因此提出了一种新的材料组合TiAlN/TiAlCN。由于碳的加入，两种材料结合在一起，表现出极好的耐腐蚀性和高热稳定性，并改善了摩擦机械性能。此外，就热残余应力而言，这两种新材料之间的相似性对它们的热膨胀系数也有很大影响，它们也是相似的。最后，对多层膜系统的涂层结构和材料组合进行了摩擦力学实验，如纳米压痕实验、球盘实验、划痕实验和冲击实验，并与以前的实验结果进行了比较。

The residual stresses present in the PVD coatings multilayer systems have high influence in their final tribo-mechanical behaviour. In previous experiments where different multilayer systems of Ti/TiAlN where deposited by means of DCMS, has been proved that the concentration of high compressive residual stresses promote the generation of cracks and spallation of the coatings. Additionally, was evidenced that compressive residual stresses increased with increasing thickness of the metallic interlayers deposited by means of DCMS, and thus, affecting tribological and mechanical properties of the compounds multilayer/substrate. It is assumed that this behavior is due to the microstructural differences of the Ti-interlayers.On this basis, the microstructure of Ti/TiAlN multilayer coatings should be varied selectively by means of HiPIMS technology. The comparison of these coating with the above mentioned, allow demonstrating the influence of different microstructures and growing mechanisms on the residual stresses of PVD multilayer coatings. For this purpose, Ti/TiAlN HiPIMS coating designs are evalu-ated by XRD and their residual stresses depth profiles generated through cross- sectional X-ray nanobeam diffraction analysis. Moreover, due to the high residual stresses and poor tribo-mechanical response of the Ti/TiAlN coatings deposited by means of DCMS, a new combination of materials are proposed for these section of the project, TiAlN/TiAlCN. The combination of two materials which exhibit great corrosion resistant and high thermal stability together with improved tribo-mechanical behavior, because of the incorporation of carbon. Besides, and in terms of thermal residual stresses, the similarity between the new two materials, both are ceramics, has a great effect in their thermal expansion coefficients, which are also similar. Thus, thermal induced residual stresses in the system are re-duced notably.Finally and to draw conclusions about the coating architecture and combinations of materials in multilayer systems, tribo-mechanical experiments as nanoindentation, ball-on-disk experiments, scratch tests and impact tests are conducted and compared between them and the results from previous experiments.