In turbojet aircraft engines, reducing fuel consumption and specific emissions of CO2 and NOx need to control the clearance between rotor and stator and consequently to master the blade-casing interactions. These interactions are strongly conditioned by the choice of the coating inside the casing. With regard to braking systems, regulations intend to reduce environmental impacts (noise, particulate emissions) and to increase performance of energy dissipation (high speeds). These specifications need to master the phenomena of friction and the choice of materials in contact. The solutions implemented by manufacturers are based on the use of feedback based approaches and "trial and error" that led to the development of "recipes of heterogeneous materials” performance, with regard to brake lining and turbojet casing coating. However, in the absence of a real understanding of phenomena, such "black box" approaches are facing the new technical and environmental requirements. Besides it generates high development costs due to the number of trials needed. The project objective is to develop a methodology to design multi-scale friction materials. This methodology fills in the missing link within the process of understanding and modelling systems (brakes and rotor-stator assemblies for jet engines) in order to increase their energy efficiency and to reduce environmental pollution (noise, pollution...) while maintaining reliability as part safe. Due to high complexity, the approach relies on the one hand on the identification of physical dominating phenomena and, on the other hand, on an experimental-numerical dialogue. Manufacturers (Snecma, FBF-Bosch and FTG-Faiveley) and some academic teams already have an extensive experience with the targeted applications and knowledge of the physical phenomena involved (LaMCoS and LML-ER5). They propose to add skills of other research teams on multi-scale approaches (IJLRDA and LML-ER4) and in the physical chemistry of surfaces (KUL). The approach is based on the following key points: - Definition of "model materials" representative of industrial material formulations reduced and controlled, which will be characterized in terms of heterogeneities and properties. - Approved friction tests with quantitative characterization of material properties and interface (third body) and their gradients. Innovative ways to rheological characterization will be implemented (rheometers and meso-tribometers). - Multi-scale multi-physics numerical innovative approach considering the heterogeneity of materials and interface. This will be done through multi-scale numerical and semi-analytical homogenization. The main benefits are to achieve: A methodology to "design" friction materials for brake applications and casing coatings for turbojet engine. A multi-scale modelling of material - contact interface, integrated into the industrial methodology for analysing performance of brake systems and aeronautic engines. From a scientific perspective, the major benefit is a "homogenization tribological interpretation" that will be a first in tribology.