Papers by Keyword: Wear Protection

Abstract: The automotive sector is one of the largest energy consumers in Germany. Requests from politics and industry to significantly reduce emissions require new developments during utilization as well as during production phase. In line with the framework concept "InnoCaT", where more than 60 companies and research facilities from Germany take part, possibilities for producing companies are developed and analyzed to reduce the resource and energy consumption and by this reducing costs along the entire process chain of car body manufacturing. One approach to design car bodies lighter and more efficiently is to use aluminium and high strength steels. By this means weight and sheet thickness are reduced. However higher strengths of the steels and the adhesion affinity of aluminium significantly increase the requirements regarding the used tool steel. Thus grooves or galling appear more frequent at highly stressed surfaces. To assure high lifetimes and by this increase especially the resource efficiency concerning use of material and setting-up times within the press plant, a local optimization at the highly stressed surfaces is necessary. For this a FEM/BEM-tool for a time efficient and exact calculation of the occurring tool loads for complex die profiles is developed. Based on this development of load calculation a shape-optimization is performed at the corresponding areas. After the geometric optimization of the tool a local laser surface treatment for further wear protection is carried out using laser cladding or laser alloying/ -dispersing. By combining the technologies a highly wear resistant surface is achievable, which increases the tool's lifetime as well as the reproducibility within production.

Abstract: The manufacturing and application of self-supporting nanocrystalline diamond foils is introduced. The high temperature manufacturing of nanocrystalline diamond foils by hot-filament chemical vapour deposition (HFCVD) is separated from the low temperature application, allowing the coating of temperature sensitive materials, which cannot be coated by HFCVD conventionally. By coating appropriate template materials and stripping-off after the CVD-process, self-supporting, flexible nanocrystalline diamond foils with high hardness (> 70 GPa) and very low thermal conductivity (< 1 W/mK) with thicknesses of up to 100 µm can be produced. Lasercutting is an appropriate method for machining any desired geometry. Thus the possibility to use the extreme properties of diamond for protection against friction and wear on new substrate materials, e.g. steels, light metals and polymers, is generated.

Abstract: Oxide coatings offer great potential for their use in forming operations in the semi-solid state. Advantages of these types of coatings are high resistance against abrasive wear, high hot hardness and low thermal conductivity. Nevertheless deposition by pulsed Magnetron Sputter Ion Plating-PVD for oxide coatings is quite challenging: deposition rates are low and insulating layers on the target surface can cause arcing. On laboratory scale it was possible to deposit γ-Alumina using PVD in a temperature range, where hot working steel can be utilized. The next important step in the development towards an industrial application for larger forming tools is the upscaling process to larger coating units. In this work the process development of oxide coatings on an industrial coating unit for large tools was described. To increase adhesion of oxide top-layer additional bond coats were applied. Different process parameters like oxygen content, total pressure and substrate bias were varied, to improve the performance. The relationship between coating properties and process parameters of the deposited films were characterized by X-Ray-diffraction, Nanoindentation and Scanning Electron Microscopy (SEM). By using reactive pulsed PVD-process it was possible to deposit γ-Al2O3 on large steel tools for semi-solid melt protection. The developed coatings showed for thixoforging processes of X210CrW12 an extraordinary stability in field tests. The lifetime of the permanent moulds was increased by using PVD thin film coatings as a tool protection.

Abstract: Thermal spraying is one of the most variable and diverse surface coating techniques concerning materials to be processed as well as possible geometries to be coated. The group of thermal spray processes covers a large parameter field to combine nearly each coating with each base material. Thermally sprayed coatings can be applied very evenly and therefore allow to be applied on final-shaped components. Otherwise, if further treatment or finishing is necessary, thermal spray coatings can be processed by grinding or even milling. Masking during the coating process permits the selective coating of specific surface parts or the application of required geometrically structures, e. q. conductor structures. The main application field of thermal spray coatings is the (combined) wear and corrosion protection of selected component parts.