Herstellung und komplexe Charakterisierung von Metall‐Keramik‐Verbundschichten

Formation and characterization of metal‐ceramic coatings The influence of the formation process and used materials of metal‐ceramic coatings on the structural properties of the deposited layers were investigated and optimized to increase the mechanical properties. There the deposition of the metal‐ceramic‐layers occurred by a combination of electrophoretic and galvanic deposition with siloxane as bonding compound. Layers with a high ceramic content were successfully created. As ceramic components commercial silicon carbide and silicon nitride were used. Nickel and Copper respectively were applied as metal component to fill the porous ceramic structure with the aim to increase the strength of the layers, where nevertheless a pre nickel‐plating or pre cupper plating of the steel substrate X6Cr17 before ceramic component deposition had to be done to increase the adhesion of the layers. The layer characterization was made by optical microscopy and scanning and transmission electron microscopy, where especially the bonding of the single particles by the siloxane was in evidence.     

Herstellung und Untersuchung des Verschleißverhaltens von induktiv eingeschmolzenen Hardpaint‐Schutzschichten

Friction and wear processes generate significant economic damage annually in industrial production due to maintenance and repair costs as well as loss associated with production downtime. Wear‐resistant coatings are a measure for reducing wear. In this context, the novel hardpaint technology for coating of parts with a fusible metal powder composition is described. Components with complex geometries as well holes or undercuts can be coated easily and inexpensively. Two protective layers are discussed and characterized in terms of their microstructure. Density measurements, hardness tests and scanning electron microscopic investigations were carried out. Both powder layers were inductively melted after application and are based on a hard alloy (iron‐based) commonly used for plasma transferred arc powder surfacing. Abrasion wear resistance is evaluated based on the results of the wear tests and microstructural investigations. Furthermore the results are discussed in comparison to a martensitic fine‐grain steel (Hardox 450), which is commonly used in abrasively stressed areas. Compared to Hardox 450 both hardpaint coatings have a much more wear‐resistant behavior due to their hard phases. In addition, it was confirmed that the hardpaint technology is able to embed thermally sensitive fused tungsten carbides which are significantly increasing the wear resistance against abrasion.     

Herstellung und Eigenschaften von glasfaserverstärkten Kunststoff-Stahl-Schichtwerkstoffen

Preparation and Properties of Layered Composites of GFK-Steel The development of insulating joints of GFK and steel is described. The strength of the GFK and steel is described. The strength of the GFK and the adhesion between the GFK and steel is in this context of special interest. Results for the Young's Modulus, the ultimate and adhesion strength measured in bursting and bending tests are compared to those measured in tensile- and adhesion tests; the data agree well with each other. The correspondence between literature data of mechanical properties of the GFK and the measured values is satisfying.     

Herstellung und Eigenschaften von metallischen Verbundfolien

Properties of metallic composite foils by directionally solidification and rolling . It is known from a serie of investigations that compositeswires consisting of well deformable metals drawn to high degrees of deformation show characteristic anomalies of mechanical and physical properties. Therefore it is interesting to investigate the possibility to prepare by rolling foils with the similar heterogenous structure. First results measured on the thin foils of an eutectic silver-copper alloy are presented. Compound foils of 35 microns thickness showed anomaleous behaviour of Youngs modulus, tensile strength and specific electrical conductivity. This anomaleous behaviour of different properties is caused by size effects. An advantage of such compoundfoils compared with “thin layers” is the easy preparation and handling of the specimens.     

Potentialunterstützte Herstellung von Metall‐Keramik‐Verbundschichten

Potential assisted fabrication of metal‐ceramic composite coatings A possibility to produce uniform metal‐ceramic composite coatings with a high content of ceramic particles up to 60 vol.% will be presented in this study. This method includes a combination of electrophoretic deposition and electrolytic deposition by several steps. A yttria‐stabilized zirconia coating (Tosoh TZ‐8Y) was first electrophoretically deposited on a ferritic steel plate and then sintered by 1100 °C to an open porous layer. In the next step nickel was electrodeposited into the pores of the layer. By a final annealing step it was possible to improve the bonding of the composit coating on the substrate by diffusion of the metal components.     

Grundlagen,Herstellung und Anwendungsaspekte des Supersolidus Flüssigphasensinterns von hochlegierten Werkzeugstählen und Metallmatrix‐Verbundwerkstoffen

Principles, manufacturing and application aspects of super solidus liquid phase sintering of high‐alloyed tool steels and metal matrix composites Iron‐based metal matrix composites (MMC) are applied for abrasive wear resistant applications. A common production route uses hot isostatic pressing (HIP) of metal and carbide powders, a comparatively cost intensive process. Using high‐alloyed tool steels as matrix materials it is possible to obtain dense materials by liquid phase sintering with an internally formed liquid phase. This contribution describes the basic principles of densification of the matrix materials taking thermodynamic calculations into consideration. It points out a production route for processing particulate reinforced, high wear resistant composite materials by sintering. Beside the sintering behaviour concepts for heat treatment as well as the abrasive wear resistance are discussed.     

IR‐empfindliche Schichten zur Herstellung von Offset‐Druckplatten

IR sensitive layers for manufacturing of offset printing plates For the formulation of IR sensitive compositions for offset printing plates, two different modes are known to use the energy stored after the absorption of an IR photon in the excited state of an absorbing molecule. A physical mode is based on generated heat after internal crossing of the excited state. In contrast, a chemical mode proceeds via formation of reactive intermediates as consequence of the IR absorption. Such species can be generated either by thermal decomposition of a thermolabile component of the composition or by interaction between an excited state molecule of the IR absorber and a ground state molecule of a suited reaction partner. The heat generated by internal crossing is already used in commercial available offset printing plates by means of coalescence or ablation processes. Single electron transfer reactions are processes of choice for a chemical deactivation of the excited state of IR absorbers. For a high efficiency of such processes, certain thermodynamic and kinetic prerequisites must be fullfilled. Electron deficient molecules such as onium salts are well suited as reaction partners for excited states of IR absorbers.     

Einsatz von Vakuumpumpen bei der Herstellung von Photovoltaik‐Modulen

Use of vacuum technology in crystal pulling and lamination application in manufacturing of photovoltaic modules Dry compressing screw type vacuum pumps such as the SCREWLINE SP 630/250 are designed to reduce cost of ownership in crystal pulling plant and in lamination processes. The construction of gear house sealings, the easy maintenance of the pump on site and the use of gas ballast guarantee a very reliable performance, and long maintenance and service intervals. In the case of crystal pulling the process does not even need a dust separator at the inlet of the vacuum pump.     

Umformende Herstellung von Al/Mg‐Werkstoffverbunden

Manufacture of Al/Mg‐composites by forming A universal theory for the bonding of metallic materials does not exist. For new material combinations and new joining technologies the bonding properties have to be examined individually. The factors affecting bonding behavior and characteristic like the bond strength have to be investigated. This paper presents a method for generating composites by a forming process and shows innovative possibilities to test and evaluate relevant parameters of the bonding process.     

Einsatz von Mikroplasmen für die Herstellung von Silizium‐Mehrlagenaufbauten

Micro Plasma Processes for MEMS Packaging The encapsulation of MEMS devices can be difficult, since released micromechanical parts (e.g. membranes, valves, and cantilevers) tend to stick to the surrounding surfaces. Area‐selective surface modification is a new approach, developed by the Fraunhofer‐Institute for Surface Engineering and Thin Films (IST), to overcome these problems. From a more general point of view, area‐selective surface tailoring with microplasmas is an attractive topic for micro systems production. The business transfer of the technique by implementation into the SU SS mask is currently being evaluated.     

Numerische und experimentelle Untersuchungen zur Herstellung von stranggepressten Aluminium/Magnesium‐Werkstoffverbunden und zur Festigkeit des Interface

Numerical and experimental investigations of the production processes of coextruded aluminium/magnesium‐compounds and the strength of the interface In the research project SFB 692 the aim of the subproject B3 is to analyze aluminium/magnesium‐compounds, especially the strength and fracture mechanical properties. Furthermore a numerical model of the interface should be created. In the following paper the main results of the investigations of the subproject are presented. Different influencing variables were analyzed, which determine the quality of the interface. It has been shown, that the compound quality and also the strength of the interface is based on several parameters of hydrostatic and indirect extrusion processes. If the quality of the interface is good, without cracks, the strength is very high. Furthermore the behaviour of the interface under loading in an extended temperature range is presented. A numerical model was found to visualize the behaviour of the compound during the loading tests.     

Anforderungen an Metalloxid‐Schichten für Interferenzoptik

Metal Oxide Films for Interference Optics: Demands on Quality – State of the Art in Production Demands on quality and stability of PVd‐metal oxide coatings are increasing with modern optical systems, complex structures and extension to short and long waves. Deposition requires always, independent on starting material, reactive technologies. Basic PVd‐processes are either fast running but low in particle energy (evaporation), or exactly the other way round (sputtering) or have disturbing side effects (arc ablation). It is shown how they are modified and improved to become effective in reliable and fast deposition of high quality, low defect films. This is performed by adding ions and plasma species or combining magnetic fields and operate the various hybrid processes in continuous or pulsed modes. Characteristic data of the processes are presented as well as properties of metal oxide films produced with energetic reactive, continuous and pulsed plasma processes.     

Neu entwickelte TiAl‐Basislegierungen für den Leichtbau von Triebwerks‐ und Motorkomponenten – Eigenschaften,Herstellung, Anwendung

Newly Developed TiAl Base Alloys for Lightweight Components in Jet Engines and Internal Combustion Engines – Properties, Production, Application Titanium aluminides are a most promising high temperature materials alternative to conventional heat‐resistant steels and superalloys for high‐performance automotive and aircraft engine applications. Intermetallic TiAl base alloys offer striking advantages for high temperature and mechanical loading applications. The specific weight of about 3.8 ‐ 4.1 g/ccm is low, the oxidation and burn resistance at temperatures up to 800 °C are good. The elastic stiffness is high and the temperature strength is enhanced. Feasible applications in combustion engines are valves, pistons and exhaust gas turbocharger rotors. Blades, vanes and discs for jet engines are under development, as well. Due to the extraordinary high specific Young’s modulus (ca. 46 GPa ccm/g) and 0.2 %‐yield strength up to 1 GPa of the TiAl base alloys in the as‐extruded state some applications at lower temperatures have also been taken into consideration, e.g. connecting rods and piston pins. The paper reviews constitutional related properties of the advanced TiAl base alloys with the respect to the industrial manufacturing of components and structural applications.     

Innovative Fügeverfahren zur Herstellung von Al‐Leichtbaustrukturen im Schienenfahrzeugbau

Innovative joining techniques for creating light‐weight aluminium structures in railway vehicle production Starting from the development in railway vehicle manufacture, the authors describe today's materials, types of construction, joining techniques, joint and weld types, filler materials and regulatory documents. In addition, they present new processing equipment and engineering principles. On the basis of these findings, they show the perspectives of new construction principles for light‐weight aluminium structures and identify the requirements, the new joining techniques have to meet. The innovative joining techniques, such as: • electron‐beam welding under atmosphere (NV‐EBW) • Friction Stir Welding (FSW) • Laser beam welding (LBW) • Laser beam/electric arc hybrid welding (LBW/LB) are studied with regard to their • properties and particularities • advantages and disadvantages • available equipment • possible applications for railway vehicle manufacture. In addition, costs are compared and an analysis of the benefit is made. Finally, the authors give an outlook on possible applications of the innovative procedures.     

Statische Vakuumentgasungsapparate bei der Herstellung und Qualitätserhöhung von Kunststoffen

Static devolatilization is a simple and older process which has been so much improved by the introduction of static mixers and by system optimization that it can fulfill all the modern demands of polymer processing, including additive mixing. Enhanced devolatilization, which continues to grow in importance, requires a high degree of efficiency – verging on the equilibrium value – in order to satisfy demands for low residual monomer values, economically and under industrial operating conditions. Contrary to expectations, this goal can be reached quite simply by the employment of static devolatilization, as it will convincingly show in this survey. Polymers with viscosities up to 20000 Pas can be discharged safely. Thanks to the substantial process improvements static devolatilization will spread increasingly to those areas where it is not yet used as standard practice.