Cross‐Magnetron‐Effekt und ITO‐Schichtabscheidung

Cross Magnetron Effect and ITO Film Deposition The large area deposition of TCO films requires a strictly homogeneous lateral distribution of the process parameters at the substrate position. In view of that, Cross Corner Effect (in case of a single magnetron source) and Cross Magnetron Effect (for dual magnetrons) can cause problems. Measurements confirm a distinct influence of these effects on the functional properties of indium tin oxide films. The effect will be discussed in terms of the concentration of the dissociated oxygen in the process gas, which depends on the plasma properties and the oxygen partial pressure.     

Herstellung von Polymer‐ und Polymer‐Metalloxid‐Kompositschichten

Preparation of polymer and polymermetal oxide composite thin films Organic materials are not yet commonly used for optical interference layer systems. The reasons therefor are their low mechanical resistivity, their often more complex deposition techniques and their poorer optical properties compared with oxide thin films. However some organic materials offer special properties that are useful for the application in optical layer systems. Because of its high mechanical flexibility mechanical stress in layer systems can be reduced. Some organic materials show specific optical properties like fluorescence or intensive colors that can be used for optical layer systems. Hydrophilic and hydrophobic organic top coatings can improve the pollution behavior of optical layer systems. Therefore we present in this work some gas phase deposition techniques for organic substances and report about some basic optical and mechanical properties of thin films coated with these as well as some important process characteristics.     

Untersuchung von Schmelz‐ und Rekristallisationsprozessen sowie Riss‐, Oxid‐ und Porenbildung beim Schweißen

Investigation of melting and re‐crystallization processes and of crack, oxide and pore formation during welding In the paper some known investigation methods of the primary re‐crystallization and of the structure of the crystallization front are discussed. All these methods have disadvantages, in some cases they cause a limited validity or are expensive. The presented new method is based on the micrographic recording of the melting and solidifying metal surfaces. The method overcomes the above‐mentioned disadvantages. It is able to investigate in the welding seams not only the primary re‐crystallization processes but also the secondary ones including the formation of cracks and pores and the appearance of non‐metallic inclusions like oxides. The facilities of the method are demonstrated on some examples of use.     

EPMA‐Analyse dünner PVD‐ und CVD‐Schichten

EPMA analysis of thin PVD and CVD layers Electron Probe Micro Analysis (EPMA) is an X‐ray spectroscopic method for determining the chemical composition of solid substances in the near‐surface region. It has a high detection sensitivity, a high spatial resolution, an adjustable depth of analysis and is easy and accurate to quantify. Less well known is the fact that the EPMA is also able to analyze the chemical composition and layer thicknesses of thin multi‐layer systems non‐destructively and with only one single measurement. In particular, it is possible to determine, for example, the composition and thickness of a layer buried under one or more other layers. Conversely, with a known film thickness, the density of thin layers can be determined, a quantity that is generally difficult to access with thin layers. The following article describes the physical basics of EPMA analysis and compares them with energy dispersive X‐ray spectroscopy (EDX) and X‐ray fluorescence analysis (XRF), which are also widely used. The principle of so‐called thin film analysis for multilayer systems is explained, and the possibilities and limitations of this method are illustrated by a number of industrial application examples.     

Zyklisches Werkstoffverhalten von Magnesium‐Druckguss‐ und ‐Knetlegierungen

Cyclic material behaviour of magnesium die castings and extrusions The cyclic deformation behaviour of the die castings AZ91 and AE42 and the extrusions AZ31 and AZ80 is investigated in strain controlled tension compression tests. The main topic of this investigation is the verification of the Masing and Memory behaviour. These two material properties are necessary for the component design by the local strain concept. The two die castings show approximately Masing behaviour, but the hysteresis of magnesium is different from the hysteresis of steel. For extrusions a totally different behaviour in tension and in compression direction can be observed. The hysteresis in experiment differs from the calculated hysteresis from the cyclic stress strain curve. The Masing behaviour is not observed because of the strong anisotropic behaviour in tension and in compression direction. All investigated magnesium alloys show the material memory M2.     

Feinst‐ und Ultrafeinkornhartmetalle: Tendenzen und Anwendungen

Submicron‐ and Ultrafine‐Grained Hardmetals: Tendencies and Applications Submicron‐ and ultrafine‐grained hardmetals are WC‐Co alloys with average WC grain diameters of ≤ 0.8 μm and ≤ 0.5 μm, respectively. The variation of grain size towards finer‐grain carbides has the advantage that both hardness and transverse rupture strength increase as grain size decreases. This combination of properties, which contrasts with the well‐known counter‐running relationship between hardness and transverse rupture strength found in conventional hardmetals, opens up a wide area of application for submicron and ultrafine grained hardmetals. Since their introduction, these hardmetals have firmly established themselves in metalcutting operations, predominantly in the areas of milling and drilling and to a lesser extent in turning and broaching. Submicron‐ and ultrafine‐grained hardmetals, particularly in combination with suitable coatings, are gaining increasingly in importance in the machining of highly heat‐treated and abrasive work materials.     

Modellbasierte Optimierung und experimentelle Charakterisierung der Thermo‐ und Kryo‐Mechanik werkstoffhybrider Bauteile

Model based optimisation and experimental characterisation of thermo and cryo‐mechanics of hybrid material components The design of hybrid material components with thermo‐mechanical requirements is supported by optimisation techniques. From a set of examples some general conclusions will be derived. Severe requirements come from cryogenic environment not only because of individual material behaviour but also due to possible mismatches between different materials to be combined. This also puts specific requirements for test set ups for determination of related material and component properties.     

PVD‐Nanocomposite‐Beschichtungen für die Zerspanungs‐ und Umformtechnik

PVD Nanocomposite coatings for the machine cutting and deformation technique Physically and chemically separated wear‐protection layers exhibit increasingly more complex structures. Similarly to the a coil of compact materials increase also here solutions develop as composite materials, which are offered in the form of Nanocomposites. An industrially available solution represents the system MeN/Si₃N₄. This is to be introduced concerning its characteristics as well as its application type within the range of the machine cutting and deformation technique.     

Gyrotron‐Forschung und ‐Entwicklung am KIT

Gyrotron Research and Development at KIT — An Important Contribution to the Fusion Research at Europe In future nuclear fusion power stations shall contribute to the continuous generation of environmentally friendly energy production. Electron cyclotron resonance heating is an important system to heating up the fusion plasma, the microwave source of which are gyrotrons. Together with its European partners, Karlsruhe Institute of Technology (KIT) has developed the series gyrotrons for the stellarator W7‐X and is developing EU gyrotrons for the tokamak ITER. Both are generating 1 MW CW of RF output power at 140 GHz and 170 GHz, respectively. Future fusion power plants will require multi‐megawatt gyrotrons operating at above 200 GHz. KIT is looking at new concepts, systematic design approaches and key components to achieve this target. In this paper the design approach for gyrotrons, the developments of key components and the modular test concept will be presented. Additionally, a brief introduction into the new test stand is given. Together with its European partners and with its industrial partner Thales Electron Devices, it is possible to develop and to produce a major key device, the gyrotron, for plasma experiments and future power plants.     

Optische in‐situ Prozessverfolgung und ‐steuerung

In situ optical monitoring and process control: Measuring transmittance and reflectance of optical coatings during deposition Optical monitoring techniques havebecome indispensable parts of deterministic preparation strategies for sophisticated optical coatings. Traditional versions of optical broadband monitoring are based on measurements of the transmission spectrum or alternatively the reflection spectrum of the growing film. In the case of practically loss‐free samples, both approaches principally deliver equivalent information. In the case of absorbing coatings, the information gained from the different spectra may be no more equivalent. Instead, it may be reasonable to record both spectra simultaneously, in order to get a more complete picture of the status of the growing film. We present a corresponding measurement setup designed for use in typical coating evaporation processes and demonstrate its application to the deposition of alumina coatings as well as aluminum mirrors.     

Entwicklung und Eigenschaften von Magnesium‐Lithium‐Legierungen

Development and Properties of Magnesium‐Lithium‐Alloys The application of Lithium in Magnesium alloys extends the properties of these regarding smaller density and clearly increased ductility. Hereby can be met to demands even on the part of the automobile industry for damage‐tolerant, better ductile magnesium components. Investigations of hexagonal Magnesium Lithium alloys show promising results, which contain not only more balanced mechanical properties but also an improved corrosion behavior.