Präparation und Charakterisierung von nanokristallinem ZrO2

Preparation and characterization of nanocrystalline ZrO₂ Synthesis routes for the preparation of nanocrystalline ZrO₂ as a component of heterogeneous catalysts are briefly discussed. Especially the relation between the phasecomposition and the synthesis parameters is investigated. The use of RAMAN spectroscopy for the phase determination of highly amorphous samples with high surface areas is illustrated.     

Die häufigsten Fehler beim Einsatz von Vakuumpumpen und deren Vermeidung

How to avoid operating errors The rising number of vacuum pump applications require, that the vacuum pump manufacturers develop and offer more and more application dedicated products. To make sure the pumps fulfil the application requirements with regards to performance and reliability, certain operational measures to be followed. From the pump manufacturers standpoint this article shall emphasize helpful tips regarding selection, operation, accessories, monitoring and preventive maintenance for users and system manufacturers for the most common vacuum pumps.     

Dekontamination von Vakuumpumpen und Komponenten aus der Halbleiter- und Elektronikindustrie

The safety aspect for the employees, environmental pollution control und product quality of the repaired components are common ideas of the new decontamination facility for vacuum pumps and components of semiconductor processes. There are a lot of rises by servicing and decontaminating vacuum components used in semiconductor equipment. The toxic materials used in the processes are still in the vacuum pump. It's not allowed that these materials are coming in the environment. This requirement comes from the health and safety reasons for the employees together with environmental aspects. The described decontamination facility near Munich is unique in Europe. Some companies have developed special machines for this facility. A cooperation with scientific and hygiene-technical support with the university of Giessen have made new progress in planning and operating the decontamination center. The decontamination facility meets the very thight criteria of the federal german pollution control and the other urban control authorities.     

Herstellung von Präzisionsschichten mittels Ionenstrahlsputtern

Precise thin film synthesis by ion beam sputter deposition Ion beam sputter deposition (IBSD) is a promising technique for the fabrication of high performance thin films because of the well defined and adjustable particle energies, which are rather high in comparison to other PVD techniques. Recent developments concerning long‐term stability and lateral uniformity of the ion beam sources strengthen the position of the IBSD technique in the field of precise thin film synthesis. Furthermore, IBSD offers a more independent choice of relevant deposition parameters like particle energy and flux, process gas pressure and deposition rate. In this paper we present our currently installed large area IBSD facility “IonSys 1600”, which was developed by Fraunhofer IWS Dresden and Roth & Rau company (Hohenstein‐Ernstthal). Substrate sizes of up to 200 mm (circular) or up to 500 mm length (rectangular) can be coated and multilayer stacks with up to six different materials are possible. Tailored 1‐ or 2‐dimensional film thickness distributions with deviations of < 0.1 % can be fabricated by a relative linear motion of the substrate holder above an aperture. In order to demonstrate the advantages of the IBSD technique especially for sophisticated materials and films with high requirements concerning purity, chemical composition or growth structure, several examples of deposited multilayers for various applications are presented.     

Hartstoffschichten für das Pressen und Prägen von Gläsern bei hohen Temperaturen

Hard and wear resistant coatings for the moulding and embossing of glasses at elevated temperatures Hard and wear resistant coatings of Titanium Aluminium Nitride TiAlN were deposited on various substrates by the application of different reactive deposition processes: RF-magnetron-sputtering, ion beam-sputtering and by the energetic cluster impact (ECI) process. The deposition of the coatings was performed under variation of biasing conditions and of process parameters such as pressures and flow rates of the process gases argon and nitrogen as well as of energies of species hitting the substrate surfaces. The microstructure particularly the growth morphology of several films was investigated by pictures of film cross sections recorded by transmission electron microscopy. Residual intrinsic film stresses were analyzed by measuring deflections of substrates in an interference optical microscope before and after the deposition of the coatings. By heating coated substrates and in-situ observation of deflections at elevated temperatures dependencies of thermally induced stresses on temperatures and variations of intrinsic stresses due to changes within the films could be analyzed and related to microstructure and growth conditions. In the paper specific characteristics of the deposition processes occuring on the scale both of atoms and of clusters which may contain several thousand of atoms are described and related to microstructure, residual stress states and damaging conditions. Different contributions to residual film stresses are analyzed on the base of theoretical considerations taking into account deposition kinetics and thermomecanical properties. The significance of achieved film properties for application, i. e. for the coating of tools for the manufacturing of optical components by moulding and embossing of glasses is discussed.     

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.     

Präparation von nichtmetallischen Werkstoffen für die lichtmikroskopische Untersuchung

Preparation of Non-Metallic Materials for Examination under an Optical Microscope Tests carried out show that the comparatively elaborate procedures necessary to produce thin polished sections can in many cases be satisfactorily replaced by more economical machining techniques. Considerable time and cost savings have been made possible by preparing monolithic specimens using a high-speed milling machine and microsections using a low-speed saw. This applies particularly to the use of the low-speed saw in quality control for components made of glass fibre reinforced polyesters. Another important application is the preparation of specimens of synthetic resin-impregnated graphite for corrosion resistance tests using a high-speed milling machine.     

Geräuscharme Flüssigkeitsring‐ Vakuumpumpen

Besides the requirements for processing, increasing investment charges and working expenses gain more and more importance during the past years as well as the noise level and noise development. Within this work new information's elaborated with regards to noise development were presented for liquid ring vacuum pumps. Based on these test and design data and its interpretation, a new pump type was designed. These studies resulted in a new type range, which corresponds to now‐a‐days standards with regards to increasing requirements on noise development. Combining new knowledge with the up‐to‐now experiences makes us considerably reduce the emissions at source. Latest technologies and production methods enabled us to create a robust construction at a favourable price.     

Fehler vermeiden beim Betrieb von Vakuumpumpen

A wide spectrum of todays vacuum applications are asking for custom taylored, hightech products, which of course require for highest uptime and optimal utilization certain maintenance and to follow operational advices. From a prospectus and experience of a components' manufacturer, the following article would like to give you helpful advices for the use, maintenance and proper system integration for the most common vacuumpumps utilized and to realize the lowest cost of ownership.     

Präzisionsverschleißmessung an dünnen Schichten als Mittel zur Qualitätssicherung und Schichtcharakterisierung

Unterüberschrift (Übersetzung) Dünne Schichten finden zunehmend Verbreitung in technisch anspruchsvollen Anwendungsgebieten. Die Qualitätssicherung von dünnen Schichten erfordert deshalb hochwertige Prüfverfahren. Das Verfahren sollte zu quantitativen Ergebnissen führen, damit eine objektive Bewertung möglich ist. Am Fraunhofer Institut für Schicht‐ und Oberflächentechnik wurde das Kalottenschliffverfahren (DIN 1071 Teil 2) zu einem Präzisionsverschleißtester für dünne Schichten weiterentwickelt. Diese Methode erlaubt es, aus Werkstoffoberflächen ein definiertes und reproduzierbares Materialvolumen auszureiben. Diese Materialkenngröße (Volumenverschleiß) charakterisiert physikalische und chemische Materialeigenschaften und kann damit zur Qualitätskontrolle und Werkstoffentwicklung herangezogen werden. Der Beitrag zeigt Entwicklungschritte, Ergebnisse und Anwendungen dieser Prüfmethode auf.     

Erweiterter Einsatz von Turbomolekular Vakuumpumpen durch Beschichtungen

Turbomolecular‐pumps (TMP) can be used for suction of gas in a wide range of pressure. Limitations are primarily due to thermal and chemical capacity especially of the highly loaded pumping rotor. Prospects and limits to extend application fields by use of adequate functional coatings are reported.     

Aufbau und Eigenschaften verschiedener ölfreier Vakuumpumpen für den Grob- und Feinvakuumbereich

The development of high vacuum pumps and systems during the last 35 years can be characterized by a trend of gradual elimination of liquids exposed to vacuum environment. The need for high purity vacuum process equipment precipitated the development of new pumping techniques: iongettering pumps, turbomolecular pumps and cryopumps. During the last 5 years, a number of dry coarse-vacuum pumps have been developed. Some are entirely oilfree, some still use lubricants at the seals separating the driving mechanism from the vacuum side. This review contains general design and performance characteristics of four classes of equipment: hermetically sealed pumps using bellows to isolate the driving mechanism, a variety of multistaged positive displacement blowers, pumping trains based on turbo-drag pumps, and multistaged reciprocal piston pumps. It is entirely practical to achieve pressure of 10⁵ to 10⁶ while discharging to atmosphere. Despite a complete absence of conventional lubrication in some of these pumps, periods exceeding 10000 hours without maintenance are obtained, providing a viable technology for clean vacuum systems.     

Beschichten,Reparieren und Generieren durch Präzisions‐Auftragschweißen mit Laserstrahlen

Laser beam build‐up welding belongs to the technical group of thermal coating. With a coating thickness between 0.1 and 3 mm it is positioned close to PTA and TIG cladding. The special features consist in the excellent controllability of the cladding process, high precision of the material deposition, low thermal influence on the workpiece and low base material mixing, the absence of mechanical effects on the melt pool as well as the large number of coating and substrate materials available for the manufacturing process. Currently, the most important application is the repair of complex shaped and expensive components and tools. Examples are wear damaged moulds, metal forming dies, or aircraft engine components, which original properties can be completely restored by accurate and local replacement of the lost material. In the field of surface protection, laser technology offers advanced solutions for the surface modification of light alloys. Components of Ti, Al or Mg alloys can be protected effectively against wear and corrosion by laser cladding, alloying, and hard particle dispersing. Generating of metal Prototypes by CNC controlled Direct Metal Deposition is a further application of the laser technique. Using this method, mould inserts, active parts of tools, or engine components can be generated directly from the 3D CAD data.     

Grenzschichtproblematik und Haftung von EB-PVD-Wärmedämmschichtsystemen

Adhesion and interface Problems of EB-PVD Thermal Barrier Coatings The adhesion of EB-PVD thermal barrier coatings on substrates before they come in service is preconditioned by the way of processing, by the substrate material and by environment. Problems of adhesion which arise from unsuitable manufacture or storage will be presented by two examples respectively which originate from the substrate, from the thermally grown oxide interlayer, and from the thermal barrier top coating.     

Bruchflächenformation und Haftmechanismen von Titan-Stahl-Sprengplattierungen

Formation of Fracture Surfaces and Adhesion Mechanisms of Titanium Steel Explosive Bondings Investigations on adhesion of the model system steel-titanium explosive platings have been carried out under the condition of an uniaxial tensile test. A bond model of explosive plating will be proposed and discusses by means of SEM-analysis of the fracture surfaces. Hence it follows, that in the range of the slow collision velocity, the bond mechanism is identical with that obtained by friction welding processes. At medium collision velocity a formation of thin hydrodynamic metal films with lubricating effects and slight adhesion in the interface region takes place. Extreme large collision velocity rate cause the bond due to fusion welding processes.     

Verschleiß von Maschinen und Werkzeugen beim Verarbeiten von verstärkten und gefüllten Kunststoffen

Wear of Processing Equipment and Moulds by Filled and Reinforced Plastics The introduction of filled and reinforced plastics into the market increased the problem of wear during processing. It is estimated that in Germany wear based losses are up to 500 Millions DM per annum. Special test methods have been developed for systematic analysis of wear phaenomena. A considerable progress has been achieved in solving these problems in close contact to the concerning industry.