Rektifikation von Dreistoffgemischen insbesondere von Sauerstoff-Stickstoff-Argon-Gemischen

Ohne Zusammenfassung VDI     

Laserbeschriftung von Hartferritmagneten zur Kennzeichnung von Druckgussteilen

With the presented method of magnetic labeling die cast components are labeled and provided with production data as well as protection against plagiarism. The magnetic labels are cast close under the surface of the component during the casting operation. Serial numbers, data and graphical information was engraved on the surface of hard ferrite magnets by laser marking using a diode-pumped ytterbium fiber laser. The data and graphical information was encoded as data matrix codes. Inexpensive strontium ferrite magnets were used. Melting processes and thermally induced material changes on the magnet surface during the laser labeling of the magnets results in a local demagnetization. The measurable decrease of the magnetic field strength is a result of local heating above the Curie temperature and the geometrical change of the magnet surface. The patterns with changing magnetic flux density can be visualized directly by a magnetic viewer or measured by magnetic field sensors such as Hall effect sensors. This paper deals foremost with the laser labeling process and the induced changes on the surface of the magnets as well as visualization and measuring test. First results of casting trials are presented, to confirm the stability of the magnetic labeling procedure during the casting operation.     

Der biaxiale Kreuzzugversuch zur Ermittlung von Werkstoffkennwerten von Airbaggeweben am Beispiel von Polyamid 6.6

A biaxial cruciform test for the determination of material data of polyamid 6.6 airbag fabric The determination of material data on samples under real, complex, test conditions is of considerable interest. In this work a cruciform test for airbag fabric and some exemplarily measurement curves for a typical polyamid 6.6 airbag fabric are presented and discussed.     

Analyse von Partikeleigenschaften beim Thermischen Spritzen von Mikropulvern

Analysis of In‐Flight Particle Properties of Thermal Sprayed Ultrafine Powders Demands on functional coatings with high dimensional accuracy and high surface quality has led to increasing interest in processing of very fine powder grades in a particle size range < 20 μm in past years. Fine powders are not only showing a distinct potential for application of thin and dimensionally accurate coatings, but are also very promising for the production of dense and homogeneous coatings with improved mechanical properties. The large specific surface of fine powders is allowing for relatively low thermal energy levels that are introduced into the process. Nevertheless is also requires a very sensitive temperature control, to prevent overheating of the particles. The reduction of the thermal energy level is resulting in significant advantages particularly for the usability of the HVOF process for coating of inner diameters. Within this work in‐flight particle properties of ultrafine carbide powders were analyzed. The studied HVOF process allows the adjustment of a broad parameter range by utilization of a hydrogen stabilized liquid fuel combustion process. A conventional straight nozzle type as well as a curved nozzle for internal spraying was studied. For a further assessment of the potential of ultrafine carbide powders also spray trials with a plasma spraying system have been made.     

Bildung von geordneten Konstruktionsfamilien unter Anwendung von Ähnlichkeitsgesetzen

The theory of Constructional Similarity bases on the theory of physical similarity. The pattern construction is a model in the theory of constructional similarity. The essence of this work is to choose such constructional features of the new designed constructional means to obtain the identical states: physical, stereo mechanical or simple like in the pattern construction.     

Untersuchung von Oberflächenschutzschichten von Gasturbinenlegierungen

Investigations on protective coatings on gasturbine alloys. It has been found by investigations of specimens of a combustion chamber pilot plant and also by experiences with gasturbines that aluminide or chromium aluminide coatings are only slightly protective under working conditions of industrial gasturbines. Chromium coatings have a distinctive better protective efficacy and are surpassed in this quality by silicide coatings. It was possible to give information on the development of silicide phases on Nimonic 105. Under the conditions of corrosive attack a surface layer of Nickelolivine is formed and the silicide phases are changed in direction of ternary phases. Even when chromium sulfides are formed in the silicide layer the specimens are stable under the test conditions. By investigations on an airfoil made from B 1900 with a protective coating of Aluminium and Silicon the presence is shown of a ternary Laves phase with Silicon.     

Anwendung von Methoden der Bruchmechanik zur Lebensdauerverbesserung von Umformwerkzeugen

Application of Fracture Mechanics for the Improvement of the Life Time of Forming Dies An investigation was undertaken to determine the life times of dies when these life times are determined by crack propagation from such stress raisers as notches. Notched DCB specimens were used to investigate the processes of crack initiation and propagation in the high temperature steel X 40 CrMo V 51 at 500°C. The results showed that the life times depend both on the heat treatment of the material and also on the length of hold time at temperature. Hold times during the forming process should be minimized in order to avoid fast creep crack propagation.     

Einfluß von Sauerstoffspuren auf die Eigenschaften von Wolfram-Schwermetallen

Influence of Oxygen Traces on the Properties of Tungsten Heavy Metals Investigation carried out with differently sintered W heavy metals showed that careful pre-reduction before liquid phase sintering is essential for obtaining satisfactory mechanical properties; otherwise oxide layers at the phase boundaries deteriorate the interface strength and thus cause premature fracture. Understandably, the water vapour content of the furnace atmosphere is of considerable importance. Appropriate sintering anticipated, even severely oxidized green compacts result in highly ductile heavy metals. Addition of scavengers, e.g. Cr or V, instead of the pre-reduction improves the interface strength, the mechanical properties however remain unsatisfactory.     

Schmelzpunkte von Reaktor-Werkstoffen

Ohne Zusammenfassung VDI     

Anpassung von Lenkkosten

Zusammenfassung Ein in der Industrie implementiertes (s,S)-Lagerhaltungsmodell wird mit einem Wagner-Whitin (WW)-Modell verglichen. Drei Kriterien werden dazu herangezogen: Mittlerer Lagerstand, Bestellhäufigkeit und Servicegrad. Es zeigt sich, daß sich im WW-Modell Lenkkostenparameter angeben lassen, für die das WW-Modell in allen Zielen dominant ist. Diese Untersuchungen bestätigen sich nicht nur an den gegebenen empirischen Nachfragezeitreihen, sondern auch an allgemeineren durch Simulation generierten Zeitreihen.

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Summary An adaptive (s,S)-inventory model being implemented in industry is compared with a Wagner-Whitin (WW)-model. Three criteria are taken into account: mean stock on hand, order frequency, and service level. It is shown that cost parameters can be chosen for the WW-model such that this model leads to dominant values for all 3 criteria. These results not only hold for the empirical time series of the company studied but also for more general time series generated by simulation.

     

Einfluß von unverformbaren Teilchen auf die Strangpresstexturen von Verbundwerkstoffen

Influence of undeformable particles on the extrusion texture of composite materials The influence of α-Al₂O₃ particles on the extrusion texture of Ni-, Cu or CuZn30-composites has been investigated, variing particle size and interparticles spacing. The rods show a 〈100〉-recrystallization texture, which decreases with greater values of the interparticle spacing. In the case of the addition-free Cu and CuZn30 a random orientation distribution of the crystals was found. These results are discussed in comparison with the results found on Al? Al₂O₃-composites.     

Charakterisierung von Aluminiumoxidschichten

Characterization of Aluminium Oxide Layers Adhesive bonding aluminium sheets is a manufacturing process which is very relevant in aircraft construction. In order to produce bonds featuring adequate strength and long-term stability, an aluminium oxide layer having certain properties must be generated on the sheet surface during pretreatment. The properties of aluminium oxide layers which are required and adequate in the light of current findings are delineated in this paper and the analytics prepared for the purpose of checking these properties are presented. Al₂O₃ layers produced by means of pickling and chromic acid and phosphoric acid anodic oxidation can be characterized adequately by means of the following:

• chemical composition (impurity)
• layer thickness
• structure
• morphology

The following methods of physical analysis are employed in order to determine these properties:

• Surface analysis (AES, ESCA, SIMS) in conjunction with ion etching for the obtention of depth profiles.
• Electron diffraction in reflection and transmission as well as X-ray diffraction.
• High-resolution scanning electron microscopy (resolution 30 Å).
• Transmission electron microscopy.

Further more, the methods of investigation which in our opinion are necessary and adequate for checking in the practice the proper pretreatment of aluminium sheets for subsequent bonding are also presented.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Messung von Stopfbuchsverlusten

Ohne Zusammenfassung The online version of the original article can be found at     

Festigkeitsberechnung von Ventilfedern

Zusammenfassung Für neuzeitliche Motoren und Einspritzpumpen sind die Federn zu hochwertigen Maschinenteilen entwickelt worden, für deren Berechnung besonders zuverl?ssige Unterlagen zu fordern sind. Mit einer Sonderprüfmaschine wurde das Verhalten derartiger Federn untersucht, woraus sich Dauerfestigkeitsbilder für die praktische Anwendung ableiten lassen.