Moderne Möglichkeiten der Verschleißmessung mit radioaktiven Isotopen

Modern use of radioisotopes in wear measurement – Modern methods using low activities and sensitive and reliable measuring equipment allow for an advantageous use of radioisotopes in wear measurements. The modern thin layer activation method using the irradiation of any visible section of an engine part with heavy charged particles originating from an accelerator creates radioisotopes only in a thin zone under the surface. Generally, the activity of engine parts activated by this method is roughly a thousand times lower than that of parts activated by thermal neutrons as usually done before. Use of different types and energies of bombarding particles will produce recognizably different patterns of radioisotopes even in targets consisting of the same material, and thus permits the simultaneous measurement of several components of wear. Handling, transportation, and storage of engine parts trated by the thin layer activation method does not create any danger and, therefore, no additional expenses. This means that wear measurements using radioisotopes can now be carried out anywhere without protective measures.     

Neue Möglichkeiten zur Charakterisierung dünner Schichten mit Indentermethoden

Novel Possibilities for Thin Film Characterisation Using Indentation Methods A novel methodology for the evaluation of the response of coated substrates to mechanical contact is presented which is based on the combination of a new theoretical method and high‐accuracy indentation experiments using a spherical diamond indenter. The concept may be extended in many respects and will be illustrated here only with few special examples: Using low loads, i. e. staying completely in the elastic region, the elastic parameters of film and substrate can be measured with high accuracy. When the indentation experiments is extended until failure of the coating substrate compound, the full stress and strain fields in three dimensions in the very moment of failure can be calculated. The knowledge of those fields enables one to draw conclusions on the relevant mechanisms. Once the failure mode has been identified, layer systems with optimum resistance to that failure mechanism can be found by theoretical simulations.     

Möglichkeiten der Geruchsmessung und ‐minderung bei Naturfaserverbunden

Possibilities of Odour Measurement and Reduction of Natural Fibre Plastics The critical attitude of the German public concerning environmental questions has also invaded the world of odours. The evaluation and reduction of odours when using plastic materials has gained increasing significance in the last years. The packaging industry that produces wrapping materials for food and other consumables was the first to test for odours. During the last years the automobile industry has also shown increased interest in pinpointing and measuring odours, not only because of the increased usage of natural fibre reinforced plastics in car interiors, but also because of the general increase of concern over clean air. Natural fibre reinforced plastics, besides having advantages compared to glass‐ and carbon reinforced materials (mechanical properties/weight, CO₂‐equilibrium) also have properties that limit their application possibilities. Emissions and unpleasant odours at certain temperature and humidity conditions are of concern. To determine the origin of odour in bonded materials the single component, production step or their combination causing it has to be found. To achieve odour neutrality in plastics is difficult since production methods or additives can only be determined through prolonged testing and where the human nose is still more important than all the physical electronic measuring methods. The origin of odours and their importance for the well being and health of the population is questioned and forces not only the plastics industry to react. The is why both, plastics‐ and automobile industries are trying to react to the tendencies of the market place and it is the goal of the auto industry to deliver the most odour‐neutral new car.     

Neue Möglichkeiten zur Grobvakuummessung in explosionsgefährdeten Bereichen

Absolut pressure gauges with fully electronic signal processing designed according to explosion protection tech nique »Intrinsic Safety« for use at hazardous locations offer many advantages at reduced cost. Capacitive pressure transducers with aluminium oxide diaphragm guarantee an optimum of corrosion resistance (especially important for chemistry applications). The absolute pressure is measured with high accuracy. Temperature‐ and long‐term drifts are minimized. The gauges do not have damageable moving parts and are insensitive to vibrations and pressure shocks. An integrated current loop interface allows automatic switch‐on and read‐out of the gauges.     

Möglichkeiten des Oberflächenschutzes von Behältern und Bauwerken in Abwasserreinigungsanlagen

Surface Protection for Tanks and Constructions in Waste Water Purification Plants The composition of waste water from chemical plants often requires a suitable surface protection for the steel or concrete substrates of constructions in water purification plants. The use of a suitable protection system will be instrumental in economizing and will enhance the availability of the plant. To study the resistance against chemical waste water, extensive tests with different corrosion protection systems were carried out under servicelike conditions. The most suitable system was a solventless epoxy-polyamin coating. Some examples and experiences in service with this protective coating are discussed.     

Charakterisierung keramischer Werkstoffe mit der Auger-Elektronenspektroskopie: Möglichkeiten und Grenzen

Understanding the relationships between mechanical and other physico-chemical properties and the microstructural chemistry is a necessity for a well-controlled development of new materials. A prerequisite for the achievement of this goal is an advanced microanalytical characterization, which can be obtained by application of surface analysis methods. Among these, high resolution Auger electron spectroscopy (HR-AES or Scanning Auger Microscopy, SAM) has proved to be extremely useful for surface, interface and depth profile analysis of ceramic materials. After a short presentation of the principles and the main areas of application, specific advantages are discussed for some examples. Those are e.g. a depth of information in the nanometer range, a sub-micrometer lateral resolution, a relatively high detection sensitivity for the light elements like B, C, N, O, and a small matrix effect in quantitative analysis. The main disadvantages are due to a variety of detrimental electron beam induced effects which are outlined for some examples of oxide and non-oxide ceramics. The generation of electrical charging of insulating ceramics and its avoidance or reduction by appropriate experimental procedures is particularly emphasized.     

Möglichkeiten zur Steigerung der Energieumsetzung durch pulsierende Verbrennung

Ohne Zusammenfassung VDI Schlu? des Aufsatzes aus Heff 4 (1965) S. 108/14.     

Möglichkeiten und Grenzen der Miniaturisierung von Ionisationsvakuummetern

The current mainstream trend in the modern vacuum measuring technique is significantly characterised by the development and the production of miniaturised vacuum gauges. By the help of modern techniques of micromachining, in the past years the most important basic operation principles of pressure measurement were already utilised in micromachined vacuum sensors. But solely the miniaturisation of ionisation gauges, the only practical gauge type for the use in the high and ultra high vacuum range, was without success (up to now). The arising difficulty results from their basic operation principle which limits the miniaturisation of this vacuum gauge type. Within the scope of this work, the reasons for the limitation of the miniaturisation of ionisation gauges will be explained and discussed.     

Chancen und Möglichkeiten der Plasmatechnologie: Eine Bestandsaufnahme

In recent years low temperature-non equilibrium plasmas have gaines considerable momentum as a powerful tool for advanced materials synthesis and processing. Due to the availability of innovative computer codes for field and gas flow simulations, novel plasma sources and related diagnostics plasma aided manufacturing has demonstrated is potential as a key-technology. However, a successful transfer from the lab to industry requires more. After some plasma basics, source principles and process examples some of these additional requirements are discussed and illustrated in the light of own transfer activities.     

Möglichkeiten zur Lebensdauervorhersage durch Eigenspannungsmessungen an einem wechselbeanspruchten austenitischen Stahl

X-Ray Stress Measurement on Austenitic Steels – A Possibility of Predicting Fatigue Damage Based on the results found for fatigue tests on a ferritic steel combined with x-ray stress analysis similar investigations were carried out for an austenitic stainless steel. For that reason the Wöhler tests were interrupted after defined load cycle numbers and the residual stress and the half value breadth of the x-ray peaks were determined in the groove of the samples. The investigation has shown correlations between residual stress, load amplitudes and load cycle numbers. These relations in connection with a dependence of the breadth of the x-ray peaks from the load cycle number have been used for a non-destructive testing model of predicting the life of samples under alternating load.     

Zielsetzung und Möglichkeiten der Messung mechanischer Eigenschaften von Lackfilmen

Objectives and facilities of measuring the mechanical properties of paint films. Satisfactory values for basic mechanical properties are required if the film is to perform the protective function reliably. The measurement of mechanical properties can be difficult, because the material under test is only a thin film and the influence of the substrate must be eliminated. The chemical structure of the macromolecular binder of the film implies the “viscoelastic” behavior, characterized by a typical dependency on temperature and time scale of stress. For practical purposes, mechanical properties are measured with technological methods which are however complicated in physical terms. This restriction is not existent for welldefined physical methods, such as the one-dimensional stress-strain test and various methods providing for periodical stress of the specimen. Results obtained with these methods are characteristic for the viscoelastic film behavior.     

Messung von Rayleighwellen zur Untersuchung der Erosion an der Oberfläche kristalliner Werkstoffe mit Hilfe der Doppelpuls-Holographie

Measuring Rayleigh Waves to Investigate the Erosion at the Surface of Crystalline Materials by Means Double-Pulse Holographic Interferometry The repeated impact of solid particles on a material surface results in erosion. For technical applications as the pneumatic transport the particle diameters are varying between 10^?610^?3 m, the mean particle velocities are up to 30 m/s. In order to investigate experimentally the mechanism of erosion for crystalline materials, planar plates of austenitic steel are damaged due to the repeated impact of spherical particles. The elastic and plastic deformations, which are produced by this impact, result in propagation of longitudinal and transverse elastic waves into the material and of Rayleigh waves along the material surface. The amplitude of the surface deflection due to a single impacting particle is only 10^?810^?7 m. At different states of damage the surface deflection which is caused by such an impact is measured by means of double-pulse holographic interferometry. Because of the small amplitude of the Rayleigh waves two-reference-beam holographic interferometry is required. The initial wear of the material is recognized by the disturbed propagation of the surface wave.     

Möglichkeiten der Kombination von Stoffen durch hohe und höchste Verformung

Possibilities of producing composites by extremely high deformation . One of the principal problem in the studies of composite-wires with metallic matrix was wether fibre textures of such wires are changed by the contents of second phases or not. An inhibition of the texture development of the matrix occours, if the flow stress of the addition is lower than that of the matrix, and the plasticity of the addition is small, compared with that of the matrix. The mechanism of plastic deformation of the second phase (crystal slip, amorphous flow) is without influence. Preparation of the speciment can be done by solidifiction from the melt, especially combined with directional solidification and furtheron by powder metallurgycal methods. A very high decrease of cross section is connected with the formation of fibres. If the diameter is beneath 1000 Å remarcable anomalies of mechanical and physical properties were observed. The compatibility of the different phases is very good, provided that a high and joint deformation occurs. It is caused by the increase of inner surface during deformation.