Fortschritt in der Vakuum‐Messtechnik

Minimum power consumption, enlarged measurement range, improved resolution, excellent stability, digital adjustment possibility, lower volume: these are – briefly – the features of the recently introduced innovative Pirani‐Vacuum‐Transmitter.     

Der Gradient der Wöhlerkurve

The Gradient of the S, N-curve. The classical two-parameter basic equations of Wöhler and Basquin and also the four-parameter equation of Palmgren/Weibull approximate the Wöhler curve in certain ranges only. They fail in particular when one attempts to use them to convert a service life increase into the appropriate gain in strength. For a more exacting analysis these approximations must be replaced by models of the Wöhler curve which are nearer to actual reality.     

Der Nachweis dünner Fremdschichten auf Kontaktoberflächen

The detection of thin contaminated layers on contact surfaces . Today electrical contacts must satisfy requirements which are growing steadily. The detection of very thin contaminated layers at contact surfaces therefore becomes very important. Clad gold contacts were contaminated with very small amounts of Zink. Contact resistance measurements and surface analysis measurements by AES and SIMS were shown to be adequate for the detection of this surface contamination.     

Untersuchung dünner Schichten mittels Röntgenreflektometrie

Thin film characterization by means of X‐ray reflectometry X‐ray reflectometry and diffractometry are widely used non‐destructive methods to characterize thin films in the total thickness range which is typically between 2nm and approximately 500nm. On special arrangements a resolution up to 1000nm layer thickness has been demonstrated. Layer stack morphology, surface topography, layer structure, material density, single layer or period thickness and surface and interface roughness are the typical structural parameters both of single layers and of multilayers which can be described by the measured data. The performance of the measurement setup is mainly influenced by the parameters of the incident X‐ray beam like beam divergence, monochromatism and photon energy. In the following the influence of the optical components in the beam path to angle and energy resolution of X‐ray reflectometry is discussed.     

Zerstöurungsfreie Prüfung dünner CFK-Laminate mit innenliegenden Fehlern

Nondestructive Testing of thin CFRP-laminates with Internal Flaws Carbon fiber reinforced plastics (CFRP) are more and more used for primary aircraft structures. Therefore, nondestructive testing is of increasing importance for quality control and maintenance. Test specimens with different flaws show the accuracy by which even very small flaws in CFRP laminates can be detected when using ultrasonic (US) and X-ray-techniques. The US-measurements (C-scans) were effected by a highly resolving US-flaw detector. Details of the system and of testing methods are described. The C-scans are compared with X-ray evaluations. Internal flaws which cannot be found in a normal X-ray image due to X-ray absorption were filled with a contrast agent (TBE); afterwards they appeared very clearly on the X-ray film. A comparison of nondestructive tests and between nondestructive and destructive tests showed a good agreement.     

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.     

Röntgendiagnostik plasma‐gestützt abgeschiedener dünner Schichten

X‐ray diagnostics of plasma deposited thin layers Grazing incidence x‐ray diffractometry (GIXD) and x‐ray reflectometry (XR) have been introduced as well suited tools for investigations of plasma deposited thin layers. They are non‐destructive techniques, therefore a sample can be reused and measured with other techniques. A combination of GIXD and XR can give a range of interesting information about chemical, physical and crystallographic properties of thin films. Conclusions can be drawn how plasma deposition techniques and plasma parameters influence the film growth. In three examples we present the analysis of phase and chemical composition, defect structure and measurements of kinetic process parameters.     

Der Einfluß der Haupt- und Seitenkerbung auf die Temperaturabhängigkeit der Kerbschlagarbeit

The effect of main notch and of side grooves on the temperature dependence of the absorbed energy in impact tests Charpy impact tests were performed on test pieces having different radii of curvature of base of main notch. Six series were sidegrooved and six series were without side grooves. The fracture mechanisms and the appearance of the fracture surfaces are discussed. It is shown that the common practice to assign lower shelf, transition range, and upper shelf in the absorbed energy-temperature curve to cleavage fracture, mixed fracture, and fibrous fracture is not always valid. Cleavage fracture may occur in the entire transition range and mixed fracture may take place in the upper shelf.     

Der Verdacht der Simulation

The Suspicion of Simulation. A Psychiatric Case History between Appropriation and Disciplinary Action at the End of the 19th Century. This case history explores how the question of agency was dealt with historically in two developing, normative orders of deviant behaviour. Examining the institutional career of the supposed adulterer, marriage swindler, and craft baker, we can trace the different observation regimes and systems of knowledge acquisition in the prison and in psychiatry. In both institutions there was talk of simulated madness; the explanations, however, were different. For the prison doctors and civil servants, the baker was a criminal; his deviant behaviour was a matter of consciously planned-out deception. For the examining psychiatrist, on the other hand, he was mentally ill and could not be held responsible for his own behaviour.     

Elektronenbeugung zur Analyse dünner Funktionsschichten

Electron Diffraction for Analysis of thin Functional Layers A short history of the diffraction techniques in crystallography is given and the basics of electron diffraction in transmission electron microscopy are explained: electrons as waves, Bragg's law, selected area and convergent beam electron diffraction. The possibilities of the often used selected area electron diffraction are demonstrated by two typical examples: determination of the crystallographic orientation in single crystalline layers (piezoelectric LiTaO₃) and phase analysis in polycrystalline structures (Ni‐Al‐O hard coatings).     

Röntgenröhren in der Medizintechnik

X‐Ray Tubes in Medical Imaging Applications The application of X‐rays in medical diagnostics has become an essential element in everyday life. Every hospital or imaging center uses X‐ray radiation to get an insight into the human body within shortest time. The technology which is used to take an image of the mandible or to create a full body scan of an emergency patient by computer tomography within a few seconds is the same. This article describes shortly the history of the invention of X‐rays. The creation of X‐rays is explained by a simple schematic. The relevance and function of the cathode to create free electrons is very important. The evolution form simple thermal filaments to electron field emitters is described. The innovation of liquid metal bearings is also essential to realize high power X‐ray tubes by effectively removing the heat from the anode. After a short excursion to the medical applications of X‐Ray imaging a completely new approach of X‐ray source is described.     

Der Beitrag der zerstörungsfreien Prüfung zur Zuverlässigkeit und Verfügbarkeit korrosionsgefährdeter Komponenten von Chemieanlagen

The part of Nondestructive Testing of Ensure Reliability and Availability of Components of the Chemical Process Industry under Corrosive Conditions Corrosion and wear failures very often are initialized or at a minimum influenced by faults in design, manufacturing and installation. If we reduce these faults, the result will be an increasing working life of the components. To solve this problem, we recommend the consequent use of NDT-techniques.     

Der Einfluß der Feuchteaufnahme auf die mechanischen Eigenschaften von Phenoplasten

The Effect of Moisture on the Mechanical Properties of Phenolic Moulded Materials In order to use thermosetting moulding material it is necessary to know how the mechanical properties are changed by absorption of water. Therefore, multiphase systems based on phenolic resin, with varying quantities of wood flour and/or powdered minerals as fillers, were examined. The relationship between moisture absorption and the change in Young's modulus, flexural strength and the strain of the outer fibre at fracture was determined. It could be shown that the increase in flexural strength as water absorption began is a result only of the swelling stress.     

Realistische Modellierung der NIR/VIS/UV‐optischen Konstanten dünner optischer Schichten im Rahmen des Oszillatormodells

Modelling the NIR/VIS/UV optical constants of thin solid films: An oscillator model approach Based on a multioscillator approach, we demonstrate the determination of optical constants of different optical coating materials. The advanced LCalc‐software allows calculating the dielectric function as well as refractive index and extinction coefficient through a fit of transmittance and reflectance spectra measured at one or several angles of incidence. Sufficiently accurate spectrophotometric measurements are carried out by means of self‐developed VN‐ The thus obtained optical constants are automatically Kramers‐Kronig‐consistent and in reasonable correspondence to various kind of side information available about the coatings. This is demonstrated for dielectric oxide coatings as well as for one transparent conductive oxide (ITO) and a metal layer (aluminium). In application to reproducibility experiments, the method allows estimating process‐inherent stochastic variations in optical constants, which represent themselves an essential input for advanced computational manufacturing runs for design optimization prior to deposition.     

Der fotograf der goldenen zwanziger Jahre

Abstract

Fragmentation involves anteriority, decay, and loss in relation to some superseded whole. As excerpts from a world that was, photographs are understandable as fragments, which means that they carry with them an invitation to reflect on and even to reconstruct former environments and totalities. The history of photography is a history of responses to that invitation, most of which are studiedly hesitant and doubtful of an outcome. One reason for this hesitation is that photographs seem to exist in a perpetual present, which means that photography inevitably has reservations about the past as past. If its personnel still exist, and if its events are still in progress, photographic representations would be better termed presentations. They belong, even if seemingly so, to an everyday in process, where everything is still to be resolved.¹