Zukunftsperspektiven für die Pulvermetallurgie durch die Betriebsfestigkeit

Future Perspectives for the Powder Metallurgy by Structural Durability Considerations The fatigue behaviour under complex variable amplitude loading cannot be simply assessed by knowledge of constant amplitude data. The peculiarity of variable amplitude loading, which occurs in almost all technical applications, is the possible frequent exceedance of the so called fatigue limit without reducing the required service life of the components. This fact which is described as structural durability enables a lightweight design of components and results in an aimed material exploitation. Thus, this advantage has not yet been considered in the design of PM parts. The paper discusses the suitability of PM steels for such complex service loadings and if the concept of structural durability may open new application perspectives.     

Erprobungsmethodik für zyklisch überelastisch beanspruchte Bauteile unter Torsion – Bauschinger‐Kenngrößen für 54SiCr6

Power transmission contains several torsion‐stressed parts. Especially shafts and springs are numerous considered. Helical springs as a special type of springs are mainly stressed by torsion load. During operation the spring's load is basically elastic. In some cases, like overload or machine disaster, the load exceeds the spring's yield stress. For a single event the deformations can be calculated easily by using flow charts. However in other cases the spring will be stressed several times with alternating plastic load. Therefore the calculation will not be as easy as in the single load case. Especially the hardening and softening mechanisms have major influence on material behavior. For high strength steel this material behavior is not fully investigated right now. Present article shows a way how to investigate several important Bauschinger parameters based on plastic torsion load for the high strength steel 54SiCr6. Finally it can be shown that 54SiCr6 is influenced by the Bauschinger effect. On the other hand the needed material characteristic can be investigated by the shown methodology. Based on the identified data, analytical and numerical calculation of alternating plastic torsion load can be done.     

EVICD – eine Lebensdauermethode für komplexe mehrachsige Betriebsbelastungen für die Praxis

EVICD – an advanced crack intiation life prediction method for engineering application In the present paper an overview of the latest stand in the development of EVICD, a crack initiation life prediction method for arbitrary multiaxial loading, is given. The incremental prediction method which was originally proposed by W. Ott and which was later extended by the introduction of a secondary damage parameter either based on the normal stress on the planes with maximum shear stresses (EVICD‐N) or the normal stress on the octahedral planes (EVICD‐J1) has been further developed: A special Input Section was created, which is open to all important types and formats of engineering input data for fatigue calculations. The results of strain measurements can also be taken. Further on, the multiaxial Neuber‐Method has been worked in for a fast determination of the elastic plastic stresses and strains at fatigue critical locations of components. At the end of the Input Section the elastic plastic stress or strain path at the fatigue critical location is transferred to the damage evaluation modul of EVICD for an evaluation of the crack initiation life. The Mróz‐Garud plasticity model has been worked in the damage evaluation model. The fatigue damage evaluation does occur after a transparent flow diagram and has been realized as a FORTRAN Code. This is important for a general use of EVICD in practice. Meanwhile EVICD has been verified on a broader basis. A representation of the prediction results after EVICD vs. the corresponding experimental results after a proposal of E. Haibach shows, that the prediction capability of EVICD has become better than that of conventional fatigue prediction methods.     

Magnesium – der Zukunftswerkstoff für die Automobilindustrie?

Magnesium – future material for automotive industry? Magnesium alloys show a very high potential in automotive applications as constructive metal, whereas the main focus lies on die cast parts. Electronic industry is the major commercial consumer for die castings besides the automobile industry. Room temperature applications like steering wheels and frame components in cars as well as mobile phone‐ or notebook housings are well established. These castings are produced with AZ‐ or AM‐magnesium alloys, which show good room temperature properties and a good castability. The great alloy development challenge in extending the use of magnesium cast alloys are application for higher temperatures. The application in powertrain components is considered to be the benchmark here. Besides alloy development there are also further research activities in development of casting processes. Semi‐solid processes like New‐Rheocasting (NRC), Thoxomolding ? or Thixocasting (TC) are adapted to the requirements of newly developed alloys. Not only cast alloys but also magnesium wrought alloys have moved to the centre of interest in the last decade. Alloy development for improving the formability on the one hand as well as process development in extrusion or rolling has to be done in order to find optimum parameters for deforming magnesium alloys properly.     

Revolution statt Evolution – Innovative Folientechnik für die Kfz‐Außenhaut

Revolution in Place of Evolution – Innovative Foil Technique for Automotive Body Shell Foil techniques represent an innovative option compared to traditional automotive painting. Cost reduction demands and light weight construction has brought forth the requirement to apply polymers at automotive body shells. Particularly, thermoplastic polymers enable a large freedom for the design of modern cars at moderate costs. The foil technique is also a promising approach for an introduction of long glass fibre reinforced thermoplastics into the outer body skin and to reach a Class A finish. One technology is the colormatchable foil technique (CFT). In cooperation with BASF Coatings AG, Münster INPRO developed this new technology to the stage of fundamental feasibility. This new technology stands short before its introduction in practice.     

Bandsägen für die Steinbearbeitung – aktuelle Technologieentwicklung

Bandsawing machines for stone cutting – state of the art Due to an EU‐research‐project BaSST a new process was developed to cut slabs and tiles in granite, marble and sandstone out of a huge stoneblock by means of a bandsaw. Such natural stones are very hard, the cutting forces generated to the sawband have to be limited. This was realized with a pivoting sawband, which allows to vary the effective length of engagement depending of the dimension of the material. Simoultaneausly a sawband with diamond cutting segments was developed and tested. Over a long period of optimization a long lifetime of the sawband was reached. The end of the service life was determined by normal wear of the cutting segments and not by breakage of the sawband together with very high cutting rates and excellent cutting surfaces. The outstanding advantage of this new cutting process is a high flexibility for the production, so far unknown till now, a very good cut quality and a remarkable reduced waste of material due to the thin sawband. The number of slabs cut from a block can be doupled due to the thin kerf of the sawband. The new cutting process allows to cut slabs and tiles from a block in a very economic way and under best environmental conditions.     

IonScan 800 – Ultrapräzise Schichtdickenkorrektur für die Halbleitertechnologie

IonScan 800 – Ultra precise Film Thickness Trimming for Semiconductor Industry Many applications in semiconductor technology are characterised by extreme requirements in terms of film thickness homogeneity. When manufacturing Bulk Acoustic Wave (BAW) components, it is necessary to adjust film thickness values of different materials with accuracy values in the nm‐range. Standard processes, such as the film deposition techniques, do not fulfil these homogeneity requirements. Thus it is necessary to perform a local correction of the film thickness in a follow‐up process. The authors here introduce a new method of local film thickness trimming and its technical implementation. During the process, the wafer is moved in front of a focussed ion beam. The local milling rate is controlled upon the residence time of the ion beam at certain positions. A modulated velocity profile is calculated specifically for each wafer, in order to mill the material at the associated positions to the homogenous target film thickness. Depending on whether an inert or reactive ion beam process is used, it is possible to apply the IonScan technology for any material desired, such as Si₃N₄, SiO₂, Al₂O₃, AlN, W, Mo, Cu or NiFe.     

Anlagenkonzept für die Abscheidung dünner Schichten durch Plasmapolymerisation

This plasma polymer layers are deposited by a plasma enhanced CVD process directly from the gas phase of an organic precursor (plasmapolymerization). Film growth rate is limited by the quantity of gas input. Plasmachemical conversion in the gas phase as well as at the film surface can be applied to affect film properties. The relation between the characteristic conversion time of the process and the application features of the plasma polymer layers lead to a vacuum technological concept for development and design making large scale applications in industry very predictable.     

Kollektorbeschichtungen für die EUV‐Lithografie

Collector Coatings for EUV Lithography Extreme ultraviolet lithography (EUVL) is the next generation lithogra phy method operating at the wavelength of 13.5 nm (14 times shorter than current lithography systems), enabling semiconductor scaling to resolutions of 22 nm and below [1]. This paper presents the successful coating of the world's largest ellipsoidal collector mirror for EUV radiation with a diameter of 660 mm ( Fig. 1 ). In order to achieve the required peak reflectivity of more than 65 %, the ellipsoidal collector was coated with a highly reflective, laterally graded multilayer using the dc magnetron sputtering system “NESSY”. A maximum reflectivity of the laterally graded multilayer of more than 65 % was achieved for radii smaller than 220 mm. For radii between 230 mm and 320 mm the reflectivity decreases to a minimum of 58 %. The targeted wavelength remains constant at (13.50 ± 0.05) nm over the entire collector surface which is well within the tight specifications for high volume manufacturing.