Bedeutung von Prüfmethoden für die Auslegung verschleißbeanspruchter Bauteile

Test Methods and Dimensioning of Tribologically Loaded Parts Owing to the complexity of tribological systems the testing of wear components is of particular significance. Here is an effort to show the advantages and disadvantages of product tests, component tests and model tests. Even with model tests good results for the products are attainable when relevant parameters are systematically varied. Hereto some examples are given.     

Die Entwicklung von Strukturmaterialien für die Kernfusion

The Development of Structural Materials for Fusion Reactors Structural materials for the First Wall and breeding blankets of future fusion reactors will be exposed to intense neutron irradiation and thermal wall loading. Fusion‐specific selection criteria for the proper choice of materials are primary damage parameters, a minimum of produced radioactivity (low activation materials) and also conventional properties like strength and corrosion resistance. Three major material groups are under discussion: ferritic‐martensitic 7–12%Cr steels, SiC‐fiber‐enforced compound materials of type SiC_f/SiC and specific vanadium‐based alloys. A short status of development and a survey on necessary further research work is given to fulfil the material requirements for the construction of the next fusion reactor devices. Finally the necessity for an appropriate 14 MeV neutron source as test bed for the material development is mentioned.     

Werkstoffauswahl für schlagartig und zyklisch belastete metallische Bauteile

Material Selection for Impact and Fatigue Loading The structural durability of components is dominated mainly by the geometry, i.e. notches. Compared with the impact resistance of forged components from ductile materials high impact values can be realized by an appropriate shaping also using less ductile cast materials. Creep deformations can be suppressed in presence of notches. The strength level of the base material remains for stress concentrations above K_t = 2.5 and for the welded state without influence on the fatigue behaviour. If sharp notches cannot be avoided by a new design, benefits from high‐strength materials can be taken only in connection with surface treatments which introduce high compressive residual stresses. Principally, advantages from high‐strength materials can be gained for unwelded components only by reduction of the stress‐concentration and in case of welded joints by smoothening or removal of the weld notches and in case of spot welds by transferring of the failure location outside of the nugget.     

Die Anwendung von Schallemission für die Schweißnahtkontrolle

The use of Acoustic Emission as a weld Quality Monitor . The results obtained from our experiments with spot welding, gas tungsten-arc welding, and submerged-arc welding demonstrate the potential of acoustic emission monitoring as a nondestructive test for welds. The real-time nature of the acoustic emission data sets this technique apart from other nondestructive methods used for weld inspection. Since the acoustic emission from weld defects is transient, empirical calibration is required for each application. Defects can be located approximately but the type of defekt cannot be determined.     

Entwicklung und Anwendung von mathematischen Optimierungsmethoden zur Ableitung von vereinfachten Prüfungen für Fahrwerksbauteile

Testing the fatigue life time of chassis components is necessary during the development process and for quality supervision during the period of series production. In many cases a simplified test is done to reduce the complexity of the test. The development engineer has to develop the specification of those simplified tests. According to the task different approaches are possible: Looking for an adaquate test load or for a simplified mounting ore both. This paper deals with several numerical methods for test specification development. Especially a numerical optimization routine is presented for detection of a signifcant load case. Also the iterative searching for a simplified mounting in combination with damage based selection of load channel is shown. Exemplary the application of the routines is demonstrated by Porsche PANAMERA wheel carrier and a suspension‐strut receiving. The actual stage of development of the numerical routines is presented. In addition intended upgrades of the software are shown.     

Die Bedeutung von Gas-Metall-Reaktionen für die Reinigung und den Einsatz hochschmelzender Metalle

Zusammenfassung Die hochschmelzenden Metalle der VA-Gruppe und der VIA-Gruppe k?nnen bei h?heren Temperaturen Gase interstitiell in L?sung aufnehmen. Dadurch ergeben sich entscheidende Ver?nderungen vieler mechanischer und physikalischer Eigenschaften der Metalle. Es werden die Vorg?nge bei der Gasaufnahme und der Gasabgabe besprochen sowie insbesondere Daten über Eigenschafts?nderungen der Metalle durch gel?ste Gase, Daten über die Kinetik der Gasaufnahme und der Gasabgabe sowie Beziehungen zum Berechnen thermodynamischer Gleichgewichte und station?rer Zust?nde angegeben. Dabei finden die Metalle V, Nb, Ta, Mo, W und die Gase N₂, O₂, H₂, H₂O, CO sowie CH₄ Berücksichtigung. An Hand einiger Anwendungs-beispiele wird auf die Bedeutung von Gas-Metall-Reaktionen in der Praxis hingewiesen.     

Die praxisnahe Ermittlung der Anfälligkeit hochlegierter Stähle für chloridinduzierte Spannungsrißkorrosion Neueste Erkenntnisse über die Aussagefähigkeit verschiedener Prüfverfahren

Methods for Testing Sensitivity of Higher Alloyed Steels to Cl-Induced SCC – Reducing the Results to Practice Resistance of stainless Cr-Ni-steels against stress-corrosioncracking – Laboratory-tests – Comparison and interpretation of the different results with regard to practice.     

Ionen- und plasmagestützte Verfahren der Oberflächentechnik für die Randschichtbehandlung von Leichtmetallwerkstoffen

Surface engineering of light weight materials with ion- and plasma-assisted methods Increasing applications of light weight materials are expected in the future. Pursuing this trend surface engineering of these materials – especially ion- and plasma-assisted methods – swill be of increasing interest to enhance their wear and corrosion resistance. In a research co-operation some promising methods were examined on different aluminium and titanium alloys to assess their potential to increase the surface properties. Among these were magnetron sputtering of chromium nitride, ion beam assisted deposition of Cr/CrN and Al/A₂O₃ layers, ion implantation and ion beam assisted nitriding. Compared to the steel substrates the assessment of the mechanical properties such as the critical load of the scratch test of the coated light weight materials is different. Furthermore, it could be shown that both spherical section and glow discharge optical spectroscopy are useful methods to characterize the near-surface zone influenced by ion implantation.     

Beurteilung der Zuverlässigkeit von Schmiermitteln für die Feinwerktechnik

Assessment of the Reliability of Lubricants for Precision Machinery. The critical examination of the reliability of lubricants for instruments and precision machinery needs first the recognition of all the parameters influencing the efficiency of the lubricants. Afterwards these parameters have to be classified according to their significance of the application of the instruments and precision machinery. These numerous influences cause unexpected and very complicated interactions which often can only be recognized, if the instruments and precision machinery are tested under practical conditions. The very small quantities of lubricants used in the instruments and precision machinery require new techniques for examining the lubricated bearings. A well equipped laboratory and a serious planning of the tests as well are therefore indispensable.     

Messung der Schweißkraft,des Abbrandes und des Kontaktwiderstandes von Kontaktwerkstoffen für die Energietechnik

Measuring of welding force and contact resistance with a testing equipment to classify contact materials for power engineering . Knowledge regarding welding force, erosion and contact resistance is very essential to select and evaluate contact materials which are to be used in electric switchgear. Measuring systems and results which are found in the literature are mostly carried out under test conditions not close enaugh to practice. An automatic test switchgear with which the mentioned technological characteristics can be evaluated is described. Test conditions can be varied in a very wide range so that every condition can be selected suiting the switchgear. Data on welding force, erosion rate and contact resistance of the contact materials like Ag 1000, AgNi 10, AgCdO 12 and AgC3 are given. A statement on the quality of braze between contacts and carrying material can be given.     

Ionenbeschuss von Polymeren für die Medizintechnik

Ion Bombardment of Polymers for Biomedical Applications Ion implantation, a standard technology in the semiconductor industry, is also used since the 1960s for biomaterials. In the following, a variation of the method is presented for illustrative — plasma immersion ion implantation (PIII). In PIII treatments process times of less than a minute are found to be sufficient to change the surface energy at least for several weeks. In addition, a modified coefficient of friction, wear and topography can be obtained, with reduced wear rates and an increased roughness having a positive impact on the biocompatibility and the bioactivity. For combined coating and implantation processes with simultaneous energetic ion bombardment, an excellent adhesion is obtained even at room temperature. In addition to the formation of photo‐active surfaces, which may have an antibacterial effect here also an osteoinductive topography can be achieved.     

Plasmapolymerisation für die Hartbeschichtung von Kunststofflinsen

The use of plastic as a substrate material for optical lenses has been increasing in importance due to smaller density, simpler machining and lower price. However scratches present a major problem wherever the lens surface is exposed to the environment. Various processes have thus been developed to protect the surfaces with hard coatings. The most common technique is the dipping process while spinning or spraying are other methodsto apply lacquer. Common to all these techniques are the required post treatments such as drying and heat or UV curing. Safety considerations as well as the long processing time and the handling required between the different steps, gave rise to the development of new technologies. Plasma polymerization, a technology relying on plasma enhanced chemical vapor deposition (PECVD), is used to deposit dense organic layers with reproducible, well defined surface properties. In contrast to dip coating, plasma polymerization even coats strongly curved structures with good uniformity. This is important for bifocal or trifocal lenses, featuring sharp edges on the surface. Due to the wide range of refraction indexes (about n = 1.5–1.8) available by using different monomers, even the latest high index materials can be coated without disturbing interference fringes. After a survey of plasma polymerization basics, some aspects of industrial equipment and processes for ophthalmic applications are presented. An outlook into the future of plasma polymerization for optical applications concludes the paper.     

Durch veränderliche Betriebslasten in Kerben erzeugte Eigenspannungen und ihre Bedeutung für die Anwendbarkeit der linearen Schadensakkumulations-Hypothese

Residual Stresses Due to Variable Service Loads and Their Importance Regarding the Applicability of the Linear Damage Accumulation Hypothesis . The linear damage accumulation hypothesis often provides unreliable life estimations. To improve its application, residual stresses at the notch root of open hole specimens (K_t = 2,5) of the aluminium alloys AlCuMg 2 (US equivalent 2024 T 3) and AlZnMgCuAg (US equivalent 7075 T 6) were continuously measured during the macro-crack-free life range. Based on the residual stress history a corrected hypothesis was applied.     

Abscheidung von Palladium und Palladiumlegierungen mit hohen Schichtdicken für die Mikrosystemtechnik

Deposition of Thick Palladium and Palladium Alloy Layers for Microsystems Technology Layers of metals and alloys deposited in microstructures usually require to be thicker than the 100 μm which is the approximate height of the structure. The deposited form of noble metals used in microsystems must be non‐stressed, ductile and free of cracks and pores. As the thickness of layers deposited from commercial noble metal electrolytes will rarely exceed 10 μm without loss of quality, developing an electrolyte system suitable for microsystems involves finding appropriate additives and deposition parameters. Details are given of deposit characterisation, the parameters of the deposition technology and some practical examples. Initial results are presented and discussed.