Mechanische,chemo-mechanische und optische Oberflächenprüfung

Every surface will experience some kind of wear which is caused by abrasion. Depending on the use of the surface this damage can affect only the optical appearance or even affect the function. It depends on the use of product whether abrasion of the surface is relevant or not. In any case there are many different methods and instruments for measuring and evaluating the mechanic, chemo-mechanic and optic degree of abrasion.     

Oberflächenschutzschichten für metallische Hochtemperatur-Werkstoffe. Teil 1: Entwicklungstendenzen,Prüfung und Herstellung von Schutzschichten

Protection of High Temperature Metallic Materials against Oxidation . Part 1: Development Trends, Testing and Preparation of Protective Layers. A comparison is given of the chemical compositions of industrial Co- and Ni- high-temperature alloys used in the past years. Due to their relatively low Cr and Al contents the more recent super-alloys require additional oxidation protection. Theoretically, the refractory metals would allow much higher working temperatures than the super-alloys, but alloys based on such metals need a much more perfect oxidation protection. The fabrication testing and methods for such protective layers are briefly reviewed. The second part of this paper will describe some specific protective layers for super-alloys and refractory metals.     

Oberflächenspannungsmesstechnik für den Prozesseinsatz

Using Surface Tension Measurement in Applications When cleaning surfaces it is crucial for the process stability that the optimum surfactant concentration is maintained. The concentration of free surfactants can be measured by determining the surface tension. SITA Messtechnik has developed an innovative sensor based on the bubble pressure method. This sensor makes it possible to continuously measure surface tension with a high reliability. With this application for monitoring cleaning baths the potential to save money arises in regard to the use of raw materials, waste disposal and the costs resulting from undiscovered production failures.     

Oberflächen‐ und Dünnschichtanalytik – unverzichtbares Werkzeug für Schichtentwicklung und ‐produktion

Surface and thin film analysis – indispensable tool for coating development and ‐production Development and production of thin films for functional coating on special materials is unalterable combined with a permanent quality control and therefore use of sophisticated analysis and measurement techniques. The field of interest is belonging to all steps of the production chain, starting with the characterization of the substrate surface (e. g. glass, plastics), followed by polishing and cleaning processes up to depth profiling of complex multilayers. The typical analyses are focused onto topographical and chemical features and their influence onto the product functionality. The use of surface and thin film analytics for problem oriented characterization is demonstrated by a few examples, which deal with surface roughness, contamination, impurities and dopand profiles as well as composition variations in the surface near region.     

Plasmachemische Mikrostrukturierung von polymeren Oberflächen für Pharmazie und medizinische Diagnostik

The plasma masking technology is a method applied to get locally selective, physical‐chemical structuring on nearly all plastic surfaces in the micrometer range. Such generated chemically functionalised, polymer‐based surface structures are suited for use as biochips and will promote the application of low priced polymer materials with appropriate modified surfaces. Provided with a biochemical treatment for analytical methods, they are used in medical diagnostics and pharmaceutical drug research. This technique supports the increasing application of high throughput screening systems (HTS) including micro arrays for genomics and proteomics as well as the development of cell biochips.     

Anorganisch‐organische Hybridschichten für die Entspiegelung optischer Oberflächen

Inorganic‐organic hybrid coatings for antireflection of optical surfaces The application of nanostructures for optical surfaces has been discussed since antireflective nanostructures have been discovered on the eyes of night‐flying insects. On injection molded plastic lenses, antireflective nanostructures can easily be produced by plasma etching. The procedure has now been adapted to vacuum evaporated organic layers. Complex coatings composed of inorganic layers and organic nanostructures are especially suitable for realizing broadband antireflection properties on glass lenses.     

Herausforderungen an Füge‐ und Oberflächentechnik für zukünftige Leichtbaukonstruktionen im Automobilbau

For the reduction of the weight of vehicle hot‐rolled magnesium alloys as well as carbon fiber reinforced plastics (CFK) shall be integrated into the body structure. Both light weight materials electrochemically are not compatible with galvanized steels or aluminium alloys, unless great efforts of corrosion protection measures are taken. From electrochemical investigations an oxidceramic surface layer deposited by plasmachemical oxidation can be recommended as a promising solution. The low‐porous oxidation deposit with limited insulation effect can be painted by e‐coat in high quality after joining in the body shop and before the full paint system will be deposited. In opposite to magnesium CFK parts have, however, electrochemically a very noble character causing galvanic corrosion of attached metallic parts when the carbon fibers are not fully embedded in the matrix or damaged by the cutting. Only joining elements made from stainless steels or titanium alloys (e. g. Ti‐6Al‐4V) are suitable for the joining of CFK by screwdriving and riveting technology to avoid galvanic corrosion. From view of compatibility of materials, a severe anodic corrosion risk can be eliminated by isolation through adhesive bonding in the flanges and an additional sealing to prevent from electrolyte ingress.     

Schützende Oberflächen für metallische Werkstoffe

Coatings for Metallic Materials . The most important coating techniques are characterized and critically described. Among the various possibilities to protect the surface of metallic materials against mechanical, chemical or mechanical-chemical attack, the coatings which are looked upon are ranging from metallic coatings over nonmetallic anorganic to the organic ones.     

Heliumlecktestgeräte für die Qualitätsprüfung von Gehäusen für Vakuumverdichter

Helium leak test devices for the quality inspection of housings for vacuum compressors The well‐known and wide‐spread helium leak test method is a safe and fast quality testing method for construction units of any kind. Due to its safe examination and the short time of examination it is predominantly inserted into automated production lines as e.g. in the automobile supporting industry up to the examination by Airbags and rims of wheel. Likewise in addition, for the construction units, machines and devices of the vacuum engineering. From this the demand results simple and in particular economical devices for the helium leak test of construction units with small numbers of items of under 200 pieces per day. For these manufacturing profiles economical ways for the helium leak test are pointed out.     

Untersuchung der Verteilung und Intensität filamentierter Barrierenplasmen für die Behandlung von Oberflächen

The application of barrier discharges at atmospheric pressure in air expands on the market of plasma technology, because it is an ecological and cost‐effective alternative to other processes of surface treatment. These plasmas usually consist of a multitude of spatially and temporally localized filaments, whose distribution should be as even as possible for homogeneous treatment. This holds especially for the plasma treatment of sensitive goods such as wool or other textiles. In equipment for continuous pass of material the barrier arrangements often consist of a system cylinder – cylinder or cylinder – plane, whereby the gap width changes locally. Space distribution and intensity of filaments has been investigated by means of short‐time photography and spatially resolved measurement of current distribution and energy distribution derived from it. The local dependency found can be explained by means of a capacitive equivalent circuit.     

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.     

Plasmapolymerschichten als Basis für maßgeschneiderte funktionale Oberflächen

Plasmapolymer coatings for tailor‐made functional surfaces The tailoring of surface properties via polymer coatings is currently a strongly pursued topic in various fields ranging from microsystem technology to bioanalytics. A precise tuning of surface properties, however, is only possible if chemically well‐defined processes are used that usually require reactive surface moieties to which molecules can be coupled. In this contribution we summarize studies that aimed at the modification of inert surfaces. For this purpose reactive groups at the surfaces are generated by plasma polymerisation of allyl amine which results in layers that contain amino groups. Initiator molecules for free radical polymerization processes are then coupled to these amino groups resulting in surfaces from which polymers can then be grown via surface‐initiated polymerization. Using these processes, polymer monolayers with very different properties can be generated by simply using different monomers.     

Oberflächenschutzschichten für metallische Hochtemperatur-Werkstoffe. Teil 2: Schutzschichten auf Superlegierungen und hochschmelzenden Metallen

Protection of High Temperature Metallic Materials against Oxidation , part 2; Protective Layers on Superalloys and High Temperature Materials. The structures of typical protective coatings of superalloys and Nb-alloys are briefly described and possible reasons for their failure are given. The importance of self-healing properties and of the reliability of such protective layers in any technical application is stressed. An order of magnitude of the duration of protection for different alloys is indicated for several coating types.     

Spannungsintensitätsfaktoren für lange axiale Oberflächenrisse in Rohren bei Thermoschockbelastung

Stress Intensity Factors for Long Axial Surface Cracks in Pipes Under Thermal Loading The stresses occurring in the pipes of the primary loop in the case of an emergency cooling may be described conservatively by a thermal shock problem. The influence of these thermal stresses on a long axially orientated surface crack is studied in this paper. By means of the weight function method stress intensity factors are calculated for this loading case.     

Werkstoffe und Oberflächenmodifikationen – Schlüssel für eine ökonomische Spritzgießfertigung

Materials and surface modifications – Keys to an economical injection moulding An economical injection moulding includes a cost‐effective tool production, a free‐moving tool, a production which consumes low amounts of resources and runs with short cycle times and last but not least a low need of tool repair all over the life‐time of the tool. It can be shown, that no material can satisfy all the mentioned demands. So it is advisable that these properties which are determined by the properties of the tool surface can be performed by a coating. Those properties which are characteristics of the tool volume can be performed by a suitable base material. Following this concept it is possible to configure a light weight tool which is running without maintenance for a long time and makes short cycle times possible. It will be shown that a tool body produced by applying an aluminium alloy finally coated with an electroless applied nickel‐plating is one possibility to achieve the aim.     

Oberflächentastschnitte als Hilfsmittel der Werkstoffprüfung

Material Testing by Means of a Stylus-Type Roughness Tracing Instrument . Our experiments and a literature of survey show the various possibilities and limits of surface roughness measurements by means of the stylus-type roughness tracing method. Through direct or, by applying an imprint technology, through indirect surface tracing on materials such as metals, plastics including coatings and lacquers (duromers, plastomers, elastomers), wood, paper, asbestos sheets, textiles and coal a connection with the properties of the materials with respect to wear, sealing and contact, roughness of fracture surfaces, material testing, surface roughness of an injection mould, process and machining, corrosion, damage analysis, optical aspect, writing pressure curves, cracking etc. has been illustrated. Two examples from the medicine (dermal and dental medicine) underline the broad range of application possibilities. In many cases the stylus-type roughness tracing method is a secondary, however, generally very informative indirect testing method. Only in some cases it is in direct connection with a certain property of material such as the surface gas tightness of asbestos sheets. The limits of the stylus-type roughness tracing method are further determined by the method of measurement (stylus pressure, radius of stylus, curvature, stylus system).     

Spannungsintensitätsfaktoren für vollständig umlaufende Oberflächenumfangsrisse in Rohren bei Thermoschockbelastung

Stress Intensity Factors for Complete Circumferential Surface Cracks in Thermally Shocked Pipes In the case of an emergency cooling of a reactor thermal stresses are generated in the pipes of the primary loop, which may be described conservatively as a thermal shock problem. In this paper complete interior circumferential surface cracks loaded by these thermal stresses are considered. By means of the weight function method stress intensity factors were calculated for this loading case.