Schweißen von Hohlstrukturen und offenporösen Metallschäumen für den Einsatz in Kombi‐Kraftwerken

Welding of Hollow Structures and Open‐Porous Metal Foams for Application in Combined Cycle Power Plants For applications within the scope of novel cooling concepts joining technologies for sandwich composites and open‐porous metal foams are researched in the context of the Collaborative Research Centre 561 “Thermally highly loaded, porous and cooled multi‐layer systems for combined cycle power plants”. The research motivation and application fields of the different structures are defined. Welding processes and strategies for manufacturing these structures are specified as well as the joining technologies’ characteristics. Planned future works for enhancements of the processes and structures are listed.     

Schäden durch kerbinduzierte Schwingbrüche

Failures by notch induced fatigue fractures Notches produce local stress concentrations and promote the formation of fatigue cracks. Characteristic types of notches as a result of design, manufacturing and operation are presented and remedial measures are discussed. Examples demonstrate the effect of different kinds of notches on various components.     

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.     

Schäden an Bauteilen mit Verschleißschutzschichten

Damage of Components with Wear Resistant Coatings The appearance of wear happened to assorted components with different wear resistant coatings is described with the aid of metallographic microstructural investigation leading to the recognition of the cause of damage. Nitrided and reinforced extruder parts have suffered from sliding wear and abrasion. Thermally sprayed coatings consisting of oxides failed because of productional defects resp. taking the wrong material. The quality of thermally sprayed coatings can be proved by tearing tests without destroying the component.     

Schäden wälzbeanspruchter DLC‐Schichten auf Stahlsubstraten unterschiedlicher Härte

Damages of slip‐rolling tested DLC coatings on steel substrates of different hardness Extremely hard diamond coatings on hard SSiC substrates, various hard DLC coatings on 100Cr6 substrates (HRC60) as well as selected DLC coatings on unhardened steel substrates (HRC20) were tested under slip‐rolling conditions. Unadditivated paraffin oil was used as a lubricant. The tests were carried out in an Amsler type twin disc tester at initial maximum pressures of P₀=2.3 GPa according to Hertz. The tests were terminated after n=1.000.000 revolutions (endurance tests: n=10.000.000 revolutions) or if a coherent damaged area of A>1 mm² occurred. The slip‐rolling tests showed that the SSiC had a supportive influence on the diamond coatings which, however, failed due to fractures in the substrate. At least two of the DLC coatings on 100Cr6 substrates (HRC60) withstood the slip‐rolling test for up to n=10.000.000 revolutions with nearly no visible damage. These coatings deposited onto a soft, nitrogen alloyed steel (HRC20) were able to adjust to the deformation of the substrate without major damaged areas (A>1 mm²).     

Schwind- und Quellverhalten reaktionshärtender Kunstharzkitte für den Säureschutzbau

Shrinking and Swelling Properties of Chemically Cured Resin Mortars for Chemical Resistant Linings In the field of acid-proof construction chemically cured mortars, especially those based on phenolic, furan, epoxy or unsaturated polyester resins are used to apply linings on floors or in vessels. Sometimes these resin mortars are used as a troweling compound for monolithic floors, more often however as a bedding and pointing material for ceramic tiles or special shaped bricks. Because of the good adherence to the supporting construction to be protected, variations in dimension of the mortar as an effect of shrinkage or swelling cause stresses, which can exceed the strength of these linings and then could cause damage to the integrity of the installation. Methods for measuring the effective, i.e. stress generating dimensional changes in resin mortars were investigated for a variety of conditions, and testing equipment for determining the stresses generating in these mortars are developed. The results are represented graphically. The evaluation is done with respect to the possible effects of the behavior of the mortars in installed brick linings and floor coverings.