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Mariager, Denmark

Olsson D.D.,R and nter Dania | Bay N.,Technical University of Denmark | Andreasen J.L.,Novo Nordisk AS
International Journal of Surface Science and Engineering | Year: 2010

A tribological test for deep drawing has been developed by which the performance of lubricants may be evaluated quantitatively measuring the maximum backstroke force on the punch owing to friction between tool and workpiece surface. The forming force is found not to give useful information regarding the lubricant performance, since it is not sensitive enough to reveal changes in the frictional contact, whereas the backstroke force is very sensitive to pick-up and galling even on micro-scale. Results from testing different lubricants with different performances are found to be consistent with visual judgement of the resulting surface of the drawn cups. Copyright © 2010 Inderscience Enterprises Ltd.

Nilsson M.S.,Topsoe Fuel Cell | Olsson D.D.,R and nter Dania | Petrushina I.,Technical University of Denmark | Andreasen J.L.,Novo Nordisk AS | And 3 more authors.
International Journal of Surface Science and Engineering | Year: 2010

Strategic stainless steel surfaces have been developed for which the tribological properties are significantly improved for sheet-metal forming compared with the as-received surfaces. The improvements have been achieved by modification of the surface to promote Micro-Plasto Hydrodynamic Lubrication (MPHL) by increasing the ratio of closed lubricant pockets and modifying the pocket geometry. These factors influence the retention and subsequent escape of lubricant during forming thus enhancing lubricant permeability to the contact between flattened workpiece asperities and contacting tool. The technique, which has been developed, is based on an electrochemical treatment changing the topography of the stainless steel surface. Comparative testing of the new surface topographies in ironing and deep drawing of stainless steel sheet shows significant improvements and possibilities of replacing chlorinated paraffin oils with environmentally friendly plain mineral oil. Copyright © 2010 Inderscience Enterprises Ltd.

Rasmussen K.E.,University of Aarhus | Moesgaard M.,R and nter Dania | Kohler L.L.,R and nter Dania | Tran T.T.,Aalborg Portland A S | Skibsted J.,University of Aarhus
RILEM Bookseries | Year: 2015

The increased attention towards the use of calcined clays as supplementary cementitious materials (SCM’s) has prompted several studies of calcined kaolinite (metakaolin) and to a lesser extent also of heat-treated montmorillonite. However, a major part of these studies does not pay specific attention to the calcination process itself. Furthermore, most studies have been performed on phase-pure clays and such clays are not economically viable for applications as SCM’s at an industrial scale. In this work we investigate the reactivity of SCM’s produced by flash calcination of a natural kaolinite sample and a natural mixed smectite/illite sample. Several key properties of the flash calcined materials are tested and compared to calcined clays obtained by a conventional soak-calcination method. The analyses include characterization of physical properties such as BET surface area, specific density and particle fineness and of the microstructure and degree of reaction by powderXRD as well as 29Si and 27Al MAS NMR. Moreover, the pozzolanic reactivity of the SCM’s are investigated by a Chapelle-like test combined with NMR studies of Portland cement—SCM paste samples at different hydration times. Finally, the performance of mortar samples produced with a 35 wt% SCM substitution level is tested with respect to compressive strength and water requirement following the ASTM standard. © RILEM 2015.

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