LUDWIG MAXIMILIANS UNIVERSITY
E-mail : jordan
lmu [dot] de
Phone : +49 8921804353
Guntram Jordan is APL professor at the Department of Geo and Environmental Sciences of LMU. He is supervising the research group for mineral surface reactivity. Furthermore, he is academic advisor for students of the bachelor program geosciences and the master program geomaterials and geochemistry.
Current research and funding
Multi-scale study of the growth kinetics of carbonate minerals with cationic additives – a new approach to understand growth of Mg-carbonates
The reason for the discrepancy between the huge amount of ancient dolomites and the comparatively low amount of modern marine dolomites has still not been understood completely. Explanations suggest various different formation mechanisms for ancient dolomites, for example replacement of Ca-rich precursor phases in Mg-rich solutions over geologic time scales or precipitation from sea water which differs in composition from modern sea water. However, lab experiments to grow dolomite from aqueous solutions generally fail at room temperature. Only by engaging microbial effects, the dehydration barrier of Mg2+ seems to be overcome which supposedly is one important cause for the growth inhibition of dolomite as well as magnesite at room temperature.
Aim of the research project is to improve the understanding of processes which control growth kinetics of Mg-carbonates using atomic force microscopy (AFM) and mixed flow reactor experiments (MFR). Important contributions can be provided by investigations of Mg bearing carbonate minerals in various different solutions.
Wet tensile strength testing in neutron radiography
Wet tensile strength testing in neutron radiography - cause-property relation studies in bentonite bonded molding sands
Bentonite bonded molding sand is among the most common mold materials used in founding. One reason for the common acceptance is its reusability. However, the binding quality of used molding sand is reduced to some degree. Therefore, 5% of new mold material is added after each cast. The quality loss of the re-used molding sand is caused by alterations of the clay minerals in the mold material and results in a reduced wet tensile strength among other effects. One consequence of the quality loss is the increased susceptibility to water-related casting flaws.
A primary aim of the research project is to quantitatively investigate the conditions which lead to casting flaws. For this purpose, wet tensile strength testing will be conducted in-situ in a neutron radiograph. By these experiments, water concentration and temperature at the position and moment of rupture of the molding sand as well as the according tensile strength and the precedent temperature and water gradient can be measured in-situ. The insights can essentially contribute to a development of strategies for an effective improvement of the re-usability of bentonite bonded molding sands.
Selected publications
• Jordan, G., Eulenkamp, C., Calzada, E., Schillinger, B., Hoelzel, M., Gigler, A., Stanjek, H., Schmahl, W.W. (2013): Quantitative in-situ study on the dehydration of bentonite bonded molding sands. Clays and Clay Minerals 61, 133-140.
• Schillinger, B., Calzada, E., Eulenkamp, C., Jordan. G., Schmahl W.W. (2011): Dehydration of moulding sand in simulated casting process examined with neutron radiography. Nuclear Instruments and Methods in Physics Research A 651, 312-314.
• Berninger, U.N., Jordan, G., Lindner, M., Reul, A., Schott, J., Oelkers, E.H. (2016): On the effect of aqueous Ca on magnesite growth – Insight into trace element inhibition of carbonate mineral precipitation. Geochim. Cosmochim. Acta, 178, 195-209.
• Saldi, G.D., Jordan, G., Schott, J., Oelkers, E.H. (2009): Magnesite growth rates as a function of temperature and saturation state, Geochim. Cosmochim. Acta., 73, 5646–5657.
