Our website is currently undergoing maintenance. This page provides
access to the published issues in the meantime. Article submissions are unaffected and
can be made through the
Editorial Manager.
Journal of Ceramic Science and Technology 2/2014
Vol. 5, No. 2 · June 2014
Future Research in Refractories: A Roadmap Approach
A. Geigenmüller, H. Spindler, K. Lenk, C. G. Aneziris
Pages 71-76 · DOI: 10.4416/JCST2013-00032
Science and technology roadmaps are valuable instruments for strategic planning in research. Especially for interdisciplinary fields such as materials science and technology, roadmaps are promising instruments for identifying relevant research themes and interfaces between different disciplines and actors. Against this background, this paper aims at developing a roadmap for refractory research in order to strategically promote the field, to initiate ground-breaking research endeavors and valuable collaborations and to advance fundamental and applied refractory research. To this end, the study …
Influence of Temperature Dependence of Bulk Modulus on Crack Propagation Velocity
D. Pilipenko, Y. Natanzon, H. Emmerich
Pages 77-82 · DOI: 10.4416/JCST2013-00033
Multiscale modeling of crack propagation in homogeneously heated aluminium oxide is presented. It is known that the crack propagation velocity depends on both the bulk modulus and surface energy of a material. The temperature dependence of surface energy is often ignored owing to the difficulty associated with obtaining a reliable measurement. Such dependence was calculated in atomic-scale calculations by means of Molecular Dynamics with MEAM potential. The dependence shows a linear decrease with an increase in temperature. The MD results are used as input for phase field simulations of fractu …
Numerical Two-Scale Simulations of Damage Evolution at Refractory Materials
D. Henneberg, A. Ricoeur
Pages 83-92 · DOI: 10.4416/JCST2013-00034
Fracture and damage processes on micro- and mesoscale are combined with macroscale simulations applying numerical multiscale approaches. Cracks and grain boundaries are reproduced in cell models that take account of trans- and intercrystalline crack growth. The global, in general thermomechanical boundary value problem is considered within a continuum mechanics framework. Two approaches are presented combining the scales. Simple processes on the smaller level are described in analytical models including the damage evolution into the constitutive laws by internal variables. More complicated mic …
Synthesis of LaCrO3 and La0.9Ca0.1CrO3 by Modified Glycine Nitrate Process
A. Bonet, N. Travitzky, P. Greil
Pages 93-100 · DOI: 10.4416/JCST2013-00024
LaCrO3 and La0.9Ca0.1CrO3 ceramics were synthesized in the modified glycine nitrate process (MGNP). The effect of the equivalence ratio Φe of precursor mixtures on the combustion reaction was investigated by means of DSC and TG-FTIR analyses. It was found that for Φe > 0.65 the combustion reaction proceeds in a self-propagating one-step process, resulting in the formation of well-crystallized single-phase powders. Further glycine addition (Φe
Experimental Characterization and Thermomechanical Modelling of Microstructure Interactions in Cellular Carbon Magnesia Refractories
G. Falk, A. Jung, W. da Silveira, S. Diebels
Pages 101-114 · DOI: 10.4416/JCST2013-00029
Experimental results and computational solutions regarding microstructural interactions and their influence on the thermomechanical strength of cellular carbon foams reinforced with yttria-stabilized zirconia (YSZ) and silicon carbide (SiC) coatings are presented. The computational approach is related to the quantification of failure stresses as a function of the microstructural size under thermal shock loading and under hot bending with microstructural-based finite element analysis. The numerical results of this simplified computational approach are correlated to the experimentally motivated …
Low-Carbon Carbon-Bonded Alumina Refractories for Functional Components in Steel Technology
V. Stein, C. G. Aneziris
Pages 115-124 · DOI: 10.4416/JCST2013-00036
Carbon-bonded alumina refractories (Al2O3-C) are essential for modern steelmaking practice. The typical carbon content for functional materials is approximately 30 wt%. With regard to environmentally friendly refractory systems, this work has observed and described the interaction of functional silicon (n-type semiconductor) with an organic binder system. With this system, it was possible to lower the carbon content to 15 wt% without downgrading the material properties. On the contrary, the properties were improved. As a result of the upgrading of the microstructural flexibility and the mechan …
Magnesium Aluminate Spinel Ceramics Containing Aluminum Titanate for Refractory Applications
K. Moritz, C.G. Aneziris, D. Hesky, N. Gerlach
Pages 125-130 · DOI: 10.4416/JCST2013-00037
The thermal shock resistance of alumina-rich magnesium aluminate spinel refractory ceramics with aluminum titanate as second phase was investigated. First, suitable thermal conditions for the formation of aluminum titanate from corundum and rutile were determined. Ground pre-synthesized aluminum titanate was added to the spinel powder. According to another route, alumina and titania powder were mixed with the spinel raw material in order to form the aluminum titanate in situ during sintering. Test bars were prepared by means of slip casting and sintered at 1650 °C. The bending strength of both …
Crack Formation and Shape of Fracture Surface in Tabular-Alumina-Based Castables with Addition of Specific Aggregates
J. Schnieder, L. Lynen, N. Traon, T. Tonnesen, R. Telle
Pages 131-136 · DOI: 10.4416/JCST2013-00039
Understanding the mechanical fracture and the microstructural behavior of refractories subject to thermal shock treatment is fundamental for the design of high-performance refractory materials. In recent decades, understanding has been focused on mechanisms occurring at the crack tip, namely in advanced ceramics. The focus recently switched to phenomena occurring in a different process zone of the crack, the wake region or following process zone. To understand the mechanisms in this wake region, specific aggregates are used in a model castable formulation based on tabular alumina, namely eutec …
Manufacture of Rotationally Symmetric Multilayer Refractory Devices for Steel Casting Applications by Spiral Winding of Ceramic Green Tapes
D. Jakobsen, R. Hammerbacher, S. Dudczig, T. Fey, A. Roosen
Pages 137-144 · DOI: 10.4416/JCST2013-00040
In order to create rotationally symmetric refractory devices from ceramic green tapes, the spiral winding method, which is mainly known from the paper industry, was applied. Different green tapes with varying properties with regard to shrinkage, porosity and Young's modulus were used to generate multilayer tubes with the spiral winding and the cold low pressure lamination technique. The tubes were fired in air and their microstructure was investigated. Thermal shock tests were conducted to evaluate the applicability of the fabricated structures for refractory applications. The correlation betw …
Numerical Prediction of Effective Thermal Conductivity of Refractory Materials: Methodology and Sensitivity Analysis
R. Zehmisch, C. Demuth, A. Al-Zoubi, M.A.A. Mendes, F. Ballani, S. Ray, D. Trimis
Pages 145-154 · DOI: 10.4416/JCST2013-00041
The present paper deals with numerical predictions of the effective thermal conductivity (keff) of refractory materials. The composite is modelled using a geometry generation method; either the Coloured Dead Leaves Model (CDLM) or the modified version of the Random Sequential Adsorption (RSA) algorithm, for coarse grain components. On the other hand, there are constituents which could not be resolved by the computational model and are, therefore, treated as a continuous interstitial phase, termed as the ‘unresolved’ or the ‘rest’ material. The generated random geometry is discretised employing …
The Influence of the Coarse Fraction on the Porosity of Refractory Castables
J. Fruhstorfer, C.G. Aneziris
Pages 155-166 · DOI: 10.4416/JCST2013-00043
In this work, the influence of the coarse fraction of a particle size distribution on the flowability and density of refractory castables is investigated. A modified Andreasen model was developed to combine distribution moduli ≤ 0.30 in the fine fraction for flowability and stability with moduli adjusted between 0.28 and 1.20 in the coarse fraction for improving density. The amount of the fine fraction was held constant. It was shown that a density-optimized batch showed self-flowing behaviour, while the other batches needed to be vibrated. The bulk density of the unfired and fired ceramics wa …
Dependent Thermo-Mechanical Behavior of Novel Alumina-Based Refractories
A. Böhm, C.G. Aneziris, J. Malzbender
Pages 167-171 · DOI: 10.4416/JCST2014-00001
Novel alumina-based refractories were assessed with regard to their thermo-mechanical behavior from room temperature to 1000 °C within the framework of the DFG SPP "FIRE" program. These refractories are being developed for use in slide gates or entry nozzles. Their elastic behavior was investigated with the impulse excitation technique. Wedge splitting tests were used to determine their fracture resistance behavior. The evaluated material characteristics and thermal shock resistance were compared to those of a standard refractory material, permitting conclusions to be drawn regarding the effec …
