Hochschule Koblenz

Remagen, Germany

Hochschule Koblenz

Remagen, Germany
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Krause O.,Hochschule Koblenz | Quirmbach P.,University of Koblenz-Landau
Proceedings of the Unified International Technical Conference on Refractories, UNITECR 2013 | Year: 2014

Amongst the international well-recognized institutes at Bergakademie Freiberg and RWTH Aachen, the Department of Materials Engineering of Koblenz University of Applied Science in Höhr-Grenzhausen represents the third party who intensively deals with education and research for the ceramic industry. The institute is closely related to the cooperative education network, BFZK (educational and research center ceramics), which allows best utilization of the existing public education structure. Since 2010 the conversion from diploma degree program to bachelor of material science has been successfully carried out and was followed by the implementation of a master degree in cooperation with the University of Koblenz-Landau. The Department follows two major tasks: Best possible and targeted education in order to provide graduates with tailor-made abilities for the ceramic industry. For this reason the ceramic industry and the State ministry of economics of Rheinland-Pfalz funded three endowed professorships, out of which two have already been converted into regular positions. The second task is to promote science projects that are closely related to the demands of the industry. The presentation will introduce the state-of-art master and bachelor curriculum and will briefly present recent research works. © 2014 The American Ceramic Society.


Simmat R.,Forschungsgemeinschaft Feuerfest e. V. | Dannert C.,Forschungsgemeinschaft Feuerfest e. V. | Krause O.,Hochschule Koblenz | Quirmbach P.,DIFK Deutsches Institute fur Feuerfest und Keramik GmbH
Proceedings of the Unified International Technical Conference on Refractories, UNITECR 2013 | Year: 2014

ASTM-C 704 and ISO 16282 are commonly in use to determine the abrasion resistance of refractory ceramic surfaces against highly accelerated particles at room temperature (RT). To facilitate the development of abrasion-resistant high-temperature refractory materials, the test setup was transferred to elevated temperatures at conditions as close as possible as specified in the standards. The development is based on six years of experience on a testing device for the industry. For the implementation of test conditions up to 1400 °C the standard setup is supplemented with a ring shaped domestic gas burner in which the coaxial abrasion nozzle made of refractory silica glass is situated. The flame is focussed into the accelerating pressured air and they mix with each other. Prior to the test it is necessary and possible to adjust the temperature of the flame mixed with the compressed air stream. Thereafter the SiC particles are fed and heated to test temperature. The device also allows testing samples at RT with best correlation to the standard facility. The change of abrasion as a function of temperature is highly reproducible and is consistent with the tests performed at RT. By now, the method is well accepted by the industry. The test setup is easy to construct and may therefore be adopted by any institute. The method is capable to be implemented in the international standardisation system in the near future. This paper discusses preconditions which are necessary to provide reliable results and reproducible results for abrasion wear at elevated temperatures. Recent perceptions derived from inter laboratory tests at room temperature are transferred to the principle test setup at elevated temperatures. © 2014 The American Ceramic Society.


Krause O.,Hochschule Koblenz | Dannert C.,Forschungsgemeinschaft Feuerfest e. V. | Redecker L.,University of Koblenz-Landau
Proceedings of the Unified International Technical Conference on Refractories, UNITECR 2013 | Year: 2014

The nature of carbon, which is obtained during a CO test, is identified. High-resolution transmission electron microscopy clearly shows besides minor amounts of microcrystalline graphite the appearance of macromolecule like carbon structures known as carbon nanotubes. The emplacement of carbon in principle requires the formation of liquid iron nano droplets, derived from iron containing impurities, which subsequently absorb carbon till attaining the saturation limit. Thereafter hexahedral carbon structures are segregated on the surface of the droplet. This kind of formation is technically known as VLS (vapour-liquid-solid) process1. Based on these facts and under consideration of the appropriate literature, the formation process of destructive carbon nanotubes and their emplacement into ceramic structure helps to consider new definitions for appropriate test methods as current test methods (ISO 12676 and ASTM C 288), which are used to verify the resistance to carbon monoxide suffer from poor reproducibility. This paper reviews the state of knowledge, mainly derived in an AiF research project, which was initiated and accomplished at Forschungsgemeinschaft Feuerfest e. V. (FGF), Höhr-Grenzhausen. It turned out that in particular the gas flow rate in the CO furnace plays an important role for the emplacement velocity of carbon. Furthermore, the influence of hydrogen in the atmosphere is examined and stated to be an accelerator, because it has the ability to reactivate the catalyst. As a consequence of this work existing normative references can be revised in terms of narrower definitions for the test conditions. Therefore it is indispensable to perform round robin tests in order to evaluate the impact of the measures as discussed in this paper. It is necessary to discuss the detailed test conditions among the participating experts. © 2014 The American Ceramic Society.


Quirmbach P.,University of Koblenz-Landau | Krause O.,Hochschule Koblenz
Proceedings of the Unified International Technical Conference on Refractories, UNITECR 2013 | Year: 2014

The Refractory Industry suffers a lack of young people in Germany. Within the past five years an integrating education concept has been developed to ensure a sustainable provision of young and best-skilled craftsmen, technicians and engineers to the Refractory Industry the aim of this presentation is to demonstrate how the sophisticated network between education, science and Refractory Industry leads to efficient fulfillment of the industry's demands. Because of a vertically open vocational education structure as provided by public legislation it is possible to promote young people even with initial limited educational achievements to finish with an academic degree. The cooperative education network BFZK (educational and research centre for ceramics), which closely cooperates with the University of Koblenz- Landau, allows best possible utilization of this public education structure. Key of success is that industry as well as schools and universities cooperate permanently in defining contents and optimizing organizational demands in view of best practice for applicants and the refractory companies. It will be demonstrated that levels of qualification (craftsmen, technicians, engineers) are adapted to each other so that a consistent system is available to lower the upon mentioned suffering. © 2014 The American Ceramic Society.


Rausch M.,Hochschule Koblenz | Schyboll F.,Hochschule Koblenz | Neeb H.,Hochschule Koblenz
Technisches Messen | Year: 2013

There is an increasing tendency towards the use of combined MR/PET scanners and combined MR-Linac (Linear accelerator) systems in both clinical and research settings. The current work therefore investigated the effects of ionising radiation on the acquired MR signal, both experimentally and using a simple theoretical model. We have observed a phase signal change in the radiated area inside a water phantom. However, the theoretical basis of this observation is not fully covered by the employed model and needs further research. © 2013 by Walter de Gruyter Berlin Boston 2013.


Despite various approaches in the past it has not been possible to accurately quantify the destructive impact of carbon monoxide on refractory materials. Several researches in this field deliver contradictory results. Even the standardized corrosion tests (ASTM C 288 and DIN EN ISO 12676) lead to divergent results. This is the reason why the assessment of the CO resistance of refractory materials is unreliable. So far only little attention was paid to the emplaced carbon in the ceramic texture, but the solution to the problem is very likely to be found here. Once the nature of the emplaced carbon is known better, its development process can also be understood better. The nature of emplaced carbon was basically ascertained in a AiF project (14161N) in 2006. It was clearly shown by transmission electron microscopy that besides little amounts of microcrystalline graphite mainly multi-walled carbon nanotubes - whiskery carbon macromolecules - are being formed. Meanwhile those results could clearly be verified by additional microscopic investigations. Other graphite structures have no significant technical impact. The emplacement of carbon nanotubes is dependent on the existence of liquid iron droplets which serve as catalysts. On the surface of these droplets CO is decomposed to CO2 and carbon while the Boudouard reaction is in place. Carbon is enriched in the iron droplets until the saturation concentration is exceeded. This causes the segregation of carbon nanotubes on the surface. This kind of formation is technically known as VLS (vapour-liquid-solid) process [1], Based on these facts and under consideration of the appropriate literature, the formation process of destructive carbon nanotubes and their emplacement into ceramic structure helps to consider new definitions for appropriate test methods. The presented results are based on the results of the IGF project (15888N) which was carried out under the auspices of AiF and financed within the budget of the Federal Ministry of Economics and Technology (BMWi) through the programme to promote joint industrial research and development (IGF|. The major result is that the carbon deposition rate - under standardized corrosion tests - are mainly dependent on the gas flow rate in the electrically heated furnace. Furthermore, various gas compositions were systematically investigated while different concentrations of CO2 und H2 were added to the furnace atmosphere. If the CO-atmosphere is diluted by CO2, the carbon deposition rate decreases systematically. The addition of H2 to the furnace atmosphere however leads to a significant acceleration of the carbon deposition rate if at least 5 Vol.-% H2 are added. In further it was proved that the carbon deposition rate is not subjected to the specific surface of the sample specimens. As a consequence of this work existing normative references can be revised in terms of narrower definitions for the test conditions. Therefore it is indispensable to perform round robin tests in order to evaluate the impact of the measures as discussed in this paper. It is necessary to discuss the detailed test conditions among the participating experts.


Despite various approaches in the past it has not been possible to accurately quantify the destructive impact of carbon monoxide on refractory materials. Several researches in this field deliver contradictory results. Even the standardized corrosion tests (ASTM C 288 and DIN EN ISO 12676) lead to divergent results. This is the reason why the assessment of the CO resistance of refractory materials is unreliable. So far only little attention was paid to the emplaced carbon in the ceramic texture, but the solution to the problem is very likely to be found here. Once the nature of the emplaced carbon is known better, its development process can also be understood better. The nature of emplaced carbon was basically ascertained in a AiF project (14161N) in 2006. It was clearly shown by transmission electron microscopy that besides little amounts of microcrystalline graphite mainly multi-walled carbon nanotubes - whiskery carbon macromolecules - are being formed. Meanwhile those results could clearly be verified by additional microscopic investigations. Other graphite structures have no significant technical impact. The emplacement of carbon nanotubes is dependent on the existence of liquid iron droplets which serve as catalysts. On the surface of these droplets CO is decomposed to CO2 and carbon while the Boudouard reaction is in place. Carbon is enriched in the iron droplets until the saturation concentration is exceeded. This causes the segregation of carbon nanotubes on the surface. This kind of formation is technically known as VLS (vapour-liquid-solid) process [1], Based on these facts and under consideration of the appropriate literature, the formation process of destructive carbon nanotubes and their emplacement into ceramic structure helps to consider new definitions for appropriate test methods. The presented results are based on the results of the IGF project (15888N) which was carried out under the auspices of AiF and financed within the budget of the Federal Ministry of Economics and Technology (BMWi) through the programme to promote joint industrial research and development (IGF|. The major result is that the carbon deposition rate - under standardized corrosion tests - are mainly dependent on the gas flow rate in the electrically heated furnace. Furthermore, various gas compositions were systematically investigated while different concentrations of CO2 und H2 were added to the furnace atmosphere. If the CO-atmosphere is diluted by CO2, the carbon deposition rate decreases systematically. The addition of H2 to the furnace atmosphere however leads to a significant acceleration of the carbon deposition rate if at least 5 Vol.-% H2 are added. In further it was proved that the carbon deposition rate is not subjected to the specific surface of the sample specimens. As a consequence of this work existing normative references can be revised in terms of narrower definitions for the test conditions. Therefore it is indispensable to perform round robin tests in order to evaluate the impact of the measures as discussed in this paper. It is necessary to discuss the detailed test conditions among the participating experts.


Based on a roller kiln plant, options are presented to reduce energy costs by the optimization of the exergy efficiency. To achieve this in a first step the energetic link of kiln and dryer is undocked and in this way the possibility is generated to supply dryers independently from kiln energy. This enables an optimized energy supply of the dryers by utilization of cogeneration. Besides this electric energy supply can be achieved by ORC units or thermoelectric generators.


Wittkowski K.M.,Rockefeller University | Sonakya V.,Rockefeller University | Bigio B.,Rockefeller University | Tonn M.K.,Hochschule Koblenz | And 4 more authors.
Translational Psychiatry | Year: 2014

The prevalence of autism spectrum disorders (ASDs) has increased 20-fold over the past 50 years to >1% of US children. Although twin studies attest to a high degree of heritability, the genetic risk factors are still poorly understood. We analyzed data from two independent populations using u-statistics for genetically structured wide-locus data and added data from unrelated controls to explore epistasis. To account for systematic, but disease-unrelated differences in (non-randomized) genome-wide association studies (GWAS), a correlation between P-values and minor allele frequency with low granularity data and for conducting multiple tests in overlapping genetic regions, we present a novel study-specific criterion for 'genome-wide significance'. From recent results in a comorbid disease, childhood absence epilepsy, we had hypothesized that axonal guidance and calcium signaling are involved in autism as well. Enrichment of the results in both studies with related genes confirms this hypothesis. Additional ASD-specific variations identified in this study suggest protracted growth factor signaling as causing more severe forms of ASD. Another cluster of related genes suggests chloride and potassium ion channels as additional ASD-specific drug targets. The involvement of growth factors suggests the time of accelerated neuronal growth and pruning at 9-24 months of age as the period during which treatment with ion channel modulators would be most effective in preventing progression to more severe forms of autism. By extension, the same computational biostatistics approach could yield profound insights into the etiology of many common diseases from the genetic data collected over the last decade. © 2014 Macmillan Publishers Limited.


Krause O.,Hochschule Koblenz | Klein T.,Hochschule Koblenz | Tischer D.,Hochschule Koblenz | Schwarz K.,Hochschule Koblenz | And 2 more authors.
InterCeram: International Ceramic Review | Year: 2014

This paper reports on the results of a science project conducted during the last two years. In this project a focus was set on the rheological and setting properties as a function of the mixing energy applied in dry and wet state. A proper adjustment of mixing time and velocity even prior to the water addition is a powerful measure to enhance the compaction properties of concretes. The products are more homogenous and show improved properties with special regard to their rheology, density, open porosity and mechanical strength. On the other hand, these encouraging results depict that results in development and research work should be read in a more qualitative way unless the preparation routine of test specimen are clearly communicated. It has to be proposed, that the mixing procedure should be an indispensable part of the procedure description. Future developments of refractory castables will even focus more consequently on the design of the particle distribution of the micro fine components in order to produce products with enhanced durability in service. However, if the matrix design turns more complex the requirements for a perfect homogenization increase exceptionally. It is necessary to define the optimum mixing energy for a proper deagglomeration without an unwanted warming of the mix that will lead to shorter pot times. As reported by many authors the setting velocity of plain cement-water suspensions is not predictable in a wanted correctness. As a spinoff of the said project, it can be shown, that the starting time of the crystallization of cement hydrate phases that correlates with the setting of the water cement suspensions is strongly dependent on the mixing energy. The starting time of the temperature increases and the distinct slope of the temperature evolution is a function of the deagglomeration degree of the cement particles during mixing.

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