03:00 pm
European and International Standardization Work in Refractories
Dr. Franziska Baensch | Deutsches Institut für Normung | Germany
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Dr. Franziska Baensch | Deutsches Institut für Normung | Germany
At European level the CEN/TC 187 "Refractory products and materials" and at international level, the ISO/TC 33 "Refractories", both lead by the British Standards Institution, are responsible for standardization of raw materials and products of the refractories industry and their properties.
Currently, the CEN/TC 187 leads two working groups: WG 1 “Dense shaped refractory products” and WG 4 “Chemical analysis”. The ISO/TC 33 manages four working groups: WG 17 “Chemical analysis”, WG 25 “Refractory test piece preparation – Gunning techniques”, WG 27 “Refractory mortars – Determination of permanent change in dimension on heating” and WG 31 “Phase quantitative analysis of residual quartz in silica bricks”.
Working groups are established as needed to standardize relevant topics. Therefore, experts all over Europe and/or all over the world share knowledge and develop voluntarily consensus-based, market relevant International Standards that support innovation and provide solutions to global challenges. To provide support and direction on the topics and contents of the future standards, active cooperation of experts from industry and research is indispensable. A prerequisite for participation in European and international standardization bodies is participation in the corresponding so called national mirror committees of the national standards institutes.
03:20 pm
Young’s Modulus of Refractories at High Temperatures: Comparison of different Testing Methods as Base for Masonry Modelling
Dr.-Ing. Thorsten Tonnesen | RWTH Aachen University | Germany
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Dr.-Ing. Thorsten Tonnesen | RWTH Aachen University | Germany
Prof. Dr. Jesus Gonzalez-Julian | RWTH Aachen University | Germany
Michel Henze | RWTH Aachen University | Germany
Prof. Dr. Gerhard Hirt | RWTH Aachen University | Germany
Comprehensive knowledge about thermomechanical behavior is mandatory for an accurate prediction of occurring stresses to design load-optimized linings. Refractory linings are, in addition to loads due to corrosion and creep processes, particularly affected by thermomechanical stresses caused by the restricted thermal expansion of the lining. These stresses can occur within individual components as well as in bricks and can lead to plastic deformation, cracks, and material failure.
This study compares methods for determination of Young’s Modulus at different temperatures for the use in refractory modelling of lining systems. In three point bending tests the deflections of different refractory materials were examined during loading by means of digital image correlation (DIC) up to high temperatures. The achieved data allows to measure HMOR and to evaluate static Young’s Modulus values respectively. In parallel refractoriness under load (RUL) tests with higher loads up to 1.5 MPa have been carried out. The measured data of change in temperature and length are then corrected by the thermal expansion and used to construct elastic lines for several temperatures, where the elastic slope is determined using the change in length and the respective load. Thus, Young’s modulus for several temperatures can be determined.
These obtained values for static Young’s modulus are then compared to values which have been determined by dynamic resonant frequency damping analysis (RFDA) measurements without load apply. Finally a validation for refractory linings using a finite element (FE) model by means of these data is discussed.
03:40 pm
Statistical Evaluation of influencing factors on various cold crushing strength determination methods
Gerhard Urbanek | World Refractories Association | Belgium
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Gerhard Urbanek | World Refractories Association | Belgium
Dr. Hans-Jürgen Klischat | World Refractories Association | Belgium
Dr. Manuel Miranda | World Refractories Association | Belgium
The cold compression strength (CCS) has been used as test method for refractories for over 100 years, although it barely describes the refractory’s performance. As its worldwide use is a key parameter in data sheets or product definitions, an attempt was made to correlate different respective standards and to quantify essential influencing parameters on the CCS. The importance of precision data applies to all standardized test methods, being a future challenge for the refractory industry. Therefore, the World Refractory Association (WRA) wants to increase activities in this field for a better understanding of test methods themselves and subsequently sampling plans and customer contact. The WRA Task Force “Testing Methods and Standards” has investigated this method regarding its precision data and comparability of different standards based on ISO 5725 standard. More than 1000 tests of 6 different refractory grades, performed by 7 laboratories, were considered in the statistically assured evaluation. As one of the results, ASTM C133 gives in average around 24% lower values compared to ISO 10059-1. As main reason identified was the interlayer between press and test specimen used for ASTM. Geometry of the test specimen (cylinders vs. cubes) and the load speed showed minor effects. The precision data indicate for the two standards a relative repeatability interval of around 20%. Regarding reproducibility, ASTM shows a slightly worse performance of 40% compared to 30% evaluated for ISO). As a recommendation the integration of the precision data and the comparative results into ISO/TC 33 for ISO 10059-1 is proposed.
04:00 pm
Evaluation of cold crushing strength methods on statistical values of various refractory brick grades
Dr. Hans-Jürgen Klischat | World Refractories Association | Belgium
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Dr. Hans-Jürgen Klischat | World Refractories Association | Belgium
Gerhard Urbanek | World Refractories Association | Belgium
Dr. Manuel Miranda | World Refractories Association | Belgium
The cold compression strength (CCS) test is a standard test method for various refractory products and is indicated in nearly all data sheets of refractory producers. It is widely known that the measurement, although theoretically quite simple, shows a wide variety of values, which may give unnecessary discussions between refractory producers and refractory users.A statistical evaluation on precision data and the comparability of different standards by the Task Force “Testing Methods and Standards” of the World Refractory Association shows the influence of application of the standards ASTM C133 and ISO 10059-1 not only regarding the influence of testing parameters, but also some material dependencies. So, a higher scatter of values values with increasing strength values was observed. Specific features are observed mainly for two brick grades. Fireclay bricks may show a special behavior due to the presence of a glassy amorphous phase, which gives the structure a more brittle property. The specialities of magnesia spinel bricks could be explained by the presence of microcracks, which influence the strain field within the specimen. Furthermore, the values of these brick grades are also affected by the laboratory measurements themselves, as various influences are considered to result in lower values. The results for the different grades require some more statistical data, so that more specific results can be considered to find their way into ISO/TC 33 for ISO 10059 and also into ASTM C133.