The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Roger Morrell - One of the best experts on this subject based on the ideXlab platform.
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instrumented indentation test for advanced Technical Ceramics
Journal of The European Ceramic Society, 2002Co-Authors: Christian Ullner, Jorg Beckmann, Roger MorrellAbstract:The standard for advanced Technical Ceramics ENV 843-4 of 1995 (Vickers, Knoop and Rockwell superficial hardness tests) was validated within the framework of the CERANORM EC-project. The paper reports on depth sensing hardness measurements done for comparison with the other hardness tests. The instrumented indentation test is a modern technique (recent issue ISO/DIS 14577) that has the potential to take into account the specific response of materials in a much better way. An evaluation has been made to establish whether the instrumented hardness technique is a appropriate method for advanced Technical Ceramics and offers potential for additional applications.
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hardness testing on advanced Technical Ceramics
Journal of The European Ceramic Society, 2001Co-Authors: Christian Ullner, Thomas Reich, Roger Morrell, A Germak, Henri Le Doussal, Willy VandermeulenAbstract:To validate the European standard ENV 843-4 for hardness measurements on Ceramics, three classes of ceramic materials, silicon nitride, silicon carbide, and aluminium oxide, involving 19 Ceramics in total, were tested using the traditional techniques Vickers (HV1), Knoop (HK2), and superficial Rockwell (HR45N). The use of new ceramic reference blocks certified according to the standards ISO 4547 and ISO 6507-1 for metallic materials was studied. If the hardness response of the tested materials does not involve chipping and cracking the application of high hardness reference blocks for training users to obtain hardness values comparable with the certified HV1 and HK2 values improves the reproducibility from about 10% to 1 to 3%. The scatter between the laboratories is similar to the scatter within the laboratories. The measurement of the indentation geometry on typical commercial ceramic materials can be made only with higher scatter and reduced reproducibility compared with typical metallic materials, which is caused by the stochastic indentation response. For such materials involving chipping and cracking (for instance SiC), the application of reference blocks with well-shaped indentations does not provide improved comparability of results between the laboratories. The actual indentation response of the ceramic material tested must be considered before selecting the appropriate hardness technique and test force. There is no significant difference between the abilities of the hardness techniques HV1, HK2, and HR45N to discriminate sensitively between materials of closely similar properties.
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european standardization activities for advanced Technical Ceramics
ASME 1993 International Gas Turbine and Aeroengine Congress and Exposition, 1993Co-Authors: Jakob Kubler, Roger MorrellAbstract:A summary of the progress being made in Europe towards the provision of standards for advanced Technical Ceramics is given. Under CEN Technical Committee 184, working groups have been preparing more than 40 standards in the areas of classification, powders, monolithic Ceramics, long-fibre composites and ceramic coatings. The target date for this work was the end of 1992. Considerable progress has been made, and by the end of 1993, most of these should have been published. It is hoped that the formation of this standards base will improve the quality of testing and the reliability of property data on this class of materials, and thus improve confidence in their use as engineering materials.Copyright © 1993 by ASME
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round robin on grain size measurement for advanced Technical Ceramics
Journal of The European Ceramic Society, 1993Co-Authors: Ljmg Ardi Dortmans, Roger MorrellAbstract:Abstract The results of a joint CEN/VAMAS round robin on grain size measurement for advanced Technical Ceramics have been analysed. Twenty-five participants from Europe, USA and Japan employed a line and circle method for determination of the mean linear intercept length, and grid methods for determination of a grain size distribution. The results show that the scatter obtained for measurement of the mean linear intercept length and the grain size distribution is primarily due to the influence of micrograph preparation and interpretation and, to a lesser extent, also due to random positioning of lines, circles and grids. The results for the mean linear intercept length measurement validate the methods described in a proposed CEN standard. The grid methods for grain size distribution measurement seem suitable for implementation in future standards. Micrograph preparation and interpretation should be given special attention, as these factors are of major importance for consistent results.
Christian Ullner - One of the best experts on this subject based on the ideXlab platform.
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instrumented indentation test for advanced Technical Ceramics
Journal of The European Ceramic Society, 2002Co-Authors: Christian Ullner, Jorg Beckmann, Roger MorrellAbstract:The standard for advanced Technical Ceramics ENV 843-4 of 1995 (Vickers, Knoop and Rockwell superficial hardness tests) was validated within the framework of the CERANORM EC-project. The paper reports on depth sensing hardness measurements done for comparison with the other hardness tests. The instrumented indentation test is a modern technique (recent issue ISO/DIS 14577) that has the potential to take into account the specific response of materials in a much better way. An evaluation has been made to establish whether the instrumented hardness technique is a appropriate method for advanced Technical Ceramics and offers potential for additional applications.
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hardness testing on advanced Technical Ceramics
Journal of The European Ceramic Society, 2001Co-Authors: Christian Ullner, Thomas Reich, Roger Morrell, A Germak, Henri Le Doussal, Willy VandermeulenAbstract:To validate the European standard ENV 843-4 for hardness measurements on Ceramics, three classes of ceramic materials, silicon nitride, silicon carbide, and aluminium oxide, involving 19 Ceramics in total, were tested using the traditional techniques Vickers (HV1), Knoop (HK2), and superficial Rockwell (HR45N). The use of new ceramic reference blocks certified according to the standards ISO 4547 and ISO 6507-1 for metallic materials was studied. If the hardness response of the tested materials does not involve chipping and cracking the application of high hardness reference blocks for training users to obtain hardness values comparable with the certified HV1 and HK2 values improves the reproducibility from about 10% to 1 to 3%. The scatter between the laboratories is similar to the scatter within the laboratories. The measurement of the indentation geometry on typical commercial ceramic materials can be made only with higher scatter and reduced reproducibility compared with typical metallic materials, which is caused by the stochastic indentation response. For such materials involving chipping and cracking (for instance SiC), the application of reference blocks with well-shaped indentations does not provide improved comparability of results between the laboratories. The actual indentation response of the ceramic material tested must be considered before selecting the appropriate hardness technique and test force. There is no significant difference between the abilities of the hardness techniques HV1, HK2, and HR45N to discriminate sensitively between materials of closely similar properties.
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Testing hardness of Technical Ceramics : A new round robin
1998Co-Authors: T. Polzin, Thomas Reich, Christian UllnerAbstract:The round robin has been conducted according to ENV 843-4 for Knoop hardness at 9.81 N on several commercial advanced Technical Ceramics. The test has been designed to discriminate between the scattering caused by the laboratories, separated into indenting and measuring, by the response of the ceramic material, and by the specific specimen. The test has confirmed that the Knoop hardness can be used for the characterization of Technical Ceramics but neither of the tested materials is appropriate to be used as reference material for Knoop hardness.
Jong Cheol Kim - One of the best experts on this subject based on the ideXlab platform.
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Processing Technical Ceramics with maltodextrins: Crosslinking by acetalation
Starch Staerke, 1999Co-Authors: Christopher H Schilling, Piotr Tomasik, Jong Cheol KimAbstract:Technical Ceramics are made by a sequential process of: (i) mixing ceramic powder with an organic carrier liquid (e.g., organic solvents, polyethylene wax) to form a plastic slurry, (ii) molding the plastic slurry into a three-dimensional shape, (iii) thermal treatment to evaporate or pyrolyze the organic carrier, and (iv) kiln firing. In this paper, the use of aqueous polysaccharide solutions is examined as environmentally-friendly, economically-viable substitutes for organic carrier liquids in ceramic molding. The central focus of the present study is to examine optimum conditions for crosslinking model slurries of maltodextrin and colloidal aluminum oxide by acetalation of maltodextrin. Crosslinking is needed to prevent the common problem of cracks that form in ceramic shapes during thermal treatment (stage iii above). Experiments involving rheology and differential thermal analysis revealed that glyoxal and glutaraldehyde are effective crosslinkers, whereas formaldehyde and pyruvic acid did not exhibit measureable changes in slurry rheology over a wide range of concentrations. Glutaraldehyde reacted faster than glyoxal, however, glyoxal produced the strongest gels. Basic conditions catalyzed acetalation. The sequence of blending the slurry components had no significant effect on slurry rheology.
A. K. Brovtsyn - One of the best experts on this subject based on the ideXlab platform.
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Ultrasonic diagnostics in the medium-material system
Refractories and Industrial Ceramics, 2005Co-Authors: A. K. BrovtsynAbstract:Results of multipurpose studies aimed at the development of advanced instrumentation for ultrasonic diagnostics of liquid media are reported. It has been inferred that, for the near decades, the most promising route will be combined (medium-interactive) ultrasonic devices based on waveguides of different design. Diagnostics data on argillaceous rocks and Technical Ceramics are given.
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Gamma-Ray Spectrometric and Ultrasonic Diagnostics of Materials
Russian Journal of Nondestructive Testing, 2001Co-Authors: A. K. Brovtsyn, A. N. Silant'evAbstract:Results of gamma-ray spectrometric and ultrasonic diagnostics of raw stocks and materials is presented with reference to fabrication of Technical Ceramics. The behavior of the radioactive nuclide content and results of ultrasonic diagnostics of argillaceous rocks and Technical Ceramics is discussed. Practical recommendations for using the diagnostics in manufacturing methods for the purpose of upgrading of the material quality are given and substantiated.
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Experimental investigations of radiation from Technical Ceramics
Russian Journal of Nondestructive Testing, 2000Co-Authors: A. K. Brovtsyn, A. N. Silant'evAbstract:The industrial demand for materials that are pure, dry, classified, and homogeneous in their physical, mechanical, and chemical properties, free from radioactive contaminants and highly resistant to radiation is on the increase. But the stock of deposits of high-quality and cheap raw materials is limited, and they are gradually depleted and contaminated, both locally and on the global scale. The more stringent requirements of the complete and versatile utilization of fossil materials, alongside higher environmental standards, generate a demand for a radical review of existing technologies.
J E Jelnes - One of the best experts on this subject based on the ideXlab platform.
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toxicology and occupational hazards of new materials and processes in metal surface treatment powder metallurgy Technical Ceramics and fiber reinforced plastics
Scandinavian Journal of Work Environment & Health, 1991Co-Authors: U Midtgard, J E JelnesAbstract:Many new materials and processes are about to find their way from the research laboratory into industry. The present paper describes some of these processes and provides an overview of possible occupational hazards and a list of chemicals used or produced in the processes. The technological areas that are considered are metal surface treatment (ion implantation, physical and chemical vapor deposition, plasma spraying), powder metallurgy, advanced Technical Ceramics, and fiber-reinforced plastics.
