耐火材料文献

耐火材料文献

作者:卓声仪器 日期:2014-05-19 11:43
High temperature characterisation of cordierite-mullite refractory by ultrasonic means
T.Chotard,,J.Soro ,H.Lemercier ,M.Huger ,C.Gault
 
 
 
IMPACT OF THERMAL SHOCK AND RELATED MICROSTRUCTURAL CHANGES
ON ELASTIC PROPERTIES OF REFRACTORIES BY NON-DESTRUCTIVE
IMPULSE EXCITATION
Thorsten Tonnesen, Rainer Telle RWTH Aachen University, Aachen, Germany
 
Young’s modulus evolution at high temperature of SiC refractory castable
O.Bahloul T.Chotard M.Huger
 
 
 
"IMPULSE EXCITATION TESTS TO DETERMINE THE HIGH TEMPERATURE ELASTIC AND DAMPING PROPERTIES OF Si3N4 AND OTHER CERAMICS"
G. Roebben, O. Van der Biest
 
The impulse excitation technique (IET) consists of exciting a free vibration in a suspended sample by mechanical impulse loading. The stiffness of the material can be deduced from the resonance frequencies of the sample. The material damping, or internal friction, is related to the exponential decay of the vibration amplitude. Recently IET-systems have been developed which allow to measure both elastic and damping properties up to 1750°C (Roebben et al. (1)). Currently investigations are being made of the phase transformations in zirconia ceramics, crystallisation in glass ceramics and densification during sintering of powder compacts. This paper presents results obtained in the study of crystallisation of intergranular phases in silicon nitride at temperatures above the glass transition temperature of the amorphous grain boundary phases.
 
"PRACTICAL USE OF A NON-DESTRUCTIVE METHOD FOR TESTING REFRACTORIES"
Richter, T.
 
 
The accuracy and advantages of the non-destructive resonant frequency technique (impulse excitation technique) for the final inspection of conventional refractory products are discussed. Mathematical models and correlations for alumina brands are presented.
 
"EVALUATION OF THERMAL SHOCK DAMAGE IN CASTABLES BY A RESONANT FREQUENCY AND DAMPING METHOD"
Thorsten Tonnesen, Rainer Telle
 
 
The paper is concerned with the characterization of the microstructure and the non-destructive measurement of the elastic an interfacial properties of different high alumina castables. The thermal shock behavior of different compositions of high alumina castables, varying in particle size distribution and cement content, has been regarded in particular by using a non-destructive testing device based on impulse excitation.
Materials: The castable compositions reveal a great variation in their grain size distribution. Typical LCC compositions with grog grain up to 6 mm were regarded as well as castables consisting of fine from 10 um to 500 um in maximum with less cement content.
Testing methods: On all castables thermal shock tests have been applied by quenching them from 1100°C. A steep thermal gradient was chosen to distinguish the thermal shock behaviour of the different castable compositions after each cycle.
To quantify the microstructural damages due to thermal shock a non-destructive testing method based on impulse excitation where a vibration is induced within a castable sample of the size 150 x 25x 20 mm² by mechanical impulses. This vibration is picked up by a microphone, the electrical signal is adapted and amplified. Finally resonance frequencies with their damping loss factor are measured. On one hand Young's Modulus (E) and internal friction ( Q-1) have been measured by using a damping analyzer. On the hand other Young's Modulus was determined using a conventional frequency to achieve resonance frequency.
Aim of the study is to evaluate the difference of the testing method: Young's Modulus achieved by damping or by resonance frequency measurements applied on heterogeneous materials of different grain size distributions. Further the application of internal friction measurements on refractory materials in regard of its sensitiveness is a focus. Due to the use of different castable compositions the influence of the particle size and the damage detection induces by thermal shocks by the given testing methods are worked out.
 
 
"High-Temperature Stiffness and Damping Measurements to Monitor the Glassy Intergranular Phase in Liquid-Phase-Sintered Silicon Carbides"
Gert Roebben, Omer Van der Biest, Diletta Scitl, Alida Bellosi, Corneliu Sarbu, Torn Lauwagie
 
 
Detailed stiffness and internal friction (Q~ ) versus temperature curves were obtained for liquid-phase-sintered silicon carbides using advanced resonant beam analysis up to 1400°C. As-sintered materials display a stable Q-1-peak near 1100DC, superimposcd on an increasing background. The change of stiffness associated with the damping peak is quantitatively related to the amount of matter in pockets of the amorphous intergranular phase in which the refractory SiC matrix grains are embedded. The successful removal of the amorphous pockets by annealing at 1900 C is deduced from the disappearance of the damping peak and confirmed with transmission electron microscopy.
 
"Experimental Evaluation of Dynamic Test Methodologies"
P. M. Amaral, L. Guerra Rosa and J. Cruz Fernandes
 
 
Two dynamic test methodologies, the resonance method and the ultrasonic method, are used for assessing the elastic behaviour of granitic rocks. The experimental results obtained using two types of specimens: (i) rectangular beams(parallelepiped specimens); and (ii) cylindrical specimens (rod specimens); show that the resonance method used in this work is more adequate when both Young's modulus and Poisson's ratio are to be determined in these types of rocks. Moreover, it is demonstrated that test results obtained by resonance techniques are less dependent on specimen's geometry, size, and even surface roughness.
 
"High-Temperature Young's Modulus of Alumina During Sintering"
Bruno A. Latella and Tianshun Liu
 
 
High-temperature Young's modulus of a partially sintered alu-mina ceramic has been studied dynamically during the sintering process. Comparative, room-temperature Young's modulus data were obtained for a suite of partially sintered alumina compacts with different porosities. The dynamic Young's modulus of a 1200°C partially sintered material was observed to decrease linearly with temperature, but then above 1200°C it increased sharply as sintering and densification of the alumina became dominant. The evolution of the Young's modulus due purely to sintering exhibited an exponential relationship with porosity in excellent agreement with room-temperature measurements of equivalent porous alumina ceramics.
 
"Differences between static and dynamic elastic moduli of a typical seismogenic rock"
M. Ciccotti and F. Mulargia
 
 
Static and dynamic elastic moduli of Calcare Massiccio mudstone-limestone, the typical seis¬mogenic rock in the Italian Apennines, are measured using a standard uniaxial static compression test, a dual cantilever forced oscillation test and ultrasonic measurement of elastic wave velocities. These measurements cover nine decades in frequency including the seismic domain. Neither a significant frequency dependence nor a pronounced strain amplitude dependence was observed, providing a Young's modulus of (75 ± 7) GPa and a Poisson's ratio of (Ü.28 ± 0.02). These values are characteristic of Calcare Massiccio in undamaged condition.
 
"Application of the dynamical flexural resonance technique to industrial materials characterisation"
P. Gadaud, S. Pautrot
 
 
The determination of the Young's modulus and damping coefficient Q-1 by means of non-destructive vibrating techniques has been applied to bulk and coated industrial materials. Extensions of a previous analytic model of composite beam allow to determine accurately the macroscopic modulus of each component of multilayerd structural materials as coated superalloys or nitride-hardened steels. Furthermore, the study of glasses and polymers has been investigated. An attempt of normalization of the modulus versus temperature curves allows to establish master curves depending on the specific structure, from metallic glasses to polymeric glasses. Finally a comparison of dynamical modulus and Q-1 values measured between resonant (>1 kHz) and subresonant techniques ( 10-3 to 10 Hz) in relation to the loading frequencies applied in real conditions has been under folder. For metallic materials such as forged or rolled titanium alloys, the brittle-to-fragile transition occurs abruptly or smoothly with a shift of 300K following the range of excitation frequencies.
 
 
"A novel resonant beam technique to determine the elastïc moduli in dependence on orientation and temperature up to 2000 °C"
W. Lins, G. Kaindl, H. Petertik, and K. Kromp
 
 
A new equipment was developed to determine the elastic moduli from the resonance frequencies of the flexural vibrations of a beam up to temperatures of 2000 °C. The elastic moduli are calculated by minimizing the difference of the experimental versus me theoretical resonance frequencies. The theoretical frequencies are obtained by numerically solving Timoshenko's equation, which takes into account the influence of the shear deformation and the rotatory inertia. From the fundamental frequency and the higher modes of vibration, one Young's modulus and two shear moduli (e.g., £11 > G12, and G13) are obtained; the latter two coincide for an elastically isotropic material. With the additional effort of cutting out specimens in specific directions, the complete elastic tensor of anisotropic materials can be measured at high temperatures. The limits and the precision of the method are discussed.
 
 
"YOUNG'S MODULUS OF BIOACTIVE GLASS COATED ORAL IMPLANTS: POROSITY CORRECTED BULK MODULUS VERSUS RESONANCE FREQUENCY ANALYSIS"
J. Schrooten, G. Roebben and J.A. Helsen
 
 
The validation of the reactive plasma spraying process and of its reproducibility, requires effective characterization of the deposited BAG-coating. Several evaluation methods, like chemical analysis, adhesion testing, in vitro and in vitro experiments, were adapted in order to perform them on the actual implant.
Also the Young's modulus, E, of the BAG-coating can be used to characterize the coating's quality in a general way. Moreover, knowing E one can calculate coaling strains of the loaded implant and the related tissue strains that have to the limited to avoid formation of fibrosis tissue. Further, finite element analysis of the adhesion tests and fracture mechanics calculations can only be performed when knowing E, and the amount of stress shielding due to the difference in Young's modulus between implant and surrounding tissue can be predicted.
 
 
Thermal shock testing of alumina-graphite refractories
J.L. Leatherland, R.D. Rawlings and RS. Rogers
 
 
Two independent thermal shock tests have been used successfully to simulate in-service continuous casting conditions and to induce microdamage in three grades of alumina-graphite.
 
 
"Non-destructive determination of Young's modulus and its relationship with compressive strength, porosity and density"
R. J. Allison
 
 
Samples of Upper Cretaccous Chalk and Upper Jurassic Portland Limestone are used to demonstrate the apparatus and its application Test specimens were prepared and analysis concluded on material extracted at a number of locations throughout the Islc of Purbeck in Dorset, UK- Samples suitable for deformation in triaxial compression were also prepared and correlations drawn between compressive strength, dynamic Young's modulus, porosity and density.