scholarly journals Thermal behaviour of ceramics obtained from the kaolinitic clays of Terra Alta, Catalonia, Spain

2021 ◽  
Author(s):  
M. Garcia-Valles ◽  
D. Cuevas ◽  
P. Alfonso ◽  
S. Martínez
Keyword(s):  
Thermal Properties ◽  
Firing Temperature ◽  
Linear Expansion ◽  
Colour Properties ◽  
Test Pieces ◽  
Different Temperatures ◽  
Fired Bricks ◽  
Firing Shrinkage ◽  
Natural Clays ◽  
Kaolinitic Clay

AbstractThe thermal properties and evolution of mineralogy and colour of kaolinitic clay from the Terra Alta region were studied. The mineralogy of these materials consists mainly of kaolinite (13–27 mass%) and quartz (48–86 mass%). Minor illite, hematite, K-feldspar and calcite also occur. The linear expansion and absorption curves were used to predict the optimal firing temperature of the raw clays. During firing, from 1100 °C the water absorption decreases steeply, due to an increase in liquid phase, which penetrates into the pores and close the porosity. At this temperature, the firing shrinkage increases progressively. The fired clays are mainly composed of quartz, cristobalite and mullite, with minor hematite and rutile. Mullite starts to appear at 1050–1100 °C. SEM observations show that porosity decreases with the firing temperature. The colour properties were measured in the raw clays and in the fired bricks at different temperatures. The lightness, L*, is lower in the fired test pieces respect to the natural clays. This colour varies according to the hematite content, being from white to reddish in the fired samples.

Estimation of Firing Temperature and Compositional Variability of Archaeological Pottery by Differential Scanning Calorimetry

2004 ◽  
Vol 852 ◽  
Author(s):  
A. Giordana ◽  
E. Peacock ◽  
M. McCarthy ◽  
K. Guilbeau ◽  
P. Jacobs ◽  
...  
Keyword(s):  
Firing Temperature ◽  
Thermal Characterization ◽  
Small Sample ◽  
Scanning Calorimetry ◽  
Blind Test ◽  
Vitrification Temperature ◽  
Archaeological Pottery ◽  
Digital Scanning ◽  
Different Temperatures ◽  
Upper Estimate

ABSTRACTDigital Scanning Calorimetry (DSC), a thermal characterization technique, can be used to rapidly obtain a rough upper estimate of the firing temperature of archaeological pottery as well as an indication of its composition. The technique involves heating a small sample (10–20 mg) of ground ceramic above the vitrification temperature, cooling and reheating. The curves of the two heating cycles are then compared. The validity of the technique was evaluated by a blind test in which 35 tiles fired at different temperatures were analyzed without knowing their firing point, and by analysis of archaeological pottery samples assumed to be local or imported based upon stylistic criteria.

scholarly journals Characterisation of Ex Vivo Liver Thermal Properties for Electromagnetic-Based Hyperthermic Therapies

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 3004 ◽  
Author(s):  
Nuno P. Silva ◽  
Anna Bottiglieri ◽  
Raquel C. Conceição ◽  
Martin O’Halloran ◽  
Laura Farina
Keyword(s):  
Thermal Properties ◽  
Ex Vivo ◽  
Tissue Perfusion ◽  
Heating Process ◽  
Volumetric Heat Capacity ◽  
Accurate Knowledge ◽  
Different Temperatures ◽  
Treatment Plans ◽  
Specific Tissue ◽  
Tissue Target

Electromagnetic-based hyperthermic therapies induce a controlled increase of temperature in a specific tissue target in order to increase the tissue perfusion or metabolism, or even to induce cell necrosis. These therapies require accurate knowledge of dielectric and thermal properties to optimise treatment plans. While dielectric properties have been well investigated, only a few studies have been conducted with the aim of understanding the changes of thermal properties as a function of temperature; i.e., thermal conductivity, volumetric heat capacity and thermal diffusivity. In this study, we experimentally investigate the thermal properties of ex vivo ovine liver in the hyperthermic temperature range, from 25 °C to 97 °C. A significant increase in thermal properties is observed only above 90 °C. An analytical model is developed to model the thermal properties as a function of temperature. Thermal properties are also investigated during the natural cooling of the heated tissue. A reversible phenomenon of the thermal properties is observed; during the cooling, thermal properties followed the same behaviour observed in the heating process. Additionally, tissue density and water content are evaluated at different temperatures. Density does not change with temperature; mass and volume losses change proportionally due to water vaporisation. A 30% water loss was observed above 90 °C.

Utilization of Glass Cutting Sludge and Sanitary Ware Sludge in Ceramic Pressed Bodies

2015 ◽  
Vol 659 ◽  
pp. 169-174 ◽  
Author(s):  
Apirat Theerapapvisetpong ◽  
Siripan Nilpairach
Keyword(s):  
Flexural Strength ◽  
Water Absorption ◽  
Firing Temperature ◽  
Soda Lime ◽  
Sanitary Ware ◽  
Production Costs ◽  
Modulus Of Rupture ◽  
Soda Lime Glass ◽  
Firing Shrinkage ◽  
Glass Cutting

Ceramic manufacturers are finding the way to decrease firing temperature and recover their wastes in order to keep production costs down. In this study earthenware ceramic bodies were prepared by adding a soda-lime glass grinding effluent powder (dried sludge) as a fluxing agent at 0–50 wt.% into either sanitary ware sludge powder (from a sanitary ware manufacturing process) or fresh pottery clay from Ang-thong, Thailand. The dried and pressed mixtures were fired at 1100, 1125 and 1150 °C and tested for the firing shrinkage, modulus of rupture, water absorption and bulk density. The formed product microstructure was observed by the scanning electron microscopy, and the phase composition was characterized by X-ray diffractometer. The results revealed that the best condition for adding the glass powder in Ang-thong pottery clay was the inclusion of 10 wt.% soda-lime glass effluent powder in the pottery clay. Its flexural strength increased from 51.25 MPa to 93.40 MPa after firing at 1125 °C with the water absorption of 0.42 wt.% and the firing shrinkage of 10.25 %. The optimum firing temperature and soda-lime glass content in sanitary ware sludge were 1150 °C and 20 wt.%, respectively. Its flexural strength increased from 103.16 MPa to 118.16 MPa with the water absorption of 0.52 wt.% and the firing shrinkage of 13.67 %. The results illustrated the potential to use soda-lime glass cutting sludge and sanitary ware sludge as raw materials for earthenware ceramic body.

Damage Prediction of CPVC Based on Energy Method at Different Temperatures

2019 ◽  
Vol 820 ◽  
pp. 179-187
Author(s):  
Fatima Gugouch ◽  
Sara Sandabad ◽  
Nadia Mouhib ◽  
Abderrazak En-Naji ◽  
Mohamed El Ghorba
Keyword(s):  
Polyvinyl Chloride ◽  
Tensile Tests ◽  
Critical Value ◽  
Hot Water ◽  
Effect Of Temperature ◽  
Strain Variation ◽  
Damage Prediction ◽  
Test Pieces ◽  
Different Temperatures ◽  
Three Stages

The Chlorinated Polyvinyl Chloride pipes used for the supply of cold and hot water are designed and manufactured for a 50 years predictive life, but defects and harmfulness may occur during the transport process, storage and operation of tubes that significantly affect these forecasts. This work deals with the study of the mechanical behavior of Chlorinated Polyvinyl Chloride (CVPC) specimens subjected to tensile tests under the effect of temperature. Moreover, a study of damage evolution by the ultimate energy makes it possible to determine the three stages of the lifetime of the test pieces studied. On the basis of the stress-strain variation curves plotted from the experimental results, the critical value of the fraction of life corresponding to the acceleration of the damage was determined.

X-ray diffraction Warren–Averbach mullite analysis in whiteware porcelains: influence of kaolin raw material

Clay Minerals ◽  
2018 ◽  
Vol 53 (3) ◽  
pp. 471-485 ◽  
Author(s):  
Angel Sanz ◽  
Joaquín Bastida ◽  
Angel Caballero ◽  
Marek Kojdecki
Keyword(s):  
Crystallite Size ◽  
Firing Temperature ◽  
Microstructural Analysis ◽  
Stoichiometric Composition ◽  
Raw Material ◽  
Size Distributions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Crystallite Sizes

ABSTRACTCompositional and microstructural analysis of mullites in porcelain whitewares obtained by the firing of two blends of identical triaxial composition using a kaolin B consisting of ‘higher-crystallinity’ kaolinite or a finer halloysitic kaolin M of lower crystal order was performed. No significant changes in the average Al2O3 contents (near the stoichiometric composition 3:2) of the mullites were observed. Fast and slow firing at the same temperature using B or M kaolin yielded different mullite contents. The Warren–Averbach method showed increase of the D110 mullite crystallite size and crystallite size distributions with small shifts to greater values with increasing firing temperature for the same type of firing (slow or fast) using the same kaolin, as well as significant differences between fast and slow firing of the same blend at different temperatures for each kaolin. The higher maximum frequency distribution of crystallite size observed at the same firing temperature using blends with M kaolin suggests a clearer crystallite growth of mullite in this blend. The agreement between thickening perpendicular to prism faces and mean crystallite sizes <D110> of mullite were not always observed because the direction perpendicular to 110 planes is not preferred for growth.

Utilization of Iron Tailings for High Strength Fired Brick

2012 ◽  
Vol 550-553 ◽  
pp. 2373-2377
Author(s):  
Wei Juan Guo ◽  
Gao Xiang Du ◽  
Ran Fang Zuo ◽  
Jing Hui Liao
Keyword(s):  
Phase Composition ◽  
Mechanical Strength ◽  
Water Absorption ◽  
Bulk Density ◽  
Firing Temperature ◽  
Glass Phase ◽  
High Strength ◽  
Optimum Conditions ◽  
Crystalline Phases ◽  
Fired Bricks

his paper studies the feasibility of preparation high strength fired bricks from iron tailings with addition of clay and coal gangue. The results indicated that the optimum conditions were found to be that the hematite tailings content were 35%–50%; the firing temperature was 1000 °C. Under these conditions, the mechanical strength, the water absorption and the bulk density of the fired bricks were 21.17–26.14 MPa, 14.55–15.47% and 1.648–1.629g/cm3, respectively, these were well conformed to standards MU20 of Chinese Fired Common Bricks Standard (GB/T5101-2003).The phase composition and microstructure of the fired specimen were characterized by XRD and SEM. The results showed that the major crystalline phases present in fired brick were quartz, albite, amphibole, hematite and muscovite, and glass phase encapsulated and cement the crystalline phases forming strong entirety which promoted the strength of bricks.

scholarly journals Investigation on the modification to solvent-containing two-component polyurethane coating by carbon nanotubes

2015 ◽  
Vol 44 (5) ◽  
pp. 300-305 ◽  
Author(s):  
X. Jiang ◽  
L. Lin ◽  
X. Bai ◽  
S. Wang ◽  
C. Wang
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Properties ◽  
Composite Coating ◽  
Acid Treatment ◽  
Mechanical And Thermal Properties ◽  
Colour Properties ◽  
Content Type ◽  
Two Component ◽  
Appearance Properties

Purpose – The purpose of this paper is to investigate the effects of carbon nanotubes (CNTs) on the mechanical, thermal and colour properties of solvent-containing two-component polyurethane (PU) coating. Design/methodology/approach – Fourier transform infrared spectroscopy and observation of dispersion stability were used to assess the effects of acid treatment on CNTs. The CNTs and PU composite coating was synthesised by in situ polymerisation and bending polymerisation, and the mechanical, thermal and colour appearance properties of coating were characterised. Findings – It was found that desirable modifications to CNTs occurred after acid treatment; thus, mainly carboxylic acid groups were introduced onto the surface of CNTs. And the acid-treated CNTs could improve the mechanical and thermal properties of PU coating, and the properties of composite coating was improved more successfully by in situ polymerisation than by blending polymerisation. Practical implications – The investigation established a method to synthesise CNTs and PU composite coating. The mechanical and thermal properties of PU coating could be improved by the inclusion of CNTs. Originality/value – This study established a method to synthesise CNTs and PU composite coating by in situ polymerisation and blending polymerisation; the effects of CNTs on modifying mechanical, thermal and colour properties of PU coating were investigated and compared in detail.

The Compression Set Behavior of Nitrile Rubber

1973 ◽  
Vol 46 (1) ◽  
pp. 305-330 ◽  
Author(s):  
H-J. Jahn ◽  
H-H. Bertram
Keyword(s):  
Test Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Nitrile Rubber ◽  
Compression Set ◽  
Test Pieces ◽  
Steep Part ◽  
Cure Time ◽  
Different Temperatures ◽  
Lower Test

Abstract The compression set (C.S.) of a vulcanizate depends on the formulation, processing, and conditions of cure. The following factors are the most important: (a) the type of elastomer, (b) the curing system, (c) the type and amount of filler, (d) the type and amount of plasticizer, (e) the type and amount of antioxidant, (f) the type of cure (press, steam, or hot air), and (g) the cure time and temperature. The present paper is intended, as far as possible, to describe these relationships quantitatively. Most tests will refer to nitrile rubber. We have modified the C.S. method described in ASTM D-395. The deviations are as follows : (1) When C.S. is plotted as a function of the duration of compression, the resulting curves rise steeply for roughly the first seven days, afterwards becoming flatter. The higher the test temperature, the steeper the curve. The ordinary compression times of 22 and 70 h still correspond to the steep part of the C.S. curve; here relatively small inaccuracies in the compression time and test temperature bring large errors in the C.S. readings. Therefore, to improve the correlation between C.S. readings and field behavior the test was extended to seven days in most cases. Longer test times would have been experimentally impractical. (2) As a rule, only C.S. figures relating to 20°, 70°, and 100° C are found in the literature, so test temperatures were extended to include practical conditions. Generally, therefore, C.S. readings were taken at twelve different temperatures ranging from −60° C to +160° C. (3) According to the standards the test pieces should be cooled to room temperature after removal of the load and before the recovery measurement is carried out. Only ASTM D-1229-62 requires the remeasurement to be taken at the load temperature. This ensures accurate measurements of the C.S. at low temperatures. In our tests this was done in every case because at high temperature the C.S. readings are lower since (1) many elastomers recover better at elevated temperatures than at room temperature and (2) the thermal expansion of the test piece can be measured in addition to the recovery. Nevertheless, the differences between remeasurements taken at room temperature and the test temperature are small if the test temperature is fairly high. Where lower test temperatures are used, the remeasurement should always be taken at test temperature if useful results are to be obtained. In all the tests the time allowed for recovery between removal of the load and the remeasurement was thirty min.

scholarly journals XXVII. On the expansion by heat of metals and alloys

1866 ◽  
Vol 156 ◽  
pp. 861-881 ◽  
Keyword(s):  
Linear Expansion ◽  
Metals And Alloys ◽  
Different Temperatures ◽  
The Difference

In a memoir “On the Expansion by Heat of Water and Mercury”*, I described a method of determining the expansion of bodies by weighing them in water at different temperatures. This method was chosen on account of its yielding accurate results with comparatively small quantities, for to purify large quantities of metal would entail immense labour and expense; so much so, in fact, that to purify sufficient quantities to make bars for the determination of the linear expansion would be practically impossible. On determining the expansion of the metals by this method, I found that they did not expand regularly between 0° and 100°. The difference, however, between the rates of expansion between 0° and 50° and 50° and 100° was found to be so great that part of it might be possibly attributed to errors in the determination of the coefficients of expansion of water, as the coefficients of expansion of the metals are comparatively small when compared with those of water. Now, although the coefficient of expansion of mercury when determined by this method agrees with Regnault's value, yet on account of this value being large, small errors in the water coefficients will not materially influence it ; for the volume of water at 4°=1·0000, at 100°=1·04316, that of mercury at 0°=l·0000, at 100°=1·01815, and that of copper, for instance, at 0°=1·00000, at 100°=1004998, showing that the expansion of copper is very small compared with that of water or mercury.

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