TRANSPORT PROPERTIES OF PURE METALS AT HIGH TEMPERATURES: I. COPPER

1967 ◽  
Vol 45 (11) ◽  
pp. 3677-3696 ◽  
Author(s):  
M. J. Laubitz
Keyword(s):  
High Temperature ◽  
Transport Properties ◽  
High Temperatures ◽  
Pure Copper ◽  
High Temperature Properties ◽  
Temperature Range ◽  
Pure Metals

This paper is the first of a series reporting our investigations into the high-temperature properties of the monovalent metals. It contains a description of the methods used in these investigations, and the results of measurements of the transport properties of pure copper, over the temperature range 300–1 250 °K. These results are compared with some previously published work, and also with standard theoretical expressions applicable to the monovalent metals.

Induction of thermodormancy in Avena sativa seeds

1993 ◽  
Vol 3 (2) ◽  
pp. 111-117 ◽  
Author(s):  
F. Corbineau ◽  
M. Black ◽  
D. Côme
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Avena Sativa ◽  
Inhibitory Action ◽  
Whole Grains ◽  
Temperature Range ◽  
Primary Dormancy

AbstractFreshly harvested oat (Avena sativa L.) seeds are considered to be dormant because they are unable to germinate at relatively high temperatures (above 20°–25°C). This primary dormancy results partly from the structures surrounding or adjacent to the embryo (pericarp, testa and endosperm) and partly lies in the embryo itself. Incubation of imbibed dormant seeds at 30°C induces a thermodormancy which is expressed as germination in a narrower temperature range. Induction of thermodormancy is apparent after 3–8 hours at 30°C, is optimal after about 1–2 days at this temperature, but diminishes with longer treatment times. Although whole grains become more dormant as a result of such treatment, the embryos themselves become less dormant, therefore the tissues covering or adjacent to the embryos must have become more inhibiting or the embryos have become more sensitive to their inhibitory action. The germination and sensitivity to ABA or oxygen of embryos isolated from such seeds are no longer so dependent on temperature. The effect of high temperature on primary dormancy and induction of thermodormancy is discussed with reference to sensitivity to ABA and temperature.

ACCURATE CALCULATION OF THE HIGH TEMPERATURE THERMOPHYSICAL PROPERTIES OF GASES

1994 ◽  
Vol 05 (02) ◽  
pp. 233-235
Author(s):  
LOUIS BIOLSI ◽  
PAUL M. HOLLAND
Keyword(s):  
High Temperature ◽  
Kinetic Theory ◽  
Transport Properties ◽  
High Temperatures ◽  
Thermophysical Properties ◽  
Intermolecular Potential ◽  
Kinetic Theory Of Gases ◽  
Accurate Calculation ◽  
Ion Interactions ◽  
Interacting Atoms

The kinetic theory of gases can be used to accurately calculate the transport properties of gases based on knowledge of the intermolecular potential between the interacting atoms, molecules or ions. This approach has been especially useful at high temperatures where experimental transport data are either sparse or unavailable. In recent years, increasingly accurate potentials for atom-atom and atom-ion interactions have become available for such calculations, and approaches for applying these potentials to calculate the high temperature thermophysical properties of gases are described.

Interface Controlled Diffusional Creep of Cu + 2.8 at.% Co Solid Solution

2012 ◽  
Vol 322 ◽  
pp. 33-39 ◽  
Author(s):  
Sergei Zhevnenko ◽  
Eugene Gershman
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Surface Tension ◽  
High Temperature ◽  
Creep Behavior ◽  
Pure Copper ◽  
Diffusional Creep ◽  
High Temperature Creep ◽  
Temperature Range ◽  
Different Temperatures

High-temperature creep experiments were performed on a Cu-2.8 ат.% Co solid solution. Cylindrical foils of 18 micrometers thickness were used for this purpose. Creep tests were performed in a hydrogen atmosphere in the temperature range of about from 1233 K to 1343 K and at stresses lower than 0.25 MPa. For comparison, a foil of pure copper and Cu-20 at.% Ni solid solution were investigated on high temperature creep. Measurements on the Cu foil showed classical diffusional creep behavior. The activation energy of creep was defined and turned out to be equal 203 kJ/mol, which is close to the activation energy of bulk self-diffusion of copper. There was a significant increase in activation energy for the Cu-20 at.% Ni solid solution. Its activation energy was about 273 kJ/mol. The creep behavior of Cu-Co solid solution was more complicated. There were two stages of diffusional creep at different temperatures. The extremely large activation energy (about 480 kJ/mol) was determined at relatively low temperature and a small activation energy (about 105 kJ/mol) was found at high temperatures. The creep rate of Cu-Co solid solution was lower than that of pure copper at all temperatures. In addition, the free surface tension of Cu-2.8 ат.% Co was measured at different temperatures from 1242 K to 1352 K. The surface tension increases in this temperature range from 1.6 N/m to 1.75 N/m. There were no features on the temperature dependence of the surface tension.

Investigations on Structure and High Temperature Properties of Iridium

2007 ◽  
Vol 539-543 ◽  
pp. 2216-2221 ◽  
Author(s):  
Jürgen Merker ◽  
Bernd Fischer ◽  
David F. Lupton ◽  
Joerg Witte
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Temperatures ◽  
Rupture Strength ◽  
Creep Behaviour ◽  
Stress Rupture ◽  
Service Performance ◽  
Metallographic Examination ◽  
Fine Grained ◽  
Pure Metals

Due to its outstanding mechanical properties at high temperatures and chemical stability iridium is used for demanding high temperature applications. In order to obtain materials data necessary for the design of high temperature equipment and the numerical simulation of their service performance the stress-rupture strength and creep behaviour have been investigated in a temperature range between 1650°C and 2300°C. The results of metallographic and fracture examinations (SEM) revealed that, in common with other pure metals, unalloyed iridium shows marked grain growth at high temperatures. Under these conditions, the deformation characteristics of iridium may not be entirely uniform and predictable, as will be demonstrated with examples from the creep studies. Both metallographic examination and investigations by means of scanning electron microscopy gave indications of possible causes for a significant anomaly in the creep behaviour. It is therefore advantageous for the mechanical properties if a fine-grained microstructure can be maintained even at the highest service temperatures.

Fracture Strength of Ultra-High Temperature Ceramics

2008 ◽  
Vol 368-372 ◽  
pp. 1785-1787
Author(s):  
Tao Zeng ◽  
Dai Ning Fang ◽  
Xia Mei Lu ◽  
Fei Fei Zhou
Keyword(s):  
High Temperature ◽  
Theoretical Model ◽  
High Temperatures ◽  
Fracture Strength ◽  
Environmental Temperature ◽  
Ultra High Temperature Ceramics ◽  
Temperature Range ◽  
Effects Of Temperature ◽  
Ultra High Temperature

This paper presents a theoretical model to predict the fracture strength of ultra-high temperature ceramics (UHTCs). According to different mechanisms, the environmental temperature is divided into four ranges. Effects of temperature and oxidation on the fracture strength of UHTCs are investigated in each temperature range. The results show that oxidation plays an important role in enhancing the fracture strength of UHTCs at high temperatures.

High-Temperature Properties of SiC-Si3N4 Particle Composites

1999 ◽  
Vol 122 (1) ◽  
pp. 8-12 ◽  
Author(s):  
G. Woetting ◽  
B. Caspers ◽  
E. Gugel ◽  
R. Westerheide
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Hot Pressing ◽  
Oxidation Behavior ◽  
Short Term ◽  
High Temperature Properties ◽  
Sintering Additive ◽  
Hot Pressing Sintering

Due to promising results in literature, SiC-Si3N4 particle composites in the range 0–100 percent SiC were evaluated. Focusing on high-temperature properties, mainly Y2O3 was used as sintering additive. Consolidation occurred primarily by hot-pressing, sintering tests were performed for comparison. Besides short-term properties like strength, toughness etc., long-term properties like creep and oxidation behavior were determined. Results as a function of SiC-content and microstructure were discussed with respect to materials’ performance at high temperatures and possibilities of their production on a technical scale. [S0742-4795(00)00201-5]

scholarly journals Refractory Materials For High-Temperature Thermoelectric Energy Conversion

1983 ◽  
Vol 24 ◽  
Author(s):  
Charles Wood ◽  
David Emin
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Energy Conversion ◽  
Transport Properties ◽  
Refractory Material ◽  
High Temperatures ◽  
Refractory Materials ◽  
Efficient Energy ◽  
Thermoelectric Energy ◽  
Material Systems

ABSTRACTTwo refractory material systems show promise for efficient energy conversion at high temperatures (>1000 K): the rare-earth chalcogenides and the boron-rich borides. The electronic and thermal transport properties of these two systems are compared and discussed.

scholarly journals Young’s modulus of iron and nickel in steels and alloys

2021 ◽  
Vol 2 (396) ◽  
pp. 67-72
Author(s):  
A. Bagerman ◽  
◽  
A. Troitsky ◽  
I. Leonova ◽  
◽  
...  
Keyword(s):  
High Temperature ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Temperature Range ◽  
Young’S Moduli ◽  
Predictive Assessment ◽  
Pure Metals ◽  
Materials Used ◽  
Full Scale Tests ◽  
Temperature Applications

Object and purpose of research. The object is steels and alloys for high-temperature applications. The purpose of the study is to obtain the necessary data for predicting the Young’s modulus of steels and alloys before their full-scale tests. Materials and methods. The data on the Young’s modulus of pure metals and reference data on the Young’s modulus of steels and alloys for high-temperature applications are the materials used in this study. The study uses the concept of "constraint" parameter to rank steels and alloys. Main results. The Young’s moduli of iron and nickel were determined during their operation as a part of steels and alloys, an algorithm for the predictive assessment of the Young’s modulus of steels and alloys was compiled in the temperature range 20–800 °С. Conclusion. It is shown that in the absence of experimental data, the Young’s modulus of steels and alloys can be estimated by the value of the "available" Young’s modulus, determined by the value of the Young’s modulus of pure metals. The results of the study showed the possibility of changing the Young’s modulus of pure metals during their operation as a part of steels and alloys, the characteristics of the Young’s modulus of iron and nickel during their operation as a part of steels and alloys and the algorithm for predicting the Young’s modulus of steels and alloys based on these metals in the temperature range of 20–800 °C were obtained.

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