Verification of Joule heat evolution model for silicate building materials with electrically conductive admixtures

2017 ◽  
Author(s):  
Lukáš Fiala ◽  
Jiří Maděra ◽  
Robert Černý
Keyword(s):  
Building Materials ◽  
Heat Evolution ◽  
Joule Heat ◽  
Evolution Model ◽  
Electrically Conductive

scholarly journals Experimental and theoretical approach to determination of heat evolution in electrically conductive aluminosilicates

2020 ◽  
Vol 24 (2 Part A) ◽  
pp. 787-794
Author(s):  
Lukas Fiala ◽  
Jiri Madera ◽  
Robert Cerny
Keyword(s):  
Building Materials ◽  
Heat Evolution ◽  
Limiting Factor ◽  
Mechanical And Thermal Properties ◽  
Building Structures ◽  
Electrically Conductive ◽  
Voltage Level ◽  
Self Heating ◽  
Electric Source

Design of progressive building materials with increased utility value is the key issue for the development of reliable modern building structures. Compared to the conventional materials, progressive building materials are supposed to exhibit not just adequate mechanical, and thermal properties, but they are also supposed to be applicable in sophisticated solutions, such as in self-sensing, self-heating or magnetic-shielding systems. In terms of electric properties, the most of building materials are electric insulators which is the main limiting factor for their applicability in such sophisticated solutions. However, this deficiency can be solved by the addition of a proper amount of electrically conductive admixtures. Within the paper, electrically conductive alkali-activated aluminosilicate with 8.89 mass.% of carbon black admixture was designed and its materials properties necessary for calculations of heat evolution by the action of an electric source were experimentally determined. The electrical conductivity of such material equal to 5.57?10?2 S m?1 was sufficiently high to ensure self-heating ability. It was observed good agreement of experimentally determined data with those modeled by means of heat equation on sample with dimensions 40 ? 40 ? 10 mm. Finally, one- and two-layered large-scaled heating elements based on materials with experimentally determined properties were designed and calculations were conducted to determine the voltage level necessary for one-hour heating from 268.15 K and 273.15 K to 278.15 K in the middle-top point of the construction.

Simulation of the Electric Current Flow in Amorphous-Crystalline Ti2NiCu Alloy with Shape Memory Effect

2016 ◽  
Vol 845 ◽  
pp. 146-149
Author(s):  
Dmitriy S. Kuchin ◽  
Victor V. Koledov ◽  
Pavel V. Bogun ◽  
Peter V. Lega ◽  
Vedamanickam Sampath ◽  
...  
Keyword(s):  
Electric Current ◽  
Current Flow ◽  
Amorphous Matrix ◽  
Volume Fraction ◽  
Current Density Distribution ◽  
Heat Evolution ◽  
Equatorial Region ◽  
Joule Heat ◽  
Electric Pulses ◽  
Electric Current Flow

A new technique for the production of nanograined alloys from rapidly quenched amorphous ribbons by serial electric pulses has been proposed recently [1]. The present work involves a theoretical study of electric current flow in a nonhomogeneous Ti2NiCu alloy consisting of an amorphous matrix with a crystalline phase of spherical morphology embedded in it. The electric current density distribution was calculated in the vicinity of a spherical nucleus, which has an electrical resistance that is only 0.4 times that of the amorphous matrix. The calculation of Joule heat density was done in the nucleus and in the amorphous volume surrounding it. It was shown that during the current pulse the Joule heat evolution in nucleus exceeds one in equatorial region in matrix, but less than near the poles. The dependence of relative resistivity of nonhomogeneous amorphous-crystalline alloy on volume fraction of spherical crystalline nuclei was calculated

Formation and dispersion of an electrolyte film on an ice electrode melting as a result of Joule heat evolution

2002 ◽  
Vol 47 (10) ◽  
pp. 1237-1245 ◽  
Author(s):  
A. I. Grigor’ev ◽  
V. V. Morozov ◽  
S. O. Shiryaeva
Keyword(s):  
Heat Evolution ◽  
Joule Heat ◽  
Electrolyte Film

scholarly journals Self-Heating Ability of Geopolymers Enhanced by Carbon Black Admixtures at Different Voltage Loads

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4121 ◽  
Author(s):  
Lukáš Fiala ◽  
Michaela Petříková ◽  
Wei-Ting Lin ◽  
Luboš Podolka ◽  
Robert Černý
Keyword(s):  
Electrical Properties ◽  
Carbon Black ◽  
Construction Industry ◽  
Functional Properties ◽  
Building Materials ◽  
Electrically Conductive ◽  
Self Heating ◽  
Heating Performance ◽  
Thermal And Electrical Properties ◽  
Furnace Slag

Sustainable development in the construction industry can be achieved by the design of multifunctional materials with good mechanical properties, durability, and reasonable environmental impacts. New functional properties, such as self-sensing, self-heating, or energy harvesting, are crucially dependent on electrical properties, which are very poor for common building materials. Therefore, various electrically conductive admixtures are used to enhance their electrical properties. Geopolymers based on waste or byproduct precursors are promising materials that can gain new functional properties by adding a reasonable amount of electrically conductive admixtures. The main aim of this paper lies in the design of multifunctional geopolymers with self-heating abilities. Designed geopolymer mortars based on blast-furnace slag activated by water glass and 6 dosages of carbon black (CB) admixture up to 2.25 wt. % were studied in terms of basic physical, mechanical, thermal, and electrical properties (DC). The self-heating ability of the designed mortars was experimentally determined at 40 and 100 V loads. The percolation threshold for self-heating was observed at 1.5 wt. % of carbon black with an increasing self-heating performance for higher CB dosages. The highest power of 26 W and the highest temperature increase of about 110 °C were observed for geopolymers with 2.25 wt. % of carbon black admixture at 100 V.

Cryogenic atomic force microscopy

1991 ◽  
Vol 49 ◽  
pp. 54-55
Author(s):  
K. A. Fisher ◽  
M. G. L. Gustafsson ◽  
M. B. Shattuck ◽  
J. Clarke
Keyword(s):  
Room Temperature ◽  
Rapid Freezing ◽  
Cryogenic Temperatures ◽  
Soft Or ◽  
Electrically Conductive ◽  
Force Microscopy ◽  
Flexible Molecules ◽  
Advantages And Disadvantages ◽  
Atomic Force ◽  
Chemical Perturbation

The atomic force microscope (AFM) is capable of imaging electrically conductive and non-conductive surfaces at atomic resolution. When used to image biological samples, however, lateral resolution is often limited to nanometer levels, due primarily to AFM tip/sample interactions. Several approaches to immobilize and stabilize soft or flexible molecules for AFM have been examined, notably, tethering coating, and freezing. Although each approach has its advantages and disadvantages, rapid freezing techniques have the special advantage of avoiding chemical perturbation, and minimizing physical disruption of the sample. Scanning with an AFM at cryogenic temperatures has the potential to image frozen biomolecules at high resolution. We have constructed a force microscope capable of operating immersed in liquid n-pentane and have tested its performance at room temperature with carbon and metal-coated samples, and at 143° K with uncoated ferritin and purple membrane (PM).

Scanning electron microscopy of asbestos-containing material where the asbestos fibers are considered locked in a binder

1993 ◽  
Vol 51 ◽  
pp. 472-473
Author(s):  
J. R. Millette ◽  
R. S. Brown
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Environmental Protection Agency ◽  
Building Materials ◽  
The United States ◽  
Protection Agency ◽  
Asbestos Fibers ◽  
Different Types ◽  
Binder Material ◽  
Scanning Electron

The United States Environmental Protection Agency (EPA) has labeled as “friable” those building materials that are likely to readily release fibers. Friable materials when dry, can easily be crumbled, pulverized, or reduced to powder using hand pressure. Other asbestos containing building materials (ACBM) where the asbestos fibers are in a matrix of cement or bituminous or resinous binders are considered non-friable. However, when subjected to sanding, grinding, cutting or other forms of abrasion, these non-friable materials are to be treated as friable asbestos material. There has been a hypothesis that all raw asbestos fibers are encapsulated in solvents and binders and are not released as individual fibers if the material is cut or abraded. Examination of a number of different types of non-friable materials under the SEM show that after cutting or abrasion, tuffs or bundles of fibers are evident on the surfaces of the materials. When these tuffs or bundles are examined, they are shown to contain asbestos fibers which are free from binder material. These free fibers may be released into the air upon further cutting or abrasion.

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