THE PROBLEM OF THE ELECTRICAL CONDUCTIVITY OF METALS

1931 ◽  
Vol 5 (1) ◽  
pp. 79-86 ◽  
Author(s):  
C. D. Niven
Keyword(s):  
Electrical Conductivity ◽  
Electrical Conduction ◽  
Superconducting State ◽  
Low Temperatures ◽  
Electron Configuration ◽  
Metallic Atom ◽  
The Right

It is pointed out that mathematicians in their attempts to form theories of electrical conduction, do not lay emphasis on the fact that at low temperatures resistance, as a rule, does not vanish. In those cases in which it does, it vanishes suddenly. In view of this, the question arises as to whether the right model for conductivity in a metal is visualized. It is suggested that fundamentally a metallic atom is one in which the electron configuration is incomplete.Ordinary conduction consists of a process whereby an electron jumps from one atom to another and remains with the atom it jumps to until it is in a sort of equilibrium with the motions of the electrons already on that atom. In the superconducting state, the electronic orbits of different atoms become synchronized so that when an electron leaves one atom, another electron automatically comes on to the atom to take its place. A study of the resistance-temperature curves as well as other points emphasizes the importance of structure in conductivity.

scholarly journals Multi-material braids for multifunctional laminates: conductive through-thickness reinforcement

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Caroline O’Keeffe ◽  
Laura Rhian Pickard ◽  
Juan Cao ◽  
Giuliano Allegri ◽  
Ivana K. Partridge ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Carbon Fibre ◽  
Electromagnetic Interference ◽  
Design Tool ◽  
Electrically Conductive ◽  
Current Collection ◽  
Wide Range ◽  
Predictive Design ◽  
The Right ◽  
Metal Wires

AbstractConventional carbon fibre laminates are known to be moderately electrically conductive in-plane, but have a poor through-thickness conductivity. This poses a problem for functionality aspects that are of increasing importance to industry, such as sensing, current collection, inductive/resistive heating, electromagnetic interference (EMI) shielding, etc. This restriction is of course more pronounced for non-conductive composite reinforcements such as glass, organic or natural fibres. Among various solutions to boost through-thickness electrical conductivity, tufting with hybrid micro-braided metal-carbon fibre yarns is one of the most promising. As a well-characterised method of through thickness reinforcement, tufting is easily implementable in a manufacturing environment. The hybridisation of materials in the braid promotes the resilience and integrity of yarns, while integrating metal wires opens up a wide range of multifunctional applications. Many configurations can be produced by varying braid patterns and the constituting yarns/wires. A predictive design tool is therefore necessary to select the right material configuration for the desired functional and structural performance. This paper suggests a fast and robust method for generating finite-element models of the braids, validates the prediction of micro-architecture and electrical conductivity, and demonstrates successful manufacturing of composites enhanced with braided tufts.

scholarly journals EFFECTIVENESS EVALUATION OF STEEL STRENGTH IMPROVEMENT FOR PYRAMIDAL-PRISMATIC BUNKERS

2020 ◽  
Vol 2 ◽  
pp. 30-38
Author(s):  
Yukhym Hezentsvei ◽  
Dmytro Bannikov
Keyword(s):  
Low Temperatures ◽  
High Strength ◽  
Operating Conditions ◽  
Professional Literature ◽  
Plastic Properties ◽  
Repair Work ◽  
Practical Engineering ◽  
Cis Countries ◽  
The Right ◽  
The Cost

In accordance with the recommendations of specialized professional literature, steel pyramidal-prismatic bunkers are projected for a service life of 20 years. However, in practice this term is often twice, or even three times lower. This is especially true for complicated operating conditions, in particular the effect of increased loads and low temperatures. Existing design techniques for such structures, both in European practice and the design practice of Ukraine and other CIS countries do not pay attention to these aspects. Therefore, in the practice of operation, the increased accident rate of steel bunker capacities has already become virtually a common occurrence. One of the possible ways to solve this problem is presented, which consists of using instead of traditional steels of ordinary strength with high plastic properties, steels of increased or high strength with reduced plastic properties. At the same time, clear theoretical recommendations are provided for choosing the right steel depending on the operating conditions, primarily when exposed to increased loads. The recommendations are presented in a form convenient for practical engineering applications. The proposed approach allows to reduce the material consumption of structures of this type on average according to theoretical estimates by 25-30% without reducing their bearing capacity. Their durability is also further enhanced by improving performance at low temperatures. Thus, the applied aspect of such a solution to this above problem is the possibility of increasing the overall reliability of steel bunker capacities, as well as reducing the cost of their periodic maintenance and repair work. A practical illustration of the presented approach is also given on the example of the design of bunkers of a bypass track for supplying charge materials for blast furnaces of one of the metallurgical plants of the northern location. As a result, this created the preconditions for monetary savings of about 0.5 million UAH in prices 2019 (about 20,000 USD)

scholarly journals A sensitive method for observing changes of electrical conductivity in single hygroscopic fibres

1924 ◽  
Vol 96 (674) ◽  
pp. 181-193 ◽  
Keyword(s):  
Electrical Conductivity ◽  
Electrical Conduction ◽  
The State ◽  
Atmospheric Conditions ◽  
Imperfect Contact ◽  
Air Movement ◽  
Experimental Values ◽  
Sensitive Method

Some years ago, after noticing that an inconstant and excessive leak from the insulated system of an electroscope was due to a barely visible filament of spider’s web, the author was struck by the beautiful way in which the arrangement responded to changing atmospheric conditions. An attempt to adapt this observation to the study of the absorption of moisture by fibrous substances has led to the method described in this paper. Our expectations as to its possibilities have been more than realised. The effect of changes in atmospheric conditions upon the state of fibrous substances, as indicated by their electrical conduction, can be followed continuously. The conductivity time curves, shown in figs..3a, 3b, 5a and 5b, where the actual experimental values are plotted, are typical examples of the accuracy obtainable. Bulk methods of measuring the conductivity of hygroscopic fibrous substances have always given complex results. By examining microscopic amounts, such as single cotton hairs 1 cm. long, we are able to reduce errors incurred by ( a ) imperfect contact, ( b ) pockets of moisture trapped in the interstices of the fibrous mass, ( c ) difficulties of conditioning large quantities of material under compression as a consequence of restriction of air movement ( d ) displacement (under pressure) of absorbed moisture from the materials whose structures are, in effect, like that of a sponge.

scholarly journals Impurity concentration dependent electrical conduction in germanium crystals at low temperatures

2019 ◽  
Vol 42 (6) ◽  
Author(s):  
Manoranjan Ghosh ◽  
Shreyas Pitale ◽  
S G Singh ◽  
Shashwati Sen ◽  
S C Gadkari
Keyword(s):  
Electrical Conduction ◽  
Low Temperatures ◽  
Impurity Concentration

WEAK LOCALIZATION AND ELECTRON–ELECTRON INTERACTION EFFECTS IN THIN METAL WIRES AND FILMS

2010 ◽  
Vol 24 (12n13) ◽  
pp. 2053-2071
Author(s):  
N. Giordano
Keyword(s):  
Electrical Conduction ◽  
Low Temperatures ◽  
Experimental Studies ◽  
Weak Localization ◽  
Thin Metal ◽  
Electron Interaction ◽  
Length Scales ◽  
Disordered Metals ◽  
Experimental Findings ◽  
Metal Wires

A brief and selective review of experimental studies of electrical conduction in thin metal wires and films at low temperatures is given. This review will illustrate the importance of various length scales and of dimensionality in determining the properties disordered metals. A few intriguing and still unresolved experimental findings are also mentioned.

Tunable Electrical Conductivity of Individual Graphene Oxide Sheets Reduced at “Low” Temperatures

Nano Letters ◽  
2008 ◽  
Vol 8 (12) ◽  
pp. 4283-4287 ◽  
Author(s):  
Inhwa Jung ◽  
Dmitriy A. Dikin ◽  
Richard D. Piner ◽  
Rodney S. Ruoff
Keyword(s):  
Electrical Conductivity ◽  
Graphene Oxide ◽  
Low Temperatures ◽  
Graphene Oxide Sheets

Electrical Conduction in Carbon Black Composites

1986 ◽  
Vol 59 (3) ◽  
pp. 432-454 ◽  
Author(s):  
Avrom I. Medalia
Keyword(s):  
Electrical Conductivity ◽  
Carbon Black ◽  
Electrical Conduction ◽  
Electromagnetic Interference ◽  
Physical Processes ◽  
Intrinsic Conductivity ◽  
Dominant Process

Abstract Electrical conductivity is important in many rubber and plastic compounds including antistatic applications, wire and cable sheathing, and shielding against electromagnetic interference (EMI). Elastomers and plastics are insulators (dielectrics) to which conductivity is imparted by addition of a finely divided or colloidal filler of high intrinsic conductivity, such as carbon black. Over the years, there has developed a sizable body of information regarding measurement of conductivity, and the factors which affect it in such compounds or composites. With regard to the physical processes involved in the conduction of electricity, various mechanisms have been proposed by various authors. It appears that many physical processes can be involved and that the dominant process depends upon the composition of the composite and the conditions of measurement. The purpose of this review is to survey the proposed mechanisms of conduction in composites of carbon black and nonconductive polymers, taking special note of recent theoretical advances, and to examine the effects of the properties of the carbon black and the composition of the composite.

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