|
Radiation Material Science
Radiation materials science is a subfield of materials science which studies the interaction of radiation with matter: a broad subject covering many forms of irradiation and of matter. Main aim of radiation material science Some of the most profound effects of irradiation on materials occur in the core of nuclear power reactors where atoms comprising the structural components are displaced numerous times over the course of their engineering lifetimes. The consequences of radiation to core components includes changes in shape and volume by tens of percent, increases in hardness by factors of five or more, severe reduction in ductility and increased embrittlement, and susceptibility to environmentally induced cracking. For these structures to fulfill their purpose, a firm understanding of the effect of radiation on materials is required in order to account for irradiation effects in design, to mitigate its effect by changing operating conditions, or to serve as a guide for creatin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Materials Science
Materials science is an interdisciplinary field of researching and discovering materials. Materials engineering is an engineering field of finding uses for materials in other fields and industries. The intellectual origins of materials science stem from the Age of Enlightenment, when researchers began to use analytical thinking from chemistry, physics, and engineering to understand ancient, phenomenological observations in metallurgy and mineralogy. Materials science still incorporates elements of physics, chemistry, and engineering. As such, the field was long considered by academic institutions as a sub-field of these related fields. Beginning in the 1940s, materials science began to be more widely recognized as a specific and distinct field of science and engineering, and major technical universities around the world created dedicated schools for its study. Materials scientists emphasize understanding how the history of a material (''processing'') influences its struc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radioactive Waste
Radioactive waste is a type of hazardous waste that contains radioactive material. It is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, nuclear decommissioning, rare-earth mining, and nuclear weapons reprocessing. The storage and disposal of radioactive waste is regulated by government agencies in order to protect human health and the environment. Radioactive waste is broadly classified into 3 categories: low-level waste (LLW), such as paper, rags, tools, clothing, which contain small amounts of mostly short-lived radioactivity; intermediate-level waste (ILW), which contains higher amounts of radioactivity and requires some shielding; and high-level waste (HLW), which is highly radioactive and hot due to decay heat, thus requiring cooling and shielding. Spent nuclear fuel can be processed in nuclear reprocessing plants. One third of the total amount have already been reprocessed. With nuclear reprocessing 96% of the spent fue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase Transition
In physics, chemistry, and other related fields like biology, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic State of matter, states of matter: solid, liquid, and gas, and in rare cases, plasma (physics), plasma. A phase of a thermodynamic system and the states of matter have uniform physical property, physical properties. During a phase transition of a given medium, certain properties of the medium change as a result of the change of external conditions, such as temperature or pressure. This can be a discontinuous change; for example, a liquid may become gas upon heating to its boiling point, resulting in an abrupt change in volume. The identification of the external conditions at which a transformation occurs defines the phase transition point. Types of phase transition States of matter Phase transitions commonly refer to when a substance tran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Growth
Cell most often refers to: * Cell (biology), the functional basic unit of life * Cellphone, a phone connected to a cellular network * Clandestine cell, a penetration-resistant form of a secret or outlawed organization * Electrochemical cell, a device used to convert chemical energy to electrical energy * Prison cell, a room used to hold people in prisons Cell may also refer to: Arts, entertainment, and media Fictional entities * Cell (comics), a Marvel comic book character * Cell (Dragon Ball), Cell (''Dragon Ball''), a character in the manga series ''Dragon Ball'' Literature * Cell (novel), ''Cell'' (novel), a 2006 horror novel by Stephen King * "Cells", poem, about a hungover soldier in gaol, by Rudyard Kipling *The Cell (play), ''The Cell'' (play), an Australian play by Robert Wales Music * Cell (music), a small rhythmic and melodic design that can be isolated, or can make up one part of a thematic context * Cell (American band) * Cell (Japanese band) * Cell (album), ''Cell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutron-induced Swelling
Neutron-induced swelling is the increase of volume and decrease of density of materials subjected to intense neutron radiation. Neutrons impacting the material's lattice rearrange its atoms, causing buildup of dislocations, voids, and Wigner energy. Together with the resulting strength reduction and embrittlement, it is a major concern for materials for nuclear reactor A nuclear reactor is a device used to initiate and control a Nuclear fission, fission nuclear chain reaction. They are used for Nuclear power, commercial electricity, nuclear marine propulsion, marine propulsion, Weapons-grade plutonium, weapons ...s. Materials show significant differences in their swelling resistance. References Radiation effects Nuclear technology Materials degradation {{nuclear-tech-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stress (mechanics)
In continuum mechanics, stress is a physical quantity that describes forces present during deformation. For example, an object being pulled apart, such as a stretched elastic band, is subject to ''tensile'' stress and may undergo elongation. An object being pushed together, such as a crumpled sponge, is subject to ''compressive'' stress and may undergo shortening. The greater the force and the smaller the cross-sectional area of the body on which it acts, the greater the stress. Stress has dimension of force per area, with SI units of newtons per square meter (N/m2) or pascal (Pa). Stress expresses the internal forces that neighbouring particles of a continuous material exert on each other, while ''strain'' is the measure of the relative deformation of the material. For example, when a solid vertical bar is supporting an overhead weight, each particle in the bar pushes on the particles immediately below it. When a liquid is in a closed container under pressure, each ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frenkel Pair
In crystallography, a Frenkel defect is a type of point defect in crystalline solids, named after its discoverer Yakov Frenkel. The defect forms when an atom or smaller ion (usually cation) leaves its place in the structure, creating a vacancy and becomes an interstitial by lodging in a nearby location. In elemental systems, they are primarily generated during particle irradiation, as their formation enthalpy is typically much higher than for other point defects, such as vacancies, and thus their equilibrium concentration according to the Boltzmann distribution is below the detection limit. In ionic crystals, which usually possess low coordination number or a considerable disparity in the sizes of the ions, this defect can be generated also spontaneously, where the smaller ion (usually the cation) is dislocated. Similar to a Schottky defect the Frenkel defect is a stoichiometric defect (does not change the over all stoichiometry of the compound). In ionic compounds, the vacancy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interstitial Defect
In materials science, an interstitial defect is a type of point crystallographic defect where an atom of the same or of a different type, occupies an interstitial site in the crystal structure. When the atom is of the same type as those already present they are known as a self-interstitial defect. Alternatively, small atoms in some crystals may occupy interstitial sites, such as hydrogen in palladium. Interstitials can be produced by bombarding a crystal with elementary particles having energy above the displacement threshold for that crystal, but they may also exist in small concentrations in thermodynamic equilibrium. The presence of interstitial defects can modify the physical and chemical properties of a material. History The idea of interstitial compounds was started in the late 1930s and they are often called Hagg phases after Hägg. Transition metals generally crystallise in either the hexagonal close packed or face centered cubic structures, both of which can be conside ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacancy Defect
In crystallography, a vacancy is a type of point defect in a crystal where an atom is missing from one of the lattice sites.Ehrhart, P. (1991) "Properties and interactions of atomic defects in metals and alloys", chapter 2, p. 88 in ''Landolt-Börnstein, New Series III'', Vol. 25, Springer, Berlin Crystals inherently possess imperfections, sometimes referred to as crystallographic defects. Vacancies occur naturally in all crystalline materials. At any given temperature, up to the melting point of the material, there is an equilibrium concentration (ratio of vacant lattice sites to those containing atoms). At the melting point of some metals the ratio can be approximately 1:1000. This temperature dependence can be modelled by :N_ = N \exp\left(\frac\right) where is the vacancy concentration, is the energy required for vacancy formation, is the Boltzmann constant, is the absolute temperature, and is the concentration of atomic sites i.e. : N = \frac where is density, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Irradiation
Irradiation is the process by which an object is exposed to radiation. An irradiator is a device used to expose an object to radiation, most often gamma radiation, for a variety of purposes. Irradiators may be used for sterilizing medical and pharmaceutical supplies, preserving foodstuffs, alteration of gemstone colors, studying radiation effects, eradicating insects through sterile male release programs, or calibrating thermoluminescent dosimeters (TLDs). The exposure can originate from various sources, including natural sources. Most frequently the term refers to ionizing radiation, and to a level of radiation that will serve a specific purpose, rather than radiation exposure to normal levels of background radiation. The term irradiation usually excludes the exposure to non-ionizing radiation, such as infrared, visible light, microwaves from cellular phones or electromagnetic waves emitted by radio and television receivers and power supplies. Applications Sterilization If ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Single Displacement Reaction
A single-displacement reaction, also known as single replacement reaction or exchange reaction, is an archaic concept in chemistry. It describes the stoichiometry of some chemical reactions in which one element or ligand is replaced by an atom or group. It can be represented generically as: :A + BC -> AC + B where either *A and B are different metals (or any element that forms cation like hydrogen) and C is an anion; or *A and B are halogens and C is a cation. This will most often occur if A is more reactive than B, thus giving a more stable product. The reaction in that case is exergonic and spontaneous. In the first case, when A and B are metals, BC and AC are usually aqueous compounds (or very rarely in a molten state) and C is a spectator ion (i.e. remains unchanged). : A(s) + \underbrace_ -> \underbrace_ + B(s) In the reactivity series, the metals with the highest propensity to donate their electrons to react are listed first, followed by less reactive ones. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ion Beam Deposition
Ion beam deposition (IBD) is a process of applying materials to a target through the application of an ion beam. Ion beam deposition setup with mass separator An ion beam deposition apparatus typically consists of an ion source, ion optics, and the deposition target. Optionally a mass analyzer can be incorporated. In the ion source source materials in the form of a gas, an evaporated solid, or a solution (liquid) are ionized. For atomic IBD, electron ionization, field ionization (Penning ion source) or cathodic arc sources are employed. Cathodic arc sources are used particularly for carbon ion deposition. Molecular ion beam deposition employs electrospray ionization or MALDI sources. The ions are then accelerated, focused or deflected using high voltages or magnetic fields. Optional deceleration at the substrate can be employed to define the deposition energy. This energy usually ranges from a few eV up to a few keV. At low energy molecular ion beams are deposited intact (ion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
