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Premelting
Premelting (also surface melting) refers to a quasi-liquid film that can occur on the surface of a solid even below melting point (T_m). The thickness of the film is temperature (T) dependent. This effect is common for all crystalline materials. Premelting shows its effects in frost heave, the growth of snowflakes and, taking grain boundary interfaces into account, maybe even in the movement of glaciers. Considering a solid-vapour interface, complete and incomplete premelting can be distinguished. During a temperature rise from below to above T_m , in the case of complete premelting, the solid melts homogeneously from the outside to the inside; in the case of incomplete premelting, the liquid film stays very thin during the beginning of the melting process, but droplets start to form on the interface. In either case, the solid always melts from the outside inwards, never from the inside. History The first to mention premelting might have been Michael Faraday in 1842 for ice surf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Premelting2
Premelting (also surface melting) refers to a quasi-liquid film that can occur on the surface of a solid even below melting point (T_m). The thickness of the film is temperature (T) dependent. This effect is common for all crystalline materials. Premelting shows its effects in frost heave, the growth of snowflakes and, taking grain boundary interfaces into account, maybe even in the movement of glaciers. Considering a solid-vapour interface, complete and incomplete premelting can be distinguished. During a temperature rise from below to above T_m , in the case of complete premelting, the solid melts homogeneously from the outside to the inside; in the case of incomplete premelting, the liquid film stays very thin during the beginning of the melting process, but droplets start to form on the interface. In either case, the solid always melts from the outside inwards, never from the inside. History The first to mention premelting might have been Michael Faraday in 1842 for ice surf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frost Heave
Frost heaving (or a frost heave) is an upwards swelling of soil during freezing conditions caused by an increasing presence of ice as it grows towards the surface, upwards from the depth in the soil where freezing temperatures have penetrated into the soil (the freezing front or freezing boundary). Ice growth requires a water supply that delivers water to the freezing front via capillary action in certain soils. The weight of overlying soil restrains vertical growth of the ice and can promote the formation of lens-shaped areas of ice within the soil. Yet the force of one or more growing ice lenses is sufficient to lift a layer of soil, as much as or more. The soil through which water passes to feed the formation of ice lenses must be sufficiently porous to allow capillary action, yet not so porous as to break capillary continuity. Such soil is referred to as "frost susceptible". The growth of ice lenses continually consumes the rising water at the freezing front. Differential f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Freezing
Surface freezing is the appearance of long-range crystalline order in a near-surface layer of a liquid. The surface freezing effect is opposite to a far more common surface melting, or premelting. Surface Freezing was experimentally discovered in melts of alkanes In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in whi ... and related chain molecules in the early 1990s independently by two groups. John Earnshaw and his group (Queen's University of Belfast) used light scattering, which did not allow a determination of the frozen layer's thickness, and whether or not it is laterally ordered. A group led by Ben Ocko (Brookhaven National Laboratory), Eric Sirota (Exxon) and Moshe Deutsch (Bar-Ilan University, Israel) discovered independently the same effect, using x-ray surface diffraction which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quasi-liquid
Quasi-solid, Falsely-solid, or semisolid is the physical term for something whose state lies between a solid and a liquid. While similar to solids in some respects, such as having the ability to support their own weight and hold their shapes, a quasi-solid also shares some properties of liquids, such as conforming in shape to something applying pressure to it and the ability to flow under pressure. The words quasi-solid, semisolid, and semiliquid may be used interchangeably. Quasi-solids and semisolids are sometimes described as amorphous because at the microscopic scale they have a disordered structure unlike the more common crystalline solids. They should not be confused with amorphous solids as they are not solids and exhibit properties such as flow which bulk solids do not. Examples Petroleum jelly - a mixture of hydrocarbons extracted from crude oil and subsequently refined, has semisolid properties. It is used topically on human skin to promote healing of minor irritati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Regelation
Regelation is the phenomenon of ice melting under pressure and refreezing when the pressure is reduced. This can be demonstrated by looping a fine wire around a block of ice, with a heavy weight attached to it. The pressure exerted on the ice slowly melts it locally, permitting the wire to pass through the entire block. The wire's track will refill as soon as pressure is relieved, so the ice block will remain intact even after wire passes completely through.'' This experiment is possible for ice at −10 °C or cooler, and while essentially valid, the details of the process by which the wire passes through the ice are complex. The phenomenon works best with high thermal conductivity materials such as copper, since latent heat of fusion from the top side needs to be transferred to the lower side to supply latent heat of melting. In short, the phenomenon in which ice converts to liquid due to applied pressure and then re-converts to ice once the pressure is removed is called ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wetting
Wetting is the ability of a liquid to maintain contact with a solid surface, resulting from intermolecular interactions when the two are brought together. This happens in presence of a gaseous phase or another liquid phase not miscible with the first one. The degree of wetting (wettability) is determined by a force balance between adhesive and cohesive forces. Wetting is important in the bonding or adherence of two materials. Wetting and the surface forces that control wetting are also responsible for other related effects, including capillary effects. There are two types of wetting: non-reactive wetting and reactive wetting. Wetting deals with three phases of matter: gas, liquid, and solid. It is now a center of attention in nanotechnology and nanoscience studies due to the advent of many nanomaterials in the past two decades (e.g. graphene, Carbon nano tube, carbon nanotube, boron nitride nanomesh). Explanation Adhesive forces between a liquid and solid cause a liqu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase Diagram
A phase diagram in physical chemistry, engineering, mineralogy, and materials science is a type of chart used to show conditions (pressure, temperature, volume, etc.) at which thermodynamically distinct phases (such as solid, liquid or gaseous states) occur and coexist at equilibrium. Overview Common components of a phase diagram are ''lines of equilibrium'' or ''phase boundaries'', which refer to lines that mark conditions under which multiple phases can coexist at equilibrium. Phase transitions occur along lines of equilibrium. Metastable phases are not shown in phase diagrams as, despite their common occurrence, they are not equilibrium phases. Triple points are points on phase diagrams where lines of equilibrium intersect. Triple points mark conditions at which three different phases can coexist. For example, the water phase diagram has a triple point corresponding to the single temperature and pressure at which solid, liquid, and gaseous water can coexist in a stab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice III
Ice III is a form of solid matter which consists of tetragonal crystalline ice, formed by cooling water down to at . It is the least dense of the high-pressure water phases, with a density of (at 350 MPa). It has a very high relative permittivity at 117 and has a density of (making it more dense than water). The proton-ordered form of is ice IX. Ordinary water ice is known as , (in the Bridgman nomenclature). Different types of ice, from Ice II to Ice XIX Ice XIX is a proposed crystalline phase of water. Along with ice XV, it is one of two phases of ice directly related to ice VI. Ice XIX is prepared by cooling HCl-doped ice VI at a pressure above 1.6 GPa down to about 100 K. As of 2022, its cry ..., have been created in the laboratory at different temperatures and pressures. See also * Ice, for other crystalline forms of ice References * Water ice {{inorganic-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frank Philip Bowden
Frank Philip Bowden CBE FRS (2 May 1903 – 3 September 1968) was an Australian physicist. Early life He was born in Hobart, Tasmania, the son of telegraph engineer Frank Prosser Bowden. Bowden received his Bachelor of Science degree from the University of Tasmania in Australia in 1925, a Master of Science degree there in 1927 and a Doctor of Science (D.Sc) degree in 1933, by which time he was working at the University of Cambridge in England. He gained his PhD from Cambridge in 1929. Career Between 1931 and 1939, Bowden worked as a lecturer in physical chemistry at the University of Cambridge. He moved back to Australia in 1939 to work at the Commonwealth Scientific and Industrial Research Organisation. He returned to Britain in 1946 as a reader in physical chemistry. In 1957, Bowden became Reader of Physics at Cambridge, and in 1966 became the Professor of Surface Physics. He made significant contributions to the field of tribology and he received the International A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Tyndall
John Tyndall FRS (; 2 August 1820 – 4 December 1893) was a prominent 19th-century Irish physicist. His scientific fame arose in the 1850s from his study of diamagnetism. Later he made discoveries in the realms of infrared radiation and the physical properties of air, proving the connection between atmospheric CO and what is now known as the greenhouse effect in 1859. Tyndall also published more than a dozen science books which brought state-of-the-art 19th century experimental physics to a wide audience. From 1853 to 1887 he was professor of physics at the Royal Institution of Great Britain in London. He was elected as a member to the American Philosophical Society in 1868. Early years and education Tyndall was born in Leighlinbridge, County Carlow, Ireland. His father was a local police constable, descended from Gloucestershire emigrants who settled in southeast Ireland around 1670. Tyndall attended the local schools (Ballinabranna Primary School) in County Carlow u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Joly
John Joly FRS (1 November 1857 – 8 December 1933) was an Irish physicist and professor of geology at the University of Dublin, known for his development of radiotherapy in the treatment of cancer. He is also known for developing techniques to more accurately estimate the age of a geological period, based on radioactive elements present in minerals, the uranium–thorium dating.Obituary, Irish Times, 16 December 1933, page 1 Career Joly was born in Holywood House (the Church of Ireland Rectory), Bracknagh, County Offaly, Ireland. He was a second cousin of Charles Jasper Joly, the astronomer. He entered Trinity College, Dublin in 1876, graduating in Engineering in 1882 in first place with several special certificates in branches of engineering, at the same time obtaining a First Class Honours in modern literature. He worked as a demonstrator in Trinity's Engineering and Physics departments before succeeding William Johnson Sollas in the Chair of Geology and Mineralogy in 1897, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
