flux

flux

1. a substance, such as borax or salt, that gives a low melting-point mixture with a metal oxide. It is used for cleaning metal surfaces during soldering, etc., and for protecting the surfaces of liquid metals

2. Metallurgy a chemical used to increase the fluidity of refining slags in order to promote the rate of chemical reaction

3. a similar substance used in the making of glass

4. Physics

a. the rate of flow of particles, energy, or a fluid, through a specified area, such as that of neutrons (neutron flux) or of light energy (luminous flux)

b. the strength of a field in a given area expressed as the product of the area and the component of the field strength at right angles to the area

5. Pathol an excessive discharge of fluid from the body, such as watery faeces in diarrhoea

6. (in the philosophy of Heraclitus) the state of constant change in which all things exist

flux

1. A measure of the energy, number of particles, etc., emitted from or passing through a surface per unit time. See also radiant flux.

2. A measure of the strength of a field of force, such as a magnetic field, through a specified area. See also magnetic flux density.

Flux

 

in field theory. The flux of a vector field through the surface Σ is expressed by the surface integral

∫∫_∑(a·n) ds = ∫∫_∑ (a_x dydz + a_y dzdx + a_z dxdy)

where a = (a_x, a_y, a_z) and n is the unit vector normal to Σ. The variation of n is assumed here to be continuous over Σ. For the field of velocities of particles in a fluid, the flux of the vector field is equal to the quantity of the fluid flowing per unit time through Σ.

---

Flux

 

a substance used in metallurgical processes to form slag or control the composition of slag, to prevent molten metals from reacting with ambient gases, or to dissolve oxides when metals are soldered or welded. In the smelting and refining of metals, fluxes are introduced to produce slags with prescribed physical and chemical properties, to slag gangue and fuel ash, and to dissolve objectionable impurities. Fluxes are used, for example, to reduce the refractoriness or viscosity of metals or to alter their electrical conductivity.

Fluxes may be basic, acid, or neutral. Basic fluxes, which contain oxides of calcium, magnesium, iron, or other metals, include limestone, dolomite, pyrite cinder, lime, and sodium carbonate. Acid fluxes—such as quartz, sand, and flint—contain silica. Neutral fluxes contain alumina or calcium fluoride and include clay, bauxites, crushed firebrick, and fluorspar.

Melts of ferrous metals and alloys are protected against oxidation by covering or protective fluxes; chlorides and fluorides of alkali and alkaline-earth metals—for example, rock salt, sylvinite, carnallite, cryolite, borax, and rosin—are most often used for this purpose. The fluxes used in soldering and welding include rosin, borax, zinc chloride, ammonium chloride, and fluorspar. A number of fluxes that are melted and processed in advance have been developed for arc welding; when such fluxes are used, welding is performed directly under the flux.

I. D. REZNIK

flux

[fləks]

(electromagnetism)

The electric or magnetic lines of force in a region.

(materials)

In soldering, welding, and brazing, a material applied to the pieces to be united to reduce the melting point of solders and filler metals and to prevent the formation of oxides.

A substance used to promote the fusing of minerals or metals.

Additive for plastics composition to improve flow during physical processing.

In enamel work, a substance composed of silicates and other materials that forms a colorless, transparent glass when fired. Also know as fondant.

(nucleonics)

The product of the number of particles per unit volume and their average velocity; a special case of the physics definition. Also known as flux density.

(physics)

The integral over a given surface of the component of a vector field (for example, the magnetic flux density, electric displacement, or gravitational field) perpendicular to the surface; by definition, it is proportional to the number of lines of force crossing the surface.

The amount of some quantity flowing across a given area (often a unit area perpendicular to the flow) per unit time; the quantity may be, for example, mass or volume of fluid, electromagnetic energy, or number of particles.

flux

1. A fusible substance used in oxygen cutting, welding, brazing, or soldering operations; assists in the fusion of metals and the prevention of surface oxidation.

2. A bituminous material, generally liquid, used for softening other bituminous materials.

flux

The energy field generated by a magnet. See luminous flux.