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Nichrome
Nichrome (also known as NiCr, nickel-chromium or chromium-nickel) is a family of alloys of nickel and chromium (and occasionally iron) commonly used as resistance wire, heating elements in devices like toasters, electrical kettles and space heaters, in some dental restorations (fillings) and in a few other applications. Patented in 1906 by Albert Marsh (US patent 811,859), nichrome is the oldest documented form of resistance heating alloy. The A Grade nichrome alloy is 80% nickel and 20% chromium by mass, but there are many other combinations of metals for various applications. Properties C Grade Nichrome is consistently silvery in color, is corrosion-resistant, has a high melting point of approximately , and has an electrical resistivity of around 1.12 μΩ·m, which is around 66 times higher resistivity than copper of 16.78 nΩ·m. Some nichrome formulations have a resistivity as low as 1.0 μΩ·m or as high as 1.5 μΩ·m. Almost any conductive w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heating Element
A heating element is a device used for conversion of electric energy into heat, consisting of a heating resistor and accessories. Heat is generated by the passage of electric current through a resistor through a process known as Joule heating. Heating elements are used in household appliances, industrial equipment, and scientific instruments enabling them to perform tasks such as cooking, warming, or maintaining specific temperatures higher than the ambient. Heating elements may be used to transfer heat via Thermal conduction, conduction, convection, or radiation. They are different from devices that generate heat from electrical energy via the Peltier effect, and have no dependence on the direction of electrical current. Principles of operation Resistance & resistivity Materials used in heating elements have a relatively high Electrical resistivity and conductivity, electrical resistivity, which is a measure of the material's ability to resist electric current. The Electri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toaster
A toaster is a small electric appliance that uses radiant heat to brown sliced bread into toast, the color caused by the Maillard reaction. It typically consists of one or more slots into which bread is inserted, and heating elements, often made of nichrome wire, to generate heat and toast the bread to the desired level of crispiness. Types Pop-up toaster In a pop-up or automatic toaster, a single vertical piece of bread is dropped into a slot on the top of the toaster. A lever on the side of the toaster is pressed down, lowering the bread into the toaster and activating the heating elements. The length of the toasting cycle (and therefore the degree of toasting) is adjustable via a lever, knob, or series of pushbuttons, and when an internal device determines that the toasting cycle is complete, the toaster turns off and the toast pops up out of the slots. The completion of toasting may be determined by a timer (sometimes manually set) or by a thermal sensor, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heating Element
A heating element is a device used for conversion of electric energy into heat, consisting of a heating resistor and accessories. Heat is generated by the passage of electric current through a resistor through a process known as Joule heating. Heating elements are used in household appliances, industrial equipment, and scientific instruments enabling them to perform tasks such as cooking, warming, or maintaining specific temperatures higher than the ambient. Heating elements may be used to transfer heat via Thermal conduction, conduction, convection, or radiation. They are different from devices that generate heat from electrical energy via the Peltier effect, and have no dependence on the direction of electrical current. Principles of operation Resistance & resistivity Materials used in heating elements have a relatively high Electrical resistivity and conductivity, electrical resistivity, which is a measure of the material's ability to resist electric current. The Electri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bridgewire
A bridgewire or bridge wire, also known as a hot bridge wire (HBW), is a relatively thin resistance wire used to set off a pyrotechnic composition serving as pyrotechnic initiator. By passing of electric current it is heated to a high temperature that starts the exothermic chemical reaction of the attached composition. After successful firing, the bridgewire melts, resulting in an open circuit. Usually a thin nichrome wire is used. Some applications also use platinum-silver alloy; other bridgewire materials in use are platinum, gold, silver, tungsten, etc. Care has to be taken when selecting the material as it is in direct contact with the pyrotechnic composition and should not undergo corrosion in such conditions. Another material, able to actively release chemical energy, is Pyrofuze, aluminium wire clad with palladium; when being heated it undergoes strongly exothermic reaction as the molten metals form an alloy. A variant with the same function consists of laminated thin alt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Match
An electric match is a device that uses an externally applied electric current to ignite a combustible compound. Electric matches use a bridgewire consisting of a heating element to ignite a pyrogen, which is a quantity of readily ignited pyrotechnic initiator composition. Electric matches can be used in any application where source of heat is needed at a precisely controlled point in time, typically to ignite a propellant or explosive. Examples include airbags, pyrotechnics, and military or commercial explosives. Design Electric matches consist of two parts, a bridgewire and a Pyrogen (pyrotechnics), pyrogen. The bridgewire is a heating element, typically in the form of a loop or coil of thin wire, which is encased in the pyrogen, which is a quantity of readily ignited pyrotechnic initiator composition. If the pyrogen is sufficiently conductive, it can act as the bridgewire as well. Electric matches also come with provisions for attaching an electric current source, and they ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Model Rocket
A model rocket is a small rocket designed to reach low altitudes (e.g., for a model) and #Model rocket recovery methods, be recovered by a variety of means. According to the United States National Association of Rocketry, National Association of Rocketry (NAR)'s Safety Code, model rockets are constructed out of lightweight and non metallic parts. The materials are typically paper, cardboard, balsa wood or plastic. The code also provides guidelines for motor use, launch site selection, launch methods, launcher placement, recovery system design and deployment and more. Since the early 1960s, a copy of the Model Rocket Safety Code has been provided with most model rocket kits and motors. Despite its inherent association with extremely flammable substances and objects with a pointed tip traveling at high speeds, model rocketry historically has proven to be a very safe hobby and has been credited as a significant source of inspiration for children who have eventually become scient ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space Heater
A space heater is a device used to heat a single, small- to medium-sized area. This type of heater can be contrasted with central heating, which distributes heat to multiple areas. Types Dominant mode of heat transfer All space heaters transfer heat to their environment via some combination of the three fundamental modes of heat transfer: convection, radiation, and conduction. Typically heaters are designed with either convection or radiation as the sole dominant mode. Convective heaters ''Convective space heaters'' utilize convection to transfer heat from the power source to a space. These heaters typically either rely on ''natural'' or ''forced'' convection. Natural convection is a phenomenon where temperature variations in an environment generate fluid flow. Forced convection heaters utilize a device like a fan to generate air flow and spread heat at a fast pace. Sometimes called "fan heaters," these are often cheap but lack in efficiency and versatility. Radia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resistance Wire
Resistance wire is wire intended for making electrical resistors (which are used to control the amount of current in a circuit). It is better if the alloy used has a high resistivity, since a shorter wire can then be used. In many situations, the stability of the resistor is of primary importance, and thus the alloy's temperature coefficient of resistivity and corrosion resistance play a large part in material selection. When resistance wire is used for heating elements (in electric heaters, toasters, and the like), high resistivity and oxidation resistance is important. Sometimes resistance wire is insulated by ceramic powder and sheathed in a tube of another alloy. Such heating elements are used in electric ovens and water heaters, and in specialized forms for cooktops. __TOC__ Types Nichrome, a non-magnetic 80/20 alloy of nickel and chromium, is the most common resistance wire for heating purposes because it has a high resistivity and resistance to oxidation at high tempe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flame Test
A flame test is relatively quick test for the presence of some elements in a sample. The technique is archaic and of questionable reliability, but once was a component of qualitative inorganic analysis. The phenomenon is related to pyrotechnics and atomic emission spectroscopy. The color of the flames is understood through the principles of atomic electron transition and photoemission, where varying elements require distinct energy levels (photons) for electron transitions. History Robert Bunsen invented the now-famous Bunsen burner in 1855, which was useful in flame tests due to its non-luminous flame that did not disrupt the colors emitted by the test materials. The Bunsen burner, combined with a prism (filtering the color interference of contaminants), led to the creation of the spectroscope, capable of emitting the spectral emission of various elements. In 1860, the unexpected appearance of sky-blue and dark red was observed in spectral emissions by Robert Bunsen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Explosive
An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An explosive charge is a measured quantity of explosive material, which may either be composed solely of one ingredient or be a mixture containing at least two substances. The potential energy stored in an explosive material may, for example, be: * chemical energy, such as nitroglycerin or grain dust * pressurized gas, such as a gas cylinder, aerosol can, or boiling liquid expanding vapor explosion * nuclear energy, such as in the fissile isotopes uranium-235 and plutonium-239 Explosive materials may be categorized by the speed at which they expand. Materials that detonate (the front of the chemical reaction moves faster through the material than the speed of sound) are said to be "high explosives" and materials that deflagrate ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platinum
Platinum is a chemical element; it has Symbol (chemistry), symbol Pt and atomic number 78. It is a density, dense, malleable, ductility, ductile, highly unreactive, precious metal, precious, silverish-white transition metal. Its name originates from Spanish language, Spanish , a diminutive of "silver". Platinum is a member of the platinum group of elements and group 10 element, group 10 of the periodic table of elements. It has six naturally occurring isotopes. It is one of the Abundance of elements in Earth's crust, rarer elements in Earth's crust, with an average abundance of approximately 5 microgram, μg/kg, making platinum about 30 times rarer than gold. It occurs in some nickel and copper ores along with some Native element mineral, native deposits, with 90% of current production from deposits across Russia's Ural Mountains, Colombia, the Sudbury Basin, Sudbury basin of Canada, and a large reserve in South Africa. Because of its scarcity in Earth's crust, only a f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kiln
A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or Chemical Changes, chemical changes. Kilns have been used for millennia to turn objects made from clay into pottery, Tile, tiles and bricks. Various industries use rotary kilns for pyroprocessing (to calcinate ores, such as limestone to Lime (material), lime for Cement kiln, cement) and to transform many other materials. Etymology According to the Oxford English Dictionary, kiln was derived from the words cyline, cylene, cyln(e) in Old English, in turn derived from Latin ''culina'' ('kitchen'). In Middle English, the word is attested as kulne, kyllne, kilne, kiln, kylle, kyll, kil, kill, keele, kiele. In Greek the word ''καίειν, kaiein'', means 'to burn'. Pronunciation The word 'kiln' was originally pronounced 'kil' with the 'n' silent, as is referenced in ''Webster's Dictionary of 1828'' and in ''English Words as Sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
