|
A pyrotechnic composition is a substance or mixture of substances designed to produce an effect by heat, light, sound, gas/smoke or a combination of these, as a result of non-detonative self-sustaining exothermic chemical reactions. Pyrotechnic substances do not rely on oxygen from external sources to sustain the reaction. Basic types of pyrotechnic compositions are: * flash powder – burns very fast, produces explosions and/or bright flashes of light * gunpowder – burns slower than flash powder, produces large amount of gases * solid propellants – produce large amount of hot gases, used as sources of kinetic energy for rockets and projectiles * pyrotechnic initiators – produce large amount of heat, flames, and/or hot sparks, used to ignite other compositions * gas generators – produce large amount of gas, either high volume at short time (for actuators and ejection charges, often using solid propellants) or controlled flow rate (e.g. chemical oxygen generators, often using thermite-like compositions) * ejection charges – burn fast, produce large amount of gas at short time, used to eject payloads from containers * burst charges – burn fast, produce large amount of gas at short time, used to fragment a container and eject its content * smoke compositions – burn slowly, produce smoke, plain or colored * delay compositions – burn at constant slow speed, used to introduce delays into the firing train * pyrotechnic heat sources – produce large amount of heat and little to no gases, slow-burning, often thermite-like compositions * sparklers – producing white or colored sparks * flares – burn slowly, produce high amount of light, used for illumination or signaling * coloured fireworks compositions – produce light, white or colored Some pyrotechnic compositions are used in industry and aerospace for generation of large volumes of gas in gas generators (e.g. in airbags), in pyrotechnic fasteners, and in other similar applications. They are also used in military pyrotechnics, when production of large amount of noise, light, or infrared radiation is required; e.g. missile decoy flares, flash powders, and stun grenades. A new class of reactive material compositions is now under investigation by military. Many pyrotechnic compositions – especially involving aluminium and perchlorates – are often highly sensitive to friction, impact, and static electricity. Even as little as 0.1–10 millijoules spark can set off certain mixtures. ==Materials used== Pyrotechnic compositions are usually homogenized mixtures of small particles of fuels and oxidizers. The particles can be grains or flakes. Generally, the higher the surface area of the particles, the higher the reaction rate and burning speed. For some purposes, binders are used to turn the powder into a solid material. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「pyrotechnic composition」の詳細全文を読む スポンサード リンク
|