A spark is an incandescent particle. [1] Sparks may be produced by pyrotechnics, by metalworking or as a by-product of fires, especially when burning wood.
A spark is an incandescent particle. [1] Sparks may be produced by pyrotechnics, by metalworking or as a by-product of fires, especially when burning wood.
In pyrotechnics, charcoal, iron filings, aluminum, titanium and metal alloys such as magnalium may be used to create sparks. [2] The quantity and style of sparks produced depends on the composition and pyrophoricity of the metal and can be used to identify the type of metal by spark testing. In the case of iron, the presence of carbon is required, as in carbon steel — about 0.7% is best for large sparks. The carbon burns explosively in the hot iron and this produces pretty, branching sparks. [3] The color of sparks used in pyrotechnics is determined by the material that the sparks are made from, with the possibility of adding different chemical compounds to certain materials to further influence the color of the sparks. The basic color of sparks is limited to red/orange, gold (yellow) and silver (white). [2] This is explained by light emission from a solid particle. Light emitted from solid particles is defined by black-body radiation. The temperature of the spark is controlled by the reactivity of the metal. Higher reactive metals lead to hotter sparks. The electronegativity has found to be a helpful indicator to estimate the temperature and consequently the color of a spark. [2] To achieve colors differing from black body emitters, vapor phase combustion of the metal is necessary. A typical example is zinc, with a relatively low boiling point of 1,180 K (910 °C; 1,660 °F). Zinc sparks show an unusual bluish/greenish white appearance. [2] Exotic sparks can be obtained from erbium powder. These sparks switch between surface and vapor phase combustion and accordingly between orange (black body) and green (element specific) emission. [4] The color-change is based on the medium-ranged boiling point of erbium, which burns only partly in the vapor phase.
The adjacent rare earth elements thulium, lutetium and yttrium can form color-changing sparks, too, although the visibility of both phases of the same spark is less pronounced due to a lower (Tm) or higher (Y, Lu) boiling point of the metal. [5] Alloys containing at least one metal with a low boiling point can be used to control the color of the spark. [6] The lower boiling component evaporates and burns in the vapor phase, while the metal with a high boiling point serves as a carrier. In the vapor phase, bright element-specific light emission takes place. For example, a eutectic ytterbium-copper-alloy forms long green sparks and burning lithium silicide shows long red spark segments. [6] The duration of a spark’s existence is determined by the initial size of the particle, with a larger size leading to a longer-lasting spark. [2]
Metals with low thermal conductivity are especially good at producing sparks. Titanium and zirconium are especially good in this respect and so are now used in fireworks. Copper, on the other hand, has a high conductivity and so is poor at producing sparks. For this reason, alloys of copper such as beryllium bronze are used to make safety tools which will not spark so easily. [7]
Robert Hooke studied the sparks created by striking a piece of flint and steel together. He found that the sparks were usually particles of the steel that had become red hot and so melted into globules. [8] These sparks can be used to ignite tinder and so start a fire. [9]
In colonial America, flint and steel were used to light fires when easier methods failed. Scorched linen was commonly used as tinder to catch the spark and start the fire, but producing a good spark could take much time. A spinning steel wheel provided a good stream of sparks when it engaged the flint, and a tinderbox designed to do this was known as a mill. [10]
In a modern lighter or firesteel, iron is mixed with cerium and other rare earths to form the alloy ferrocerium. This readily produces sparks when scraped and burns hotter than steel would. This higher temperature is needed to ignite the vapour of the lighter fluid. [11]
Molten metal sparks can be created when metal is heated by processes such as Bessemer conversion of iron to steel or arc welding.
Arc welding uses a low voltage and high current electric arc between an electrode and the base material to melt the metals at the welding point, which often creates sparks. To reduce the risk of burns, welders wear heavy leather gloves and long sleeve jackets to avoid exposure to extreme heat, flames, and sparks. In spot welding, metal surfaces that are held in contact are joined by the heat from resistance to electric current flow. It is common for a spray of sparks in the form of molten metal droplets to be ejected from the parts being joined. [12] or the resistance heating of spot welding. [13]
Fires may produce sparks as updrafts carry particles of the burning fuel aloft. This was a great problem with steam locomotives as the sparks might set fire to the adjacent landscape or even to the train itself, especially if the engine burned wood rather than coal. [14] To prevent this dangerous nuisance, a variety of spark arrestors were invented and fitted. [15]
The chimneys and exhausts of other fuel-burning engines such as steam engines or internal combustion engines might also have spark arrestors fitted if there would be a fire risk from their operation. For example, a trail bike might be fitted with a centrifugal arrestor, which will trap glowing hot pieces of soot. [16]
The significance of a spark as a source for a flame or a conflagration shows clearly, for example, in the naming and motto of Lenin's newspaper Iskra [The Spark]. The spark metaphor has often been used in philosophy since Stoicism [17] and, recently, after Jacques Lacan. The “creative spark” has come to be considered as inherent to metaphor itself. [18] Hasidic philosophy contains a doctrine of holy sparks (nitzotzot) from the kabbalism of Isaac Luria in which there is a duty to gather the sundered light of creation. [19]
In the Book of Job (Job 5:7), it is written, "Yet man is born unto trouble, as the sparks fly upward." The use by King James' translators of the word sparks here is a poetic one rather than a literal one. [20] The sparks of fire are identified by some translators as the sons of Resheph - a Canaanite deity of lightning and pestilence. [21]
Welding is a fabrication process that joins materials, usually metals or thermoplastics, primarily by using high temperature to melt the parts together and allow them to cool, causing fusion. Common alternative methods include solvent welding using chemicals to melt materials being bonded without heat, and solid-state welding processes which bond without melting, such as pressure, cold welding, and diffusion bonding.
Thermite is a pyrotechnic composition of metal powder and metal oxide. When ignited by heat or chemical reaction, thermite undergoes an exothermic reduction-oxidation (redox) reaction. Most varieties are not explosive, but can create brief bursts of heat and high temperature in a small area. Its form of action is similar to that of other fuel-oxidizer mixtures, such as black powder.
Fireworks are low explosive pyrotechnic devices used for aesthetic and entertainment purposes. They are most commonly used in fireworks displays, combining a large number of devices in an outdoor setting. Such displays are the focal point of many cultural and religious celebrations, though mismanagement could lead to fireworks accidents.
A welder is a person or equipment that fuses materials together. The term welder refers to the operator, the machine is referred to as the welding power supply. The materials to be joined can be metals or varieties of plastic or polymer. Welders typically have to have good dexterity and attention to detail, as well as technical knowledge about the materials being joined and best practices in the field.
Shielded metal arc welding (SMAW), also known as manual metal arc welding, flux shielded arc welding or informally as stick welding, is a manual arc welding process that uses a consumable electrode covered with a flux to lay the weld.
Submerged arc welding (SAW) is a common arc welding process. The first SAW patent was taken out in 1935. The process requires a continuously fed consumable solid or tubular electrode. The molten weld and the arc zone are protected from atmospheric contamination by being "submerged" under a blanket of granular fusible flux consisting of lime, silica, manganese oxide, calcium fluoride, and other compounds. When molten, the flux becomes conductive, and provides a current path between the electrode and the work. This thick layer of flux completely covers the molten metal thus preventing spatter and sparks as well as suppressing the intense ultraviolet radiation and fumes that are a part of the shielded metal arc welding (SMAW) process.
Arc welding is a welding process that is used to join metal to metal by using electricity to create enough heat to melt metal, and the melted metals, when cool, result in a binding of the metals. It is a type of welding that uses a welding power supply to create an electric arc between a metal stick ("electrode") and the base material to melt the metals at the point of contact. Arc welding power supplies can deliver either direct (DC) or alternating (AC) current to the work, while consumable or non-consumable electrodes are used.
A ball mill is a type of grinder filled with grinding balls, used to grind or blend materials for use in mineral dressing processes, paints, pyrotechnics, ceramics, and selective laser sintering. It works on the principle of impact and attrition: size reduction is done by impact as the balls drop from near the top of the shell.
Plasma cutting is a process that cuts through electrically conductive materials by means of an accelerated jet of hot plasma. Typical materials cut with a plasma torch include steel, stainless steel, aluminum, brass and copper, although other conductive metals may be cut as well. Plasma cutting is often used in fabrication shops, automotive repair and restoration, industrial construction, and salvage and scrapping operations. Due to the high speed and precision cuts combined with low cost, plasma cutting sees widespread use from large-scale industrial computer numerical control (CNC) applications down to small hobbyist shops.
Spark testing is a method of determining the general classification of ferrous materials. It normally entails taking a piece of metal, usually scrap, and applying it to a grinding wheel in order to observe the sparks emitted. These sparks can be compared to a chart or to sparks from a known test sample to determine the classification. Spark testing also can be used to sort ferrous materials, establishing the difference from one another by noting whether the spark is the same or different.
Gas tungsten arc welding is an arc welding process that uses a non-consumable tungsten electrode to produce the weld. The weld area and electrode are protected from oxidation or other atmospheric contamination by an inert shielding gas. A filler metal is normally used, though some welds, known as 'autogenous welds', or 'fusion welds' do not require it. A constant-current welding power supply produces electrical energy, which is conducted across the arc through a column of highly ionized gas and metal vapors known as a plasma.
Ferrocerium is a synthetic pyrophoric alloy of mischmetal hardened by blending in oxides of iron and/or magnesium. When struck with a harder material, friction produces hot fragments that oxidize rapidly when exposed to the oxygen in the air, producing sparks that can reach temperatures of 3,315 °C (6,000 °F). The effect is due to the low ignition temperature of cerium, between 150 and 180 °C.
The weldability, also known as joinability, of a material refers to its ability to be welded. Many metals and thermoplastics can be welded, but some are easier to weld than others. A material's weldability is used to determine the welding process and to compare the final weld quality to other materials.
A pyrotechnic colorant is a chemical compound which causes a flame to burn with a particular color. These are used to create the colors in pyrotechnic compositions like fireworks and colored fires. The color-producing species are usually created from other chemicals during the reaction. Metal salts are commonly used; elemental metals are used rarely.
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.
Magnalium is an aluminium alloy with 50% magnesium and 50% aluminum.
A welding helmet is a piece of personal protective equipment used by welders to protect the user from concentrated light and flying particles. Different welding processes need stronger lens shades with auto-darkening filters, while goggles suffice for others. OSHA and ANSI regulate this technology, defining shades based on the transmittance of light.
Oxy-fuel welding torch and oxy-fuel cutting are processes that use fuel gases and oxygen to weld or cut metals. French engineers Edmond Fouché and Charles Picard became the first to develop oxygen-acetylene welding in 1903. Pure oxygen, instead of air, is used to increase the flame temperature to allow localized melting of the workpiece material in a room environment.
Mechanical alloying (MA) is a solid-state and powder processing technique involving repeated cold welding, fracturing, and re-welding of blended powder particles in a high-energy ball mill to produce a homogeneous material. Originally developed to produce oxide-dispersion strengthened (ODS) nickel- and iron-base superalloys for applications in the aerospace industry, MA has now been shown to be capable of synthesizing a variety of equilibrium and non-equilibrium alloy phases starting from blended elemental or pre-alloyed powders. The non-equilibrium phases synthesized include supersaturated solid solutions, metastable crystalline and quasicrystalline phases, nanostructures, and amorphous alloys.The method is sometimes is classified as a surface severe platic deformation method to achieve nanomaterials.
Gas metal arc welding (GMAW), sometimes referred to by its subtypes metal inert gas (MIG) and metal active gas (MAG) is a welding process in which an electric arc forms between a consumable MIG wire electrode and the workpiece metal(s), which heats the workpiece metal(s), causing them to fuse. Along with the wire electrode, a shielding gas feeds through the welding gun, which shields the process from atmospheric contamination.
