Thermite welding

At high temperatures, aluminum reduces many oxygen-containing compounds, particularly metal oxides. These reactions, of the type shown in equation 6, are used in the manufacture of certain metals and alloys, as well as in the thermite welding process. ... 

Connection of cable pipes by Thermit welding, field coating, including material and earthworks DM 700... 

Thermit-bom be, /. thermite bomb, -brand-bombe, /. thermite incendiary bomb, -fiil-iung, /. thermite filling or charge, -ladung, /. thermite charge, -schweissung,/. thermite weld(ing). -verfahren, n. thermite process. 

An intimately powdered mixture, usually ignited by magnesium ribbon as a high-temperature fuse, reacts with an intense exotherm to produce molten iron and was used formerly (before the advent of gas or arc welding) in the commercial thermite welding process. Incendive particles have been produced by this reaction on impact between aluminium and rusty iron. (The term thermite reaction has now been extended to include many combinations of reducing metals and metal oxides) [1], Some accidents in demonstrating the thermite reaction are described [2],... 

Thermite welding is used for joining iron rails and also for liberating elements such as W and V from their oxides. The welding process involves heating a mixture of aluminium powder and hematite (thermite) the vigorous reaction which results produces AI2O3 and iron, i. e. 

The amount of heat liberated is so high that it melts iron or steel with which it comes in contact The liberated heat is readily used in thermite welding. A lower ferrous oxide (FeO) content of the hammer scale produces a considerably better flame and better propagation of burning. However, the improvement is slight for values below 22% FeO. 

The common practice of thermite welding is another application of the Goldschmidt process. Iron rails are often welded together by this procedure. The ends to be welded together are surrounded by a packing of sand and clay. Molten iron is produced by the reaction... 

This is done to ensure ease of algebraic addition and subtraction of the chemical equations. Stated differently, we can conclude that the lines lying lower in the diagram denote a more stable oxide. An element, e.g., Al, capable of giving a more stable oxide can reduce a relatively less stable oxide (e.g., FeO). The reaction between Al and FeO is the basis of the Thermit Welding Process. 

Many other pyrotechnic articles are in use including gas generators, heat generators, theatrical effects (simulated bullets, smoke, flash powder), flashbulbs, airbag inflators, and thermitic welding kits. There is not a clear division between these and certain explosive articles. 

In the field of rail welding, the thermite process supplements and sometimes replaces flash or gas-pressure welding. The latter methods require very costly factory installations. They furnish rails about one-quarter of a mile long, which are hauled to the point of field installation. Here one can resort to the old-fashioned mechanical join-Ing (a source of most maintenance on a railroad) or use field welds. The best of these is the thermite weld. It may be used exclusively with specialty items such as crossings, for haulage tracks in coal mines, and for crane rails. ... 

M. Karasev, Termit i iermiinaya svarka reVsov ( Thermite Thermite Welding of Rails ), Gostransizdat, Moscow, 1936. 

Figure 13.17 Holes being drilled for sacrificial anode installation (a) thermit welding of anode connection on watermain (b) anode cluster ready to be buried and connected to fire hydrant tap. (Courtesy of Drinking Water Services, City of Ottawa)...

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