. The street railway review . mit process of welding steel rails dates from the year1899, and is the discovery of Dr. Hans Goldschmidt, of Essen, Ger-many. Thermit, as described by the discoverer, consists of a mixtureof powdered aluminum and iron oxide, and its application to weldingdepends upon the following fact. If the mixture is ignited at a singlepoint by means of a special ignition powder, peroxide of bariumand aluminum, combustion proceeds without further supply of ex-terna! heat and without any combination with the oxygen of theair, at the same time developing a temperature estimated
. The street railway review . mit process of welding steel rails dates from the year1899, and is the discovery of Dr. Hans Goldschmidt, of Essen, Ger-many. Thermit, as described by the discoverer, consists of a mixtureof powdered aluminum and iron oxide, and its application to weldingdepends upon the following fact. If the mixture is ignited at a singlepoint by means of a special ignition powder, peroxide of bariumand aluminum, combustion proceeds without further supply of ex-terna! heat and without any combination with the oxygen of theair, at the same time developing a temperature estimated at 3,000° C. By the reaction the iron oxide is reduced to nearly chemically pureiron, the oxygen of the iron oxide combining with the aluminumto form aluminum oxide or artificial corundum, the reaction beingchemically expressed by the equation Fej03+2.\i=Ai!0»-l-2Fe. Thealuminum oxide having the lower specific gravity separates from theiron, rising to the top where it may be decanted oflf or the pure irondrawn from COMPLETE WELUINC, OCTITT. This iron, when poured upon metals to be repaired or welded,has the property of uniting intimately with them, due to the veryhigh temperature to which it is raised. When used for weldingsteel other ingredients, such as carbon, manganese, etc., are addedto the thermit mixture to give the resultant metal more or less theproperties of the steel with which it unites. The reaction is carried on in a special crucible made of sheet ironlined with some very refractory material, usually magnesia or alu-minum , the by-product of the reaction itself. complete outfit for welding steel rails consists of the cruciblejust described, a pair of molds made to fit the section of rail tobe welded, a pair of clamps to hold the molds in place, a wire brushto clean off the dirt from the ends of the rails, a small gasolinetorch to dry off any moisture which may be present on the parts tobe welded and to take the chill out of the m
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Keywords: ., book, bookcentury1800, bookdecade1890, booksubjectstreetrailroads
