The invention relates to a thermite with tailored properties to be employed for obtaining certain relatively pure metals and the alloys thereof, using the powder metallurgy and the metallothermy of Fe, Cu, Mg oxides or the like, the thermite being used in particular for the aluminothermic welding of underground, tramway or train rails or for other special welding operations. According to the invention, the thermite can be obtained using various ratios of Fe oxide quantities, depending on the smelting and casting temperature of the thermitic steels involved, as follows: a. for obtaining modified scales as compared with the natural case, in which the ratio of lower oxides FeO is increased in comparison with the ratio of higher oxides FeOor FeO, the scales are heated in revolving furnaces with reducing atmosphere at temperatures ranging between 600...700°C, said scales being employed in making the thermite needed in the aluminothermic welding of underground, tramway or train rails; b. for obtaining scales in which the ratio of higher oxides FeOor FeOis increased to the detriment of the ferrous oxide FeO, the scale is heated under an oxidating atmosphere, at temperatures ranging between 1200...1300°C, said scales being employed in making the thermite needed in special welding operations where the steel smelting temperature can reach even 2750°C.
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