Steel and Tungsten Fibers

Metal fibers exhibit a range of valuable properties e.g. electrical and thermal conductivity, high tensile strength, high elasticity modulus and high melting points (see Table 5.2-14). 

Metal fibers can be produced by metal-cutting processes, by foil cutting processes, powder metallurgically by the sintering of metal powders which can be extruded with the help of organic binders to fibers, by metallization of non-metalic fibers and also by the controlled chemical dissolution of wires to the required fiber thickness. Thin metal wires and thick metal fibers can in principle be produced by the same methods. 

In addition to these process, special processes are known, particularly for the manufacture of thin metal fibers the continuous filament process, melt spinning processes and the Taylor process. 

Much thinner metal fibers are manufactured by the so-called bundle pulling process, in which wires are embedded in a ductile matrix (e.g. copper) and are jointly subjected to a continuous filament process. The fibers remaining, after removal of the matrix, have diameters down to 12 pm, but diameters down to 0.5 pm can be obtained with this process. 

Continuous filament process multiple pulling of wires througli ever narrower dies with intermediate annealing. The process is used for the manuraclure of steel fibers for tire cord (ca. 1.50 pm) 

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