Ferroboron

Dispersed mixtures of boron and another metal are used as deoxidizing and degassing agents to harden steel (qv) (5,6), to increase the conductivity of copper (qv) in turbojet engines, and in the making of brass and bronze (see Copper alloys). Two examples are alloys of ferroboron and manganese boron. 

A number of boron chemicals are prepared directly from boric acid. These include synthetic inorganic borate salts, boron phosphate, fluoborates, boron ttihaHdes, borate esters, boron carbide, and metal aHoys such as ferroboron [11108-67-1]. 

Ferro-, ferrous, ferro-, ferroeo-, iron(II). -ammonsulfat, n. ammonium ferrous sulfate, -azetat, n. ferrous acetate, iron(II) acetate, -bor, n. ferroboron. -bromid, n. ferrous bromide, iron(II) bromide, -chlorid, n. ferrous chloride, iron(II) chloride, -chrom, n. ferrochrome, ferrochromium. 

The reduction diffusion process has also been used for the production of powders of the magnetic neodymium-iron-boron alloy (Nd15Fe77B8). The reaction involves use of a powder mix of neodymium oxide, iron, ferroboron and calcium. The reaction is conducted by heating the powder charge mixture at 1200 °C for 4 h under vacuum. Neodymium-iron-boron alloys are much more prone to oxidation than samarium-cobalt alloys and a proprietary leaching procedure is used for the separation of the alloy and calcium oxide. 

Ferroboron. A ferro-alloy averaging 16.2% boron used as hardening agent in special steels. It also is an efficient deoxidizer. 

When ferroboron is heated in chlorine, iridescent green crystals of 3FeCl2.BCl3 are obtained.9... 

Combustion of Ferroboron in Nitrogen and Synthesis of Boron Nitride... 

Figure 7.29 SEM images of original ferroboron particles (a) and products of nitriding with a stopped combustion front (quenched) (b).

The microstructure of products of ferroboron combustion in nitrogen has various morphological forms. At the same time, a significant difference is visible in shape of particles of external and central parts of the burned sample. The presence of amorphous boron in the original material influences the process of nitride formation because (according to XRD analysis) amorphous boron contains boric acid which decomposes during combustion forming boric anhydride and water. 

Figure 7.30 SEM images of particles of products of ferroboron nitriding with addition of 10% of amorphous boron (a-d) outer part of the combusted sampie.

O. Yucel, F.C. Sahin, A. Tekin, The Preparation of Ferroboron and Ferrovanadium by Aluminathermic Reduction, High Temperature materials and Processes, 15 (1-2) (1996) 103-106. 

Boron is used as an alloying element for steel. For that reason, the alloy ferroboron, with 20% boron, is manufactured in electrometallurgical processes and used as a raw material. Low boron contents, as low as 0.003% B, have a marked effect on the hard-enability of steels with medium high carbon contents. It leads to hardening through the component section without alloying the steel with expensive elements such as chromium and nickel. Boron steels of this type have been very much utihzed for agricultural machinery. 

The results obtained by [2001War] showed that complete nitridation of ferroboron precmsor in a mixture of NH3 + H2 under ambient pressure with BN formation can be achieved at 400°C with 20 vol.% NH3. The nitrided product consists of amorphous BN, Fe and metastable Fe nitrides. An alternative route using 100 vol.% N2 is also possible, but a higher reaction temperature (>1430°C) is needed. The product from the high temperature route contains partially crystallized ABN, Fe and virtually no metastable Fe nitrides [2001War]. 

War] Warner, T, Liu, C., Fray, D.J., Synttiesis of Boron Nitride from Ferroboron Part I -Nitriding , Mater. Sci. Technol, 17(9), 1039-1044 (2001) (Experimental, Calculation, Phase Relations, 17)... 

---