Conclusions
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1.
According to thermodynamic calculations, in the initial stage boronizing may occur through a dual mechanism: simultaneous active diffusion of atomic boron and direct reaction resulting in the formation of higher iron borides.
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2.
It is demonstrated that in powder boronizing the nature of the activator has a pronounced effect on the concentration and character of distribution of pores in the boride layer and hence on the quality of the resultant coating.
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3.
On the basis of data yielded by thermodynamic calculations and experimental results it is shown that iron oxides can be successfully employed as activators of the powder boronizing process.
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4.
Experiments have shown that a powder mixture consisting of 80% boron carbide and 20% magnetite is comparable in activity to mixtures with halide activators, but surpasses them in other respects: It possesses good processing characteristics, is nontoxic, shows no sinterability, and is capable of being used repeatedly without regeneration.
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5.
Mixtures with oxygen transport of boron offer greatest promise for the boronizing of high-alloy stainless steels.
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Translated from Poroshkovaya Metallurgiya, No. 4(196), pp. 26–30, April, 1979.
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Yakhnina, V.D., Kozlov, A.M. & Luk'yanitsa, A.I. Physicochemical characteristics of powder boronizing. Powder Metall Met Ceram 18, 237–240 (1979). https://doi.org/10.1007/BF00793807
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DOI: https://doi.org/10.1007/BF00793807