Abstract
To study the effect of Ni and Cr on the formation of borider layer the gas boronizing of Fe-Ni alloy, Fe-Cr alloy and Ni with BCl3 and H2 were carried out in the temperature range from 700°C to 1000°C. From microscopic examination, X-ray diffraction, the measurement of microhardness and chemical analysis, the following results were obtained.
(1) The boride layer comprised of two layers of (Fe, Ni)B and (Fe, Ni)2B in Fe-Ni alloy, and FeB and Fe2B in Fe-Cr alloy.
(2) The boride layer of Ni was made up of three layers, in which NiB and Ni2B were observed.
(3) 40% or more addition of Ni accelerates the formation of the boride layer of Fe-Ni alloy, but its formation is impeded in Fe-Cr alloys as the addition of Cr is larger.
(4) Microhardness of the boride layers of Ni and permalloy is smaller than that of iron.
(5) The boride layers had a high corrosion resistance against corrosive action of 10%- and concentrated aqueous solution of HCl and H2SO4 but were badly damaged by 10%- and concentrated HNO3.
