Effect of various additions on the electrodeposition of ternary iron-cobalt-nickel alloys

Conclusions

• 1. It was established, using the method of electron microscopy, that the particle shape and size of fine iron-cobalt-nickel alloy powders produced in a two-layer electrolytic bath in the presence of various addition agents change depending on the nature of the addition employed.

• 2. Additions introduced into the electrolyte shift the ϕ vs i polarization curve to the right by 1.5–3 V (tartaric, sulfamic, and sulfosalicylic acids, urea, Tween-60, Tween-80) or even 4–7 V (monoethanolamine, thiourea, didodecyl-3-propylammonium bromide, trimethyloctyl).

• 3. The composition of the resultant alloy is altered by the presence in the electrolyte of monoethanolamine, thiourea, and didodecyl-3-propylammonium bromide, but is practically unaffected by the other additions investigated.

• 4. An x-ray diffraction study demonstrated that the size of primary crystallites (blocks) decreases in the presence of most additions in the electrolyte. However, sulfamic and sulfosalicylic acids increase the block size (to 325 and 416 A, respectively, from 256 Å, obtained in the “pure” electrolyte).

• 5. In an investigation of the magnetic properties of fine iron-cobalt-nickel alloy powders produced in the presence of additions, it was found that the latter invariably slightly decrease the coercive force; the coefficient of relative remanent induction increases (with acetylsalicyclic acid and didodecyl-3-propylammonium bromide additions) because of the small size of the alloy particles produced and their pronounced shape anisotropy.