INTERACTION OF MERCURY WITH AMORPHOUS AND CRYSTALLINE ALLOYS OF IRON AND COBALT WITH PHOSPHORUS IN THEIR ELECTRODEPOSITION PROCESS

V.V. Bondar'

Dept. of Chemistry, All-Russian Inst. of Scientific and Technical Information, 20 Usievich St., Moscow, 125219 Russia, bvv@viniti.msk.su

Keywords: electrodeposition process, interaction of mercury, alloys of iron and cobalt, phosphorus

Precipitates having a glitter surface, sometimes having even a mirror surface, form often at electrodeposition of alloys of simple electrolytes containing no additives.

As a rule, a glitter or semiglitter surface having no visible elements or having a microsamotoide structure according to the electron microscopy data is typical for electrodeposited amorphous alloys. In particular, it relates to the case of deposition of iron, cobalt and nickel alloys with phosphorus in the amorphous precipitate formation region (more than 13 at.% of phosphorus). But the precipitates of these alloys containing 8 - 13 at.% of phosphorus having a crystalline structure are glitter also. It was reasonable to suggest that at the electrolysis process the amorphous layers of the alloy formed initially in this interval of compositions, and a phase transition temperature into a crystalline state of these layers was lower than that of the room, this lead to their further crystallization.

In order to verify this suggestion a combined two-phase electrode consisting of a mercury drop and a platinum (iron, cobalt and another) wire in contact with it was used. In the potentiostatics regime the electrodeposition of a metal or an alloy on such an electrode takes place only on the wire, as the process does not practically proceed on the mercury because of higher charge overpotential of the metal ions.

Investigating the deposition of cobalt, iron and their alloys with phosphorus on the combined electrode three types of interaction of the precipitates with mercury were found:

1. At the deposition of pure metals their precipitates were wetted by mercury within a few seconds, and a current fell till zero. The same situation was observed at the deposition of the alloys containing less than 8 at.% of phosphorus.
2. At the deposition of the amorphous alloys an interaction of the precipitates with mercury was not observed during the electrolysis process and during many years as the additional investigations showed.
3. At the precipitation of alloys containing 8 - 13 at.% of phosphorus during the first minutes an interaction of mercury with the precipitate was not observed as in the case 2, then the precipitate began "to swell", and the surface became mosaic, the current was falling till zero gradually.

By such a way, the results obtained can be indirect confirmation of formation of the electrolytic layers through an amorphous phase with its following crystallization.

Vladimir V. Bondar', Professor

Department of Chemistry,

All-Russian Institute of Scientific and Technical Information, Usievicha Str. 20A, Moscow 125319, Russia

E-mail goe@viniti.msk.su

Phone: (095) 1525981

Fax : (095) 9430060

Abstract title: INTERACTION OF MERCURY WITH AMORPHOUS AND CRYSTALLINE ALLOYS OF IRON AND COBALT WITH PHOSPHORUS IN THEIR ELECTRODEPOSITION

Preferred form of presentation: Poster

Collected Abstract only

Topics C1,

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Sincerely yours

Prof. Bondar'

28.04.1998