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Codeposition of Nonmagnetic Particles with Aid of Magnetic Field

IP.com Disclosure Number: IPCOM000087210D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 17K

Publishing Venue

IBM

Related People

Romankiw, LT: AUTHOR

Abstract

This is a process for coating particles on a substrate including: (1) Precoating nonmagnetic particles P with a film of a magnetic material such as Fe(3)O(4), Gamma Fe(2)O(3) or CrO(2). (2) Placing a substrate to be coated in a solution containing the particles P from step (1) and containing a material M to be plated upon the substrate.

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Codeposition of Nonmagnetic Particles with Aid of Magnetic Field

This is a process for coating particles on a substrate including:

(1) Precoating nonmagnetic particles P with a film of a magnetic material such as Fe(3)O(4), Gamma Fe(2)O(3) or CrO(2).

(2) Placing a substrate to be coated in a solution containing the particles P from step (1) and containing a material M to be plated upon the substrate. Then codeposit the particles P and material M upon the substrate in the presence of a magnetic field applied to the substrate. The material M is a metal preferably combined with a hardening material, such as a hypophosphite or the like. (a) The magnetic field can be oriented horizontally,

vertically, annularly, or locally focused (e.g.,

magnetic coatings on nonmagnetic cathodes).

(b) Stirring solution during codeposition,

(c) Then, plating after codeposition.

Nonmagnetic particles can be codeposited either along with Ni, Co and Fe or any alloy thereof or with nonmagnetic metals: Cu, Rh, Cr, Sb, Sn, In, Au, Ag, Pt alloys of these metals within the group or alloys of these metals with the transition metal group elements including Mo, V, W, Cu, etc.

(1) Precoating of particles P.

(2) Use of magnetic field to attract the particles to the plated surface and to hold them at the surface sufficiently long to become incorporated in the plated metal matrix. The magnetic field is supplied by a permanent magnet, magnets behind the cathode and/or Helmholtz coils, etc. In case of plating of a wire (as for diamond saws) the field preferably is created around the wire by flowing the current through the wire and/or pulling the wire slowly past a series of magnetic poles providing a magnetic field gradient.

(3) The codeposited particles can consist of metal, metal oxides, metal sulfides, metal carbides, diamond, BC, BaSO(4), aluminum phosphides, etc. The particles can be precoated by using a standard SnCl(2) - SnCl(4) sensitization solution and PdCl(2) activation solution process, followed by electroless plating of Ni, Co, Fe or any alloy thereof or by precipitating Fe(3)O(4), Gamma Fe(2)O(3) or CrO(2) on the particles. The sensitizing process can be avoided and the particles also can be pretreated using only activation with acidified PdCl(2) solution prior to plating. Some particles are sufficiently self-catalytic so that the electroless plating is carried out without pretreatment other than mild HCl or similar acid or alkaline wash. This is particularly true for very small particles.

Alternatively, particles are precoated by magnetic material using evaporation, sputtering, CVD (chemical vapor deposition) active H(2) at elevated pressure and temperature, e.g., Sherritt Gordon Mines metal reduction process.

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Codeposition can be carried out by electrodeposition from a solution containing reducing agents such as sodium hypophosphite, borohydrides, amine borines, tartrate, formate or any other similar chemical with reducing power. If the elec...