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Pretreatment Process for Organic Coating Or Neodymium-Iron-Boron Magnets

IP.com Disclosure Number: IPCOM000099558D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 1 page(s) / 41K

Publishing Venue

IBM

Related People

Coleman, P: AUTHOR [+3]

Abstract

This article relates to a process of acid pickling and calcium-modified phosphating Neodymium-Iron-Boron (NdFeB) magnets, formed of sintered or plastic bound powder, in order to promote adhesion of a subsequent organic protective coating. When so coated, the magnets can be used in clean environments, such as disk files without causing particulate contamination.

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Pretreatment Process for Organic Coating Or Neodymium-Iron-Boron Magnets

       This article relates to a process of acid pickling and
calcium-modified phosphating Neodymium-Iron-Boron (NdFeB) magnets,
formed of sintered or plastic bound powder, in order to promote
adhesion of a subsequent organic protective coating.  When so coated,
the magnets can be used in clean environments, such as disk files
without causing particulate contamination.

      NdFeB magnets are preferred to other types of magnets because
of their high performance and lower cost.  Most magnets require a
permanent impervious coating before they can be fitted into
equipment, such as disk files, sensitive to magnetic particles, to
contain any flaking or crumbling. Unfortunately, NdFeB material
suffers from rapid oxidation which places great emphasis on the
integrity of the coating process.  Unlike other high energy magnetic
materials, effective organic coatings painted on NdFeB cannot survive
the stringent environmental test cycles required if the paint has
been applied directly.  A suitable low-cost pretreatment is required
before painting to provide corrosion protection.

      The following Zinc Phosphate process has been selected for
sintered or plastic bound NdFeB magnets to satisfy the high standards
for contamination in disk file enclosures. It is suitable for volume
production, uses existing treatment facilities and allows NdFeB
magnets after coating to be placed inside a disk file...