Process for preparing neodymium-iron-boron permanent magnetic material surface gradient function coating layer

Abstract

A neodymium-iron-boron permanent magnetic materials surface gradient function coating preparation method overcomes current slug type neodymium iron boron surface processing method existent problem. Said method adopts new surface modification process means combined with tradition electroplating ( or chemical plating ) advantages and sol-gel technologic property, thereby avoiding single cladding material poor cladding material adhesion, less compactness, easy resulting slough, having pore and too thin single sol coating shortages. Said method forms tight sol coating on neodymium iron boron base material surface, to obtain oxide ceramics coating after sintering treatment, then cladding material on gel coating to form function gradient coating to take complete corrosion protection.

Description

technical field [0001] The invention relates to the fields of chemical industry, metal materials and surface modification, and belongs to the surface modification treatment method of NdFeB magnetic materials, in particular to a preparation method of gradient functional coating on the surface of NdFeB permanent magnet materials. Background technique [0002] Since the third-generation permanent magnet NdFeB permanent magnet material came out in 1984, it has quickly stepped out of the laboratory and become the new favorite of magnetic materials in the global industrial field due to its excellent magnetic properties and low price. NdFeB permanent magnet is a kind of energy storage device with high energy, which can realize the mutual conversion of energy and information with high efficiency, and its own energy is not consumed. Modern science and technology and information industry are developing in the direction of integration, light weight and intelligence, and the emergence o...

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Problems solved by technology

[0015] Alloying cannot fundamentally solve the corrosion problem of NdFeB magnets; although some achievements have been made in the surface modification treatment method, there are still problems: the conversion film obtained by chemical conversion coating treatment is brittle and porous, and generally can only be used as a decoration and intermediate protection process. It is not suitable as a long-term anti-corrosion protective film, and the more mature chromium treatment process contains hexavalent chromium ions, which is toxic and pollutes the environment, and is prohibited from being used in industrialization; The best disadvantages, such as the precipitation of hydrogen, lead to embrittlement, pulverization, whitening and bubbling of the coating after plating; there are also obvious limitations in electroless plating, such as: the cost is much higher than that of electroplating; the stability of the plating solution is relatively high Poor; when the workpiece is plated, hydrogen is precipitated, causing hydrogen absorption and hydrogen embrittlement; the coating has holes, etc.; NdFeB after organic coating is not suitable for use under high temperature conditions, and organic coatings have requirements for the working environment, corrosion resistance The time is not long; the process conditions of vacuum ion plating are harsh and there are still difficulties in industrialization.

[0016] So far, there is no research report on the preparation of oxide films on the surface of NdFeB by sol-gel technology, and then coating on the sol film layer to form a functionally graded protective layer