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The Surface Treatment Available For Perment Magnet


The passivation methods we factory (China Magnets Source Material Ltd)applies were developed under our own direction and are clearly distinguishable from the general phosphating method. The technology was developed to remove corrosion accumulations after the processing of magnets and to stabilize the surface to protect it against further external corrosive influences. The passivation cannot be referred to as a coating in the classical sense, but as an immersion bath method. It is applicable for transportation and storage, as a basis for further coatings and for certain applications, for which the magnet will be used bandaged or encapsulated or for which he is going to be processed at non-critical locations.


Combined with our passivation (PASS) the aluminum-pigmented (AL) varnishing technique achieves outstanding wear resistance to corrosion. The parts are varnished either in a hanging position or in a drum once or repeatedly, depending on the geometry and the corrosion requirements of the work piece. Subsequently a special process condenses the surface. This type of coating originates in the aerospace industry. The technique can be applied for sterilized motors. The sophisticated method and the soft coating surface have a negative impact on the properties of the Passal coating.

Galvanic Nickel plating (NiCuNi)
The galvanic nickel plating is a widespread method to coat sintered NdFeB-magnets. The coating is applied on the magnet in three layers: A basic Ni-layer, middle Cu- and at last a covering Ni-layer. The galvanic nickel plating has advantages considering the rigidity of the surface, the cost-effective production and the outstanding stability in moist environments and under high temperature. On the other hand it is difficult to meter the thickness of the layers. Additionally the method results in a problematic adhesion and in a loss of magnetic flow caused by short circuits.

Chemical Nickel electroplating (NiCuNi)
This process is similar to the galvanic nickel electroplating. Unlike the galvanic nickel surface coating, the final Nickel layer is plotted chemically. This technique results in an improved corrosion protection under the terms of sterilization, a reduced loss of the magnetic flux and enhanced adhesive properties.

Galvanized Nickel-Tin (NiCuSn)
The cost-effective galvanized Nickel-Tin process is suited for applications in a wet environment that require an increased adhesive property. The reduced hardness of the final Tin layer has a disadvantageous effect. It especially exacerbates the handling of magnetized items.

Galvanized Zinc (Zn) (optional: blue and yellow chromate coating)
The zinc coating of NdFeB-magnets is a wide-spread technique. It is the custom that a chromate coating is applied on the galvanized parts in a special bath. The customer can decide between a blue and a yellow chromate coating. The Cr+6 –rich, “yellow” coating is not applied in the automotive- and ROHS-conform production anymore, due to its manufacturing processes that are hazardous to health. The customer can fall back on the “blue”, sometimes called “white”, chromate coating. This coating offers a lower corrosion protection compared to the properties of the “yellow” coating. On the other hand it excludes impairments of human health and damages to the environment. The zinc coating can only be recommended for temperatures up to 80° C, due to its mechanical stability. The simple identification of coating thickness and the good handling make this technique very attractive. The process is most appropriate in cases of zinc-coated carrier material.

Epoxy (KTL)

Our Epoxy coating is a cathodic dip-paint coat (KTL). Unlike our Epoxy varnishing technique and the NiCuEpoxy coating,the Epoxy KTL coating features a special stability in moist environments and in contact with weak acids as well as alkaline and saline solutions. Due to these properties the Epoxy KTL coating is highly recommended for applications in tidal power plants and Offshore-wind turbines. Furthermore, the KTL coating offers a significantly better strip-off performance for glue-sheer off tests.

Contact information
China Magnets Source Material Limited
Tower B, Qiongzhu Building,
Huawang Rd,Longhua District,
Tel: +86 755 28174720
Fax: +86 755 28174720