JPS61163266A - Method for preventing rusting of rare earth element-iron type permanent magnet - Google Patents

Abstract

PURPOSE:To maintain the performance of a small-sized electronic appliance for a long period by coating the surface of a rare earth element-iron type permanent magnet with an oxidation inhibiting protective film having high adhesion by a PVD method such as vacuum deposition. CONSTITUTION:An R-Fe-M permanent magnet (R is Nd, Pr, Ce or Dy, and M is a metalloid element such as B or Si) liable to oxidize in the air is coated with an oxidation inhibiting protective film by a PVD method such as vacuum deposition, sputtering or ion plating. The protective film is made of a metal such as Ti, Cr or Ni, a metallic oxide, nitride, carbide or boride such as TiN or Al2O3. It is preferable that the magnet is heated especially at <=600 deg.C during PVD. By this method, a rust preventing effect can be produced while the magnet characteristics are restored.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for preventing rust of rare earth iron-based permanent magnets that are easily oxidized in the atmosphere.

[Prior Art] Among rare earth iron-based permanent magnets, R-Fe-M permanent magnets (R is Nd, Pr, Ce, Dy, M is a meta-1]oid element such as 3, Si, etc.) are particularly suitable for rare earth iron-based permanent magnets. Because it is easily oxidized in the atmosphere, it is used in small electronic devices and other parts where precision is required, such as magnetic circuits containing permanent magnets.
) When such permanent magnets are incorporated, the performance of small electronic devices deteriorates due to permeance fluctuations due to substantial changes in the magnetic gap due to deterioration of magnetic properties when its surface is oxidized. There are many things.

Therefore, J
: Antioxidation has been achieved by coating the surface of lithium.

[Problems to be Solved by the Invention] However, wet plating means does not allow plating because the surface of the permanent magnet itself is corroded during the degreasing and II compound removal steps before plating. Moreover, after plating, a gap is likely to occur between the permanent magnet interface and the plating layer, so peeling occurs from that part.

Furthermore, there is one drawback: rust can easily form from pinholes.

In consideration of this point, the present invention aims to provide a rust prevention method in which the adhesion of the coating layer is good and does not have an adverse effect on the active material to be coated.

[Means for Solving the Problems] The present invention provides dry plating such as PVD such as vacuum evaporation, sputtering, and ion plating, as opposed to wet plating.
In a rare earth iron permanent magnet, the surface of the permanent magnet is coated with an anti-oxidation protective film by the PVD method while heating the permanent magnet itself. The antioxidant protective film is mainly made of metals, such as Cr, Ni, etc., or metal oxides.

TiN is a nitride, carbide, TII compound, and silicide.

Examples include ^'203. It is preferable to set the heating temperature to 600°C or less. The reason for this limitation is 61
Fe-rich has a large influence on the magnetic properties of rare earth iron permanent magnets at around 0°C.

In order for the three phases of the B-rich and R-rich layers to form a ternary eutectic, they are heated above this temperature and processed by PVD: Ti, Cr, old, TiN, Al103.
This is because if the sintered particles are coated with , defects will occur in the surface layer of the sintered particles and the coercive force will deteriorate.

[Example 1] As an example of the present invention, a vacuum evaporation chamber was used to coat the former. Inside the chamber 1. Evacuate to OX 10' Torr or higher, and remove the permanent magnet that is the covering on the substrate at 45°C.
It was heated to 0° C. and evaporated at 1000 7 mtn to form a single source Ni phase on the surface. FIG. 1 shows 4πI −1-1 magnetic characteristic curves of a permanent magnet 1 before coating, a conventional wet-plated permanent magnet 2, and a permanent magnet 3 deposited with N1 according to the present invention.

As is clear from the drawing, the permanent magnet before coating is for mechanical use]
Second, J: There is a deformation of the demagnetization curve, which deteriorates the squareness due to wet plating, but according to the present invention I)
It can be seen that the original magnetic properties are maintained by the coating treatment by VD means.

[Effects of the invention] The present invention provides an R-Fe-M permanent magnet (R is N
(1, Pr, Cc, Dy, and M is a metalloid element such as J3.Si), while preventing surface oxidation of Ti, Cr, old or TiN.

Since the Al2O3 layer is dense and strong, corrosion or peeling of the coating layer does not occur, making it possible to maintain the performance of small electronic devices for a long period of time. In addition, when heating to 300° C. or higher, the coating treatment is performed while removing processing strain, so that it is possible to restore the magnetic properties while providing a rust-preventing effect. As an actual example, for flat motor magnets 1~, the axial relationship between the magnetic gap and the armature coil is important, and if the magnet surface corrodes, the magnetic gap may change or the armature coil may be damaged. However, the treatment according to the present invention was effective because it deteriorated the characteristics of the motor.

[Brief explanation of drawings]

FIG. 1 shows a 4πI −1-1 magnetic characteristic curve of a permanent magnet. 1: By permanent magnet before coating. 2: Wet-plated permanent magnet. 3: Using a permanent magnet formed by Ni vapor deposition.

Claims (3)

[Claims] (1) A method for preventing rust of a rare earth iron permanent magnet, which comprises coating the surface of the rare earth iron permanent magnet with an antioxidant protective film by PVD means such as vacuum evaporation, sputtering, or ion plating. (2) A method for preventing rust of a rare earth iron-based permanent magnet according to claim (1), wherein the PVD treatment is performed while heating the permanent magnet itself. (3) A method for preventing rust of a rare earth iron-based permanent magnet according to claim (2), wherein the heating temperature is set to 600° C. or lower.