KR20180114622A - Permanent magnet, method for manufacturing the magnet, and motor including the magnet - Google Patents

Abstract

According to an embodiment, a permanent magnet comprises: a base magnet written by a-b-c, wherein a has a rare-earth element, b has a transition element, and c has boron (B); and a coating layer coated on a surface of the base magnet. The coating layer has a compound including metal that has magnetism. The compound comprises: phosphorus (P); and metal belonging to Period 4 of the periodic table.

Description

TECHNICAL FIELD The present invention relates to a permanent magnet, a method of manufacturing the permanent magnet, and a motor including the permanent magnet.

Embodiments relate to a permanent magnet, a method of manufacturing the same, and a motor including the permanent magnet.

Recently. Nd-Fe-B based permanent magnets are used for motors such as automotive motors and elevator motors. These permanent magnets may be exposed to high temperature or humidity environments, especially salty moisture, depending on their use. Therefore, there is a demand for a permanent magnet which can be manufactured at a low manufacturing cost while having high corrosion resistance.

In addition, since the permanent magnet can be heated to 200 DEG C to 300 DEG C or higher in a manufacturing process or operating environment of a motor current for a short time, high heat resistance is also required. The Nd-Fe-B based permanent magnet has a Curie temperature of about 300 DEG C, which loses magnetic force. Therefore, recently, heavy rare earth elements such as dysprosium (Dy) and terbium (Tb) elements are used in order to keep the permanent magnets in a high temperature environment, but heavy rare earth elements are expensive.

Therefore, in order to reduce the amount of expensive heavy rare earth elements, studies have been made to improve the grain boundaries by applying a heavy rare earth element to the surface of the permanent magnet and then conducting diffusion heat treatment.

In addition, since the Nd-Fe-B system permanent magnet is easily oxidized when it comes into contact with air, the magnetic force can be reduced, and the surface of the permanent magnet can be plated and coated to form a protective layer on the surface of the permanent magnet. For example, the protective layer may comprise a phosphate coating, epoxy, electrolytic / electroless Ni and Al. However, since the conventional protective layer formed on the surface of the permanent magnet is made of a non-magnetic material, the performance of the permanent magnet may be deteriorated.

In addition, when a protective layer is formed on the surface of the permanent magnet by a phosphate coating, since there are relatively many pin holes, the permanent magnet exposed to the moisture containing the salt may be rusted. Further, when a protective layer is formed on the surface of the permanent magnet by resin coating, corrosion resistance and heat resistance may be insufficient.

The embodiment provides a permanent magnet having excellent corrosion resistance, heat resistance, prevention of oxidation and improved magnetic properties, a method for manufacturing the permanent magnet, and a motor including the permanent magnet.

A permanent magnet according to an embodiment includes a base magnet denoted by a-b-c (where a includes a rare-earth element, b includes a transition element, and c includes boron (B)); And a coating layer coated on a surface of the base magnet, wherein the coating layer comprises a compound containing a metal having magnetism, and the compound is selected from the group consisting of phosphorus (P); And metals belonging to four cycles of the periodic table.

For example, the a may be neodymium (Nd) and the b may be iron (Fe).

For example, the surface of the base magnet may include voids, and at least a portion of the coating layer may be embedded in the void of the base magnet.

For example, the metal belonging to the four cycles of the periodic table may include one selected from iron (Fe), cobalt (Co), and nickel (Ni). The metal belonging to the four cycles of the periodic table may be cobalt (Co). The content of phosphorus (P) may be between 1% and 12%.

For example, the size of the particles constituting the coating layer may be smaller than the size of the void.

For example, the thickness of the coating layer may be greater than the depth of the void. The thickness of the coating layer may be from 1 [mu] m to 20 [mu] m.

For example, the coating layer may include a first side facing the base magnet; And a second surface opposite to the first surface, wherein a roughness of an outer surface of the base magnet may be larger than a roughness of the second surface of the coating layer.

For example, when the ambient temperature of the permanent magnet is 120 ° C, the permanent magnet may have a residual magnetic flux density greater than 11.71 kG.

For example, when the ambient temperature of the permanent magnet is 120 ° C, the permanent magnet may have a coercive force greater than 7 kOe.

For example, when the ambient temperature of the permanent magnet is 120 ° C, the permanent magnet may have a maximum magnetic energy of greater than 32 MGOe.

For example, when the ambient temperature of the permanent magnet is 120 ° C or more, the permanent magnet may have an angular exponent of greater than 100%.

For example, when the ambient temperature of the permanent magnet is 120 ° C, the absolute value of the temperature coefficient expressed as follows may be 0.6% / ° C or less.

Where Tc denotes the coercive force at the ambient temperature Tp and Tc denotes the coercive force at the ambient temperature Tc and Tc denotes the coercive force at the ambient temperature Tc. ) And the room temperature (Tr).

A method of manufacturing a permanent magnet according to another embodiment includes the steps of: preparing a base magnet represented by a-b-c (where a is a rare earth element, b is a transition element, and c is boron (B)); And forming a coating layer on the surface of the base magnet, wherein the coating layer comprises a compound having magnetism, and the compound is selected from the group consisting of phosphorus (P); And metals belonging to four cycles of the periodic table.

For example, the coating layer may be formed on the surface of the base magnet using an electroless plating method or an electrolytic plating method.

According to another embodiment of the present invention, there is provided a motor comprising: a stator having a cylindrical through-hole; A plurality of stator winding slots disposed on an inner circumferential surface of the stator; A rotor disposed in the through-hole of the stator; And a plurality of permanent magnets coupled to the rotor, wherein the permanent magnets are represented by abc (a includes rare-earth elements, b includes transition elements, and c includes boron (B)). Base magnet; And a coating layer coated on a surface of the base magnet, wherein the coating layer comprises a compound containing a metal having magnetism, and the compound is selected from the group consisting of phosphorus (P); And metals belonging to four cycles of the periodic table.

For example, the a is neodymium (Nd), the b is iron (Fe), the coating layer includes phosphorus (P) and cobalt (Co) %. ≪ / RTI >

The permanent magnet according to the embodiment, the method of manufacturing the same, and the motor including the same have antioxidation, excellent heat resistance, improved magnetic characteristics, excellent price competitiveness and productivity.

1 is a sectional view of a permanent magnet according to an embodiment.
FIGS. 2A to 2D are photographs in which the surface appearance of different coating layers is locally enlarged according to phosphorus content when the coating layer is implemented as CoP. FIG.
FIG. 3 is a photograph showing an actual enlarged photograph of the 'A' portion of the permanent magnet according to the embodiment shown in FIG.
FIG. 4 is a graph showing the residual magnetic flux density of the permanent magnet according to the embodiment by the thickness of the coating layer.
FIG. 5 is a flowchart for explaining a permanent magnet manufacturing method according to an embodiment for manufacturing the permanent magnet shown in FIG. 1. FIG.
6A and 6B are process cross-sectional views for explaining the method shown in FIG.
7 is a view showing a schematic structure of an electroplating apparatus according to an embodiment.
8 is a graph showing the variation of the magnetic flux density with respect to the intensity of a magnetic field externally applied at room temperature in the comparative example and the first and second embodiments.
9 is a graph showing changes in magnetic flux density with respect to the intensity of a magnetic field applied externally according to temperature in the comparative example and the first embodiment.
10 is a graph showing changes in magnetic flux density with respect to the intensity of a magnetic field applied from the outside according to temperature in the comparative example and the second embodiment.
Fig. 11A is a sectional view of the SPM motor, Fig. 11B is a sectional view of the IPM motor, and Fig. 11C is a sectional view of the spoke type motor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to facilitate understanding of the present invention. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. Embodiments of the invention are provided to more fully describe the present invention to those skilled in the art.

In the description of the present embodiment, in the case of being described as being formed "on or under" of each element, the upper (upper) or lower (lower) on or under includes both the two elements being directly in contact with each other or one or more other elements being indirectly formed between the two elements.

Also, when expressed as "on" or "on or under", it may include not only an upward direction but also a downward direction with respect to one element.

It is also to be understood that the terms "first" and "second," "upper / upper / upper," and "lower / lower / lower" But may be used to distinguish one entity or element from another entity or element, without necessarily requiring or implying an order.

1 is a cross-sectional view of a permanent magnet 100 according to an embodiment.

The permanent magnet 100 shown in FIG. 1 may include a base magnet 110 and a coating layer 120.

The base magnet 110 may be denoted by a-b-c. Here, a includes a rare-earth element, b includes a transition element, and c may include boron (B).

a may be any one of rare earth elements La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu. For example, a may be neodymium (Nd) or samarium (Sm), but the embodiment is not limited thereto.

Also, b may be any one of the transition elements and may be, for example, iron (Fe), but the embodiment is not limited thereto.

Therefore, the base magnet 110 denoted by a-b-c may be, for example, NdFeB.

In addition, the surface of the base magnet 110 may include voids (VOID).

1, the coating layer 120 may be disposed on the surface of the base magnet 110 in a coated state. Coating layer 120 may comprise a compound comprising a metal having magnetic properties. The compound contained in the coating layer 120 may include phosphorus (P) and metals belonging to four cycles of the periodic table, for example, iron (Fe), cobalt (Co), nickel (Ni)

When the compound contained in the coating layer 120 is CoP, that is, when the metal belonging to four cycles of the periodic table is cobalt (Co), CoP can function to prevent oxidation of the base magnet 110, .

Accordingly, the coating layer 120 may include phosphorus (P) and cobalt (Co), but the embodiment is not limited thereto.

FIGS. 2A to 2D are photographs of a partially enlarged photograph of the surface of the coating layer 120 different in content of phosphorus (P) when the coating layer 120 is implemented with CoP.

FIG. 2B shows a case where the content of phosphorus (P) is 1% to 6%, FIG. 2C shows a case where the content of phosphorus (P) is 7% to 12% , And FIG. 2 (d) shows a case where the content of phosphorus (P) exceeds 12%. Reference numeral 120A denotes fine nanocrystalline CoP.

2A, if a content of phosphorus (P) contained in the coating layer 120 is less than 1%, an excessive crystal grain having a size of 10 μm to 20 μm is generated and the voids existing on the surface of the base magnet 110 (VOID) may be difficult to fill the particles of the coating layer 120.

If the content of phosphorus (P) contained in the coating layer 120 exceeds 12%, the degree of amorphization increases sharply with reference to FIG. 2D, and the surface of the base magnet 110 and the surface of the coating layer 120, And the peeling of these peels 110 and 120 may occur. Accordingly, the content of phosphorus (P) contained in the coating layer 120 may be 1% to 12%, but the embodiment is not limited thereto.

As described above, by adjusting the content of phosphorus (P) contained in the coating layer 120 within the range of 1% to 12%, the particle size of the coating layer 120 buried in the VOID can be controlled.

Referring to FIG. 1, at least a portion of the coating layer 120 may be embedded in voids present on the surface of the base magnet 110. For this purpose, the particle size of the coating layer 120 may be smaller than the void size. For example, the width? Of the void may be between 10 μm and 40 μm, and the size of the particles forming the coating layer 120 may be smaller than the width? Of the void, but the embodiment is not limited thereto.

FIG. 3 is a photograph showing an actual enlarged photograph of the portion "A" of the permanent magnet 100 according to the embodiment shown in FIG.

1 and 3, it can be seen that the thickness T of the coating layer 120 is greater than the depth D of the void VOID.

Further, the thickness T of the coating layer 120 shown in FIG. 1 may be 0.1 μm to 1.0 mm, but the embodiment is not limited thereto.

Hereinafter, the residual magnetic flux density Br of the permanent magnets according to the comparative example and the example will be described with reference to the accompanying drawings. The permanent magnet according to the comparative example phosphates the surface of the base magnet 110 instead of forming the coating layer 120 on the surface of the base magnet 110 shown in Fig. In the case of the phosphate treatment, the surface of the base magnet 110 is artificially oxidized.

4 is a graph showing the residual magnetic flux density Br of the permanent magnet according to the embodiment by the thickness T of the coating layer 120. The vertical axis shows the residual magnetic flux density Br.

FIG. 4 is a graph obtained when the base magnet 110 shown in FIG. 1 according to the embodiment is implemented with NdFeB and the coating layer 120 is realized with CoF, It can be seen that the residual magnetic flux density Br of the permanent magnet 100 is different.

4, when the thickness T of the coating layer 120 is 5 占 퐉 (T = T1), 10 占 퐉 (T = T2), 15 占 퐉 (T = T3), or 20 占 퐉 It can be seen that the residual magnetic flux density (Br) is larger than the comparative example.

As illustrated in FIG. 4, the residual magnetic flux density Br tends to decrease as the thickness T of the CoP as the coating layer 120 increases by 20 μm in the permanent magnet 100 according to the embodiment. have. This is because the interaction between NdFeB, which is the base magnet 110, and Co contained in the coating layer 120 is reduced. Also, as the thickness T of CoP plating as the coating layer 120 becomes smaller by 1 占 퐉, the possibility of the surface of NdFeB, which is the base magnet 110, and oxygen may increase and rust may occur.

Accordingly, the thickness T of the coating layer 120 shown in FIG. 1 may be 1 to 20 占 퐉, but the embodiment is not limited thereto.

In addition, the coating layer 120 may include first and second surfaces S1 and S2. The first surface S1 is a surface facing the base magnet 110 and the second surface S2 is a surface opposite to the first surface S1.

The roughness of the outer surface of the base magnet 110 facing the first surface S1 of the coating layer 120 may be larger than the roughness of the second surface S2 of the coating layer 120. [ That is, since the conventional permanent magnet includes only the base magnet 110 and does not include the coating layer 120, the outermost surface of the permanent magnet has a large roughness.

On the other hand, in the permanent magnet 100 according to the embodiment, since the coating layer 120 is formed on the surface of the base magnet 110, the roughness of the outermost surface of the base magnet 110 can be reduced compared to the conventional permanent magnet. This is because the coating layer 120 can be embedded in the voids (VOID) of the base magnet 110.

Hereinafter, a method of manufacturing the permanent magnet 100 according to the above-described embodiment will be described with reference to the accompanying drawings.

5 is a flowchart for explaining a permanent magnet manufacturing method 200 according to an embodiment of manufacturing the permanent magnet 100 shown in FIG.

6A and 6B are process cross-sectional views illustrating the method 200 shown in FIG.

Hereinafter, the permanent magnet 100 shown in Fig. 1 is described as being manufactured by the method 200 shown in Fig. 5, but the embodiment is not limited thereto. That is, the permanent magnet 100 shown in FIG. 1 may be manufactured by a method different from the method 200 shown in FIG. In addition, the method 200 shown in Fig. 5 may produce a permanent magnet 100 different from that shown in Fig.

As shown in FIG. 6A, according to the permanent magnet manufacturing method 200 of the embodiment, first, the base magnet 110 is prepared (Step 210). The base magnet 110 may be represented by a-b-c, as described above. Here, a, b, and c are the same as described above, and redundant description will be omitted.

If the base magnet 110 is NdFeB, operation 210 may be performed as follows.

The base magnet 110 can be formed by molding, sintering / heat-treating, cutting, and polishing a magnetic powder of several tens of micro-microns. Since the method of generating the base magnet 110 made of NdFeB is general in general, detailed description thereof will be omitted here.

In operation 210, the coating layer 120 is formed on the surface of the base magnet 110 (operation 220). The coating layer 120 includes a compound containing a metal having magnetism and the compound includes phosphorus (P) and metals belonging to four cycles of the periodic table, for example, iron (Fe), cobalt (Co), nickel can do. Since the compounds contained in the coating layer 120 are as described above, a duplicate description will be omitted. 6B, the CoP particles 120A are plated on the surface of the base magnet 110 to fill the voids VOID while covering the coating layer 120. In this case, As shown in FIG.

According to one embodiment, step 220 may be performed using electroless plating or electrolytic plating. That is, the coating layer 120 may be formed on the surface of the base magnet 110 using an electroless plating method or an electrolytic plating method.

Hereinafter, the 220th step of forming the coating layer 120 by the electrolytic plating method will be described as follows.

7 is a view showing a schematic structure of an electroplating apparatus 300 according to an embodiment.

The electrolytic plating apparatus 300 shown in Fig. 7 may include a water tank 302, an electrolytic solution 304, an anode 305, a cathode 306, and a power supply unit 308.

The step 220 shown in FIG. 5 may be performed in the electroplating apparatus 300 shown in FIG. 7, but the embodiment is not limited thereto. That is, step 220 shown in FIG. 5 may also be performed in an electroplating apparatus having a different configuration from the electroplating apparatus 300 shown in FIG.

First, an electrolytic solution 304 containing a cobalt (Co) metal and phosphorus (P), that is, a plating solution is placed in a water tank 302. At this time, the anode 305 and the cathode 306 are inserted into the water tank 302 and a current is supplied from the power supply unit 308 to the two electrodes 305 and 306. In order for the current to flow continuously, charge movement must take place at the interface between the electrodes 305, 306 and the electrolyte aqueous solution 304. At this time, the cobalt metal ions in the electrolyte aqueous solution 304 are reduced at the interface of the cathode 306, and the anions are oxidized at the anode 305. As described above, the cobalt metal ion 310 is reduced and precipitated in the cathode 306, so that a thin CoP film as the coating layer 120 can be formed on the surface of the base magnet 110 placed on the cathode 306.

Hereinafter, the permanent magnet 100 according to the above-described embodiment and the permanent magnet according to the comparative example will be compared as follows. In the case of the comparative permanent magnet, as described above, the coating layer 120 is not formed on the surface of the base magnet 110, and the surface of the base magnet 110 is subjected to the phosphate treatment. In the case of the permanent magnet according to the embodiment, it is assumed that the coating layer 120 made of CoP is formed on the surface of the base magnet 110 made of NdFeB.

Generally, residual magnetic flux density (Br), coercive force (Hc), knee point (Hk), maximum magnetic energy product ( (BH) max), angular exponent (Hk / Hc), and the like. The coercive force (Hc) corresponds to a magnetic field having a magnetic flux density (B) of '0' in a hysteresis loop. Also, the maximum magnetic energy potential corresponds to the maximum area of the B-H quadrangle in the second quadrant of the hysteresis curve and can be used as a relative index of the magnetic intensity of the permanent magnet.

The magnetic properties of the permanent magnet according to the comparative example and the permanent magnet 100 according to the embodiment are compared with the temperature coefficient.

In the first embodiment, the content of phosphorus (P) contained in the coating layer 120 is 1% to 6%, and the content of phosphorus (P) contained in the coating layer 120 is 7% % To 12%. In each of the first and second embodiments, the thickness of the coating layer 120 was 6 탆, and the current density was assumed to be 2.0 (A / dm 2).

Also, the first temperature coefficient alpha, which is one of the temperature coefficients, is calculated according to the following Equation 1, and the second temperature coefficient beta, which is another one, can be calculated as Equation 2 below.

In the formula (1), Br (Tr) represents the residual magnetic flux density at the room temperature (Tr), Br (Tp) represents the residual magnetic flux density at the ambient temperature (Tp) Tr) and Hc (Tp) represents the coercive force at the ambient temperature (Tp). In Equations (1) and (2),? T represents the temperature difference between the ambient temperature Tp and the room temperature Tr. For convenience of explanation, the temperature coefficients (?,?) Are denoted by absolute values in Table 1.

Although not shown in Table 1, Br (Tr) in the case of calculating the first temperature coefficient (?) Of each of the first and second embodiments is the value of Br (Tr) in the comparative example is 13.44 KG , And Hc (Tr) at the time of calculating the second temperature coefficient (beta) of each of the first and second embodiments was substituted by 18.88 kOe, which is the comparative Hc (Tr) value at room temperature.

Referring to Table 1, it can be seen that the permanent magnet 100 according to the embodiment has excellent magnetic characteristics at the same temperature in comparison with the comparative example. That is, in comparison with the comparative example, the permanent magnet 100 according to the embodiment has improved magnetic characteristics and an excellent temperature coefficient because the coating layer 120 is disposed on the surface of the base magnet 110. This will be described in detail as follows.

The permanent magnet 100 according to the embodiment may have a residual magnetic flux density (Br) of greater than 11.71 kG at an ambient temperature of 120 ° C and a residual magnetic flux density Br greater than 11.07 kG at an ambient temperature of 150 ° C ).

The permanent magnet 100 may have a coercive force (Hc) of greater than 7 kOe at an ambient temperature of 120 ° C and a coercive force (Hc) of greater than 6 kOe at an ambient temperature of 150 ° C. .

In addition, the permanent magnet 100 according to the embodiment may have a maximum magnetic energy of greater than 32 MGOe when the ambient temperature is 120 ° C and a maximum magnetic energy of greater than 28 MGOe when the ambient temperature is 150 ° C .

In addition, the permanent magnet 100 according to the embodiment may have an angular formation index greater than 94.6%, for example, greater than 100% when its ambient temperature is 120 ° C or higher.

The absolute value of the second temperature coefficient beta may be 0.6% / ° C or less when the ambient temperature of the permanent magnet 100 according to the embodiment is 120 ° C. When the ambient temperature is 150 ° C, 2 The absolute value of the temperature coefficient (beta) may be 0.55% / DEG C or less. The fact that the absolute value of the second temperature coefficient beta is small means that the variation amount of the coercive force Hc is small although the temperature Tp around the permanent magnet 100 is changed. Therefore, considering the fact that the second temperature coefficient beta of the permanent magnet 100 according to the embodiment is 0.6% / DEG C or less, the change amount of the coercive force Hc in accordance with the change of the temperature Tp around the permanent magnet 100 This is small.

As described above, the permanent magnet 100 according to the embodiment has an angular exponent and an improved temperature coefficient (?,?) Superior to the permanent magnet according to the comparative example at the same temperature.

Therefore, when the permanent magnet 100 according to the embodiment is attached to a motor or the like, since the torque of the motor is proportional to the residual magnetic flux density Br, a higher magnetic flux density can be provided from the viewpoint of the operating point, It may also contribute to improvement.

In general, the characteristics of a magnet can be easily determined by the size and shape of the hysteresis curve. For example, a soft magnetic material is relatively easily magnetized by an external magnetic field. This soft magnetic material exhibits a small hysteresis loop. For example, a soft magnetic material has a high initial permeability and a low coercive force. On the other hand, it is difficult to magnetize a hard magnetic material initially by an external magnetic field. The light magnetic body shows a large hysteresis loop. For example, hard magnetic materials have high residual magnetism and high saturation flux density.

8 to 10 are graphs showing changes in magnetic flux density (J) with respect to the intensity H of the magnetic field applied from the outside according to the temperature in the comparative example shown in Table 1 and the first and second embodiments In the graph, the abscissa axis represents the intensity H of the magnetic field applied from the outside, and the ordinate axis represents the magnetic flux density J induced in the magnetic material when the magnetic material is placed in the magnetic field.

In FIG. 8, the magnetic flux density changes of the comparative example and the first and second embodiments are compared at room temperature. In the case of FIG. 9, the magnetic flux density changes of the comparative example and the first embodiment are compared as the temperature rises from room temperature to a high temperature. In the case of FIG. 10, the magnetic flux density changes of the comparative example and the second embodiment are compared with each other as the temperature rises from room temperature to a high temperature.

Referring to FIGS. 8 to 10, it can be seen that the first and second embodiments have better magnetic properties than the comparative example. The reason for this is as follows.

There are many voids, such as VOID, on the surface of the base magnet 110. Nuclei are generated from defects on the surface of the base magnet 110, and the magnetic domain moves to the entire magnet, thereby generating potatoes. In the case of the permanent magnet according to the comparative example, the surface of the base magnet 110 may be subjected to a phosphating treatment to prevent oxidation of the base magnet 110. However, since the VOID is still present on the surface of the base magnet 110, And the magnetic properties may be deteriorated.

On the other hand, in the case of the permanent magnet 100 according to the embodiment, the voids (VOID), which is a main cause of the generation of the inverse of the surface of the base magnet 110, are filled with the coating layer 120 having the fine nanocrystalline particles. In addition, since the coating layer 120 has excellent magnetic performance, it can interact with the base magnet 110 to improve the potato performance of the permanent magnet 100. [

In the case of the permanent magnet according to the comparative example, the surface of the base magnet 110 is subjected to a phosphate treatment or a protective layer is formed using a non-magnetic element (for example, Cu, Sn, Zn, Al) Can be prevented. As described above, the protective layer formed on the surface of the base magnet 110 is mainly intended to prevent oxidation.

On the other hand, in the case of the permanent magnet 100 according to the embodiment, the coating layer 120 having magnetism is formed on the surface of the base magnet 110 to improve the heat resistance as well as the oxidation, and to have excellent magnetic characteristics.

Unlike the conventional method using expensive heavy rare earth elements (for example, Dy and Tb) to improve the heat resistance of the permanent magnets, according to the embodiment, a magnetic material having a lower price than a heavy rare earth element, for example, CoP The coating layer 120 is formed on the base magnet 110 by the electroless plating method or the electrolytic plating method. Therefore, the cost of the permanent magnet 100 can be reduced, thereby enhancing the price competitiveness and increasing the productivity.

The permanent magnet 100 according to the embodiment can be applied to various fields such as a car, an elevator or clean energy, for example, a motor, a generator or a battery.

Hereinafter, an embodiment of a motor including a permanent magnet 100 according to an embodiment will be described with reference to the accompanying drawings.

Fig. 11A is a cross-sectional view of an SPM (Interior Permanent Magnet) motor, Fig. 11C is a cross-sectional view of a spoke type motor inserted into a side surface of a rotor, .

As an energy-efficient motor, there is a permanent magnet (PM) permanent magnet motor. The permanent magnet motor can be divided into the SPM motor shown in Fig. 11A, the IPM motor shown in Fig. 11B, and the spoke type motor shown in Fig. 11C. Here, the spoke type motor shown in Fig. 11C is a modified embodiment of the IPM motor shown in Fig. 11B.

Each of the SPM motor, IPM motor and spoke type motor shown in Figs. 11A, 11B and 11C includes stator 402, 412, 422, stator winding slots 404, 414, 424, permanent Magnets 406,416, and 426 and rotors 408,418, and 428. In one embodiment,

The stator 402, 412, 422 has a ring-shaped cross section in which the inside thereof penetrates in a cylindrical shape. A plurality of stator winding slots 404, 414 and 424 are formed on the inner circumferential surfaces of the stator 402, 412 and 422 so as to extend in a direction passing through the stator 402, 412 and 422. The coils can be wound along the winding slots 404, 414 and 424 in the extending direction thereof. The number of winding slots 404, 414, 424 may vary depending on the design of the motor, for example, 27 winding slots 404, 414, 424 may be arranged at regular intervals, It does not.

In addition, the rotors 408, 418 and 428 may be disposed in the stator 402, 412, and 422 as shown in FIGS. 11A to 11C. 11A and 11B, the stators 402 and 412 may penetrate in a cylindrical shape. The rotors 408, 418 and 428 are members provided in the space through which the stators 402, 412 and 422 are passed, and the electromagnetic forces generated by the currents flowing through the coils wound on the stators 402, 412 and 422 And a plurality of permanent magnets 406, 416, and 426 so as to rotate. Rotors (not shown) may be connected to the rotors 408, 418, and 428 to transmit rotational force to a compression unit provided inside the compressor. To this end, a plurality of insertion holes formed in parallel with the rotation axis of the rotors 408, 418, 428 so that the permanent magnets 406, 416, 426 can be inserted into the rotors 404, 418, . The permanent magnets 406, 416 and 426 can be inserted into the insertion holes in a direction parallel to the rotational axis direction of the rotors 408, 418 and 428 or in the rotational axis direction, respectively. In this case, The magnets 406, 416 and 426 can be inserted.

As the permanent magnets 406, 416 and 426 shown in Figs. 11A to 11C, the permanent magnet 100 according to the above-described embodiment can be used. Since the permanent magnet 100 according to the embodiment has a large coercive force Hc, it is applied to the motor shown in FIG. 11A, FIG. 11B, or FIG. 11C, and the coils of the stator 402, 412, It is possible to improve the performance of the motor. That is, the direction of the inverse magnetic field generated when the permanent magnet 100 according to the embodiment is mounted on the motor is mostly opposite to the out-of-plane direction, and the larger the coercive force Hc in this direction, the better the performance. In consideration of this, a reverse magnetic field (external magnetic field) is formed in the magnet while a current flows through the stator coil. When the coercive force (Hc) is large, the ability to withstand this inverse magnetic field is improved and the performance of the motor can be improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

100: permanent magnet 110: base magnet
120: Coating layer 300: Electroplating apparatus
302: Water tank 304: electrolytic solution
305: anode 306: cathode
308: Power supply unit 402, 412, 422: Stator
404, 414, 424: stator winding slot
406, 416, 426: permanent magnets 408, 418, 428: rotors

Claims (21)

abc (a is a rare earth element, b is a transition element, and c is boron (B)); And
And a coating layer coated on a surface of the base magnet,
Wherein the coating layer comprises a compound comprising a metal having magnetic properties,
The compound
Phosphorus (P); And
Permanent magnets containing metals belonging to four cycles of the periodic table. The permanent magnet according to claim 1, wherein the a is neodymium (Nd) and the b is iron (Fe). 2. The magnetron according to claim 1, wherein the surface of the base magnet comprises voids,
And at least a part of the coating layer is embedded in the void of the base magnet. The permanent magnet according to claim 1, wherein the metal belonging to the periodic table includes one selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni). 5. The permanent magnet according to claim 4, wherein the metal belonging to the four cycles of the periodic table is cobalt (Co). The permanent magnet according to claim 1, wherein the phosphorus (P) content is 1% to 12%. 4. The permanent magnet according to claim 3, wherein the size of the particles forming the coating layer is smaller than the size of the void. The permanent magnet according to claim 3, wherein the thickness of the coating layer is larger than the depth of the void. The permanent magnet according to claim 1, wherein the coating layer has a thickness of 1 to 20 占 퐉. The method of claim 1, wherein the coating layer
A first surface facing the base magnet; And
And a second side opposite to the first side,
Wherein a roughness of the outer surface of the base magnet is larger than a roughness of the second surface of the coating layer. The permanent magnet according to claim 1, wherein the permanent magnet has a residual magnetic flux density greater than 11.71 kG when the ambient temperature is 120 ° C. The permanent magnet according to claim 1, wherein the permanent magnet has a coercive force greater than 7 kOe when the ambient temperature is 120 캜. The permanent magnet according to claim 1, wherein when the ambient temperature of the permanent magnet is 120 캜, the permanent magnet has a maximum magnetic energy of greater than 32 MGOe. 2. The permanent magnet according to claim 1, wherein the permanent magnet has an angular exponent of greater than 100% when the ambient temperature is 120 DEG C or higher. The permanent magnet according to claim 1, wherein an absolute value of the temperature coefficient expressed by the following expression is 0.6% / ° C or less when the ambient temperature of the permanent magnet is 120 ° C.

Hc (Tp) represents the coercive force at the ambient temperature (Tp), and? T represents the coercive force at the ambient temperature (Tr) Tp) and the room temperature (Tr).) preparing a base magnet represented by abc (wherein a is a rare earth element, b is a transition element, and c is boron (B)); And
And forming a coating layer on the surface of the base magnet,
Wherein the coating layer comprises a compound having magnetic properties,
The compound
Phosphorus (P); And
Wherein the periodic table includes four metals belonging to the periodic table. 17. The permanent magnet manufacturing method according to claim 16, wherein the coating layer is formed on the surface of the base magnet by electroless plating or electrolytic plating. A stator having a cylindrical through-hole formed therein;
A plurality of stator winding slots disposed on an inner circumferential surface of the stator;
A rotor disposed in the through-hole of the stator;
And a plurality of permanent magnets coupled to the rotor,
The permanent magnets are abc (a is a rare earth element, b is a transition element, and c is boron (B)). And
And a coating layer coated on a surface of the base magnet,
Wherein the coating layer comprises a compound comprising a metal having magnetic properties,
The compound
Phosphorus (P); And
A motor comprising a metal belonging to four cycles of the periodic table. 19. The motor of claim 18, wherein the a is neodymium (Nd) and the b is iron (Fe). The motor according to claim 18, wherein the coating layer comprises phosphorus (P) and cobalt (Co). The motor according to claim 18, wherein the content of phosphorus (P) is 1% to 12%.

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