JPH01129402A - Magnetic anisotropic bonded magnet and manufacture thereof - Google Patents

Abstract

PURPOSE:To form pores effective for the impregnation of a binding agent in an R-B-Fe based and R-B-Co-Fe based thermally treated molded forms having sufficiently large coercive force and magnetic anisotropy, and to obtain an excellent bonded magnet by impregnation by optimally combining particle diameter (particle size distribution), porosity, the composition and mixing ratio of a pore forming agent on manufacture, molding pressure in a magnetic field, a heat treatment temperature, the impregnation method of the binding agent, etc. CONSTITUTION:The average particle diameter of an alloy mainly comprising 20-45wt.% R (R represents at least one kind of rare earth elements), 0.1-3.0wt.% B and 52-79.9wt.% Fe or Fe+Co (where Co is brought to half or less of Fe) is brought to 1-10mum, a resin as a pore forming agent and a lubricant are mixed into the alloy at 1-10wt.% in total, the alloy is molded at pressure of 0.5-10t/cm<2> in a magnetic field, and the molded form is thermally treated at a temperature of 350-1050 deg.C. The porosity of the thermally treated body after cooling extends over 15-40%, and 60-100% in the pores is communicated with the surface, and the thermally treated body is impregnated with a resin or a low melting-point metal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to R-B-Fe systems and R-B-Cs which have H-effective pores to exhibit their anisotropy.

The present invention relates to a -Fe-based magnetically anisotropic bonded magnet and a method for manufacturing the same.

[Prior Art] The following two methods are known as methods for producing R-B-Fe and R-B-Co-Fe bonded magnet powders.

(a) A method in which the alloy is made by melting and casting or a reduction method, heat-treated as necessary, and then finely pulverized. (b) A method in which the alloy is melted and solidified by rapid liquid cooling to produce a powder. In order to orient the powder in a magnetic field, it is necessary to pulverize the powder to a single crystal size, but such pulverization creates magnetic defects on the surface of the powder, making it impossible to change the large coercive force. In order to increase the coercive force of such powder, there is a method of heat treating the powder, but the powder oxidizes or the powders aggregate, and when this powder is crushed, the coercive force decreases. Therefore, it is difficult to obtain powder with high coercive force.

Ichinoj, (ri) method yields powder with a sufficiently large coercive force, but since the powder is amorphous or an aggregate of microcrystals, it is usually difficult to orient it using a magnetic field. Therefore, it is difficult to provide magnetic anisotropy.

Another method is to create an aggregate of particles with magnetic anisotropy by pulverizing a sintered anisotropic magnet, but even in this case, the coercive force decreases due to the mechanical strain caused by the pulverization.

As described above, conventional methods either result in a magnetic material with almost no magnetic properties, or only provide isotropic bonded magnets.

[Problems to be Solved by the Invention] The present invention is directed to the use of binders in R-B-Fe and R-B-Co-Fe heat-treated molded products that have sufficiently large coercive force and magnetic anisotropy. The impregnation of the pores is made good,
The purpose is to obtain an excellent bonded magnet by impregnation.

[Means for solving the problem] In order to solve the above problem, particle size (particle size distribution),
Optimal combinations of porosity, composition and mixing ratio of pore-forming agent during production, molding pressure in a magnetic field, heat treatment temperature, binder impregnation method, etc. are required. The present invention has discovered the optimal conditions.

That is, the first invention of the present invention has R of 20 to 45 Jllii9'6 (R is one of rare earth elements) 0.1 to 3.0 ffl m 96 (7) B52 to
79.9% by weight of Fe or Fe+C.

(However, Co is less than 1/2 of Fe), and has an average grain size of 1-10 μl, and has a porosity of 15-40%, with 60% of the pores being
Although ~100% of the pores pass through the surface, the pores are impregnated with a resin or a low-melting point metal.

K1 second invention is as follows: 20-45 tonne 9.6 R (Ri,! At least one rare earth element) 0.1-3.0 weight 96 B 52-79, 9 weight % Fe or Fe Ten C.

(Co is less than 1/2 of Fe) with an average particle size of 1 to 10 μm, and a total of 1 to 10% by weight of a resin and a lubricant as a pore forming agent are mixed therein. and molded in a magnetic field at a pressure of 5 to 10 t/c++2,
This molded body is heat-treated at 350 to 1050°C, 1u degree,
The heat-treated body after cooling has a porosity of 15 to 40%, 60 to 100% of the pores communicate with the surface, and is then impregnated with a resin or a low melting point metal. This is a method for manufacturing a oriented bonded magnet.

In the alloy composition, R is Sc, Y, lanthanide,
selected from rare earths of the actinide series, especially Y1
Elements of the lanthanide series are preferred. The amount of R is 20ffi
If ff is less than 1%, high coercive force cannot be obtained, and 45
If the amount is more than 1% by weight, the magnitude of magnetization decreases and both become unsuitable for permanent magnets. Co exceeds the Curie temperature
? Is it possible to replace Fe in L1-like manner?
If more than 1/2 of eu is substituted, the magnitude of magnetization will decrease, making it unsuitable for use as a permanent magnet. In addition, Lj properties that increase the coercive force of the alloy include Al5Si, Ti, V,
Cr, Mn, Ni.

Cu, Zn, Ga5Ge, Zr, Nb, Mo.

It is also possible to add Sn, Sb, Hfs Ta, W, Bi, etc. as necessary.

When the ilJ and average particle size of the alloy powder are made smaller than 1 μm, it takes time to grind and there is a risk that the powder will oxidize or catch fire, making it difficult to handle.

Moreover, if the +1 average particle diameter of the powder exceeds 10 μm, a sufficiently large coercive force cannot be obtained even by heat treatment, and the orientation due to a magnetic field is reduced.

Further, if the porosity is less than 15%, even if the magnetic properties are excellent after impregnation with the binder, the mechanical strength as a permanent magnet is insufficient. On the other hand, if the porosity exceeds 40%, excellent magnetic properties cannot be obtained even after heat treatment. This limitation on the penetration rate of the pores to the surface is also due to the fact that if it is less than 60%, sufficient mechanical strength cannot be obtained.

Further, the resin or low melting point metal used in the present invention is not particularly limited, and known resins can be used.

The reasons for limiting the manufacturing conditions are as follows.

In the pore-forming agent, the resin bonds with the magnet powder, and the lubricant smoothes the movement of the magnet powder during molding. If these pore-forming agents are less than 1 mm%, sufficient pores will not be formed;
If it exceeds % by weight, sufficient magnetic properties cannot be obtained after heat treatment. This also relates to limiting the porosity, so that within the framework of the present invention an appropriate porosity can be obtained.

If the molding pressure is lower than 0.5 L/cm2, the strength of the molded product will not be sufficient and handling will become difficult. Moreover, when the molding pressure is made larger than lot/clI12,
Difficulties arise in industrial production due to increased mold strength and molding cycles.

The heat treatment temperature of the molded body to obtain the skeleton is 350
At temperatures lower than 1050°C, the pore-forming agent cannot be completely dispersed and is ineffective in generating a sufficiently large coercive force, and at temperatures exceeding 1050°C, the compactness of the compact is The process progresses rapidly and becomes a sintered magnet.
It cannot be impregnated with resin or low melting point metal, making it unsuitable for bonded magnets.

[Example] The present invention will now be described by way of examples.

Example 1 An alloy having a composition of 33.5% by weight Nd, 1.3% by weight B, and the balance Fe was arc melted in Ar gas, coarsely and finely pulverized to normal in beef sun, and the average particle size was 4. It was set to 5 μm. This was mixed with acrylic resin powder 5 weight 96 and stearic acid powder 'ff' m96 (A),
A sample (B) containing no pore-forming agent was molded in a magnetic field of 15 KOe at a pressure of 8 L/co+' in a direction perpendicular to the direction of the magnetic field. This molded body was placed in an atmosphere of A (0.5 kg).
The temperature was raised to 400° C. at a rate of 5° C./h under a pressure of /ca+2 and held there for 1 hour.

Subsequently, it was heated at 900°C in a vacuum of 4 X 1O-4 Torr.
After heat treatment for 2 hours, the mixture was cooled in the furnace. The porosity calculated from the true density in this state is (A) -31%, (13)
-10%, and the porosity that communicated with the surface was determined by the BET method, and as a result, 65% of the pores in (A) and 28% of the pores in (B) communicated with the surface.

The thus prepared skeleton was impregnated with an epoxy solution diluted three times in vacuum, hardened at 80° C. for 1 hour, and subjected to magnetic Al11 determination. The results were as shown below.

i! 1'4 parallel direction 11 vertical direction samples
(A) (13) (A')
(B)Br (kG) 10.2
9.0 0.9 +, 3iHc (koe)
8.5 7.8 9.2 9.5 (131
1>□, (MGOc) 24.1 17
J O, 20, 7 Furthermore, the mechanical properties of this sample were investigated and the results were as described below.

=t Material Transverse rupture force Izod impact 1st shift (kgl
'/cIf12) (kgr-cm/cm2)
(A) 520 5
．． 0(n) 80 0
．． 7 Thus, it can be seen that the material to which the pore-forming agent is added clearly has better magnetic and mechanical properties than the material to which no pore-forming agent is added.

Example 2 An alloy having the composition shown in Table 1 was arc melted, finely pulverized,
>J? so that the average particle size is 4 to 6 μm. l-ta.

Acrylic resin powder 4.5 weight total 96 with pore forming agent and 12
, 2.5% by weight of stearic acid powder was mixed with each magnet powder, and molded at a pressure of 5t/ea+' in a magnetic field of 15k Oe. This molded body was heated to 100°C at lO°C/11
Pressure and temperature increase (A r OJkg/ca+”) 1, .
After holding for 1 hour, the skeleton was vacuumed to 4 x 10' Torr and heat treated at 800°C for 4nyi to give a skeleton of 11I. The porosity of these skeletons is 38%, so
T) The porosity leading to the inner surface was 70 to 80%.

This was converted into 50B i -25P b -25S n alloy (
It was immersed in a molten metal with a melting point of about 1 (0°C) for 0.5 hours, taken out, and cooled to solidify. The magnetic and mechanical properties of the
Shown below.

Table 1 Table 2 In addition, mechanical properties i! r, 1. , the tensile strength is 5
00~700kg! '/1oI11', similar to the mechanical properties of a low melting point metal of a flexible binder.

Example 3 29 Small Q %N d , 4 txmOop Y %
1.5 heavy melon% B.

An alloy of i41 composition with the balance being Fe was arc melted and finely pulverized to produce a powder with an average grain size of 65 μm.

This has +19 pores. Acrylic resin powder as a component is 3
! 11m 96, stearic acid powder 4 times Q 06
and 8ifi Wl 96 added sample (e), (d
) was molded in a magnetic field of 15 kOe with a force of Gt/cm'. The 19 adult bodies were treated with Ar at 0.3 kgr/cm2.
The temperature was raised to 380° C. at a rate of 7° C./h under gas pressure, and the temperature was kept at F for 1 hour. Continue vacuum level 5 X IQ' Torr
After heat treatment at 950°C for 3 hours, the 3-fold diluted epoxy resin iI was cured at 80°C for 30 minutes. Its characteristics are shown below.

Sample Dr(KG) 1lle(kOi:) (1
1.II),. (MGOi, r,) (C) 9.
0 15.0 19.5 (D)
13.5 11.3
10.2 test drilling, 1 Porosity Penetration rate Transverse rupture strength (%) (96) (kgr/co”
)(C) 32 70 4
80(D) 45 55
110 Example 4 25 weight 96Ndx5 ton Q 06 P r, 4-fold H
An arc-melted button containing Ce, 15 weight fa', 6B% 8 weight km 9o CO1 balance Fe was coarsely ground in a stamp mill, and further finely ground in a ball mill to have various average particle sizes. Pore forming agent is acrylic resin powder 4
ffLm %li, stearic acid powder 3 LII m
96 is added and mixed into magnet powder with δ average particle size (7,15k
Molding was carried out at a pressure of 4 L/cm2 in a magnetic field of Oe. The heat treatment was performed by raising the temperature to 350°C at a rate of 5°C/h under an Ar pressure of $'l'/cm' to 0.3°C, and after holding at this temperature for 2 hours, 5 × 1
The reactor was vacuum pumped to 0'1° orr, heated to 980°C, held for 2 hours, and cooled with gas in the furnace. This skeleton was impregnated with epoxy and after curing at room temperature, the coercive force of each sample was determined to be A11J. The results are shown in Figure 1. The characteristics indicated by white circles in the figure are samples that were not subjected to the above-mentioned heat treatment.

Example 5 A skeleton of an arc-melted button-in-bottom 1 consisting of 34N d -2D y -1,5B -6Co and the remainder being Fe was made by the manufacturing method shown in Example 4.

In this case, the heat treatment involved elution of the pore-forming agent at 350°C, and then holding at each temperature from 350°C to 1100°C for 4 hours. Figure 2 shows the relationship between heat treatment temperature and coercive force. From this, the molded body was molded in a magnetic field at 350°C.
It can be seen that the coercive force is increased by heat treatment at a temperature higher than (completely removing the pore-forming agent) above the lu degree, resulting in an excellent bonded magnet.

Although the coercive force increases even if the heat treatment temperature exceeds 1050° C., as mentioned above, densification progresses and the magnet becomes unsuitable for use as a bonded magnet. This is especially important when the sample is ring-shaped.

That is, ordinary R2Fe, B compounds and R2(Fe
CO) 14B compound, in its square form, a
Because the linear expansion coefficients of the axis and a-axis are significantly different, when a ring-shaped sample is sintered with a magnet powder compact that is anisotropically oriented in the radial direction, cracks will occur and the magnet will no longer be formed. is normal. In comparison, the skeleton magnet of the present invention can avoid cracking due to the presence of pores, and it is also important that it can easily produce radially oriented ring-shaped magnets, which are difficult to produce with ordinary sintered bodies. It is a characteristic.

[Effects of the Invention] According to the present invention, it is possible to perform both the heat treatment to obtain a Nd-based bonded magnet, which was previously impossible, and the heat treatment to produce a mechanically excellent magnetic body as a bonded magnet. By using Sgelton, it is possible to easily produce a radially anisotropic magnet, which is extremely difficult to manufacture using a sintered type.

[Brief explanation of the drawing]

FIG. 1 is a graph of Apl fixation of coercive force in Example 4, and FIG. 2 is a graph showing the relationship between heat treatment temperature and coercive force in Example 5.

Claims (1)

[Claims] (1) 20 to 45% by weight of R (R is at least one rare earth element) 0.1 to 3.0% by weight of B 52 to 79.9% by weight of Fe or Fe+Co ( However, Co is an alloy with a main composition of 1/2 or less of Fe), an average grain size of 1 to 10 μm, a porosity of 15 to 40%, and 60% of the pores
A magnetic anisotropic bonded magnet characterized in that ~100% of the pores pass through the surface, and the pores are impregnated with a resin or a low melting point metal. (2) 20-45% by weight of R (R is at least one kind of rare earth element) 0.1-3.0% by weight of B 52-79.9% by weight of Fe or Fe+Co (however, Co is 1% of Fe) /2 or less) with an average particle size of 1 to 10 μm, mixed with a total of 1 to 10% by weight of a resin and a lubricant as a pore forming agent, and heated at 0.5 to 10 t/cm in a magnetic field. The molded body is molded at a pressure of ^2, and the molded body is heat-treated at a temperature of 350 to 1050°C. After cooling, the porosity of the heat-treated body is 15 to 40%, and 60 to 100% of the pores communicate with the surface. 1. A method for producing a magnetically anisotropic bonded magnet, which comprises: and then impregnating it with a resin or a low melting point metal.