JPH0620816A - R-t-m-n bonded magnet and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a bonded magnet having high coercive force by a method wherein a required melted metal alloy is formed into a super-quenched alloy having the specific average crystal particle diameter, it is pulverized and a nitriding treatment is conducted thereon in N2 gas under the specific condition. CONSTITUTION:This R-T-M-N bonded magnet is composed of R of 7 to 9wt.% (R indicates at least a kind of rare earth element, and also it contains one or two kinds of P5 or Na of 50wt.% or more), T of 76 to 87wt.% (T indicates that Fe or a part of Fe is substituted by Co and Ni of 50wt.% or less), M of 3.5 to 17wt.% (M indicates that it contains at least a kind of Ti, V, Cr or Mo), N of 3 to 12wt.%, and alloy powder of ThMn12 type structure is coupled by resin. As a result, magnet powder of ultramicroscopic crystal, having the coercive force of 3 kOe or higher, can be manufactured easily, and a highly corrosion-resistance bonded magnet can be obtained at low cost using this powder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an RTMN-N type bonded magnet which can be used in various motors, actuators and the like, and a method for producing the same. The alloy powder having a ThMn ₁₂ type structure obtained by pulverizing, further pulverizing with N ₂ gas jet mill, and nitriding treatment is combined with a resin to form a bonded magnet having a small amount of rare earth elements, low cost, and high corrosion resistance. Get R-T-M
-N type | system | group bonded magnet and its manufacturing method.

[0002]

2. Description of the Related Art As powders for Nd-Fe-B system permanent magnets, powders for magnets having an ultrafine structure obtained by a superquenching method have been used. The Nd-Fe-B system permanent magnet powder has a low Curie point (Tc) of around 300 ° C,
Since the temperature coefficient of Br and iHc is large, there is a problem that the temperature coefficient of magnet characteristics is large.
Although it is possible to increase the temperature coefficient of Br by increasing c, the temperature coefficient α of Br is at most −0.08% / d.
The limit was about eg.

Recently, the R ₂ Fe ₁₇ compound has occluded N ₂ to increase Tc nearly twice as much as an absolute temperature, resulting in Nd-
160 ° C higher than Tc of Fe-B system, and further Sm ₂
It has been reported that the Fe ₁₇ nitride can provide an anisotropic magnetic field exceeding the anisotropy of R ₂ Fe ₁₄ B.

[0004]

Since the Sm ₂ Fe ₁₇ nitride contains a large amount of Sm, which is a small amount of resources, there is a problem that it is relatively expensive, and a permanent magnet containing a rich amount of other elements. A powder is sought.

Nd-Ti-Fe nitride based magnets have also been proposed, but Nd-Ti-Fe nitride based magnets are magnetized by containing about 18 wt% of Nd, which is a low melting point zinc-bonded magnet. Although it can be used for production, a sufficient coercive force was not obtained as a resin-bonded magnet. This is because in the zinc-bonded magnet, the crystal grain size of the main phase having the ThMn ₁₂ type crystal structure is much larger than the critical diameter of single domain grains and is several μm. That is, when a zinc-bonded magnet is pulverized as a powder for a bonded magnet, the crystal grain size is not sufficiently smaller than the particle size of the powder, so that a large dependence of the magnetic properties on the powder grain size appears, and when the grain size becomes small, it is unique. There is a problem that the coercive force iHc is extremely deteriorated.

In order to obtain a bonded magnet having a ThMn ₁₂ type structure having a composition which replaces the Sm ₂ Fe ₁₇ N _{2 3} system permanent magnet, the present invention is an ultrafine crystal powder for the magnet, which has a coercive force of 3 kOe or more. R-T-M-, which can be easily manufactured, and which is easy to handle powder and magnetize bond thereafter.
The purpose is to provide an N-based bonded magnet and a method for manufacturing the same.

[0007]

The present invention provides R 7-9.
at% (R: at least one rare earth element and 50% or more of one or two Pr or Nd), T 7
6 to 87 at% (T: Fe or a part of Fe is 50%
Substituted with Co and Ni below), M 3.5 to 17 at%
(M: contains at least one of Ti, V, Cr and Mo),
R− characterized by comprising an alloy powder containing N 3 to _{12 at} % and having a ThMn ₁₂ type structure bonded with a resin.
It is a T-M-N bond magnet.

The present invention also provides R 7-9 at%
(R: at least one rare earth element and Pr or N
50% or more of 1 type or 2 types of d), T 76-8
7 at% (T: Fe or a part of Fe is replaced with 50% or less of Co and Ni), M 3.5 to 17 at% (M:
Containing at least one of Ti, V, Cr and Mo), N 3
Consists ~12at%, the structure of average grain size 0.01~1.0μm have ThMn ₁₂ type structure is formed by an alloy powder having an average particle size 2~300μm occupying total more than 80% bound with resin The R-T-M-N system bonded magnet characterized by the above.

The present invention also provides 1) R 7-9 at%
(R: at least one rare earth element and Pr or N
50% or more of 1 type or 2 types of d), T 76-8
7 at% (T: Fe or a part of Fe is replaced with 50% or less of Co and Ni), M 3.5 to 17 at% (M:
A molten alloy containing at least one of Ti, V, Cr, and Mo) is subjected to ultra-quenching with a rotating roll to obtain a ThMn ₁₂ type crystal structure having a structure with an average crystal grain size of 0.01 to 1.0 μm. After obtaining the ribbon-shaped ultra-quenched alloy, 2) the alloy is made into a finely pulverized powder having an average particle diameter of 2 to 300 μm, and 3) the finely pulverized powder is 300 to 65 in a N ₂ gas of 0.1 to 10 atm.
Nitriding treatment was carried out by holding at 0 ° C. for 10 minutes to 6 hours, and obtained R 7 to 9 at%, T 76 to 87 at%, M 3.
ThMn containing 5 to 17 at% and N 3 to 12 at%
_A method for producing an R-T-M-N based bonded magnet, which is characterized in that an alloy powder having a _12- type structure is bonded with a resin.

The present invention also provides 1) R 7-9 at%
(R: at least one rare earth element and Pr or N
50% or more of 1 type or 2 types of d), T 76-8
7 at% (T: Fe or a part of Fe is replaced with 50% or less of Co and Ni), M 3.5 to 17 at% (M:
When a molten alloy containing at least one of Ti, V, Cr, and Mo) is subjected to ultra-quenching treatment with a rotating roll, the ultra-quenching rate is increased to obtain a ribbon-shaped ultra-thin structure having no ThMn ₁₂ type crystal structure. To obtain a quenched alloy, 2) 600 ℃
After heat treatment at 950 ° C. for 5 minutes to 60 minutes to obtain a ribbon-shaped alloy of ThMn ₁₂ type crystal structure having a structure with an average crystal grain size of 0.01 to 1.0 μm, 3) average grain size of the alloy Diameter 2
˜300 μm finely pulverized powder, 4) this finely pulverized powder was subjected to a nitriding treatment in which it was kept at 300 to 650 ° C. for 10 minutes to 6 hours in 0.1 to 10 atm of N ₂ gas to obtain R.
7-9 at%, T 76-87 at%, M 3.5-1
A method for producing an R-T-M-N based bonded magnet, characterized in that alloy powder containing 7 at% and N 3 to _{12 at} % and having a ThMn ₁₂ type structure is bonded with a resin.

[0011]

The present invention has been studied variously for the purpose of producing a ThMn ₁₂ type RTMN-based alloy powder for bonded magnets, which is easy to produce and easy to handle thereafter. The R-T-M type ultra-quenched alloy ribbon having a ThMn ₁₂ type crystal structure of a specific crystal grain size obtained by subjecting the R-T-M type molten alloy to a super-quenching process with a rotating roll is roughly crushed, and further By jet-milling the coarsely pulverized powder in a supersonic stream of N ₂ gas, the surface of the finely pulverized powder can be activated and the surface area can be increased. By nitriding in N ₂ gas under specific conditions It becomes possible to perform nitriding, and by further resin-bonding as a bonded magnet, a ThMn ₁₂ type RTMN-based alloy bonded magnet containing N 3 to _{12 at} % can be obtained.

Further, according to the present invention, when the super-quenching rate is increased during the above-mentioned super-quenching treatment, amorphous or TbCu is formed.
_The structure has a _7- type crystal structure, but it can be converted into a ThMn _12- type crystal structure phase by subjecting it to a specific heat treatment,
This is similarly nitrided and resin-bonded to form N 3-12.
A ThMn ₁₂ type RTMN-based alloy bonded magnet containing at% is obtained.

Reasons for Limiting Composition of Molten Alloy and Obtained Alloy Powder In the present invention, the rare earth element R is Y, La, Ce,
Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, T
m, Lu, at least one of which contains one or two of Pr or Nd in an amount of 50% or more of R, and all of R is Pr, Nd, or P.
There are cases of r and Nd. 50% or more of R is Pr or N
The reason for using 1 or 2 kinds of d is that sufficient residual magnetization cannot be obtained when 1 or 2 kinds of Pr or Nd is less than 50%.
There is an effect of reducing raw material cost as compared with. R is 7 at
If it is less than 0.1%, the coercive force is reduced due to the protrusion of α-Fe, and if it exceeds 9 at%, the R ₂ Fe ₁₇ phase and the like are protruded to deteriorate the coercive force.

It is important that the iron group element T contains at least one of Fe, Co and Ni, and contains Fe in an amount of 50% or more of T. That is, when Fe in T is less than 50%, sufficient magnetization cannot be obtained, which is not preferable. Note that Co is 5 of T
It is particularly preferable to add less than 0% because the Curie temperature rises and the anisotropic magnetic field increases slightly. T is 67a
If it is less than t%, the second phase having a low coercive force is projected to lower the coercive force, and if it exceeds 87 at%, the coercive force due to α-Fe precipitation,
Since the squareness is deteriorated, it is set to 67 to 87 at%.

M, that is, at least one of Ti, V, Cr and Mo is RFe _12-x M having a ThMn ₁₂ type structure.
It is an essential element for forming the _x compound, and if it is less than 3.5 at% (x is less than 0.5), the R ₂ Fe ₁₇ phase and α-Fe are precipitated, and the desired compound cannot be obtained.
If it exceeds t% (x exceeds 2.0), the magnetization remarkably decreases, so the content is set to 3.5 to 17 at%.

When N is less than 0.8 at%, uniaxial anisotropy cannot be obtained, and when it exceeds _{12 at} %, the ThMn ₁₂ type structure becomes unstable, and the parent phase becomes R ₂ Fe ₁₇ phase or α-Fe. Since it is not preferable because it decomposes, it is set to 0.8 to 12 at%.

Reasons for Limiting Manufacturing Conditions In the present invention, it is most important to obtain the alloy powder as a fine crystal aggregate having a ThMn ₁₂ type crystal structure, and ultra-quench treatment can be adopted to obtain the fine crystal aggregate. As a specific method, a super-quenching method using a known rotating roll can be adopted. For example, when a Cu roll is used, a roll surface peripheral velocity in the range of 10 to 30 m / sec is preferable because a suitable structure can be obtained. That is, when the peripheral speed is less than 10 m / sec, a ThMn ₁₂ type crystal structure is obtained, but the crystal grain size becomes coarse, which is not preferable. on the other hand,
When the roll surface peripheral velocity exceeds 30 m / sec, a structure in which the RT-M phase of the TbCu ₇ type crystal structure, the α-Fe phase, and the amorphous phase are mixed, or an alloy thin film composed of the amorphous phase according to the powder X-ray diffraction pattern It becomes a belt.

By heat-treating this alloy ribbon at 600 to 950 ° C. for 5 to 60 minutes, 80% or more of the whole is Th.
It can be a ribbon having an Mn ₁₂ type structure. If the temperature during this heat treatment is less than 600 ° C., a sufficient reaction does not proceed. If it exceeds 950 ° C., it is carried out in a temperature range where the ThMn ₁₂ type structure is stabilized, and the crystal grains become coarse, so that pinning type coercive force cannot be obtained, which is not preferable. Further, the heat treatment may be performed after pulverization, but it is desirable to perform the heat treatment in a ribbon state because of problems such as oxidation. Therefore, in the present invention, it is essential that 80% or more of the obtained powder contains a phase having a ThMn ₁₂ type structure as a main phase.

If the average crystal grain size of the ultra-quenched alloy ribbon obtained by subjecting the molten alloy to ultra-quenching with a rotating roll is less than 0.01 μm, sufficient iHc cannot be obtained. It is necessary to make it significantly larger, stable manufacturing becomes difficult, and the product recovery rate also decreases, which is not desirable.
If the average crystal grain size exceeds 1.0 μm, the grain size becomes much larger than the single domain grain size, and the pinning type coercive force required for the alloy powder for bonded magnets cannot be obtained. The crystal grain size is limited to 0.01 to 1.0 μm.

If the average particle size of the finely pulverized powder is less than 2 μm, the fluidity of the alloy powder for bonded magnets deteriorates.
If it exceeds μm, nitriding of the powder is difficult to proceed, so the average particle size is limited to 2 to 300 μm.

The reason for limiting the temperature during nitriding treatment to 300 to 650 ° C. is that nitriding does not proceed below 300 ° C.
This is because if the temperature exceeds 0 ° C., α-Fe and RN are formed, the RTM compound (RT _12-x M _x ) is decomposed, and the magnet characteristics are deteriorated. However, the optimum nitriding temperature depends on the composition. For example, when M is Ti 7.4 to 80 at%, it is 35
0 ° C to 450 ° C, M is Mo 14.5 to 15.5 at%
In this case, the temperature is preferably 500 to 650 ° C. If the holding time during the nitriding treatment is less than 10 minutes, sufficient nitriding does not proceed, and 6
If the time is exceeded, decomposition will occur and the magnet characteristics will be deteriorated, so the time is set to 10 minutes to 6 hours. The reason for limiting the N ₂ pressure during nitriding treatment to 0.1 to 50 atm is 0.1 atm.
If it is less than 50 atm, the nitriding reaction rate is slow, and if the pressure is increased, the reaction proceeds rapidly, but if it exceeds 50 atm, the processing equipment becomes too large, which is not preferable in terms of industrial production cost.

In the present invention, in order to accurately form a magnet having a complicated shape or a thin shape as a bonded magnet,
The particle size of the magnet powder needs to be sufficiently small. On the other hand, if the particle size of the powder is too small, it is necessary to use a large amount of resin as a binder as the specific surface area increases. , Therefore the powder particle size is 3 μm
To 500 μm.

The Fe-BR type bonded magnet according to the present invention relates to anisotropic and isotropic magnets, and is known by the following compression molding, injection molding, extrusion molding, rolling molding, resin impregnation method and the like. Any of the above manufacturing methods may be used.
In the case of compression molding, a thermosetting resin, a coupling agent, a lubricant, etc. are added to the magnetic powder and kneaded, followed by heating after compression molding,
It is obtained by curing a resin. In the case of injection molding, extrusion molding, and rolling molding, it is obtained by adding and kneading a magnetic powder with a thermoplastic resin, a coupling agent, a lubricant, etc., and then molding by injection molding, extrusion molding, or rolling molding. . In the resin impregnation method, the magnetic powder is compression-molded, heat-treated as required, impregnated with a thermosetting resin, and heated to cure the resin. In addition, the magnetic powder is obtained by compression molding, heat treatment if necessary, and then impregnated with a thermoplastic resin.

In the present invention, the filling rate of the magnetic powder in the bonded magnet depends on the manufacturing method, but is 70-9.
It is 9.5 wt% and the balance 0.5 to 30 wt% is resin or the like. In the case of compression molding, the filling rate of magnetic powder is 9
5-99.5 wt%, 90-95w in case of injection molding method
t%, and in the case of the resin impregnation method, 96 to 99.5 wt% is preferable. In the present invention, the synthetic resin used as the binder may be either thermosetting or thermoplastic, but a thermally stable resin is preferable, for example, polyamide, polyimide, polyester, phenol resin, fluororesin, silicon resin, epoxy resin. Etc. are appropriately selected.

Example 1 No. 1 shown in Table 1 obtained by melting in a high frequency melting furnace. 1
Cu alloy with a diameter of 250 mm and a width of 30 mm
Ultra-quick cooling was performed at a roll surface peripheral velocity shown in Table 1 with a rotating roll manufactured by the company, and the phases shown in Table 1 were obtained. The alloy ribbons having a structure other than ThMn ₁₂ were heat-treated under the conditions shown in Table 1 to obtain alloy ribbons of the ThMn ₁₂ type crystal structure having the texture of the average crystal grain size shown in Table 1. The average grain size at that time was determined by SEM of the ribbon cross section.
It is evaluated by photographs and shown in Table 1. Thickness about 15μm, width 2
The ultra-quenched alloy ribbon of mm has an average particle size of 0.
It was pulverized to 1 mm to obtain a finely pulverized powder having an average particle size of about 20 μm. Further, each finely pulverized powder was subjected to a nitriding treatment in N ₂ gas having an N ₂ partial pressure of 1.0 atm (converted to normal temperature) at the temperature and time shown in Table 1, and then cooled to obtain an RTMNM-based alloy. A powder was obtained.
Table 2 shows the nitriding amount of this R-T-M-N alloy powder and the magnetic properties after resin bonding with 2 wt% epoxy.

Comparative Example 1 Composition No. 1 in Table 1 of Example 1 After mechanically pulverizing the same coarsely pulverized powders as 1 to 3 into fine powders having an average particle size of 50 μm, nitriding treatment under the same conditions as in Example 1 was performed, and the nitriding amount of the obtained alloy powder and 2 wt %, The magnetic properties of the resin-bonded bonded magnet were measured. The results are shown in Table 2.
Shown in.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

Industrial Applicability According to the present invention, nitriding by nitriding in N ₂ gas under specific conditions is carried out by crushing the required molten alloy into an ultra-quenched alloy having an average crystal grain size of 0.01 to 1.0 μm. A ThMn ₁₂ type R-T-M-N based alloy powder for bonded magnets is obtained which is possible and easy to manufacture and thereafter the powder can be easily handled. Further, by binding the alloy powder with a resin, the amount of rare earth element can be increased. And a low cost, high corrosion resistance bonded magnet can be obtained.

Claims (4)

[Claims] 1. R 7-9 at% (R: at least one rare earth element and 50% or more of one or two Pr or Nd), T 76-87 at% (T: Fe or Fe Part is replaced by 50% or less of Co and Ni), M 3.5 to 17 at% (M: Ti, V, Cr,
An R-T-M-N based bonded magnet, characterized in that an alloy powder containing at least one of Mo) and N 3 to _{12 at} % and having a ThMn ₁₂ type structure is bonded with a resin. 2. R 7 to 9 at% (R: at least one kind of rare earth element and containing 50% or more of one or two kinds of Pr or Nd), T 76 to 87 at% (T: Fe or one of Fe) Part is replaced by 50% or less of Co and Ni), M 3.5 to 17 at% (M: Ti, V, Cr,
Mo containing at least one kind), N 3 to _{12 at} %, having a ThMn ₁₂ type structure and having an average crystal grain size of 0.01 to
Average grain size of 80% or more of 1.0 μm structure 2
An R-T-M-N based bonded magnet, characterized in that an alloy powder having a particle size of 300 μm is bonded with a resin. 3. R 7-9 at% (R: at least one rare earth element and 50% or more of one or two Pr or Nd), T 76-87 at% (T: Fe or Fe Part is replaced by 50% or less of Co and Ni), M 3.5 to 17 at% (M: Ti, V, Cr,
A molten alloy containing at least one of Mo) is subjected to an ultra-quench treatment with a rotating roll to obtain an average crystal grain size of 0.01 to 1.
After obtaining a ribbon-shaped ultra-quenched alloy having a ThMn ₁₂ type crystal structure having a structure of 0 μm, the alloy was made into a finely pulverized powder having an average particle size of ₂ to 300 μm, and the finely pulverized powder was 0.1 to 10 atm of N ₂ A nitriding treatment was carried out by holding the gas at 300 to 650 ° C. for 10 minutes to 6 hours, and the obtained R 7 to 9 at% and T 7 were obtained.
6 to 87 at%, M 3.5 to 17 at%, N 3-1
A method for producing an R-T-M-N based bonded magnet, characterized in that an alloy powder containing 2 at% and having a ThMn ₁₂ type structure is bonded with a resin. 4. R 7 to 9 at% (R: at least one kind of rare earth element and containing 50% or more of one or two kinds of Pr or Nd), T 76 to 87 at% (T: Fe or one of Fe Part is replaced by 50% or less of Co and Ni), M 3.5 to 17 at% (M: Ti, V, Cr,
When super-quenching the molten alloy containing at least one of Mo) with a rotating roll, the super-quenching rate is increased to obtain a ribbon-shaped super-quenched alloy having a structure not having a ThMn ₁₂ type crystal structure. 5 minutes to 60 at 600 ℃ to 950 ℃
Heat treatment for a minute, average crystal grain size 0.01-1.0μ
After obtaining a ribbon-shaped alloy having a ThMn ₁₂ type crystal structure having a structure of m, the alloy was made into a finely pulverized powder having an average particle diameter of ₂ to 300 μm, and the finely pulverized powder was contained in 0.1 to 10 atm of N ₂ gas Nitriding treatment is carried out by holding at 300 to 650 ° C. for 10 minutes to 6 hours, and the obtained R7 to 9 at% and T 76 to 87 at are obtained.
%, M 3.5 to 17 at%, N 3 to _{12 at} %, and an alloy powder having a ThMn ₁₂ type structure, which is bonded with a resin, to manufacture an R-T-M-N based bonded magnet. Method.