JP2015070141A - Method for manufacturing r-t-b-based sintered magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an R-T-B-based sintered magnet which is arranged to prevent the slip of a compact after covering the surface of a compact with an oil solution, which would lead to the collision of the compact with another compact thereby chipping the compact, and arranged to eliminate the need for a long time for removal of the oil solution at the time of sintering.SOLUTION: A method for manufacturing an R-T-B-based sintered magnet comprises: a compacting step for compacting alloy powder for the R-T-B-based sintered magnet (where R represents at least one of rare earth elements (including yttrium (Y)), which certainly includes neodymium (Nd), T represents iron (Fe) or a combination of iron and cobalt (Co), and B represents boron) thereby preparing a compact, provided that in the alloy powder for the R-T-B-based sintered magnet, the oxygen content is 4000 mass ppm or less; a spray step for spraying an oil solution on the entire surface of the compact under a pressure of 0.2-0.4 MPa with a spray amount of 1-2 L/hr for a spray time of 3-6 seconds; and a sintering step for sintering the compact after the spray step.

Description

  The present invention relates to a method for producing an RTB-based sintered magnet.

R-T-B based sintered magnet (R is at least one rare earth element (including yttrium (Y)), and it always includes neodymium (Nd), T is iron (Fe) or iron and cobalt (Co), B (Means boron) is mainly composed of a main phase composed of a tetragonal compound of R ₂ T ₁₄ B and an R-rich phase composed of Nd or the like. The R-T-B based sintered magnet can be improved in magnetic properties by increasing the abundance ratio of the main phase R ₂ T ₁₄ B tetragonal compound.

The R-rich phase requires a minimum amount for liquid-phase sintering. However, R reacts with oxygen in the atmosphere to produce an oxide such as R ₂ O _3, so that a part of R is used for sintering. It will be consumed in useless parts. For this reason, extra R is required for the consumption by oxidation. Oxide generation becomes more pronounced as the oxygen concentration in the atmosphere increases. Therefore, by reducing the amount of oxygen in the atmosphere at the time of manufacturing alloy powders for RTB-based sintered magnets (hereinafter sometimes referred to as “RTB-based alloy powders”). It has been studied to suppress the formation of oxides. By suppressing the formation of oxide, the amount of R consumed by oxidation can be suppressed. Thereby, the abundance ratio of the main phase can be increased and the magnetic characteristics can be improved.

  However, if the oxygen content of the R-T-B system alloy powder is reduced to, for example, 4000 ppm by mass or less, the R-T-B system alloy powder may react vigorously with oxygen in the atmosphere and ignite in a few minutes even at room temperature. There is. Therefore, even if it is understood that it is desirable to reduce the oxygen content of the RTB-based alloy powder in order to improve the magnetic properties, there is a problem that it is extremely difficult to actually handle at the manufacturing site. there were.

  In order to solve this problem, in the method for producing rare earth magnets described in Patent Documents 1 and 2, after molding an alloy powder (corresponding to an R-T-B alloy powder), the obtained compact is treated with an organic solvent ( It is proposed to be put into the “oil agent” of the present invention. Even in the case of an alloy powder having a low oxygen content (4000 mass ppm or less), the molded body is covered with an organic solvent by putting the obtained molded body into an organic solvent, so that the molded body is directly in contact with oxygen in the atmosphere. Contact is suppressed. As a result, the risk of ignition can be avoided. As a result of being able to safely suppress the increase in oxygen content of the alloy powder by the methods of Patent Documents 1 and 2, the amount of excess R consumed by oxidation is suppressed, and an R-T-B system sintered magnet It is possible to improve the magnetic properties of the RTB-based sintered magnet by increasing the abundance ratio of the main phase.

JP 2002-8935 A JP 2002-170728 A

  However, in the methods of Patent Documents 1 and 2, when a plurality of molded bodies taken out from the tank are placed on a sintered plate or the like in order to perform the subsequent sintering step, In some cases, the molded body on the upper side slips due to the organic solvent adhering to the surface of the molded body, which causes the molded bodies to collide with each other and cause chipping. This is presumably because a large amount of an organic solvent adheres to the surface of the molded body because the molded body is put in the tank, and the surface of the molded body is covered with the organic solvent. Furthermore, a large amount of organic solvent adheres to the sintered plate or the like on which the molded body is placed, for example, by dripping the organic solvent from the surface of the molded body. In some cases, a long time treatment was required to remove the organic solvent.

  The present invention was made to solve the problems in Patent Documents 1 and 2, and after the surface of the molded body was covered with an oil agent (organic solvent), the molded body collided with the sliding molded body with the oil agent. Of the R-T-B system sintered magnet which prevents the chipping from occurring in the molded body and does not require a long time for the treatment for removing the oil during sintering. An object is to provide a manufacturing method.

  Aspect 1 of the present invention is an alloy powder for an RTB-based sintered magnet having an oxygen content of 4000 mass ppm or less (R is at least one rare earth element (including yttrium (Y)) and neodymium (Nd). (T means iron (Fe) or iron and cobalt (Co), B means boron), and a molding step for producing a molded body by this, and an oil agent is pressured over the entire surface of the molded body A spraying step of spraying at a spray amount of 1 L / hr to 2 L / hr, a spraying time of 3 seconds to 6 seconds, and a sintering step of sintering the compact after the spraying step; The manufacturing method of the RTB system sintered magnet containing these.

  Aspect 2 of the present invention is an alloy powder for an RTB-based sintered magnet having an oxygen content of 4000 mass ppm or less (R is at least one rare earth element (including yttrium (Y)) and neodymium (Nd). And T is iron (Fe) or iron and cobalt (Co), and B is boron). Thus, a molding step for producing a molded body, and the molded body is impregnated with the oil agent. The oil agent is placed on the plate-like member, and the oil is applied to the surface of the molded body other than the surface in contact with the plate-like member at a pressure of 0.2 MPa to 0.4 MPa, a spray amount of 1 L / hr to 2 L / hr, and a spray time of 3 It is a manufacturing method of the RTB system sintered magnet including the spraying process sprayed in 2 seconds or more and 6 seconds or less, and the sintering process which sinters the forming object after the spraying process.

  Aspect 3 of the present invention is the production of the R-T-B system sintered magnet according to aspect 1 or 2, wherein the spraying step covers the molded body with a container and sprays in the container. Is the method.

  According to the present invention, after the surface of a molded body is covered with an oil agent, the molded body is prevented from occurrence of chipping of the molded body due to collision of sliding molded bodies with the oil agent. Can be provided. Moreover, the manufacturing method of the RTB type | system | group sintered magnet which can be made not to require the process for removing the oil agent at the time of sintering for a long time can be provided.

It is explanatory drawing which shows the spray form in this invention. It is explanatory drawing which shows the spray form in this invention. It is explanatory drawing which shows the spray form in this invention. It is explanatory drawing which shows the spray form in this invention. It is explanatory drawing which shows the spray form in this invention. It is explanatory drawing which shows the spray form in this invention.

  In the present invention, the oil agent is sprayed on the entire surface of the molded body under predetermined conditions. This prevents a large amount of oil from adhering to the molded body as in the case of putting the molded body into a tank as in Patent Documents 1 and 2, so that the molded body does not slip even when placed on a sintered plate or the like. The occurrence of chipping due to the collision between the molded bodies can be prevented. Furthermore, since a large amount of oil does not adhere to the sintered plate or the like, the processing time for removing the oil during sintering can be shortened.

[Formation step of compression-molding an RTB-based sintered magnet alloy powder having an oxygen content of 4000 mass ppm or less, thereby producing a compact]
First, an RTB-based alloy powder having an oxygen content of 4000 mass ppm or less is prepared. R-T-B type alloy powder having an oxygen content of 4000 mass ppm or less (R is at least one rare earth element (including yttrium (Y)) and necessarily contains neodymium (Nd), and T is iron (Fe) or iron And cobalt (Co) and B means boron) can be used R-T-B type alloy powder produced by a known R-T-B type alloy powder composition and production method. As the RTB-based alloy powder, one type of alloy powder is used so as to have a predetermined composition, or two types of alloy powders (first alloy powder and second alloy powder) having different compositions are prepared. There are cases where a predetermined composition is obtained by mixing them. For example, when one kind of alloy powder is used, an R-TB alloy containing R: 10 atomic% to 30 atomic%, B 0.5 atomic% to 28 atomic%, balance: Fe, and inevitable impurities is used. Create molten metal. The melt of the RTB-based alloy is rapidly solidified into a thin plate having a thickness of 0.03 mm to 10 mm at a cooling rate of 10 ² to 10 ⁴ ° C / second by a strip casting method, and further roughened by a hydrogen pulverization method. A coarsely pulverized powder having a particle size of about several hundred μm is prepared by pulverization. Then, the coarsely pulverized powder is finely pulverized to a mean particle size of about 3 to 7 μm by a jet mill to prepare an RTB-based alloy powder. The “average particle diameter” refers to the volume median diameter (median diameter). In order to prepare an RTB-based alloy powder having an oxygen content of 4000 mass ppm or less, the above-described fine pulverization is performed by a jet mill using an inert gas (for example, N ₂ , Ar, He, or the like). It is preferable. The oxygen concentration in the inert gas is preferably controlled to 2000 ppm by mass or less.

  It is preferable to add a liquid lubricant containing a fatty acid ester or the like as a main component to the obtained RTB-based alloy powder. By adding the liquid lubricant, it is possible to prevent oxidation of the powder particles of the RTB-based alloy powder, to uniformize the density of the formed body at the time of forming, and to suppress disorder of orientation.

  Next, molding is performed in a magnetic field using the obtained RTB-based alloy powder to obtain a compact. Molding in a magnetic field is a dry molding method in which a dry alloy powder is inserted into a mold cavity and molding is performed while a magnetic field is applied. The slurry is injected into the mold cavity and the slurry dispersion medium is discharged. Any known forming method in a magnetic field may be used, including a wet forming method.

[A spraying step of spraying the oil agent over the entire surface of the molded body at a pressure of 0.2 MPa to 0.4 MPa, a spray amount of 1 L / hr to 2 L / hr, and a spray time of 3 seconds to 6 seconds]
An oil agent is sprayed on the obtained molded body. Depending on the shape and size of the molded body and the number of molded bodies sprayed at one time, the sprayer can be sprayed onto the molded body at any location so that the oil agent is sprayed over the entire surface of the molded body. Decide on and spray. In the present invention, “the entire surface of the molded body” refers to all surfaces constituting the molded body, for example, six surfaces in a block shape, and an outer peripheral surface and two end surfaces in a cylindrical shape. Therefore, normally when spraying, after spraying on the surface of the molded body other than the surface on which the molded body is placed (five surfaces for block shape, outer peripheral surface and one end surface for cylindrical shape) The oil agent is sprayed on the entire surface of the molded body by spraying the surface on which the molded body is placed by inverting the body. Further, “spraying” refers to spraying the oil agent in a mist form, and can be performed using a known sprayer that can spray at a predetermined pressure, spray amount, and spray time.

  As the oil agent, petroleum solvents such as isoparaffin, naphthene solvents, fatty acid esters such as methyl caproate, methyl caprylate and methyl laurate, saturated hydrocarbon solvents such as higher alcohols and higher fatty acids can be used. Furthermore, not only the saturated hydrocarbon solvent, but also an unsaturated hydrocarbon solvent formed from α-pinene, cyclobutene, cyclohexane, diethylbenzene or the like can be used. However, since the unsaturated hydrocarbon solvent may react with the powder in which the active surface is exposed through the pulverization step, it is preferable to use a saturated hydrocarbon solvent.

In the present invention, the oil agent is sprayed on the entire surface of the molded body at a pressure of 0.2 MPa to 0.4 MPa, a spray amount of 1 L / hr to 2 L / hr, and a spray time of 3 seconds to 6 seconds. If the pressure, spray amount, and spray time deviate from the above ranges, the amount of oil applied to the molded body will be too small and the molded body will ignite, or conversely, the amount of oil applied to the molded body will increase and spraying may occur. There is a possibility that a large amount of the oil agent adheres to the surface of the molded body and the effect of the present invention cannot be obtained. In addition, the said range of a pressure, the amount of spraying, and the spraying time is the spraying conditions of one sprayer. When using a plurality of sprayers depending on the shape and size of the molded body and the number of molded bodies sprayed at one time, the pressure, spray amount, and spray time of each sprayer are set to be within the above ranges. Further, as the gas mixed with the oil agent, an inert gas (N ₂ or Ar) is used instead of oxygen so that the molded body does not ignite.

[The molded body is placed on a plate-like member impregnated with an oil agent, and the oil is applied to the surface of the molded body other than the surface in contact with the plate-like member with a pressure of 0.2 MPa to 0.4 MPa and a spray amount of 1 L / hr. Spraying step of spraying at 2 L / hr or less and spraying time of 3 seconds or more and 6 seconds or less]
Preferably, the molded body is placed on a plate-like member impregnated with an oil agent, and the oil agent is sprayed on the surface of the molded body other than the surface in contact with the plate-like member.
A preferred spray form in the present invention is shown in FIG. As shown in FIG. 1, two sprayers 3 are arranged on the surface of the molded body 1 other than the surface in contact with the plate-shaped member 2 by placing the molded body 1 on the plate-shaped member 2 impregnated with the oil. Then, the oil agent 4 is sprayed. Thereby, the surface of a molded object can be covered with an oil agent by spraying once. When the plate-like member 2 is not impregnated with the oil agent, the oil agent does not adhere to the surface of the molded body 1 that is in contact with the plate-like member 2 (hereinafter sometimes referred to as “contact surface”). Thus, after spraying the surface of the molded body other than the contact surface, the contact surface is sprayed again, for example, by reversing the molded body 1. Therefore, a step of reversing the molded body 1 is required, and there is a risk of occurrence of chipping when reversing. Therefore, in order to reduce the number of steps in the spraying process (from 2 times to 1 time) and to prevent the occurrence of chipping when the molded body is reversed, the plate-like member 2 is preferably composed of a member impregnated with an oil agent. The oil agent can be impregnated by using a felt or sponge.

  A more preferred spray form is shown in FIG. As shown in FIG. 2, the molded body 1 is placed on a plate-like member 2 impregnated with an oil agent, the molded body 1 is covered with a container 5, and spraying is performed in the container 5 with a sprayer 3. The container 5 may completely seal the molded body, or a gap may be left between the plate-like member 2 as shown in FIG. By spraying in the container 5, the sprayed mist oil 4 hits the container 5, and the mist oil wraps around the surface of the molded body other than the sprayed direction. The surface of the molded body can be efficiently covered. Therefore, the shape of the container 5 is prepared according to the number of installed sprayers and the place of installation so that the mist-like oil sprayed from the sprayer hits the container. Further, examples are shown in FIGS. FIG. 3 is a top view of the molded body 6 placed on the plate-like member 2 impregnated with the oil, and the installation location of the sprayer 3 is indicated by a circle. As shown in FIG. 3, four molded bodies 6 are placed on the plate-like member 2. And in order to spray an oil agent on the surface of a molded object other than a contact surface, the sprayer 3 is installed in four places. On the other hand, as shown in FIG. 4, the molded body 6 is covered with a container 5 set so that the mist-like oil sprayed from the sprayer 3 hits the container as shown in FIG. 4. In the case of FIG. 4, the surface of the molded body 6 can be covered with the oil agent by spraying the oil agent in the container 5 and installing and spraying two sprayers 3. By using the container 5 in this way, the number of sprayers installed can be reduced.

[Process of sintering the compact]
For the step of sintering the formed body, a method similar to a known method for producing an RTB-based sintered magnet can be used. For example, a deoiling process is performed at 250 ° C. for 1.5 hours to remove the oil agent from the molded body, and a treatment is performed at 1040 ° C. for 6 hours. In the present invention, since a large amount of oil agent is not applied to the entire surface of the molded body and the sintered plate, the processing time of the deoiling process can be shortened. In order to prevent oxidation due to the atmosphere during sintering, the atmosphere gas is preferably replaced with an inert gas such as helium or argon.

  Furthermore, it is preferable to perform a heat treatment for the purpose of improving magnetic properties on the sintered RTB-based sintered magnet. Known conditions (eg, 3 hours at 500 ° C.) can be used as the heat treatment conditions such as the heat treatment temperature and the heat treatment time. Note that final magnet dimension adjustment may be performed by machining such as grinding. In this case, it may be performed before or after the heat treatment.

Example 1
The composition of Nd 22.3%, Pr 6.2%, Dy 4.0%, B 1.0%, Co 0.9%, Cu 0.1%, Al 0.2%, Ga 0.1% balance Fe (unit: mass%). The molten alloy was melted by a high frequency melting furnace, and a flaky raw material alloy having a thickness of 0.2 mm to 0.4 mm was obtained by a strip casting method. The obtained flaky raw material alloy was hydrogen embrittled in a hydrogen-pressurized atmosphere and then subjected to dehydrogenation treatment by heating and cooling to 550 ° C. in a vacuum to obtain coarsely pulverized powder. The coarsely pulverized powder thus obtained was finely pulverized by a jet mill controlled so that the oxygen concentration in the pulverization chamber was 50 ppm or less, and a powder having an average particle diameter of 4.0 μm was produced. The oxygen content of the finely pulverized powder obtained was about 1000 ppm. The “average particle diameter” refers to the volume median diameter (median diameter).

Next, using a rocking mixer, 0.4% by mass of a liquid lubricant is added to the finely pulverized powder, and then molded in a magnetic field to obtain a molded body of length 30 mm × width 10 mm × thickness 10 mm. It was. The compact density was 4.3 to 4.4 g / cm ³ .

  Next, the oil was sprayed on the resulting molded body as shown in FIG. FIG. 5 is a top view of the molded body 10 (length 30 mm × width 10 mm × thickness 10 mm) placed on the plate-like member 12, and the installation location of the sprayer 13 is indicated by a circle. The plate member 12 is configured by placing a felt impregnated with an oil on a fluororesin plate. As shown in FIG. 5, six molded bodies 10 are placed on the plate-like member 12. And four sprayers 13 are installed in order to spray the oil on the surface of the molded body 10 other than the contact surface. In addition, when the sprayer 13 was installed at four places or less (3 places, 2 places, 1 place), the oil agent could not be sprayed on the surface (other than the contact surface) of all the molded bodies 10 (six pieces). Isoparaffin was used as the oil. The pressure, spray amount, and spray time at which the oil was sprayed are shown in “Pressure (MPa)”, “Spray amount (L / hr)”, and “Spray time (seconds)” in Table 1. Note that the pressure, spray amount, and spray time in Table 1 are the pressure, spray amount, and spray time in one sprayer, and are the same in all four locations. In addition, sample No. No. 15 did not spray the molded body, put the molded body into a tank containing an oil (isoparaffin), held the molded body in the tank for 3 seconds, and then removed it. In addition, sample No. 16 comprises the plate-like member 12 only with a fluororesin plate (no felt impregnated with an oil agent), and after spraying the surface of the molded body 10 other than the contact surface with the sprayer 13, the molded body is further inverted. The contact surface was sprayed by the sprayer 13.

  Next, the molded body covered with the oil was left in the indoor atmosphere, and the temperature of the molded body was measured. The temperature of the compact was measured with a thermometer on the surface of the compact. The increase in the temperature of the molded body is due to oxidation of the rare earth element in the molded body, resulting in heat generation and an increase in temperature. The rise in the temperature of the molded body after spraying stopped for all the samples after about 2000 seconds had passed after spraying. It should be noted that if the heat generation exceeds 90 ° C., there is a risk that ignition may occur and it is dangerous. Therefore, when the molded body reaches 90 ° C., it is necessary to discard the molded body for safety. Therefore, the temperature of the molded body needs to be less than 90 ° C. The measurement result of the molded body temperature is shown in “temperature (° C.)” in Table 1. The temperature (° C.) in Table 1 describes the maximum value of the molded body temperature in 2000 seconds after spraying.

  Furthermore, sample no. After spraying 120 molded bodies with an oil agent under spraying conditions of 1 to 16 (sample No. 15 was not sprayed into the oil tank), 12 molded bodies were placed on the sintered plate. The compact was placed on the sintered plate at a constant pressure for gripping the compact using a robot arm and the speed of releasing the compact from the compact onto the sintered plate. When the molded body was separated from the robot arm and placed on the sintered plate, the number of chips generated by the molded body sliding on the sintered plate and colliding with each other was counted. The number of counts is shown in “Number of missing pieces” in Table 1.

  Next, the molded body whose surface was covered with the oil agent was subjected to a deoiling process at 250 ° C. to remove the oil agent, and further subjected to a sintering treatment at 1040 ° C. for 6 hours. The processing time required for the deoiling step for removing the oil agent is shown in “Oil agent treatment (time)” in Table 1. In addition, the time of the oil agent treatment in Table 1 describes the shortest processing time for measuring the C amount after the end of the sintering step and obtaining a predetermined C amount (for example, less than 1000 ppm by mass).

The sintered RTB-based sintered magnet was heat treated at 500 ° C. for 3 hours to evaluate the magnetic properties. The magnetic properties were determined as follows. First, sample no. It was obtained by machining three RTB type sintered magnets of 1 to 9, 11, 12, 15, 16 to 10 mm × 10 mm × 10 mm each and measuring with a BH tracer (room temperature 20 ° C.). It calculated | required by the average value of three magnetic characteristics. The magnetic characteristics are shown in Sample No. 1-9, 11, 12, 15, and 16 were Br = 1.35-1.36T and _HcJ = 1730-1780 kA / m. Sample No. Nos. 10, 13, and 14 were discarded because the temperature of the molded body was 90 ° C. and could ignite. For this reason, an RTB-based sintered magnet could not be produced, and the magnetic properties could not be measured.

  As shown in Table 1, Sample No. In Nos. 1 to 8 and 16, chipping of the molded product did not occur. In contrast, Sample No. in which any one of the pressure, spray amount, and spray time for spraying the oil exceeds the upper limit of the present invention. 9, 11, 12 and Sample No. No. 1 in which the molded body was put into the tank. In No. 15, chipping occurred. Sample No. 1 in which any of the pressure, spray amount, and spray time for spraying the oil is less than the lower limit of the present invention. Nos. 10, 13, and 14 had the molded body temperature after spraying heated to 90 ° C. as described above, and therefore, there was a risk of ignition and the molded body was discarded. Furthermore, the present invention was able to shorten the processing time required for oil treatment compared to the comparative example.

(Example 2)
As shown in FIG. 6, sample No. 1 in Example 1 was used except that the sprayer 13 was changed from four to two in the container 14 covered with the molded body 10. An RTB-based sintered magnet was produced under the same conditions as in No. 8. The magnetic characteristics were also measured in the same manner as B _r = 1.35 T and H _cJ = 1750 kA / m. Equivalent to 8. And under the same conditions as in Example 1, the temperature of the molded body, the number of chips generated when 120 molded bodies were produced and placed on the sintered plate, it took a deoiling step to remove the oil agent. Each treatment time was measured. The results are shown in Table 2.

  As shown in Table 2, even if the number of sprayers is changed from four sprayers to two sprayers by spraying the oil in the container covered with the molded body, the sample No. The effect similar to 8 can be obtained.

(Example 3)
Each raw material is blended so as to have the composition of the first alloy powder and the second alloy powder shown in Table 3, each is melted, and a flaky raw material alloy having a thickness of 0.2 mm to 0.4 mm is formed by strip casting. Obtained. The obtained flaky raw material alloy was hydrogen embrittled in a hydrogen-pressurized atmosphere, and then subjected to a dehydrogenation treatment in which it was heated and cooled in vacuum to 550 ° C. to obtain coarsely pulverized powder. The coarsely pulverized powder of the first alloy powder and the coarsely pulverized powder of the second alloy powder thus obtained were sample Nos. 18 to 21 are 9: 1, sample No. No. 22 was put into a V-type mixer at a mass ratio of 8: 2 and mixed to obtain a mixed powder. The mixed powder was finely pulverized by a jet mill so that the oxygen concentration in the pulverization chamber was 1000 mass ppm or less, and a powder having an average particle size of 3.0 μm was produced. The oxygen content of the finely pulverized powder obtained was about 3000 ppm by mass. The “average particle diameter” refers to the mass median diameter (median diameter).

Next, using a rocking mixer, 0.4% by mass of a liquid lubricant is added to the finely pulverized powder, and then molded in a magnetic field to obtain a molded body of length 60 mm × width 25 mm × thickness 5 mm. It was. The compact density was 4.3 to 4.5 g / cm ³ .

Next, with respect to the obtained molded body, the sample No. The oil agent was sprayed on the molded body under the same conditions as in 1. The sprayed molded body was deoiled at 250 ° C. to remove the oil agent, and further subjected to a sintering treatment at 1050 ° C. for 2 hours. The sintered RTB-based sintered magnet was heat treated at 480 ° C. for 3 hours, and the magnetic properties were measured. Table 3 shows the composition and magnetic properties (B _r (T), H _cJ (kA / m)) of the _{obtained RTB} -based sintered magnet. The method for measuring the magnetic properties is the same as in Example 1.

  Further, under the same conditions as in Example 1, the molded body temperature, the number of chips generated when 120 molded bodies were produced and placed on the sintered plate, the treatment according to the deoiling process for removing the oil agent Each time was measured. The results are shown in Table 4.

  As shown in Table 4, Sample No. In any of Examples 18 to 22, sample No. The molded body temperature and the oil treatment time were the same as those of No. 1, and no chipping occurred.

Claims (3)

Alloy powder for RTB-based sintered magnet having an oxygen content of 4000 ppm by mass or less (R is at least one rare earth element (including yttrium (Y)), and it always includes neodymium (Nd), and T is iron ( Fe) or iron and cobalt (Co), B means boron), thereby forming a molded body,
A spraying step of spraying the oil agent over the entire surface of the molded body at a pressure of 0.2 MPa or more and 0.4 MPa or less, a spray amount of 1 L / hr or more and 2 L / hr or less, a spraying time of 3 seconds or more and 6 seconds or less;
A sintering step of sintering the compact after the spraying step;
The manufacturing method of the RTB type | system | group sintered magnet containing this. Alloy powder for RTB-based sintered magnet having an oxygen content of 4000 ppm by mass or less (R is at least one rare earth element (including yttrium (Y)), and it always includes neodymium (Nd), and T is iron ( Fe) or iron and cobalt (Co), B means boron), thereby forming a molded body,
The molded body is placed on a plate-like member impregnated with the oil agent, and the oil agent is applied to the surface of the molded body other than the surface in contact with the plate-like member at a pressure of 0.2 MPa to 0.4 MPa and a spray amount of 1 L / a spraying step of spraying at a time of not less than hr and not more than 2 L / hr, a spraying time of not less than 3 seconds and not more than 6 seconds;
A sintering step of sintering the compact after the spraying step;
The manufacturing method of the RTB type | system | group sintered magnet containing this. The said spraying process covers a molded object with a container, and sprays in the said container, The manufacturing method of the RTB type | system | group sintered magnet of Claim 1 or 2 characterized by the above-mentioned.

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