Search

CN-122025397-A - Sintered alnico magnet and preparation method thereof

CN122025397ACN 122025397 ACN122025397 ACN 122025397ACN-122025397-A

Abstract

The invention provides a sintered aluminum nickel cobalt magnet and a preparation method thereof, belonging to the field of permanent magnet alloy materials. The preparation method comprises the steps of weighing required metal raw materials according to the component ratio, obtaining alloy throwing pieces based on a vacuum melting-throwing technology in a protective gas environment, adding an auxiliary agent after crushing the alloy throwing pieces, pressing the alloy throwing pieces into pressed blanks, carrying out vacuum sintering on the pressed blanks, cooling and discharging the pressed blanks to obtain sintered blanks, carrying out heat treatment on the sintered blanks under the action of a magnetic field, carrying out tempering treatment, and finally removing surface oxide skin to obtain the sintered alnico magnet. The preparation method of the invention simplifies the preparation process, reduces the oxygen content of the magnet, ensures the uniformity of the magnet components, and simultaneously has good magnetic performance, for example, the prepared AlNiCo5 alloy has higher remanence which is more than 1.2kGS, and the coercive force of the AlNiCo8H alloy can be more than 170 kA/m.

Inventors

  • FAN JINKUI
  • SUN ZHUO
  • FENG JIANTAO
  • XU DAOBING
  • WANG DONG
  • PENG WEI
  • ZHUO YU
  • ZHANG XUEFENG

Assignees

  • 杭州永磁集团有限公司
  • 杭州电子科技大学

Dates

Publication Date
20260512
Application Date
20260316

Claims (10)

  1. 1. The preparation method of the sintered alnico magnet is characterized by comprising the following steps: (1) Weighing the required metal raw materials according to the component proportion, and obtaining an alloy throwing piece based on a vacuum smelting-throwing technology in a protective gas environment; (2) Crushing the alloy throwing pieces, adding an auxiliary agent, and pressing into a pressed compact; (3) Vacuum sintering is carried out on the pressed blank, cooling and discharging are carried out, and a sintered blank is obtained; (4) And carrying out heat treatment on the sintered blank under the action of a magnetic field, then carrying out tempering treatment, and finally removing surface oxide skin to obtain the sintered aluminum nickel cobalt magnet.
  2. 2. The preparation method according to claim 1, wherein in the step (3), the vacuum sintering method comprises the steps of heating from room temperature to 400-500 ℃ at a rate of 3-10 ℃ per minute, preserving heat for 10-60 min, heating to 650-800 ℃ and preserving heat for 60-180 min, heating to 1100-1250 ℃ and preserving heat for 10-60 min, heating to 1250-1400 ℃ and preserving heat for 60-180 min.
  3. 3. The preparation method according to claim 1 or 2, wherein in the step (2), the alloy throwing piece is crushed into coarse powder of 50-200 μm and fine powder of 4-10 μm, the coarse powder and the fine powder are uniformly mixed according to the mass ratio of 0.2-5:1, an auxiliary agent is added in the mixing process, and finally pressed into a pressed compact.
  4. 4. The preparation method according to claim 3, wherein the auxiliary agent is aluminum stearate, and the addition amount of the aluminum stearate is 0.1-2.0 wt.% of the total mass of the coarse powder and the fine powder.
  5. 5. The method according to claim 1 or 2, wherein in the step (4), the heat treatment is performed under the action of a magnetic field, wherein the sintered blank is preheated at 600-850 ℃ for 20-60 min, then subjected to solid solution at 1200-1300 ℃ for 10-50 min, then subjected to air cooling for 0.2-5 min, then subjected to cooling to a temperature below 600 ℃ or 750-850 ℃ in a magnetic field of 2000-10000 Gs, and then subjected to air cooling to room temperature in the magnetic field for 15-60 min.
  6. 6. The preparation method according to claim 1 or 2, wherein in the step (4), the tempering treatment is performed by heat preservation at 630-680 ℃ for 1-6 h, heat preservation at 600-620 ℃ for 3-10 h, heat preservation at 570-590 ℃ for 5-20 h and heat preservation at 500-560 ℃ for 10-30 h under the condition that the air pressure is less than or equal to 10 -1 Pa or under the protection of protective gas, and then cooling to room temperature along with a furnace.
  7. 7. The preparation method according to claim 1 or 2, wherein in the step (1), the vacuum melting-melt-spinning technology is that the vacuum is firstly pumped to below 2×10 -2 Pa, then the shielding gas is introduced to 5-5×10 4 Pa, and the metal raw material is melted and subjected to rapid hardening melt-spinning.
  8. 8. A sintered alnico magnet prepared by the method of any one of claims 1 to 7.
  9. 9. The sintered AlNi-Co magnet according to claim 8, wherein the sintered AlNi-Co magnet comprises, by mass, 5-10% of Al, 12-15% of Ni, 25-40% of Co, 0-10% of Ti, cu not more than 5%, 0-1% of Nb, and the balance of Fe.
  10. 10. The sintered AlNiCo magnet according to claim 2, wherein the sintered AlNiCo magnet is AlNiCo8 or AlNiCo8H alloy comprising, by mass, 6 to 9% Al,12 to 15% Ni,35 to 40% Co,5 to 9.5% Ti,1 to 4% Cu,0 to 1% Nb, and the balance Fe; Or the sintered AlNiCo magnet is an AlNiCo5 alloy, and comprises, by mass, 6-9% of Al,12-15% of Ni, 25-30% of Co, 1-4% of Cu, 0-1% of Nb and the balance of Fe.

Description

Sintered alnico magnet and preparation method thereof Technical Field The invention relates to the technical field of preparation of permanent magnet alloy materials, in particular to a sintered aluminum-nickel-cobalt magnet and a preparation method thereof. Background The alnico permanent magnet alloy has high curie temperature, low magnetic temperature coefficient and long-term stability, and also has excellent corrosion resistance and oxidation resistance, and has an irreplaceable position in environments with large temperature fluctuation and precision instruments in long-term service. The preparation method of the alnico permanent magnet alloy mainly comprises a casting method and a powder sintering method, wherein the sintered magnet prepared by the powder sintering method has the advantages of small raw material consumption, mechanical property superior to that of the magnetic steel prepared by the casting method, smooth surface and accurate size, can directly press complex geometric shapes, and can reduce the requirement of subsequent mechanical processing, thus being widely applied in industry. The conventional powder sintering method generally uses simple substance powder such as Fe, co, ni, cu and alloy powder such as CoAl, nbFe, tiFe as raw materials, wherein the simple substance powder has higher purchase cost, and the simple substance powder needs to be subjected to high-temperature hydrogen reduction in advance to enter a mixing process, and the alloy powder needs to undergo smelting, crushing and ball milling processes, so that the conventional powder sintering method has complex process, long time consumption and certain danger. In addition, in the sintering process of the traditional powder sintering method, alloy simple substance powder (such as Cu) and alloy powder (such as TiFe) are extremely easy to oxidize in a high-temperature environment, so that the magnetic performance of a final product is endangered, and the product sintered by the traditional powder sintering method also has poor element composition consistency, density and compactness of different parts, and influences the overall magnetic performance of the product. The Chinese patent document authority publication No. CN115233111B discloses a high-performance powder sintered aluminum nickel cobalt magnetic material and a preparation method thereof, wherein the high-performance powder sintered aluminum nickel cobalt magnetic material comprises, by mass, 5-7wt% of Al, 12-14wt% of Ni, 3-4wt% of Cu, 36-38wt% of Co, 0.5-0.8wt% of Nb, 5.5-7wt% of Ti and the balance of Fe. The method comprises the steps of carrying out vacuum melting and rapid hardening on Cu, ti, fe, part of Co and Nb metal raw materials to obtain a throwing piece A, carrying out vacuum melting and rapid hardening on part of Al ingots and the rest of Co metal raw materials to obtain a throwing piece B, carrying out vacuum melting and rapid hardening on the rest of Al and Ni to obtain a throwing piece C, carrying out vacuum annealing treatment on the throwing pieces A, B and C, sequentially crushing, coarse crushing and air flow grinding and crushing the three throwing pieces, adding 0.5wt% of aluminum stearate, pressing to form, carrying out vacuum sintering, carrying out magnetic field heat treatment, carrying out four-stage tempering and the like. The magnetic material has the remanence of 0.855-865 kGS, the coercive force of 120-124 kA/m and the magnetic energy product of 43.1-47.8 kJ/m 3, and has the problem that the remanence needs to be further improved or the coercive force needs to be further improved. And the vacuum sintering is carried out at 1330-1350 ℃ for 4.5-6 hours, so that the problem of long heat preservation time at high temperature exists. Disclosure of Invention In view of the above, the invention provides a sintered AlNiCo magnet and a preparation method thereof, which simplify the preparation process, reduce the oxygen content of the magnet and ensure the uniformity of the magnet components, and the prepared magnet has good magnetic properties, such as the prepared AlNiCo5 alloy has higher remanence of more than 1.2kGS, and the coercive force of the AlNiCo8H alloy can be more than 170 kA/m. In order to achieve the above object, the present invention provides a method for preparing a sintered alnico magnet, comprising the steps of: (1) Weighing the required metal raw materials according to the component proportion, and obtaining an alloy throwing piece based on a vacuum smelting-throwing technology in a protective gas environment; (2) Crushing the alloy throwing pieces, adding an auxiliary agent, and finally pressing into a pressed compact; (3) Vacuum sintering is carried out on the pressed blank, cooling and discharging are carried out, and a sintered blank is obtained; (4) And carrying out heat treatment on the sintered blank under the action of a magnetic field, then carrying out tempering treatment, and finally removing surface oxide skin