On July 23rd, 20 19, 16, Dongfang Shengfan received the reexamination decision made by the Patent Reexamination Board to cancel the rejection decision, and on July 23rd, 20 19, it received the Notice of Handling Registration Procedures issued by the State Information Bureau, and obtained the patent right.
The case took only two months from receiving the entrustment of the parties to revoking the rejection and obtaining the patent right, which fully demonstrated the good strength of Dongfang Shengfan.
The following are the specific details of the case:
The patent rights involved in the announcement are as follows:
1. A preparation method of samarium iron-nitrogen permanent magnet material, which is characterized by comprising the following steps: (1)SPD treatment: metastable samarium iron alloy is subjected to large plastic deformation, and the true strain εt is 5-8 to obtain the deformed metastable samarium iron alloy, and the premixed component is SM2FE 10/. Metastable samarium iron alloy is all metastable samarium iron alloy, or a part of metastable samarium iron alloy with metastable structure accounting for not less than 60%; The high-pressure torsion method is adopted, with the torsion temperature T≤ 100℃ and the torsion pressure 4 ~ 5.5 GPA.
(2) nitriding: nitriding the obtained deformed metastable samarium-iron alloy in a high vacuum nitriding furnace to obtain samarium-iron alloy nitride; The temperature of the high vacuum nitriding furnace is 300-350 DEG C, the nitriding atmosphere is N2, NH3, N2+NH3 mixed gas or N2+H2 mixed gas, the pressure is 0.6- 1.2 MPa, and the nitriding time is 2.5-3 hours;
(3) annealing crystallization treatment: carrying out annealing crystallization treatment on samarium nitride in a vacuum annealing furnace, wherein the temperature of the vacuum annealing furnace is 550-620 DEG C, the vacuum degree is more than or equal to10-2pa, and the annealing time is more than or equal to 8 hours; So as to obtain the samarium iron nitrogen permanent magnet material.
In the request for reexamination, the agent thinks that claim 1 has at least the following technical features compared with the comparison file 1:
(1) Claim 1 of this application limits the strain during large plastic deformation to 5-8;
(2) Claim 1 of this application defines torsion temperature and torsion pressure;
(3) Claim 1 of this application limits the nitriding temperature to 300 ~ 350℃ and the nitriding time to 2.5 ~ 3h.
Those skilled in the art know that some recovery will occur during thermal deformation, which will reduce the purpose of deformation and increase the number of defects. Compared with large plastic deformation, the number of defects is relatively small, and defects are channels for atomic diffusion, so the nitriding effect of large plastic deformation is better than that of ordinary thermal deformation. As we all know, Sm-Fe alloy is easily oxidized at high temperature. It is a difficult problem to control Sm-Fe alloy from being oxidized at a certain temperature, which requires a corresponding high vacuum nitriding atmosphere, otherwise the magnetic properties of the oxidized Sm-Fe-N magnetic material will be seriously reduced. However, under the horizontal limitation of the existing large plastic deformation equipment (the high-pressure torsion equipment itself does not have high vacuum degree and high-temperature atmosphere), it is impossible to introduce high temperature in the large plastic deformation (torsion) stage. However, if nitrogen atoms are nitrided at low temperature in the process of large plastic deformation, although the movement channel of nitrogen atoms is increased, the diffusion speed is very low, so it is not easy to nitriding, which will increase the nitriding time. Therefore, at present, the preparation process of Sm-Fe permanent magnet material is not suitable for large plastic deformation and high temperature nitriding at the same time from two aspects: controlling the oxidation of magnetic materials and accelerating the diffusion of nitrogen atoms.