Samarium cobalt permanent magnet industry has great potential for development

The second-generation 2:17 SmCo permanent magnet with high Curie temperature and excellent magnetic stability is the first choice for high-temperature permanent magnet applications. It is used in electronic communications, electronic interference and countermeasures, precise guidance and positioning, aerospace and other defense equipment It plays an irreplaceable role in the world and is one of the hot spots of cutting-edge technology development and strategic competition in all countries in the world. In recent years, 2:17 SmCo permanent magnets have also begun to be used in high-power traction motors for subways and high-speed rails. Due to the rich application scenarios, it is beneficial to the development of the 2:17 type samarium cobalt permanent magnet industry, attracting many countries to deploy in this field, and the market competition is fierce.


According to the "2022-2027 2:17 Type SmCo Permanent Magnet Industry Market In-Depth Research and Investment Prospect Forecast Analysis Report", as the application of SmCo permanent magnets in high-end magnetic power fields such as high-speed and high-temperature motors continues to increase, in the dynamic Under the complex multi-force field environment, the 2:17 SmCo magnet is prone to fracture and fragmentation, which not only makes the processing loss rate of the magnet high, greatly increases the cost of the magnet, but also is extremely easy to Damage, which limits the assembly accuracy of the motor, brings great safety hazards to equipment applications, and becomes one of the main bottlenecks restricting the performance of high-speed permanent magnet motors.


A higher theoretical energy product can be obtained by increasing the Fe content. Therefore, the development of Fe-rich high energy product magnets can not only further reduce the volume of equipment, but also significantly reduce production costs, which is an important development direction in the field of SmCo permanent magnets. Aiming at the root cause that it is difficult to form a complete nano-cellular structure with increasing Fe content, pulverization technologies such as hydrogen crushing and jet milling, as well as microstructure control technologies such as intermediate heat treatment and pre-aging, multi-stage aging treatment, and double alloys have been developed at home and abroad. Research and development of high energy product samarium cobalt.


The 2∶17 SmCo sintered magnets can be mainly divided into three categories: high magnetic energy product, high working temperature and low temperature coefficient. Among them, high magnetic energy product magnets are an important basis for ensuring the miniaturization and high efficiency of high-power motors and other equipment, and obtaining higher magnetic energy products has always been the development goal of 2:17 SmCo for more than 40 years. With the continuous deepening of research and the advancement of modern technology, the production and application of 2:17 type samarium cobalt permanent magnets have also made leaps and bounds.


According to analysts, the application range of 2:17 type samarium cobalt high temperature permanent magnet material is continuously expanding, and improving the magnetic energy product is an important development direction of this material at present. Focusing on the magnetic performance bottleneck of Fe-rich magnets, new technologies such as intermediate heat treatment, multi-stage aging, and double alloys have been developed in recent years at home and abroad to optimize the cellular microstructure and effectively increase the magnetic energy product and coercive force. Constructing a complete nanocellular structure in magnets with higher Fe content, obtaining high squareness and coercive force, is expected to further improve the magnetic energy product.


High Temperature Processing for Samarium Cobalt Manufacturing

Both sintering and aging belong to high-temperature treatment process, that is, put the compact after isostatic pressing into a high-temperature vacuum sintering furnace for firing, and then shrink and densify the compact after high-temperature sintering, so that the magnet has a high permanent magnetic performance. microstructure characteristics. Aging is the heat treatment process after sintering. Through aging treatment, the crystalline structure of the sintered body can be changed, and the magnetic properties of the magnet can be improved purposefully. The operation of sintering and aging treatment is usually divided into two consecutive processes.


After the powder is pressed, a green compact with a certain shape is obtained, the relative density is generally about 60%, and the porosity is about 40%. During the sintering process, the green compact undergoes a series of physical and chemical changes, so that the pores in the green compact shrink and disappear, and the density and physical and mechanical properties of the final sintered body are close to those of non-porous dense materials. The sintering process is continuous, and the temperature gradually increases until it reaches the sintering temperature and is kept for a period of time. This process can be roughly divided into three stages:


(1) Low temperature stage, mainly occurs the discharge of water and waste gas, evaporation and volatilization of organic matter, etc. At this stage, the density is basically unchanged, but the metal contact surface between the powder particles is increased, and the electrical conductivity is improved.


(2) In the medium temperature stage, recrystallization begins, the mechanical contact between particles is transformed into metal bond connection, the contact surface between particles expands, and the electrical conductivity is further improved.


(3) In the high-temperature sintering stage, point contact expands to surface contact, and the size and number of pores decreases. As a result, the sintered body shrinks significantly and its density increases. After holding the heat for a long enough time, all properties will reach a stable value, and sintering will be completed after a while.


Heat treatment refers to a process in which the alloy is heated, kept warm and cooled in the solid state to change its structure and obtain the required properties. If there is a phase change during heat treatment, it is called aging. The matrix phase of 2:17 in the samarium cobalt magnet is not a single phase, and there will be a phase change during the heat treatment process, so it must be subjected to aging treatment. The matrix phase of 1:5 is single-phase, and no phase change occurs during heat treatment, so no aging treatment is required.


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