AlNiCo aluminum nickel cobalt permanent magnet material
Aluminum nickel cobalt permanent magnet material
Advantages: High residual magnetism, extremely low temperature coefficient, and good corrosion resistance; Disadvantages: Low mechanical strength, poor machinability, and low intrinsic coercivity, not resistant to vibration and impact. Based on the low coercivity of aluminum nickel cobalt permanent magnet materials, in order to enhance their anti demagnetization ability, the magnetic pole surface is often designed in the form of long columns or long rods. At the same time, the reverse magnetic field in the magnetic steel usage environment must be strictly controlled to avoid local irreversible demagnetization or distortion of magnetic flux density distribution in the magnetic steel. The demagnetization curve of aluminum nickel cobalt is a nonlinear variation, and the recovery line does not coincide with the demagnetization curve. After magnetization, stable magnetic aging treatment is required.
Commercial aluminum nickel cobalt grades can generally be classified into grades 2, 3, 4, 5, 6, 8, and 9 based on their magnetic properties and composition. Among them, grades 2, 3, and 4 are isotropic magnetic steels, while the rest are anisotropic magnetic steels. The theoretical maximum magnetic energy product of AlNiCo magnets can reach 30-35 MGOe, while in reality, commercial magnets only reach about one-third of the theoretical value. If aluminum nickel cobalt can reach around 80% of the theoretical value like other permanent magnet materials such as ferrite, samarium cobalt, and neodymium iron boron, its excellent corrosion resistance and temperature stability will have greater application prospects.
There are two production processes for aluminum nickel cobalt magnets: casting and sintering. Among them, casting aluminum nickel cobalt has higher performance and is also the mainstream application in the market. However, due to the poor workability of cast aluminum nickel cobalt, sintered aluminum nickel cobalt is preferred for small parts, complex shapes, or scenarios that require uniformity.
The production process of casting aluminum nickel cobalt: batching → melting → casting → heat treatment → performance testing → mechanical processing → inspection → packaging. Cast aluminum nickel cobalt products are mainly used in fields such as metrology and testing, instrument magnets, automotive parts, high-end audio, military equipment, and aerospace. Sintered aluminum nickel cobalt is produced by powder metallurgy, with the production process being: batching → powder milling → pressing → sintering → heat treatment → performance testing → mechanical processing → inspection → packaging. Sintered aluminum nickel cobalt is suitable for producing complex, lightweight, thin, and small products, mainly used in electronic communication, permanent magnet suction cups, magneto electric switches, and various sensors.
Market situation
At present, except for a few companies such as Hitachi Metals, most foreign manufacturers have basically stopped production and turned to other industries, while high-quality aluminum nickel cobalt magnets in China have completely filled this demand. The prospects of aluminum nickel cobalt magnets are inevitably limited by the resource supply and market prices of two strategic metals, cobalt and nickel. At the same time, the aluminum nickel cobalt production line still has a low degree of automation, poor operating environment, and requires a lot of manual labor. Only by improving the automation level of the production line, optimizing the magnetic circuit and device design level, and exploring new application areas, can aluminum nickel cobalt continue to occupy a place in permanent magnet materials.