ALNICO MAGNETS (ALNICO MAGNETIC MATERIALS)
Development History of Alnico Magnets
Alnico magnets were developed during the 1930s and are made of aluminum, nickel, cobalt, and iron alloys. The development of this type of magnet was initially in response to strong magnetic field demand in radio equipment, speakers, and other electrical devices. They were a significant breakthrough in permanent magnets at their discovery.
The cost of Alnico magnets is relatively modest for today’s neodymium magnets. NdFeB magnets are employed in many places due to their high magnetic energy product and intense magnetic force. However, its price volatility and high dependence on rare earth minerals have pushed its development and application. Even though NdFeB magnets can perform well in some sectors, Alnico magnets have unparalleled benefits in some settings. Operating in high-temperature environments, Alnico magnets can retain their magnetism even at prolonged high temperatures, up to 500°C or more, but NdFeB magnets are prone to demagnetization at high temperatures, which limits their use in such conditions.
Characteristics of Alnico Magnets
One of the advantages of Alnico magnets is that they have excellent temperature stability, and their magnetism remains relatively stable at high temperatures. They suit aerospace, military affairs, automotive engines, and high-temperature equipment. Besides, Alnico magnets have some advantages in corrosion resistance and machinability. They can resist severe environmental conditions over long periods and are easily machinable into different shapes. At the same time, neodymium magnets would require further protection against oxidation and corrosion.
| Property | Ferrite | NdFeB | SmCo | AlNiCo |
|---|---|---|---|---|
| Remanence (Br) | 0.2-0.42 T | 1.05-1.45 T | 0.8-1.1 T | 0.6-1.15 T |
| Coercivity (Hcj) | 220-260 kA/m | 875-2786 kA/m | 1200-1500 kA/m | 10-96 kA/m |
| Max Energy Product | 0.8-4.1 MGOe | 26-55 MGOe | 15-23 MGOe | 1.2-12 MGOe |
| Temp. Coefficient | -0.2%/℃ | -0.12%/℃ | -0.04%/℃ | -0.02%/℃ |
| Max Operating Temp. | 250℃ | 80-200℃ | 250-350℃ | 450-550℃ |
| Cost | Very Low | High | Very High | Medium |
ALNICO Magnetic Properties
| Grade | Remanence Induction Br |
Coercive Force Hcb |
Maximum Energy Product (BH)max |
Temperature Tw |
Density |
|||
|---|---|---|---|---|---|---|---|---|
| T | KGs | KA/m | KOe | KJ/m³ | MGOe | ℃ | g/cm³ | |
| LN10 | 600 | 6000 | 40 | 500 | 10 | 1.2 | 450 | 6.9 |
| LNG13 | 700 | 7000 | 48 | 600 | 12.8 | 1.6 | 450 | 7.2 |
| LNGT18 | 580 | 5800 | 100 | 1250 | 18 | 2.2 | 550 | 7.3 |
| LNG37 | 1200 | 12000 | 48 | 600 | 37 | 4.65 | 525 | 7.3 |
| LNG40 | 1250 | 12500 | 48 | 600 | 40 | 5 | 525 | 7.3 |
| LNG44 | 1250 | 12500 | 52 | 650 | 44 | 5.5 | 525 | 7.3 |
| LNG52 | 1300 | 13000 | 56 | 700 | 52 | 6.5 | 525 | 7.3 |
| LNG60 | 1350 | 13500 | 59 | 740 | 60 | 7.5 | 525 | 7.3 |
| LNGT28 | 1000 | 10000 | 57.6 | 720 | 28 | 3.5 | 525 | 7.3 |
| LNGT36J | 700 | 7000 | 140 | 1750 | 36 | 4.5 | 550 | 7.3 |
| LNGT40J | 750 | 7500 | 144 | 1800 | 40 | 5 | 550 | 7.3 |
| LNGT38 | 800 | 8000 | 110 | 1380 | 38 | 4.75 | 550 | 7.3 |
| LNGT40 | 820 | 8200 | 110 | 1380 | 40 | 5 | 550 | 7.3 |
| LNGT44 | 850 | 8500 | 120 | 1500 | 44 | 5.5 | 550 | 7.3 |
| LNGT60 | 900 | 9000 | 110 | 1380 | 60 | 7.5 | 550 | 7.3 |
| LNGT72 | 1050 | 10500 | 112 | 1400 | 72 | 9 | 550 | 7.3 |
| LNGT80 | 1080 | 10800 | 120 | 1500 | 80 | 10 | 550 | 7.3 |
| LNGT88 | 1100 | 11000 | 120 | 1500 | 88 | 11 | 550 | 7.3 |
| LNGT92 | 1120 | 11200 | 120 | 1500 | 92 | 11.5 | 550 | 7.3 |
| LNGT96 | 1150 | 11500 | 120 | 1500 | 96 | 12 | 550 | 7.3 |
Aluminum-Nickel-Cobalt Magnets: Sintered and Cast Types
Alnico magnets are classified as sintered or cast depending on the production technique. The primary distinction between sintered and cast aluminium-nickel-cobalt magnets is how the various manufacturing processes alter the magnet’s structure. Sintering creates a finer grain structure, making it ideal for precision design applications. On the other hand, casting enables more complicated geometric shapes, making it an excellent alternative for applications requiring greater design flexibility.
Applications of Alnico Magnets
The properties that make Alnico magnets very much in demand across all industries are their high-temperature stability, corrosion resistance, and strong magnetic properties. Its applications include, among others, commonly representative ones, such as its use in manufacturing pickup guitars and loudspeakers. High-temperature stability finds enormous applications in motors of automotive engines, aerospace, and general industrial equipment. As for corrosion resistance, they may serve in crucial applications such as underwater sensors, drilling equipment, and magnetic separating devices.
Price Trends of Aluminum-Nickel-Cobalt Magnets
Some critical factors include but are not limited to, alloy composition, manufacture complexity, product specificity, and performance requirements. Those factors affect the price trend as the demand for magnets continually rises for high-performance applications with customized uses.
