Magnetic materials are ancient and widely used functional materials. The magnetic properties of materials were known and applied as early as 3000 years ago. For example, ancient China used natural magnets as compasses. Magnetite, which exists widely in nature, is a natural magnet, and its molecular structure is Fe3O4. In modern times, with the development of industry and technology, a large number of new magnetic materials have been discovered, which are roughly divided into three generations according to their main applications: the first generation of aluminum nickel cobalt (AlNiCo), the second generation of ferrite, and the third generation of rare earth permanent magnets. . Among them, rare earth permanent magnets are divided into three stages: the first stage SmCo5, the second stage Sm2Co17, and the third stage Nd2Fe14B. The following is a brief history of the development of magnetic materials:
In the 1st century BC, Sima Qian's "Historical Records" described the Yellow Emperor's use of a compass in battle.
In 1086, Shen Kuo's "Mengxi Bi Tan" of the Song Dynasty recorded the manufacturing method of the compass.
In 1119, Song Dynasty Zhu or "Pingzhou Ke Tan" recorded that the compass was used for navigation.
1600 British William. Gibert, the earliest book "De Magnete".
In 1820, Denmark (H.C. Oersted) first discovered that electric current can generate a magnetic field.
In 1822, the French Lussac invented the electromagnet, that is, the middle iron block can be magnetized by the current passing through the winding wire.
In 1826, French Ampere discovered Abe's law, the right-handed spiral rule.
In 1831, Faraday demonstrated the phenomenon of electromagnetic induction and revealed the relationship between electromagnetics.
In 1832, French A.H. Pixi invented a permanent magnet rotating alternator made of natural magnets.
From the 19th century to the 20th century, Europe’s new types of DC and AC motors/generators were overwhelmed.
In 1931, Japan's T. Mishima invented AlNiCo AlNiCo magnetic steel. Before the discovery of rare earth magnets in the 1970s, AlNiCo was the strongest permanent magnet material. (The first generation of magnetic materials)
In 1933, Japan's Kato and Takei discovered Co-containing ferrite Fe2O3. In terms of weight, ferrite is still the most widely used magnetic material in the world today. (Second-generation magnetic material)
In 1935, Snoek in the Netherlands invented soft ferrite
In 1965 Mader and Nowick prepared CoP ferromagnetic amorphous alloy
In 1967, Strnat in the United States discovered 1:5 SmCo, marking the arrival of the era of rare earth permanent magnets (third-generation magnetic materials).
In 1977, Japan's Ojima discovered 2:17 SmCo, and contained a small amount of Cu and Zr.
In 1983, Sagawa of Japan discovered Nd2Fe14B, NdFeB known as the contemporary magnetic king.
In 1983, General Motors in the United States discovered neodymium iron boron after Japan, and each had a patent.
In 1984, the National Iron and Steel Research Institute developed NdFeB with a magnetic energy product exceeding 35MGOe.
In 1992, domestic companies successively purchased patents of Sumitomo NdFeB.
In 2002, the annual output of NdFeB in China reached 8,000 tons, surpassing Japan to become the world's first.
In 2008, there were more than 100 NdFeB manufacturers in China, with an annual output of 46,000 tons.
In 2011, the price of rare earths skyrocketed, downstream customers were hit harder, and substitution and dysprosium reduction became a trend. At the same time, a large amount of hot money has poured into the rare earth industry, causing serious overcapacity in the entire industry chain, including NdFeB.
In 2013, the industry predicts that the domestic NdFeB production capacity has reached 335,000 tons, which is approximately 270,000 tons multiplied by a factor of 0.8, but the actual annual demand is only 110,000 tons, and the production capacity has been severely surplus, especially for the low-end products.
In 2014, with the exception of Hitachi Metals, Shin-Etsu Chemical, TDK and VAC in Germany, Molybdenum Corporation in the United States has a small amount of production. Accounted for more than half of the points.
Some interesting phenomena can be found from the above brief history of development:
1. China was the first to pay attention to magnetic materials, and the application of the compass changed the history of navigation in the world. However, there was a gap in the middle, and finally relying on reform and opening up, it became the world's largest manufacturing base for magnetic materials. However, the grade of NdFeB products in China is quite low, and the added value is far behind Japanese companies.
2. In the 19th century, European science and technology were developed, and pioneering theories and practices of modern electromagnetics, engines, and generators were all initiated by Europeans.
3. Beginning in the 1930s, the locomotive developed by the world's magnetic materials has been replaced by Japan and the United States. In particular, Japan was already the world leader in magnetic materials research and development before the war, and therefore had to admire the Japanese achievements in the field of materials science, which is worthy of the Chinese to learn.
NdFeB has been born in the laboratory for more than 30 years. Due to the high price of rare earths, especially the lack of heavy rare earths in dysprosium and terbium, countries all over the world are vying to develop a new generation of magnetic materials, such as samarium iron nitrogen permanent magnets, Nanocomposite rare earth permanent magnets, etc., but the current effect is still not ideal. NdFeB will remain unshakable in the visible ten to twenty years.
