Alnicos ;are a group of heat-treated Fe–Co–Ni–Al–Cu alloys that can be divided into two main subgroups: isotropic alloys containing 0–20 wt.% Co (alnicos 1–4) and anisotropic alloys with 22–24 wt.% Co and titanium content of 5–8 wt.% (alnicos 5–9). The anisotropy in the case of alnicos 5–9 is produced by controlled cooling or isothermal heat treatment in a saturating magnetic field. The main source of anisotropy is the shape anisotropy associated with elongated Fe–Co particles in a Ni-Al matrix aligned parallel to the magnetic field during spinodal decomposition of the alloy. Alnicos are widely used as permanent magnets. The most important applications are loudspeakers, watt-hour meters, electric motors, generators, and alternators.
Samarium–cobalt magnet
A samarium–cobalt (SmCo) magnet, a type of rare-earth magnet, is a strong permanent magnet made of two basic elements: samarium and cobalt.
They were developed in the early 1960s based on work done by Karl Strnat at Wright-Patterson Air Force Base and Alden Ray at the University of Dayton. In particular, Strnat and Ray developed the first formulation of SmCo5.
Samarium–cobalt magnets are generally ranked similarly in strength to neodymium magnets, but have higher temperature ratings and higher coercivity.
Attributes
Extremely resistant to demagnetization
Good temperature stability (maximum use temperatures between 250 °C (523 K) and 550 °C (823 K); Curie temperatures from 700 °C (973 K) to 800 °C (1,070 K)
Expensive and subject to price fluctuations (cobalt is market price sensitive)
Samarium–cobalt magnets have a strong resistance to corrosion and oxidation resistance, usually do not need to be coated, and can be widely used in high temperatures and poor working conditions.[4]
They are brittle and prone to cracking and chipping. Samarium–cobalt magnets have maximum energy products (BHmax) that range from 14 megagauss-oersteds (MG·Oe) to 33 MG·Oe, which is approx. 112 kJ/m3 to 264 kJ/m3; their theoretical limit is 34 MG·Oe, about 272 kJ/m3.
Sintered Samarium–Cobalt magnets exhibit magnetic anisotropy, meaning they can only be magnetized in the axis of their magnetic orientation. This is done by aligning the crystal structure of the material during the manufacturing process.
FeCrCo & Crovac
Descriptions of products
FeCrCo/Crovac ;as a new type of magnet has come into the world in the 1970s. It is widely used in space, aviation, shipping instrument, automobile instrument, magnetic motor, compasses, computer embroider machines and signal systems, etc.
FeCrCo/Crovac has good plasticity, ductility, and machining ability. And can be drilled, planned, stamped, and other machining operations. The minimum diameter can be 0.05 mm and the thickness of the strip can be 0.1 mm, especially suited for tinny elements with accurate dimensions and complicated shapes, such as strip, wire, bar, tube, etc.
FeCrCo/Crovac has excellent temperature stability, good corrosion resistance, and a high Curie temperature(around 680℃). The maximum working temperature is 400℃.
Neodymium magnet
A neodymium magnet (also known as NdFeB, NIB, or Neo magnet) is the most widely used] type of rare-earth magnet. It is a permanent magnet made from an alloy of neodymium, iron, and boron to form the Nd2Fe14B tetragonal crystalline structure. Developed independently in 1984 by General Motors and Sumitomo Special Metals, neodymium magnets are the strongest type of permanent magnet available commercially.
NdFeB ;magnets can be classified as sintered or bonded, depending on the manufacturing process used. They have replaced other types of magnets in many applications in modern products that require strong permanent magnets, such as electric motors in cordless tools, hard disk drives, and magnetic fasteners.