Magnets materials costs

M-type ferrites are mainly used as permanent magnet material. They have largely replaced the alnicos as preferred permanent magnet material, as a result of the lower material and processing costs. These ferrites were first introduced under the trade name Ferroxdure, the isotropic form in 1952 (22) and the anisotropic (crystal oriented) form in 1954 (23), and are widely available commercially under various trade names such as Oxid and Koerox. They cover about 55% of the world market of permanent magnet materials, corresponding to 1100 million U.S. doUars (1991), as weU as 55% of the U.S. market, at 300 million. 

Chromium—Cobalt—Iron Alloys. In 1971, a family of ductile Cr—Co—Fe permanent-magnet alloys was developed (79). The Cr—Co—Fe alloys are analogous to the Alnicos in metallurgical stmcture and in permanent magnetic properties, but are cold formable at room temperature. Equivalent magnetic properties also can be attained with substantially less Co, thereby offering savings in materials cost. 

The enclosure is constructed of non-magnetic material, generally aluminium, in view of its low cost and weight as compared to copper The nonmagnetic material eliminates hysteresis and eddy current losses in the enclosure, as i result of mutual induction,... 

There is considerable interest in developing new types of magnetic materials, with a particular hope that ferroelectric solids and polymers can be constructed— materials having spontaneous electric polarization that can be reversed by an electric field. Such materials could lead to new low-cost memory devices for computers. The fine control of dispersed magnetic nanostructures will take the storage and tunability of magnetic media to new levels, and novel tunneling microscopy approaches allow measurement of microscopic hysteresis effects in iron nanowires. 

The Nd-Fe-B magnets are based on the intermetallic compound of the formula Nd2Fei4B. The interest in these magnets is due to the fact they are stronger than other materials and of low cost. The magnetic energies and costs of the most common magnetic materials as of 1986 are presented in Table 12.12. 

Materials cost per ampere meter. In those applications where the critical current density and strain characteristics make the magnet technically feasible, we must consider the cost. We focus here on the superconducting materials cost and the total refrigeration cost including the cryostat and capitalized refrigerant costs. 

If the cost per ampere-meter of YBaCuO at 77 K remains higher than conventional superconductors it will not be competitive in applications where the superconductor materials cost dominates, i.e. very large magnets... 

Cost, J.R., R.D. Brown, A.L. Giorgi and J.T. Stanley, 1987b, in High Performance Permanent Magnet Materials, Mater. Res. Soc. Symp. Proc. 96, 321. 

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