Permanent magnetism

Alnico alloys Alloys containing Al, Ni, Co and Fe. Used for permanent magnets. 

Energetic analysis shows the dependence of using magnetie materials from relation of coercive force on magnetization to remanent induction. The permanent magnets... 

Fig. 10. Cross section of an EMFC weighing cell. Item 1, pan 2, hanger 3, parallel guide 4, chassis 5, flexure 6, lever 7, flexible link 8, pivot point 9, position indicator 10, position sensor 11, permanent magnet 12, permanent magnet air gap 13, compensation cod. See text.

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. 

Data Handbook on Permanent Magnets, Philips Components, Eiadhoven, the Netherlands, 1991. 

M. McCraig and A. E. Clegg, Permanent Magnets in Theoj and Practice, Pentech, London, 1987. 

The most spectacular applications of ECLs are the possibiUty of direct overwrite (DOW) with laser modulation (79,80) and of magnetically iaduced superresolution (81,82). The stacks comprise at least a storage layer s and a bias layer b. For both appHcations, the storage layer s has the lower and the higher at room temperature when compared to the bias layer b. At room temperature, b is homogeneously magnetized (initialized) by an external permanent magnet is about 400 kA/m (5 kOe)). 

H, for which J = 0, is the intrinsic coercivity whereas the usual coercivity, for which S = 0, is denoted by H or H. For permanent magnets, the value (BH), the maximum energy product, is an important measure of quaHty. The value (BH), iadicated ia the secoad quadrant of Figure 1, represents the poiat of maximum efficieacy where a givea amouat of magnetic flux is produced by the smallest amouat of material. 

Table 9. Magnetic Properties of Commercial Permanent Magnet Materials...

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