Coercive forces

It is known that diagram " Stress - Deformation " ( SD) is more vividly specifying the current metalwork condition. However, such diagram can be obtained only by destructive testing. The suggested non-destructive magnetic method in the report for the evaluation of SD condition and for the prediction of residual resource of metalwork, where the measurement of coercive force (CF) is assumed as a basis. 

For the practical implementation of the above mentioned facts, the portable electronic digital coercive force meter with self-contained power supply, attached converter and closed type magnetic core. Instrument error is 5 %. ... 

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

Magnet Applications. For magnets of the type FeNdB, a small amount of gallium is effective in improving the intrinsic coercive force (53). It slows the pinning type recoil loop. The thermal stabiUty is increased. The irreversible loss is less than 1.5% under 373 K (1000 h). 

Fig. 7. Thermomagnetic recording, (a) A focused laser beam generates a thermal profile in the magnetic layer, (b) The coercive force in the layer is reduced and its magnetisation can be reversed by a small magnetic field, here 30 kA/m. At room temperature, the coercive force is high and the written domains are...

As the appHed field is reduced, the iaductioa does aot retrace curve 1 but foUows curve 2 as the domaias at first merely rotate back to the aearest local easy axis directioa. The value of B at i/ = 0 is the remanent iaductioa. At H = which is the coercive-field strength of coercive force or... 

Fig. 1. The effect of (------) coercive force, ( ) lesistivity, and ([[aitl]]) magnetoiesistance coefficient foi Permalloy films (a) at a constant argon...

Fig. 6. Changes in ( coercive force, (----) saturation magnetization Af, and (— —) coercive squareness ratio, A, of Co—Cr—Ta/Cr films...

Nickel—Iron and Cobalt—Iron Alloys. Selenium improves the machinabifity of Ni—Ee and Co—Ee alloys which are used for electrical appfications. Neither sulfur nor tellurium are usefiil additives because these elements cause hot britdeness. The addition of 0.4—0.5% selenium promotes a columnar crystal stmcture on solidification, doubling the coercive force of cobalt—iron-titanium alloy permanent magnets produced with an equiaxial grain stmcture. 

In addition to chemical analysis a number of physical and mechanical properties are employed to determine cemented carbide quaUty. Standard test methods employed by the iadustry for abrasive wear resistance, apparent grain size, apparent porosity, coercive force, compressive strength, density, fracture toughness, hardness, linear thermal expansion, magnetic permeabiUty, microstmcture, Poisson s ratio, transverse mpture strength, and Young s modulus are set forth by ASTM/ANSI and the ISO. 

Magnetic properties of iron nanocrystals nested in carbon cages, which grew on the cathode deposit, have been studied by Fliura el al.[29]. Magnetization (M-H) curves showed that the coercive force. He, of... 

Hysteresis curves for a magnetically hard and a magnetically soft ferromagnetic material. S = saturation magnetization, R = remanent magnetization, K = coercive force... 

Magnetic properties remnant magnetization, coercive force Morphology... 

Strength H r is needed to remove the remanence. He, the magnetic field at which Js becomes zero, is called coercive force or coercivity. Each type of magnetism shown in Figure 6.8 is associated with characteristic features which are displayed by the different Fe oxides. 

The amount of energy (i. e. the coercive forces) necessary to achieve these changes is related to three different types of magnetic anisotropy. 

Tab. 7.7 Maximum coercive force for natural single domain phases with different types of anisotropy and their critical diameter, dcrit, for the transition from single domain to pseudo-single domain type (from Soffel, 1991 with permission)...

Maximum coercive force, HJmT Shape Stress Crystal... 

Whether a phase displays SD, PSD orMD behaviour, can be determined from the shape of its hysteresis loop. In MD particles the Bloch walls can be moved by lower energies than the directions of magnetization in SD particles. The hysteresis loops of MD particles, therefore, are much narrower than those of SD particles (Fig. 7.12). For ferrimagnetic phases, the ratios Jrs/Js and Har/Hc (Fig. 7.9) (Day et al., 1977) can be used to distinguish between SD, PSD, and MD particles (Fig. 7.12, right). It should be kept in mind, however, that the coercive forces also depend on particle morphology. Calculations by Butler and Banerjee (1975) show that deviations from the rounded isometric shape towards elongated needles stabilize the SD behaviour and even SP particles may become SD (Fig. 7.13). 

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