Ferrite composite

The ferritic steels may also undergo intercrystalline corrosion as a result of grain boundary carbide formation. In the normal softened state (treated i 800 C) the carbon is largely precipitated and the ferrite composition homogenised so that further heating at lower temperatures has no adverse effect. During solution treatment above 950 C, however, carbon is redissolved. Sensitisation can then occur at lower temperatures but the rate is so rapid that it can only be suppressed by very rapid cooling which is not practically feasible. Thus weld decay is very possible in service unless a remedial... 

A disc, 2 cm in diameter and 5 mm thick, magnetized normal to its faces and manufactured from a ferrite with Br = 0.3 T and Hc = 200 kA m 1 is required. Comment on the practical feasibility of the requirement. Assuming the ferrite composition to be fixed, what steps might be taken to realize the requirement [Answer HD = 238 kA m ]... 

This system includes the Ca2(Alj,Fej, )205 series of ferrite compositions. The bounding, binary system Ca0-Fe203 includes three compounds, viz. CjF, CF and CFj. C2F, as an end member of the above series, was discussed in Section 1.5. The other two compounds are of lesser importance to cement... 

Swayze (S8,S10) extended the work of Lea and Parker (L4,L5) by considering the effects of variable ferrite composition and of the presence of MgO as an oxide component. In the work with MgO, a constant 5% of the latter was present in all the compositions examined. This was considered sufficient to saturate the liquid, as small amounts of periclase were detected in nearly all the products. Fig. 2.8 shows the results for the system in the presence of... 

If the result for aluminate is negative, this phase is absent and its composition should be replaced in the matrix A by that of the low- aluminium ferrite phase given in Table 1.2. From the compositions ) and proportions found for the two ferrite components, the content and composition of the ferrite may be estimated. Similarly, if the result for ferrite is negative, the ferrite composition is replaced by that j of low-iron aluminate. These conditions will occur at ARs below about < 1.0 and above about 4.0, respectively. The data for the low-aluminium ... 

Fig. 7.30 Pitting potential versus factor, Cr + 3.3 Mo + 1 6 N. Steels were austenite, martensite, tempered martensite, or ferrite. Composition range 0-29 wt% Cr, 0-20 wt% Ni, 0.3-4 wt% Mo, 0.01-0.5 wt% N, and 0-0.3 wt% Nb. Redrawn from Ref 47...

This method of ferrite formation is based on the formation of aqueous solutions of chlorides, nitrates or sulphates of Fe, and of divalent Ni, Co, Mg, Ba, Sr, etc., in the concentrations required for the ferrite composition, and their simultaneous precipitation in the form of hydroxides by NaOH. The precipitate is then filtered, washed and dried. The ferrite particles are obtained by calcination at 180-300 °C in air. Particles with a narrow size distribution in the range 50-500 nm may be obtained, with high purity. The final ferrite body is obtained by sintering at temperatures considerably lower than in the case of the ceramic method. 

S. P. Gairola, V. Verma, L. Kumar, M. A. Dar, S. Annapoorni, R. K. Kotnala, Enhanced Microwave Absorption Properties in Polyanihne and Nano-Ferrite Composite in X-Band. Synth Met 2010, i 60, 2315-2318. 

Figure 15.1 shows the Nio.5Zno.5Fe204 ferrite structure with octahedral sites in red and tetrahedral sites in dark yellow. This ferrite is formed by a solid solution of Ni203 (nickel oxide), ZnO (zinc oxide) and iron oxide (Fe203) in haematite form (a-Fc203), where this last oxide contains about 70% by weight of ferrite composition. 

Figure 15.13 Flow chart for the mechanical tests of compression type assisted by magnetic field for rubber ferrite composites (RFC).

Malini et al prepared rubber ferrite composites containing nickel zinc ferrite (NZF) and examined the variation of tensile strength, elongation at... 

Makled et a/. reported the influence of co-precipitated hexagonal barium ferrite BaFei20ig phase on the cure characteristics and dynamic properties of NR-ferrite composites as a function of ferrite loading up to 2-20 phr (parts per hundred parts of rubber). The results showed that the scorch time decreased dramatically with increasing ferrite content until 160 phr BaF loading, this is because of the heat of mixing increases as the filler loading. 

N. Viart, G. Pourroy, J.M. Greneche, Study of metal-ferrite composites complementary use of Fe Mossbauer spectrometry. X-ray diffraction and TG analysis. Eur. J. Phys. Appl. Phys. 18, 33 0 (2002)... 

Kommareddi N S, Tata M, John V T, McPherson G L, Herman M F, Lee Y S, O Cannor C J, Akkara J A and Kaplan D L, Synthesis of superparamagnetic polymer-ferrite composites using surfactant microstrucmres , Chem Mater, 1996 8 (3) 801-809. 

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