Characterization and Synthesis of Ni0.6Zn0.4(Fe2O4)1 Nano-Particles Using Sol-Gel Method

Ni-Zn ferrite is a kind of important magnetically soft material that has been used widely in medical signal deal and medical apparatus. So, many people are interested in both the prepare process of Zn ferrite (especially the prepare process of nanometer ferrite) and the study of its structure and properties. In this paper the condition in which Ni-Zn ferrite powders was prepared by sol-gel methods was studied. The pH value, calcined temperature, calcined time were investigated. With the designing experiment, the best condition was confirmed. The microstructures and particles size were characterized by means of TEM、IR、XRD and so on.

Experimental and Theoretical Study on Magnetoelastic Buckling of a Ferromagnetic Cantilevered Beam-Plate

When a cantilever of magnetically soft material is inserted with its wide face normal to a uniform magnetic field and the magnetic field is increased to a critical value the cantilever will buckle. The experimental magnetoelastic buckling fields and the theoretical ones differ by a factor of two. A magnetic field distortion near an edge of the specimen is here evaluated based on the finite-element method and the results are applied to the experimental results so as to explain the discrepancy between the experiment and the theory. The corrected experimental values are within 15 percent of the theoretical values. The effect of demagnetization on the buckling field is here demonstrated as well as the effect of specimen dimensions.

Magnetoelastic Buckling of Thin Magnetically Soft Plates in Cylindrical Mode

When a plate of magnetically soft material is supported with its wide face normal to a uniform magnetic field, it will buckle when the field reaches a critical value. It is shown theoretically that the critical buckling field for a “half-restrained” rectangular plate should be 0.833 of that for a half-restrained elliptical plate of identical dimensions and material. Limited experimental data support this conclusion. The effect of plate width upon critical buckling field is investigated experimentally and an empirical formula is presented which fits the data reasonably well.

Magnetoelastic Buckling of Beams and Thin Plates of Magnetically Soft Material

When a plate of magnetically soft material is supported with its wide surface normal to a uniform magnetic field, it will buckle when the field reaches a critical value. This paper formulates the problem quite generally for thin plates (including beams) and carries the solution as far as can be done without making specific assumptions as to plate geometry and constraints. The special case of wide cantilever beam, considered earlier by Moon and Pao, is carried through in detail. It is shown that if their theoretical result is modified to take account of the increased field intensity caused by the plate, agreement with experiment is within 20 percent.