Metal-bonded Co-ferrite composites for magnetostrictive torque sensor applications

Abstract

A new class of magnetomechanical sensor materials, Co-ferrite (Co0.Fe203) and metal-bonded (Ag, Ni, CO) Co-ferrite composites, has been investigated. These materials exhibited magnetostriction in excess of 200 ppm and high d3, (aUiJH), coefficient, 1.3~10' A'm, at low applied field (<lOOWm). Selected compositions were formed into test samples in the form of rings brazed to stainless steel through-shafts. Changes of surface axial magnetic field in response to applied torque as high as 64 AN'm" were observed for a demonstration sample of dimensions 25 mm OD, 12.5 mm ID, and 8 mm high. A hysteresis off 0.5 N.m was observed. These materials appear to be promising candidates for torque sensors, and other magnetostrictive sensor and actuator applications.Index Term-Ferrite, torque sensor, magnetostriction, magnetomechanical effect.

Composite Magnetostrictive Materials For Advanced Automotive Magnetomechanical Sensors

“…13 Our experimental results confirmed that the metal-bonded Co-ferrite composite exhibits the same behavior. This effect, which is due to the magnetic moments on different lattice sites changing differently with temperature, also caused part of the decrease with increasing temperature of the remanent magnetization of the ring-shaped ferrite composite.…”

“…16,19,21 Due to the fact that the magnetizations of the sublattices of ferrites have opposite signs and different temperature dependence, the temperature dependence of the magnetic properties of ferrites, such as saturation magnetization and anisotropy can be complicated. 13 Metal-bonded Co-ferrite composites are even more complex systems due to the metal additives and different processing from pure Co ferrite. 20 The temperature dependence can be explained by the changes of magnetostriction, anisotropy, spontaneous magnetization and pinning of domain walls caused by the availability of increased thermal energy.…”

“…12 In order to overcome this problem, a study involving metallic binders or sintering aids was undertaken. Ag/Ni, Ag/Co, or Co was used in order to bind the ferrite together; 13 Ag, which has a low oxygen affinity, has the advantage of not chemically reducing the ferrite. However, Ag does not wet the ferrite properly during fabrication.…”

Dependence of magnetomechanical performance of CoGaxFe2−xO4 on temperature variation

“…The need to control the magnetostrictive properties has resulted in several studies including the influence of vacuum sintering, 1 annealing and quenching heat treatment, 2 metal bonding, 3 and cation substitutions. [4][5][6][7] Of these, cation substitution has been found very useful for improving the strain response of cobalt ferrite to applied magnetic field.…”

Temperature dependence of magnetic anisotropy of germanium/cobalt cosubstituted cobalt ferrite

“…[1][2][3][4][5][6] Chemical substitution can enhance the properties of cobalt ferrite by altering the cation distribution in the cubic spinel structure, therefore, influencing the magnetoelastic properties of these materials. Previous studies have shown that the substitution of M 3+ ͑Mn 3+ , Cr 3+ , and Ga 3+ ͒ 2,3,7 in place of some of Fe 3+ reduces the hysteresis and increases the strain derivative of cobalt ferrite for certain compositions with, however, a decline or no improvement in the magnitude of magnetostrictive strain amplitude.…”