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ISBN 978-952-5726-09-1 (Print)
Proceedings of the Second International Symposium on Networking and Network Security (ISNNS ’10)
Jinggangshan, P. R. China, 2-4, April. 2010, pp. 047-049
Influences of Powder Content on the
Piezomagnetic Effect of Rubber-based Soft
Magnetic Composite Film
Daguo Jiang
College of Mathematic and Physical , Jinggangshan University , Ji’an, China
e-mail: jgsxy_jdg@sohu.com
Abstract—Composite film was preparated from the heat
treated Fe73.5Cu1Nb3Si13.5B9amorphous powders as
reinforced material and butyl rubber as matrix by means of
molding to shape, and its piezomagnetic effect is also tested.
The results showed that the impedance of composite film
decreases with the morer powder content; the rangeability
of impedance increases first and then decreases with
increasing powder content.Piezomagnetic effect of omposite
film is theoretically analyzed with resistance and
capacitance in series model and the conclusions are
consistent with the experimental results
Index Terms—Fe73.5Cu1Nb3Si13.5B9; butyl rubber;
composite film;piezomagnetic effect
I. INTRODUCTION
Strain occurs and the material internal magnetization
state changes when the ferromagnetic materials are under
the action of mechanical force,which resulting in a
significant change in impedance of the phenomenon
called piezomagnetic effect. A variety of pressure
magnetic sensors are developed based on piezomagnetic
effect, including pressure magnetic non-contact torque
sensors, amorphous piezomagnetic acceleration sensors
piezomagnetic pressure sensors [1-2]. In the literatures [3-
5], the skin effect was used for qualitative analyzing the
piezomagnetic effect of rubber-based soft magnetic
composite film. As composite film is large resistivity and
low permeability, and composite film has excellent
piezomagnetic effect under low frequency, so the skin
effect depth under alternating current is bigger than the
film thickness. In this paper, the soft magnetic composite
films were prepared with the non-powder
Fe73.5Cu1Nb3Si13.5B9 as composite phase and the butyl
rubber as base, and the influence of powder content on the
piezomagnetic effect was studied. Theoretically analysis
with resistance and capacitance in series model is done,
which showed the conclusions are consistent with the
experimental results .
II. EXPERIMENTAL PRINCIPLES AND METHODS
First, 7.2 μm FeSiB amorphous powders is put into
titanate (NDZ-105) THF solution for surface process; and
then uniformly mix the powder with butyl rubber by
different mass ratio, then add sulfur, paraffin and other
additives for adequate mixing; put the mixture between
the two copper foil papers, pressure forms;finally a
composite film with 200 μm thickness is achieved after
cured at 160 ℃ for 1 hour.
Figure1 Schematic of piezomagnetic effect test
The test method of piezomagnetic effect is shown in
Figure 1 where the effective area in the film between the
copper foil is 6mm × 5mm,then apply point pressure on
the film center, pressure head diameter 5mm [6-8] . Two
copper ends are connected with 4284A impedance
analyzer, and the compressive stress and current are all
along composite film thickness direction.
Impedance is tested with 4284A impedance analyzer,
where current amplitude is 10mA, AC frequency is
0.6kHz and compressive stress is 0MPa to 1.182MPa.
Use the rangeability of impedance ΔZ
to
characterize the film’s piezomagnetic properties.
ΔZ
= Zσ −
(1)
Z 0
In the equation, Zσ
is for impedance value when the
compressive stress is σ ; Z
0
is for impedance value
when the compressive stress is 0.
III.
EXPERIMENTAL RESULTS AND ANALYSIS
A. The equivalent circuit model of composite film
piezomagnetic effects
The composite film sandwiched between two copper
foils, current flows through along thickness direction of
composite films sandwiched between two copper foils,
and the compressive stress and current are all along
composite film thickness direction.the copper foil is a
conductor, and the composite films is an insulator with
large resistivity, so the composite film and copper foils
form a parallel-plate capacitor. So the system can be
equivalent as a resistance and capacitance in series model.
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