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B. Influences of powder content on the impedance of
composite film
Table I is the influences of powder content on the
impedance of composite film at 0.6kHz . Known from
table, the impedance of composite film decreases with the
powder content increases.
The impedance of composite film is consisting of
resistance and reactance. Resistance is mainly depending
on the degree of perfection (resistivity) of amorphous
powder particle chains forming in the rubber base and the
effective length of composite film that the current flows
through;reactance of composite film is decided by the
capacitance, which mainly depends on the thickness of
composite film and the AC frequency.So the impedance
of composite film is:
Z +
2 2
= R X
(2)
The powder content is defined as P ,the composite
film resistivity and dielectric constant decrease with the
bigger powder content P ,it means that,the resistance and
resistance decreases with the bigger powder content P ,
so the impedance of composite film decreases along with
the powder content P increases.
Table I Influences of powder content on the impedance of composite
film
Z/ kΩ
σ/MPa 1:3 1:4 1:5 1:6
0 2159.39 1439.92 1397 938.626
0.065 2153.53 1425.87 1393.65 936.747
0.108 2153.24 1423.35 1393.31 936.32
0.147 2152.77 1422.75 1392.94 935.79
0.201 2152.72 1421.83 1392.52 935.294
0.397 2151.69 1420.89 1391.43 934.167
0.607 2150.72 1420.23 1390 933.391
0.802 2150.69 1417.21 1389.14 932.184
0.992 2150.04 1415.58 1388.55 931.797
1.182 2149.53 1412.13 1387.99 931.366
Figure 2 is the influences of powder content on the
rangeability of impedance of composite film at 0.6kHz.
Known from Figure, the rangeability of impedance
increases first and then decreases with increasing powder
content; it is the biggest When the powder with butyl
rubber according to the mass ratio of 4 to 1.
The resistance of composite film R and the reactance
of composite film X is inversely proportional to powder
dC dD
content P , so supposed R = , X = , where
P P
C 、 D are constants, and according to equation (2)and
equation (1) , the impedance of composite film is:
d C
2 2
+ D
Z = (3)
P
the rangeability of impedance of composite film is:
2 2 ( d
0−dσ
)
Δ Z = C + D
(4)
P
The elastic modulus of composite film increased With
the P increases ,and the deformation of composite film
decreases under constant stress, it means that,
decreases with the P increase; so supposed
E
d =
P
d
σ
σ
,
where E is constant; d
0
is constant ,according to
equation (4), the rangeability of impedance of composite
film is :
E
( d
0−
)
2 2 P
2 2 ( d
0P
− E)
Δ Z = C + D = C + D
(5)
2
P
P
2
d(
ΔZ)
2 2 (2PE
−d
0P
)
= C + D
4
dP
P
When
2E
d(
ΔZ)
P < , > 0
d dP
0
, ΔZ
increases
2E
with powder content P increase;While P > ,
d
0
d(
ΔZ)
< 0 , Δ Z decreases with powder content P
dP
increase.
ΔZ/kΩ
30
25
20
15
10
5
1:3
1:4
1:5
1:6
0
0.0 0.2 0.4 0.6 0.8 1.0 1.2
stress/MPa
Figure 2 Influences of powder content on the rangeability of
impedance of composite film
IV. CONCLUSIONS
Large piezomagnetic effect of Fe-based amorphous
ribbon can be produced only at high frequency, while it
can be produced at low frequency in soft magnetic
composite films prepared with IIR as base and amorphous
powders grinded from iron-based amorphous ribbon as
composite phase.. the impedance of composite film
decreases with the morer powder content; the
rangeability of impedance increases first and then
decreases with increasing powder content, the rangeability
of impedance is the biggest When the powder with butyl
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