Page 500 - Book Hosokawa Nanoparticle Technology Handbook

APPLICATIONS 13 ENHANCEMENT OF THE PERFORMANCE OF INSULATING MATERIALS

99 70
95
90 60
50
Frequency (%) 10 Erosion volume (mm 3 ) 40
50

5
30
1 20
10
10 15 20
0
Electrical breakdown strength (kV/mm) 10% micro 30% micro 50% micro 5% nano 10% nano
Nanoparticle added (12nm-SiO , without coupling agent) SiO particle addition
2
2
, without coupling agent)
Micron particle added (1.6 m-SiO 2
, with coupling agent) Figure 13.6
Nanoparticle added (12nm-SiO 2
Erosion volume of silicon rubber [8].
Micron particle added (1.6 m-SiO , with coupling agent)
2
Figure 13.5
Withstand voltage of epoxy resin [7]. 250°C 300°C 350°C 400°C
100000
260°C
There is another report, in which two kinds of SiO 2 280°C
particles, of sizes 1.6 m and 12 nm, were used and 20000
the effect of the coupling agent used for the particle 10000
surface modification was compared [7]. As a result of 245°C
the withstand voltage test under an alternating voltage
of 50 Hz, only modest difference in the effect in the
case of micron-sized particles was apparent, as seen
in Fig. 13.5. 1000
Conversely however, the electrical breakdown Lifetime (h)
strength was increased by 50% using the surface
treated nanoparticles and became larger than that with
the micron-sized particles. This is considered attribut-
able to the fact that the electric tree progress is hin- 100
dered, due to the reduced inter-particle distance when
the nanoparticles are applied, and that the weak points Silica dispersed polymide wire (nickel-plated copper)
at the interface between the resin and particles can be Polymide wire (nickel-plated copper)
decreased by treating the nanoparticle surface. Polyimide wire (copper)
10
2. Tracking-resistance and erosion-resistance 2.0 1.9 1.8 1.7 1.6 1.5 1.4
characteristics Temperature 1/T(×10 K )
-3
-1
There is a report [8] comparing the properties of Figure 13.7
silicon rubber with the addition of SiO particles of Heat-resistance index [11].
2
differing sizes, namely 5 m and 12 nm. The erosion
volume in the test sample was then measured under
2–2.5 kV AC.
Consequently, it was found to be reduced with the In addition, the strong adhesion of nanoparticles to
increasing addition of both micron- and nanosized the silicon rubber is also considered to be one of the
particles, as shown in Fig. 13.6. The addition of just reasons hampering the decomposition of the silicon
10% of nanoparticles resulted in an erosion volume rubber [9].
similar to that obtained by the 50% addition of It is also reported that the addition of 5 wt% SiO to
2
micron-sized particles, while that reportedly caused the silicon rubber increased the tracking resistance
by the decomposition of silicon rubber was hindered [10]. It was explained that oxygen and flammable gas
by the silica layer that formed when the nanoparticles hardly penetrated into the silicon rubber because the
were added. nanoparticles occupied the free volume space inside it.

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