Superhydrophobicity in Power Applications

Superhydrophobicity in Power Applications ICC - Sub B Fall 2008 Nigel Hampton, Frank Lambert NEETRAC ICC Fall 2008 1 Lotus Effect - Superhydrophob...
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Superhydrophobicity in Power Applications ICC - Sub B Fall 2008 Nigel Hampton, Frank Lambert NEETRAC

ICC Fall 2008

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Lotus Effect - Superhydrophobicity Contact angle: > 150˚ Hysteresis smaller than 10˚ (Hysteresis= γa- γr ) Dir

ect ion of D

γr

rop

Mo vem en

γa

A droplet on a superhydrophobic surface: The droplet touches the leave only in a few points and forms into a ball. It completely rolls off at the slightest declination.

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Why This Is Interesting • Lotus effect surface: Dust with a particle size larger than the surface roughness is complete cleaned with a water droplet, rough surface in effect. • Smooth surface: Dirt is only moved by the droplet.

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Contact Angle Measurement • Goniometer for Contact Angle and Hysteresis measurements

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Scanning Electron Microscope • Surface morphology • Surface structure size / particle size measurement • Surface elemental analysis

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Starting Structures • Superhydrophobic coatings were prepared on various insulating polymer materials using CF4 and SF6 plasma etching. 100 W, 5 min 200W, 5 min

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Multi Factor Ageing

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Looks Good But !!!!!!

Contact Angleact (Degree) Wat er cont angl e

170 160 150 140 130 120 110 100 90

Superhydrophobicity Lost But Still Looks Good Though Heading for the Floor

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Uncur ed Cur ed

0

50 100 150 Multi Factor Ageing UV exposur e t Time i me ( (h) h)

200 8

Degradation Of Polymer Film • After 48 hours exposure the superhydrophobicity is totally lost. The contact angle drops from 160˚ to only 80˚.

After exposure

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Next Step - An Inorganic Film Inorganic material, stable under multifactor ageing. Low energy surface can be achieved. Roughness control through diameter control.

Contact angle: ~162˚ hysteresis: < 5˚ ICC Fall 2008

SEM image: Surface roughness

10

Can Control Particle Sizes 700

Calculated Particle Size (nm)

600 500

Perfect Correlation

400 300 200 100 4 components

0 0

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100

200

300 400 500 Actual Particle Size (nm)

600

700

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One species, too perfect packing, not enough roughness Contact angle: 134˚

TiO2: ~800 nm SiO2: 90 nm Enough roughness can be achieved

Contact angle: 168.3˚, hysteresis < 4˚ ICC Fall 2008

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Multi Factor Ageing - Results Hysteresis (degree)

50

Contact Angle (degree)

180

Material M T

40 160 Superhydrophobic

30

150 140

20

10

10

Normal Silicone Level

120 0

120

Superhydrophobic 0

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1000 2000 3000 4000 5000

0

1000 2000 3000 4000 5000

13

Recovery Hysteresis 0

40

314

670

20

Hysteresis (degree)

10 0 1000

40

1947

2113

20 10 0 4531

40

4797

0

7

20 10 0 0

7

14

21

0

7

14

21

Measurement Delay (Days)

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Sample No 1 1 2 2 3 3 4 4

Test A B A B A B A B

14

Transition to “Real Life”

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Salt Fog

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Salt Fog

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HiVARC

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Semi Quant STRI Classifications

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STRI Assessment Bad 6

MEDIAN STRI

5

4

3

2

1

Good

1

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3

4

5

6 7 SAMPLE

8

9

10

11

12

20

Full Size Insulator Test Device

Salt Fog Endurance

HiVARC

STRI Hydrophobicity

Tracking Wheel Endurance

Suspension Insulator Phase I

12.5kV 1382 hours

YES

YES

-

Suspension Insulator Phase II

20kV 1233 hours

YES

YES

-

Polymer Cut Out

-

-

-

YES

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Tracking Wheel

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Let There Be Light

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Tracking Wheel Failures

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Tracking Wheel Test on Cutout 99

Treated Untreated

90 80 70 60 50

Percent

40 30 20 10

End of Tracking Wheel Test

5 3 2 1

10000

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15000

20000 Cycles to Failure

30000

40000

25

Tracking Wheel Test on Cutout 99

Treated Untreated

90

Same Gradients Indicate Same Failure Mechanism

80 70 60 50

Percent

40 30 20 10

End of Tracking Wheel Test

5 3 2 1

10000

ICC Fall 2008

15000

20000 Cycles to Failure

30000

40000

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Tracking Wheel Test on Cutout 99 Treated Untreated

90 80 70 60 50

Treated Fail later Than Untreated see 10% probabilities

Percent

40 30 20

10 5

2 1

10000

ICC Fall 2008

15000

20000 Cycles to Failure

23886

18677

3

End of Tracking Wheel Test

30000

40000

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Field Test Participants •Polymer Silicone Insulators •Southern Company Transmission Lines •Hubbell

MISSISSIPPI CHEMICAL MOSS POINT EAST 115 KV T.L. ICC Fall 2008

Insulator Installation Site 28

Field Test Site

MISSISSIPPI PHOSPHATE

X X

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CHEVRON PLANT

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Solution Applied To New Insulators

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Installing New Insulator At Str.# 54

Performance is being monitored on a 3 monthly basis ICC Fall 2008

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Conclusions • • • • •

Robustness and longevity are very important Coatings work on all of the main insulations Accelerated tests are underway Coatings are in use at 15 & 115 kV Work planned for EHV

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