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Surface Treatment Issues for Surface Treatment Issues for

Surface Treatment Issues for - PowerPoint Presentation

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Surface Treatment Issues for - PPT Presentation

RF Structure Fabrication Juwen Wang SLAC National Accelerator Laboratory XBand Accelerating Structure Review November 2014 CERN 2 Outline Etching Tests Revisit and Discussion Etching Time Studies Using TD24 Cups ID: 259261

seconds etching minutes surface etching seconds surface minutes acid clean rinse td24 water machining cups time gallons surfaces cold

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Slide1

Surface Treatment Issues for RF Structure Fabrication

Juwen

Wang

SLAC National Accelerator Laboratory

X-Band Accelerating Structure Review

November, 2014, CERN

Slide2

2

Outline

Etching

Tests Revisit and Discussion

Etching Time Studies Using TD24 Cups

Chemical

Treatment Procedure Slide3

3

Done by R. Kirby, C. Pearson and F.

Pimpec

in 2002.

Etching Tests Revisit and DiscussionSlide4

4

Microbalance ResultsSlide5

5

Etch Rate vs. Etch HistorySlide6

6

Single-Crystal Diamond Machining

5 seconds

metallographic

image reveals grains;

10 seconds optical shows grain edges developing;

5 – 10 seconds etching is proper. Slide7

7

Polycrystalline Diamond

Machining

60 seconds

mettallographic

image reveals grains;

60 -120 seconds optical shows grain edges developing;

45 seconds or little more etching is proper. Slide8

8

Surface Roughness

after Different Etching TimeSlide9

9

Discussion on Amount of Etching

The amount of etching required depends very much on the condition of the machined surface. 

A single crystal diamond turned axis-symmetric surface only need the slightest etching.  Its purpose may only be to assist in removing light residues of machining fluids and other light contamination.  

Conventionally machined surfaces by a polycrystalline tool or cells with milling operations, need to be etched more heavily.  In this case the purpose of the etching will be to remove burrs, to etch sufficient material to remove embedded particulates or entrained fluids.Slide10

10

Discussion on Surface Roughness Change

Etching and firing the diamond turned surfaces will slightly degrade the surface due to revelation of grain boundaries and the possible creation of etch pits. 

The converse is true for conventionally machined surfaces with >8 micro-inch finishes.  The rougher finishes benefit from etching due the preferential removal of sharp or protruding features, and benefit from firing due to the smoothing effects of

recrystallization

and surface diffusion. Slide11

11

2. Etching

Time Studies Using TD24 CupsSlide12

12

2. Etching

Time Studies Using TD24 Cups

30 seconds etching time was experimentally decidedSlide13

13

Four TD24 cups were chemical etched for 30-second or 60-second, then followed with SEM studies:

14R20C: SEM, 60-second etching 11/18, SEM, chemical cleaning 12/2, SEM

14R21B: 30-second etching 11/22, SEM

14R22B: 30-second etching 12/2, SEM

14R23B: 60-second etching 12/2, SEM

30-second etching could completely remove all burrs and large machining defects.

60-second etching produce too deep and too much etching pits.

Some contaminations and residues are created and remained on the surface after chemical cleaning procedure, we believe most of them would be burnt out in the heating processes in hydrogen furnaces.

2. Etching

Time Studies Using TD24 CupsSlide14

14

TD24 Structure Assembly

I’d like to confirm the time of heavier etching for TD24 Cups. 30 seconds? Slide15

15

TD24 Cups before Etching

Machining burrs

Machining burrs

Rough machining surfaces

ParticlesSlide16

16

After 30 Seconds EtchingSlide17

17

After 60 Seconds EtchingSlide18

18

For accelerator structure parts with single diamond tuning surfaces:

Vapor degrease in 1,1,1

trichloroethane

or equivalent degreaser for 5 minutes.

Alkaline soak clean in

Enbond

Q527 for 5 minutes at 180ºF.

Cold tap water rinse for 2 minutes.

Immense in 50% hydrochloric acid at room temperature for 1 minutes.

Cold tap water rinse for 1 minute.

Immense in the following solution for maximum of

5 seconds

depending on the surface finish required:

Phosphoric Acid, 75% 21 gallons

Nitric Acid, 42º Baume 7 gallons

Acetic Acid, Glacial 2 gallons

Hydrochloric Acid 12.6 fluid ounces

Temperature Room

7. Cold tap water rinse for minimum of 2 minutes until the film on part disappears.

Ultrasonic in DI Water for 1 minute.

Ultrasonic in new, clean alcohol for 1 minute.

Final Rinse to be done in new, clean alcohol.

Hold in clean alcohol in stainless steel containers.

Dry in a clean room using filtered N2.

For accelerator structure parts with regular machining surfaces:

6. Immense in the following solution for maximum of

30-60 seconds

depending on the surface finish required:

3. Chemical Treatment ProcedureSlide19

19

Vapor degrease in 1,1,1

perculoroethylene

or equivalent degreaser for 5 minutes.

(Now in use)Slide20

20

2. Alkaline soak clean in Enprep 527 for 5 minutes at 180

ºF.Slide21

21

3. Cold tap water rinse for 2 minutes.Slide22

22

4. Immense in 50% hydrochloric acid at room temperature for 1 minutes.Slide23

23

5. Cold tap water rinse for 1 minute.Slide24

24

6. Immense in the following solution for maximum of

5 seconds

depending on the surface finish required:

Phosphoric Acid, 75% 21 gallons

Nitric Acid, 42º Baume 7 gallons

Acetic Acid, Glacial 2 gallons

Hydrochloric Acid 12.6 fluid ounces

Temperature RoomSlide25

25

7. Cold tap water rinse for minimum of 2 minutes until the film on part disappears.Slide26

26

8. Ultrasonic in DI Water for 1 minute. Slide27

27

9.

Ultrasonic in new, clean alcohol for 1

minute, then final rinse and storage in stainless container.Slide28

28

11. Hold in clean alcohol in stainless steel containers. Slide29

29

Ready to ship for brazing or diffusion Bonding Slide30

30

12. Dry in a clean room using filtered N

2

Slide31

31

Ready to

move to furnace area