Graphite Purification Procedure

1. Clean graphite foils and discs with ethanol and kimwipes
   
   1. Keep cleaned disks and foils protected with kimwipes at all times.
2. Clean “fork” with ethanol and kimwipes, (should be underneath oven).
3. Insert disks and foils into oven (maximum of 6).
   
   1. Make sure to alternate disks and foils; there should be 2 foils for every 1 disk.
   2. Place them close together but not touching, do NOT go too far into oven.

    

   3.  
4. Clean end cap with ethanol and kimwipes.
5. Check mechanical pump for sufficient oil and if plugged in
   
   1. Be sure it smells and sounds like it is running properly.

    

   2.  
6. Make sure the end of the quartz tube is clean and apply a very small amount of vacuum grease to the O-Ring.

 

7.  
8. Be sure ALL valves on ALL gas lines are closed.
9. While one person is holding the end cap on the end of the quartz tube, another person should VERY slowly turn the valve labeled “pump” from closed to open.

 

10.  
11. Place mesh casing around quartz tube and thermometer in cable tie of end caps.
12. Wait until the vacuum is well below 1000 millitorr on both thermocouple gauges.

 

13.  
14. Put all fans in position and turn them on high.
15. Turn the power switch on the oven to the on position.
    
    1. Wait until the temperature on all three displays appears.
    2. Hold in the blue buttons labeled “set” until “PrG” appears in red.
    3. Push the run button (down arrow) until “-1” appears in green.
    4. Press the set button until “SSP” appears in red (7 times), be sure desired temperature is set using arrow buttons.
    5. Press the set button twice more until “En-1” appears, and set the desired run time in green using the arrows. This time should be at least 45 minutes longer than the actual bake-out time for that particular disk set. The oven’s timer begins when the oven starts to heat up, but we usually want to run for a particular time at exactly 1000°C.
       1. The optimal bake time is generally 1 hour.
    6. Hold the set button in until the temperature appears on the display again.
    7. Hold the run button in until the run light appears.
    8. Repeat b through h for all three displays.
    9. Make sure that a timer is set for the proper temperature once the oven reaches that desired temperature.

     

    10.  
16. Refresh on all fire safety precautions, (refer to poster on wall above computer).
17. Let oven run for desired time while monitoring thermometers and thermocouple gauges, (this is VERY important!!)
18. External temperature readings should NOT exceed:
19. Thermometers :

    T1, T2, T3 à 70C

          T4 (rubber tube) à 50C

          T5 (glass)à 140C

          T6 (end cap)à 70C

     Thermocouples:

          V1, V2à 1000millitorr

     *If temperature or pressure exceeds limits contact student in charge and then Dr. Padalino immediately.

20. When time is up, turn power switch off.
21. Wait until the oven reaches room temperature (about 20°C). You can check the temperature of the oven simply by turning the power switch back on.)
22. Remove temperature probe and mesh casing from end of quartz tube.
23. While HOLDING end cap securely have someone turn “pump” valve from open to closed. (Remember end cap is heavy and may take time to pop off, be ready.)
24. Have large Ziploc bag and large O-ring ready (must be clean) to immediately cover quartz tube when end cap comes off.
25. Turn large valve on Argon tank to “open.”
    
    1. Twist skinny bar tighter (this actually opens it).
    2. Open small black valve.
    3. Slowly open knob labeled “Ar” on front panel. The end cap should come off at this time.
    4. Be sure the Ziploc bag at end of quartz tube is on with O-ring and is slightly bulging so that you can feel the Argon pressure.
    5. Wait the specified amount of time for backfilling.
       1. The optimal bake time is generally 1 hour.

     

    6.  
26. When done backfilling attach glove bag to end of quartz tube using cable ties (glove bag must be previously prepared with hole to fit over tube end). 
27. Squeeze as much air as possible out of glove bag.
28. Make sure the other end of the glove bag is sealed with plastic clasps.
29. Turn Argon up slightly.
30. From inside glove bag remove Ziploc bag and O-Ring, allow glove bag to fill up with Argon (about 2/3 full).
31. Clean fork, aluminum clip and vacuum bags with ethanol and kimwipes.
32. Create small hole in end of glove bag between plastic squeezers for fork and vacuum bags.
33. Insert clean fork, aluminum clip and vacuum bags into glove bag (1 bag per disk set).
34. Extract disks and insert into vacuum bags, all within the glove bag.
    
    1. (Disk sets consist of foil, disk, foil; stacked in that order.)
35. Place circular holder on disk set completely so all the slack of the vacuum bag is at the back of the disk set.
36. Clip the bag shut with the aluminum clip.
37. Slide the clipped vacuum bag out of the small opening in the glove bag and IMMEDIATELY seal with the vacuum sealer.
38. Remove circular holder and place in glove bag to be used for other disk sets.
39. When all disks are removed along with foils and every bag is properly sealed, close all valves and turn off the oven.
40. Remove the glove bag from the end and replace with large Ziploc bag and O-Ring again.
41. Be sure each vacuum bag is properly labeled.
42. Make Argon bubbles for each vacuum bag.
43. Be sure each bubble is properly labeled.

 

44.