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Jon Paul Johnson’s Montage Ductile Iron Images

Jon Paul Johnson’s Montage Ductile Iron Images. Technical Objective. To train you to use the electron microscopes on lower campus Start with the Leo 440i We control it! It’s currently running

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Jon Paul Johnson’s Montage Ductile Iron Images

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  1. Jon Paul Johnson’s MontageDuctile Iron Images

  2. Technical Objective • To train you to use the electron microscopes on lower campus • Start with the Leo 440i • We control it! • It’s currently running • Once you have learned the concepts on one microscope, in principle everything else is “knobololy” (Figuring out where the knobs are that control the feature you want to use.)‏ • It’s not easy or expensive to break (please don’t prove me wrong!)‏

  3. Electron gun “Upper Valve” Vac-ion Pump 10-6—10-8 Torr Column Pumping system for Leo W-filament SEM (actually LaB6)‏ Column Valve Chamber Exhaust Penning gage Oil Filter Sample Stage Oil-sealed Rotary Mechanical Pump Turbo-molecular pump 760—10-3 Torr 10-3—10-7 Torr

  4. Upper valve Electron gun Column Chamber valve Aperture adjustment micrometers Turbomolecular pump behind here Leo 440i SEM

  5. Gun Vac-ion pump Everhard-Thornley Detector Leo SEM: rear of column

  6. LN2 tank Beam blanker EDS side of SEM

  7. Oil-sealed rotary mechanical pump

  8. Administrative matters • Nothing in life is free • Log onto the SEM with the sheet on the desktop • Enter your name • Enter the name and contact information of whoever will be paying • Record how many times you coated samples • Click on “View/Status”. Enter the filament lifetime when you start. • Enter the time of day when you start. • Repeat the last two steps when you finish.

  9. Notes on the computer • The SEM is about 15 years old. It runs on a 66 MHz 486 under Windows 3.11. • Plan on having to reboot at least once per day. • In windows 3.11 you cycle among active applications with ALT TAB. (Hold down ALT; every time you hit TAB, it cycles one application.)‏

  10. Getting started with the Leo • Typical conditions when you walk in: • Ion pump is running • Chamber is under vacuum • “Upper valve” (gun valve) is closed • Column valve is open • All pumps are running

  11. Sample Mounting • Leo uses mounting stubs with 1/8” shafts • Carbon tape (double sticky) is simplest • Carbon dots have lower vapor pressure • Multiple samples can be mounted on turret • Make a drawing in your research notebook of the locations of your samples on the turret • Single mount is easiest for tilting • Vertical mount is also an option • Tighten gently with Allen wrench; ditto for sample holder on stage

  12. To insert your sample • Check vacuum • Stage/vac • Vacuum status • Chamber pressure should be 10-5 – 10-6 Torr • Column pressure should be few x 10-7 Torr • Close column valve • Vent (Stage/vac, Specimen change or right yellow arrow)‏ • Insert sample. Remember where samples are! • Close and latch door. Do not overtighten! • Pump (Stage/vac, Specimen change or right yellow arrow)‏ • After the pressure goes below 10-4 Torr you may open the column valve and turn on the beam.

  13. Left mouse button Middle mouse button Beam on Beam off Standby Pump Vent Vacuum control Drop Down List Box and Tool Bar(nearly all SEM functions are mouse-controlled)‏ Alternatively, double click on a box to enter data directly Roll mouse left to decrease value Roll mouse right to increase value

  14. Go! • Turn on beam • Turn up brightness • Hopefully you will see something • Optimize beam • Backup plan • If you fail to get an image, under File/(run) Standard! These are factory-installed parameters

  15. Decide on operating parameters • 40 kV for highest resolution • 20 kV for EDX • Low voltage for optimum topography and least damage • 100 pA for good resolution • 300 pA for EDX for better signal-to-noise • 25 mm WD for EDX • 7 – 8 mm WD for maximum resolution

  16. Center of Stage (Red square)‏ Stage will move in direction of arrow when left mouse button is depressed Speed increases with distance cursor is from beam Beam location (Blue square)‏ Cursor!

  17. OptiBeam on Use when OptiBeam is off

  18. Filiment Gun tilt lens lens aperature lens Pictoral explanation of gun shift With the gun shift centered, the electron beam heads straight down the column. The image is brighter and can also be focused better. Otherwise the image moves when you change focus.

  19. Center filament image with “Tilt” option

  20. Adjust beam shift when OptiBeam is turned on

  21. Voila! An image!

  22. Optimize image • Start with low magnification • Look for dirt or some large feature • Move feature to center of screen • Go to reduced raster…Why? • Focus • Increase magnification…preferably 2-5X what you will use for the image you record. Why? • Focus • Iterate • Full screen image

  23. Saving an image • Get good quality image • 2 minute scans over a few kX • Faster scans at lower magnification • Under “Image/Noise reduction”, click on “Freeze at end”

  24. Saving images, cont’d • Under “File/Export tiff”, choose e:\ as the destination. The E:\ drive is mapped to the support PC that is next to the machine. From this machine you can use a USB memory stick or transfer files through the internet-- web mail or file transfer. • Enter a filename: 6 characters (related to your sample) + 2-digit counter (00)‏ • All students need to bring their own USB stick; files are approximately 1 MB

  25. Check “Export/Photo setup” to assure it is not set to “HRRU”!

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