Anodizing Aluminum

1. Polish samples to required specifications.
2. Create connection point for samples to allow a current to flow.
   • For mounted and puck-shaped samples, drill a hole through the mounting material from the back to the metal. Thread the hole and insert a headless screw of appropriate size into the hole. This creates a connection point through the non-conductive material. Puck shaped only need to have a small hole for the threaded screw to go in.
   • For non-mounted, make sure there is a point on the sample that can easily be clamped into with the cable clamps. If there isn’t, follow the previous instructions for puck/mounted samples.
3. Collect glass beaker, power supply, anodizing solution, and cathode.
   • Cathode used by MTU was Platinum plated Stainless Steel wire mesh tube
   • 1.25% concentration Barker’s Reagent (HBF4) used for solution for aluminum alloys
   • At this point, it is best to put on gloves to ensure the safety of the user. Most solutions used for anodizing are acids. Keeps gloves on for rest of procedure .
4. Place components in fume hood and turn on.
5. Plug in power supply
6. Pour solution into breaker; enough to almost completely submerge cathode cage.
7. Connect cathode to positive end of power supply with clamp and cord. Put cathode in beaker with solution
8. Flip power switch for power supply and adjust voltage using coarse and fine dials to between 20 and 30 volts, or about 30 milliamps per cm. Turn off power after adjustments are made.
9. Connect sample to negative end.
10. Partially submerge sample in the solution. Sample should be in the middle of the cathode cage.
    • Do not let solution touch the screw or clamp connected to the negative end. This will cause the current to flow improperly and decrease the quality of the anodization.
11. Turn on power supply and keep on for a very short amount of time. Once time of anodization is reached, IMMEDIATELY turn off power supply.
    • 6082 Aluminum alloy was run for only 15 seconds.
12. Take sample out of solution and rinse under cold water.
13. Spray with squirt bottle of ethanol and evaporate ethanol with hair dryer.
14. Sample surface should have a pearl-like sheen on it. If sample is over/under anodized, re-polish sample with last grit used (0.5 micron colloidal silica in Hydro group’s samples). This removes the anodized layer, allowing for re-anodization with adjusted parameters/times.