anodizing

so my boss and I were talking about materials that were electrically insulating, didn't outgas in vacuum, and could be machined with typical high speed steel tools. The best solution we came up with was anodized aluminium. (Anodized aluminium is aluminium on which an oxide has been grown. Aluminium oxide is much harder than aluminium and also a much better insulator.)

I had wanted to learn to anodize so that I could manufacture aluminium bicycle parts, like aluminium axles. My boss thought it would take me a few days to learn to anodize, but I bet him all the change in our pockets-$1.50 each- I could do it before the end of the day. I did some reading, and got a trial going. Things seemed to be going well, but then I got impatient and really turned up the current. Not sure what happened, but the signs of well going eventually vanished (the voltage to current ratio eventually began decreasing). This part did not get anodized. I decided that either there was too much turbulence from the gasses being evolved, the cathode was not a good material to use, or the temperature was getting too high. As such I got a new cathode, and I turned the power down a bit, and things actually worked. Who knew. Next I'd like to master controlling the properties of the anodization coating that is form. I think I won the bet, but my boss was gone.
Perhaps someday I'll tell the story about how my boss bet I couldn't solder to aluminium.