Typically you'll find things like Cor-ban (and its even nastier predecessor Mastinox) used in places where you're going to get a lot of moisture exposure and otherwise have really corrosive environments, and the items in question are things that need to be able to come apart again. These compounds don't harden like sealants do so you are able to undo the sealed items.
On large aircraft you'll see it used on bolts, nuts, etc. on major landing gear fittings, like the giant castle nut that holds the wheels on or the bolts that retain the trunnion pins. You might also see it on the hardware at control surface hinges. It keeps the threaded parts from seizing and keeps water from seeping into the separable joints and corroding things there.
On a small aircraft you're probably better off just using a good thick grease at such locations, and keeping your aircraft hangared. Most of us aren't typically going to be flying in poor, icy weather with lots of deicing fluid.
Now, if you want to fay seal steel vs. aluminum in a permanent joint, you could just use a little leftover fuel tank sealant--it won't hurt anything. There's a similar sealant (MIL-PRF-81733, aka PS 870) that's more corrosion inhibitive but for our purposes tank sealant will keep the water out and that's good enough.
EXCEPTION: Don't use any of these on fluid connections (fuel, brakes, etc.). Only use proper sealants there!
TLDR: If you want to use something, use grease on separable joints and tank sealant on permanent joints. Cor-ban and similar stuff is expensive and nasty.