The black oxide process is a very cost effective way to protect small parts like nuts, bolts and brackets from rusting. Every automobile manufacturer uses this process on their vehicles. It is a very simple process that anyone can do. The Eastwood Company sells a kit for $40, and includes everything you will need.
Start with your rusty or dirty parts.
Clean them up, sandblasting is the best method.
Dip the parts into the Blackening solution for approximately 30 seconds.
Rinse parts of with water (Distilled water recommended)
Dip parts in Sealant for 2-3 minutes, shake off excess.
Let parts dry, usually overnight.
That's all there is to it, now your parts will be permanently protected from rust and look great as well.