At 06:18 PM 8/24/2002 -0700, you wrote: >However, cast iron is >>tribologically<< very compatible >with cast iron, ... > > >OK, I'll bite. What does that word mean in reference to metal? Means that the two materials "get along" well when rubbed against each other, with low friction and low wear. Usually, similar materials do not get along too well when rubbed with each other. For example, aluminum rubbed against aluminum usually causes galling, shavings, and even seizure. Chrome is compatible with many metals, that's why surfaces of machine parts are often chrome plated (talking about hard industrial chrome here like the chrome on piston rings, not decorative chrome). However, chrome is incompatible with chrome, so often only one of the mating surfaces is plated. D^2