Graphite as a corrosion inhibitor 1

[myredrocket7]

Has anyone ever heard of adding a small quantity of graphite to an automotive cooling system to inhibit corrosion?
I've found the attached link, but can find no other references to the practice anywhere.
Does it make sense that a light deposit on the various metals in the engine block might neutralize the electrical potential between them?

http://www.malibuwater.com/graphite.html

 

[romke]

there is a type of corrosion called "graphitizing" - where cast iron parts loose some of their C contained in the metal structure and then become brittle. In those circumstances it is thought that a suitable coating might retard the proces - perhaps a certain amount of graphite (C!) might prevent the graphite contained in the cast iron dissolving in the surrounding coolant.

in the past graphitizing of cilinders was rather common in larger bore engines, but now it seems to occur very seldom, perhaps due to improved materials and/or casting techniques.

i must say i have come across this phenomenon in big engines in the past 30 years ago, but never saw it in automotive engines.

coating of coolant parts has been used though for other purposes like preventing caviation erosion. a small amount of emulsifiable oil in the coolant would be able to stop or retard the process - but here also due to better coolants and metals the probelems seem to have disappered nowadays.

 

[NickE]

Whoa.... I've never seen graphitization being described as corrosion.... From what I know its due to the movement of carbon atoms at higher temperatures in steels.

In grey cast iron the carbon primarily forms as interconnected 3D flake shapes, this carbon is exposed on all cut surfaces and is the primary reason for the use of this material.

I dont see how graphite will prevent corrosion in modern engines. In fact if IIRC graphite and Aluminium form a great (horrible) corrosion couple.

Nick