OXIDE STEEL? 2

[DISH]

Does anyone out there know the speciality about black oxide-steel? one of out suppliers speccified this on a shaft collar, but i don't know exactly what is special about this type of steel.

 

[TVP]

Black oxide refers to a coating on the steel, not the steel alloy. This is a common coating used for protecting steel components from corrosion in atmospheric environments. The oxide is black because it is Fe₃O₄ not the more common red rust, Fe₂O₃.

 

[kenvlach]

See
'Black Oxide Coating Specification'
thread723-56683
for discussion of the AMS specification (AMS 2485).
The coating gives some wear and corrosion resistance, chiefly as the result of lubricant that adheres to the oxide surface.

From MIL-DTL-13924D “Only very limited corrosion protection, under mildly corrosive conditions, is obtained as a result of black oxide coating.”
The MIL spec. is a free download at

http://assist2.daps.dla.mil/quicksearch/