Clipped name for molybdenum coatings, flame-sprayed from wire or plasma-sprayed from powder. Moly bonds well to clean steel, holds oil in its fine porosity and resists scuffing, so it is the classic coating for piston rings, synchronizer rings and shift forks, as well as a bond coat. It oxidizes readily above about 400 °C in air, which limits hot service.
Heard on the job
Synchro rings go through moly on the wire gun, eight passes, then off to the lathe.
Also heard as
- molybdenum
- moly coat
Related terms
Flame spray
The simplest thermal spray process: powder or wire melted in an oxy-fuel flame and blown onto the part.
Bond coat
The first layer sprayed on a substrate to help the following coat stick and sometimes protect the metal.
Nickel aluminum
Nickel-aluminum composite that reacts in the flame to give a strongly bonded first layer.