Plasma nitriding in which parts are made the cathode in a low-pressure nitrogen-hydrogen gas and a high-voltage glow discharge ionizes the gas, heats the surface and drives nitrogen in. Adjusting the gas mix lets operators eliminate or tailor the white layer, and areas can be masked with simple steel covers. Stainless steels nitride readily because the plasma sputters away their chromium oxide film.
Send the extrusion dies out for ion nitriding with no white layer, the last batch spalled at the corners.
Also heard as
- plasma nitriding
- glow discharge nitriding
- ion nitride
Related terms
Nitriding
Diffusing nitrogen into steel below its critical temperature to form a hard case with no quench.
White layer
The thin, hard compound layer of iron nitrides that forms on the surface during nitriding.
Stop-off
A paint, paste or plating applied to areas of a part that must not carburize or nitride.
FNC
Ferritic nitrocarburizing: adding nitrogen and carbon below the critical temperature for a thin, hard layer.