Oxynitriding / Oxynitrocarburizing Onc

In-process post-nitriding/nitrocarburizing oxidation

When resistance to atmospheric corrosion and an attractive black finish are the main requirements, ONC® is the best technology.

Oxynitriding/oxynitrocarburizing transforms the very top portion of the white layer obtained with either Nitreg® or Nitreg®-C technologies into a complex spinel type structure consisting mostly of Fe3O4 type of iron oxide. As a result, the post-nitriding oxidation treatment has a net effect of enhancing the corrosion resistance of an already nitrided component. This integrated process (i.e. Nitreg® + ONC® or Nitreg®-C + ONC®) simultaneously enhances corrosion and wear resistance of steel, while giving the surface an attractive dark or black appearance, expressly desired by many customers.

ONC® is a clean technology that, in many instances, can replace chrome plating and salt bath nitriding which may involve pollution and cost challenges. Depending on the type of steel, parts treated with the Nitreg® + ONC processes can easily pass well over 200 hours of salt-spray test per ASTM B117 before a corrosion spot appears.


  • Improves corrosion resistance
  • Imparts an attractive black surface finish
  • Enhances inherent wear resistance