What is Diffox?

When good sliding wear resistance combined with good corrosion resistance is required, Diffox is the answer. Diffox is also a diffusion process hence there is no danger of delamination as found with coatings such chrome plating or nickel plating.

The process starts with the Specialized Nitriding cycle, followed by a surface oxide conversion. This oxide imparts several important properties such as: 

  • improved corrosion resistance
  • improved wear resistance
  • an attractive black appearance


Diffox is a surface conversion rather than a coating and therefore it is integral with the material surface. Conventional nitriding does not allow the diffusion depth and white layer to be optimized, however our Diffox coating does exactly that. It provides an optimal surface for the specific application, plus the added benefit of the surface sealing oxide that enhances the corrosion resistance.

Corrosion Resistance

Diffox can provide En19 with salt spray corrosion resistance of more than 200 hrs. On low alloy steels, red corrosion will show only after ± 400 hrs in salt spray testing.


  • High resistance to seizing and scuffing
  • High resistance to corrosion
  • High resistance to fatigue
  • High resistance to wear
  • Insignificant or minimal distortion/size change
  • Good retention of lubrication

What can Diffox be applied to?

Diffox is suitable for a wide variety of carbon steels, low alloy steels and even cast irons. Because it is a medium temperature process, part distortion is reduced provided the initial heat treatment and tempering has been done correctly. Correct heat treatment will avoid unexpected size changes and hardness changes in the base metal. Please enquire with us about this. 

Typical applications:

  • Shafts 
  • Hinges and Pins
  • Actuator rods and hydraulic shafts
  • Rock drill components
  • Gears and Cams
  • Valves, crankshafts, tappets, stops
  • Wear plates and sliding mechanisms