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White Layer in Plasma Nitriding: What It Is and Why It Matters

  • Writer: redesiht
    redesiht
  • Jun 10
  • 1 min read

Microhardness profile of a plasma-nitrided surface, showing the white layer, diffusion zone, and hardness gradient.
Microhardness profile of a plasma-nitrided component. The image highlights the white layer and diffusion zone, with Vickers indents marking hardness measurements at different depths.

White layer is the outermost layer, with a maximum thickness of 25 micrometers (0.025 microns), rich in iron nitrides (Fe₄N and Fe₃N). It is characterized by:

  • High surface hardness: Significantly higher than the core material.

  • Wear resistance: Excellent resistance to abrasive and adhesive wear, especially the latter.

  • Potential brittleness: It may be more brittle compared to the diffusion zone.


Beneath the White Layer, there's a layer up to 0.7 mm thick, known as the Diffusion Zone, characterized by the presence of nitrogen diffused into the metallic matrix.

  • Maintains the hardness of the base material with improved wear characteristics.

  • Hardness decreases gradually from the white layer to the core.

  • Fatigue resistance: Enhanced due to the compressive stresses induced by nitrogen.




📊 Download infographic: Unveiling the Compound Zone (White Layer)

📊 Related resource: Reactions that occur at the surface of the part during Plasma Nitriding

📊 Related resource: White Layer, asset or liability?


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