Liquid nitriding is a subcritical surface enhancement process with one of the longest track records of success of any case hardening technology.
PVD coatings involve the deposition of thin (2-10 microns; 0.0001" – 0.0004") films on the surface of tools and components.
Liquid nitriding is a subcritical surface enhancement process with one of the longest track records of success of any case hardening technology. It is widely used to enhance the wear and corrosion resistance of plain carbon steels; low alloy steels; and stainless steels.
In a liquid nitriding bath which is maintained between 500 - 630°C (930 - 1165°F), nitrogen-bearing salts produce a controlled and highly uniform release of nitrogen at the surface of the workpiece. Nitrogen diffuses into, and chemically combines with, nitride-forming elements in the metal, producing, through a catalytic reaction, a tough, ductile compound layer with exceptional mechanical properties. This hard compound layer has wear properties that are 200% to 1000% greater than the original material, and greatly enhanced resistance to corrosion, galling and scuffing. Below the compound zone is another distinctive region, the diffusion zone. This zone results from the progressive diffusion of nitrogen and the formation of a solid solution of nitrogen in the base material. The diffusion zone contributes a critical fourth benefit of salt bath nitriding: substantial enhancement of fatigue strength, typically 20% to 100%.
After Nitriding, the surface can be oxidized to create a 1-3 μm corrosion resistant, black iron-oxide layer