Parts are surface hardened in this process. The furnace consists of a vacuum chamber in which a workload is suspended. Surface hardening takes place in the plasma of a current-intensive glow discharge. A regulated voltage is applied between the chamber and workpiece in a vacuum, producing the ionized ionitriding/carburizing plasma. The ground chamber well forms the anode, and the work-piece becomes the cathode.

After evacuation of air, a reaction gas (a nitrogen-hydrogen mixture in the case of nitriding, and a gas such as methane is the source of carbon for carburizing) is introduced, and a voltage is applied between the anode and cathode to start the corona discharge. The reaction gas is ionized in the corona discharge, causing the nitrogen gas (in nitriding) to accelerate toward the workpiece where the impingement cleans and depassivates the surface. Part of the kinetic energy is converted into thermal energy that heats the work uniformly. Nitrogen ions, (in nitriding) react at the surface of the work,forming iron and alloy nitrides that increase resistance to wear, surface hardness, and fatigue strength. Treatment time varies form 20 min to 36 h, heating and cooling rates can be controlled, providing good structural stability and minimum distortion of parts. 

Heat Treating Applications:

• Nitriding i.e. extrusions and D2 tool steel
• Carburizing of steel

Advantages:

• Heating and cooling rates are controlled
• Case depths are uniform
• Surfaces are hard, resistant to wear and fatigue
• Environmentally clean process
• Minimum distortion of parts
• Low operating costs