Plasma nitriding

Plasma nitriding is a thermo chemical heat treatment process and is carried out at temperatures of between 350 and 600 °C. Positively charged ions strike the workpiece – connected as a cathode – at high impact speed in front of the furnace wall (anode). Initially this ion bombardment causes an intensive cleaning of the workpiece surface (sputtering), which subsequently results in a heating up and nitridation of the surface. The parts are then cooled down to the withdrawal temperature. Today, nitriding is carried out almost exclusively in direct current and in pulsed plasma.

The principle advantages of the process include an improvement in the friction and sliding characteristics, the generation of corrosion-resistant layers and the minimisation of distortion. Generally, plasma nitriding is only carried out on completed parts, which require no further mechanical production processing after this them chemical heat treatment, such as grinding for example. Due to the increased process assurance it has been possible to develop plasma nitriding into an economical and technically significant surface hardening process for the metalworking industry.

Plasma nitriding usually takes place in shaft or bell furnaces, which can be integrated into the production line due to process automation and environmental compatibility. Due to the fact that extremely powerful power supplies are now available, there are no limits with respect to part size.

It is possible to employ plasma nitriding with all commercially available steel, cast and sintered materials. Unalloyed, low and high-alloyed steels are all suitable materials.