Plasma nitriding

Technique for hardening metals, notably steel. The part is connected to the cathode and exposed to a nitrogen/hydrogen plasma at high temperature. The first reaction is the removal of the layer of oxide, then the atoms of nitrogen penetrate into the structure of the metal – near to the surface – the result being to increase the hardness. Furthermore, friction is reduced and resistance to corrosion is increased. Other than steel, aluminium and titanium can be nitrided.