Effective nitriding of steels outside low-pressure microwave discharges

This paper reports on nitriding of low-alloy steel samples which are placed outside the plasma and exposed only to the effect of activated nitriding gas diffusing from a low-pressure microwave discharge with electron cyclotron resonance (ECR). It is shown that efficiency of nitriding of the samples located inside the discharge (i.e. at a standard distance d=250 mm from the output aperture of the ECR source) and practically outside the plasma of microwave discharge (i.e. at a large distance d=750 mm) is almost the same when 30% of hydrogen is added into the nitrogen hydrogen gas mixture and the pressure is decreased to 0.15 Pa. This finding is of principal importance because it enables to develop a new generation of nitriding devices.