Plasma characterization for nitridation of aluminium alloy using 50 Hz ac discharge

Abstract

A 50 Hz ac abnormal glow discharge is characterized as a function of filling pressure (1-4 mbar) using a Langmuir probe. It is found that electron temperature, electron density and electron energy distribution function decrease with the gas filling pressure. Nitriding of aluminum alloy (Al−Mg 2 −Si) is performed for various time durations (3, 6, 9 and 12 h) and pressures (1 and 2 mbar) by keeping the input power (100 W) and substrate temperature (250 • C) constant. To explore the surface properties induced by plasma, X-ray diffractometer, optical micrography, atomic force microscopy and Vickers micro-hardness tester diagnostic techniques are used. Results exhibit the formation of cubic aluminum nitride. A significant increase in surface hardness is observed when samples are exposed at 1 mbar pressure for 12 h of processing time. A rapid decrease in surface hardness values with the imposed load suggests the formation of a thin modified surface layer.

Nitriding molybdenum: Effects of duration and fill gas pressure when using 100-Hz pulse DC discharge technique

“…Nitriding for longer durations supplies more nitrogen and results in the formation of more molybdenum nitride and hence denser layers, resulting in enhanced packing density. [27] Hence it is concluded that the nitrogen supply to the modified surface layer of molybdenum is enhanced with increased nitriding time, due to which molybdenum nitride concentration at the surface is enhanced, resulting in the formation of more compact pore-free films for longer nitriding (10 h) duration. Figures 6(a)-6(c) show the surface morphology of the plasma-nitrided specimens for 2 mbar and 3 mbar fill gas pressures.…”

Nitriding of Aluminium Alloy in Nitrogen and Nitrogen-Helium Mixture Using 100 Hz-Pulsed DC Glow Discharge

“…The thickness of nitride layer is approximately 4 µm for a treating duration of 4 h, and increases to 14 µm for a nitriding treatment of 12 h. At a helium concentration of 40%, the thickness of nitride layer is 11.2 µm and at a helium concentration of 50% it is about 12 µm. It is found that the growth of nitride layer takes place mainly by the diffusion of nitrogen [55] .…”