Deposition of molybdenum nitride thin layers on substrates of stainless steel AISI304 using a Mather-type of plasma focus device

This study focuses on effects of number of shots and the distance from the top of anode on Mo-N deposition process on the surfaces of AISI304 samples using a low energy (2.8 kJ) plasma focus device (AECS PF-1) at room temperature. The structural, morphological, elemental composition, surface roughness and micro-hardness properties of treated surfaces were investigated versus the number of shots and the axial distance from the anode. The obtained XRD spectra show that some of the treated surfaces were in crystalline phase with gamma-Mo2N (FCC) structure (at 3 cm with 10- 40 shots and at 5 cm with 30 and 40 shots) and some others had amorphous structure at 5 cm with 10 and 20 shots and at 7 cm with 10-40 shots. SEM images indicate that the thermal effect occurred at 3 cm and the deposition process of Mo-N at 5 cm and 7 cm from the anode with an increase in number of shots. The atomic ratio for nitrogen was 10.62%, 12.88%, and for molybdenum it was 0.23%, 3.36% at 3 cm, respectively. The atomic ratio for nitrogen has achieved 14.95% and 22.17%, however, the atomic ratio for molybdenum was 2.11% and 7.17 % at 5 cm, respectively. The surface roughness and size of grains on the surface of deposited layers were investigated by AFM analysis. Furthermore, the variation in the micro-hardness of the Mo-N thin layers deposited by different number of shots at different distances from the tip of anode was explained, qualitatively, on the basis of morphological characteristics of the thin layers. The decreasing rates of hardness in the case of 10 shots were 146%, 117% and 112%, and at 40 shots were 237%, 149% and 141% with the increasing of distances 3, 5 and 7 cm, respectively.