2016 Volume 65 Issue 7 Pages 517-524
The S-phases (γN-phases) of SUS304 steel were prepared using direct current plasma nitriding (DCPN) and active screen plasma nitriding (ASPN). Furthermore, diamond-like carbon (DLC) films on these S-phases were prepared using plasma chemical vapor deposition (PCVD). The nitride layers included the γ'Fe4N phase. The X-ray stress constant K of the nitride layers were evaluated using γN (200)+γ'Fe4N(200) diffraction with CrKα characteristic X-rays. The γN (200)+γ'Fe4N(200) diffraction angle 2θ of DCPN powder and ASPN powder were 73.49° and 72.98°, respectively. The X-ray stress constants of the γN (200)+γ'Fe4N(200) phase nitrided using DCPN and ASPN, E / (1+ν) , were 202 GPa and 153 GPa, respectively. The X-ray stress constant K of the γN (200)+γ'Fe4N(200) phase nitrided using DCPN and ASPN were -2,365 MPa/deg and -1,809 MPa/deg, respectively. The X-ray residual stress of these S-phases prepared using DCPN and ASPN were approximately -5.3 GPa and -2.6 GPa, respectively. On the other hand, Raman microprobe spectroscopy was used for residual stress measurements of the DLC films deposited on these S-phases. The Raman spectra of the DLC films were classified into the disorder (D') peak at 1,150 cm-1, D peak, and graphite (G) peak. The residual stresses in the DLC films on these S-phases as estimated from the Raman shift of the G peak for DCPN and ASPN were -3.2 GPa and -3.0 GPa, respectively. The hardness of the DLC films as determined using the nano-indentation method was very large. It is possible that increases in compressive residual stresses in the DLC films caused decreases in the contact areas and the indentation depth of the indenter, which appeared to cause increases in the Young's modulus and hardness of the DLC films.
