Abstract
The S-phases (γN-phases) of JIS standard SUS304 steel were prepared via direct current plasma nitriding (DCPN) and active screen plasma nitriding (ASPN). Furthermore, diamond-like carbon (DLC) films were prepared on these S-phases via plasma chemical vapor deposition (PCVD). The nitride layers included the γ’Fe4N phase. The X-ray stress constant K for the nitride layers was evaluated using γN (200) + γ’Fe4N (200) diffraction with CrKα characteristic X-rays. The γN (200) + γ’Fe4N (200) diffraction angles 2θ of the DCPN and ASPN powders were 73.49° and 72.98°, respectively. The X-ray stress constants, E / (1 + ν), of the γN (200) + γ’Fe4N (200) phase that was nitrided using DCPN and ASPN were 202 and 153 GPa, respectively, and the K values of the same were -2365 and -1809 MPa/deg, respectively. The X-ray residual stresses of these S-phases were approximately -5.3 and -2.6 GPa, respectively. However, Raman microprobe spectroscopy was used for residual stress measurements of the DLC films that were deposited on these S-phases. The Raman spectra of the DLC films were classified into the disorder peak D’at 1150 cm-1, the D peak, and the graphite peak G. 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 and -3.0 GPa, respectively. The hardness of the DLC films was determined using the nanoindentation method, and the films were found to exhibit high levels pf hardness. The increase in compressive residual stresses in the DLC films could have caused the decrease in contact areas and the indentation depth of the indenter, which may have increased the value of Young’s modulus and hardness of the DLC films.
