Publication

Abstract : A commercially available DAC-10 tool steel substrates were plasma nitrided followed by vacuum heat treatment. Titanium nitride (TiN) with and without chromium (Cr) interlayer was deposited using a cathodic-arc deposition technique. The surface morphology of thin films was analyzed using X-ray diffractometry (XRD) and field emission scanning electron microscopy (FE-SEM) respectively. On both the TiN and Cr/TiN films, subsequent investigations comprising nanoindentation and nanoscratch tests were carried out. A notable 21.94 % increase in hardness was seen in the Cr/TiN film compared to TiN, plasma nitride, and heat-treated DAC-10 tool steel. There is an important variable that contributed to this improvement i.e., chromium (Cr) atoms had diffused into the TiN film from the Cr interlayer, which was also detected in the XRD pattern with (2 2 0) plane orientation. Along with an increase in hardness, the Cr/TiN film showed a 12.3 % increase in elastic modulus over the TiN film. Additionally, it was discovered that the strain hardening exponent was higher for the Cr/TiN film (0.38 vs. 0.33 TiN), indicating less pile-up formation during indentation in the Cr/TiN film. The Cr/TiN film’s scratch width and depth were reduced due to the higher scratch hardness. The projected wear rate of the scratched Cr/TiN film was significantly reduced by 71.23 % as a result of the coefficient of friction decreasing from 0.45 ± 0.05 for the TiN film to 0.33 ± 0.04 for the Cr/TiN film. These results show surface modification was the best alternative to enhance the nanomechanical and tribological properties of DAC-10 tool steel.