Improved surface properties of AISI-420 steel by TiC based coating using graphite cathodic cage with titanium lid in plasma deposition

In this work, titanium‑carbon (TiC) based coating is deposited on AISI-420 martensite stainless steel samples to improve surface properties. The coating is deposited using a graphite cathodic cage equipped with a titanium lid, which acts as a source of carbon and titanium. The hardness of samples (untreated hardness of 220 HV0.25) is increased up to 1337 HV0.25 and 1524 HV0.25 by coating deposition at cathodic (base plate connected with cathodic cage) and floating potential (with no external potential). The sample treated at cathodic potential exhibits expanded martensitic phase due to diffusion of carbon atoms. In contrast, additional TiC and chromium carbide Cr23C6 peaks are formed while treated at floating potential. The thickness of carburizing layer is 80 and 77 μm, when the coating is deposited at cathodic and floating potential, respectively. The wear volume of the untreated sample (1200 × 10−4 mm3) is reduced to ∼ (20 × 10−4 mm3) after the coating deposition, and the friction coefficient is also reduced due to the coating deposition. A significant decrease in corrosion rate is also observed, specifically at floating potential. It suggests that Ti-C-based coating using this modified cathodic cage plasma deposition (CCPD) is beneficial for the hardness, wear, and corrosion resistance of AISI-420 steel.