Enhancement of surface properties of nanocrystalline TiN coated plasma nitrided AISI 310 austenitic stainless steel

摘要

The surface modification with combination of plasma nitriding and TiN coating on 310 stainless steel significantly improved the surface hardness and corrosion properties. X-ray diffraction showed the expanded austenite, CrN and TiN phases along with austenite phase. The nitrided layer was found in 10-50 mu m range and the TiN layer was about 200 nm. The Raman band at 803 cm(-1) corresponds to an untreated sample. The bands at 220 cm(-1), 250 cm(-1), and 468 cm(-1) is for CrN/Cr2N and at 280 cm(-1) and 589 cm(-1) for TiN. The hardness is increased from 1.6 GPa to 10.4 GPa after coating. The corrosion current density about 4.6 x 10(-7) Acm(-2) was measured and the ICR was reduced from 90 m Omega cm(2) to 11 m Omega cm(2) at 150 N cm(-2) after coating. The enhancement in conductivity after coating is due to conductive nature of TiN particles which might be providing a path for electron transportation.