Abstract
An electroless nickel deposit is introduced as an interlayer between carbon steel substrate and r.f. magnetron sputtered TiN films, and a compound coating assembly TiN/Ni 3 P/Fe is derived after appropriate heat treatment. The employment of electroless Ni-P deposit results in an increase in the surface microhardness and the adhesion strength. The surface hardness as high as 2266 HK 1 close to the hardness of bulk TiN can be achieved in the Ni 3 P interlayer modified TiN coating. It is observed that the track depth after pin-on-disk test in TiN/Ni 3 P/Fe is about an order of magnitude small than that in the Fe substrate, and the introduction of electroless Ni interlayer in TiN coating provides a beneficial wear resistance. Corrosion behavior of the TiN coating assembly is evaluated through the polarization technique. The corrosion currents for TiN/Fe, Ni 3 P/Fe and TiN/Ni 3 P/Fe are 200, 40-70 and 5-7 μA/cm 2 , respectively. The presence of the electroless Ni-P interlayer in the modified TiN coating provides a better corrosion resistance as compared to conventional TiN coating on carbon steel.