TiN coatings modified by an interlayer of electroplated chromium on mild steel

Abstract

TiN films on mild steel were deposited by reactive d.c. magnetron sputtering; electroplated chromiunt was incorporated as an interlayer, Surface hardness, measured by the Knoop indentation method under a load of 25 gf, phase analysis by the X-ray diffraction method and corrosion behaviour by the potentiodynamic measurement technique of these coatings have been evaluated. Surface hardness values were found to increase from about 1000-1100 for TiN coatings on mild steel to about 1800-1900 (HK 25 ) for TiN coatings with chromium as interlayer, Potentiodynamic corrosion tests, performed in IN H 2 SO 4 solutions, have shown that with a chromium interlayer the corrosion resistance increases significantly as compared to TiN only sputtered coatings on mild steel samples. No spalling of TiN coatings was observed during full sweep voltage of -1000 mV to +1000 mV when they were tested with a chromium interlayer.