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

TiN films on mild steel were deposited by reactive d.c. magnetron sputterin g; electroplated chromium was incorporated as an interlayer. Surface hardne ss, measured by the Knoop indentation method under a load of 25 gf. phase a nalysis by the X-ray diffraction method and corrosion behaviour by the pote ntiodynamic measurement technique of these coatings have been evaluated. Su rface hardness values were found to increase from about 1000-1100 for TiN c oatings on mild steel to about 1800-1900 (HK25) for TiN coatings with chrom ium as interlayer. Potentiodynamic corrosion tests, performed in 1N H2SO4 s olutions, have shown that with 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 inter layer.