The effect of Cr interlayer on the microstructure of CrN coatings on steel

The effect of electroplated Cr interlayer on the microstructure of CrN coatings on AISI 4140 steel were investigated. Two types of CrN-coated specimens by cathodic are plasmas were prepared with and without an intermediate layer deposited by electroplated hard chrome (CrN/steel and CrN/Cr/steel). The microstructure and crystallinity of chromium nitride have been investigated using X-ray diffraction (XRD), cross-sectional transmission electron microscopy (XTEM) and selected area diffraction (SAD). Both CrN/steel and CrN/Cr/steel coating assemblies exhibit microcolumnar morphologies. However, it is noted that the columnar structure of CrN coating directly on steel is less evident, strong, and upward in comparison with that deposited on electroplated chromium layer. For CrN/Cr/steel assembly, the preferred orientations of CrN(220) and Cr(200) are observed. (C) 2000 Elsevier Science B.V. All rights reserved.