Electrodeposition, assisted by abrasive polishing, of crack-free hard chromium with compressive stress

Crack networks and residual tensile stresses are general characteristics of electrodeposited hard chromium coatings. In this paper, crack-free hard chromium coatings with compressive stresses have been obtained by an electrodeposition process assisted by abrasive polishing. The deposited coatings had mirror-like smooth surfaces, values of hardness in the range 800–1000 HV and compressive stresses between 1000 and 1600 MPa. A model involving hydrogen disentanglement from the lattice is proposed to explain the effects of abrasive polishing on the complete elimination of cracks and the generation of a compressive stress. This explanation is discussed in terms of the variations in properties of the coating with the rotation speed of the cathode.