Iridium coating prepared on rhenium substrate by electrodeposition in molten salt in the air atmosphere

Compact and smooth iridium coating was obtained on the surface of the rhenium substrate by electrodeposition from molten salts of chlorides at the temperature of 600 degrees C in the air. The deposition rate is about 25 mu m/h at cathodic current density of 25 mA/cm(2). The iridium coating has a columnar structure with preferential growth orientation of < 111 >. The coating/substrate interface exhibits excellent adherence with no evidence of delamination, cracks, or other defects. No obvious diffusion layer is found within the as-deposited coating. The microhardness of the coating is 442 kg/mm(2) and the bond strength between the coating and substrate is higher than 16 MPa. (C) 2011 Elsevier B.V. All rights reserved.