CHARACTERIZATION AND HARDNESS OF Co–P COATINGS OBTAINED FROM DIRECT CURRENT ELECTRODEPOSITION USING GLUCONATE BATH

Abstract

Direct current electrodeposition of Co – P alloy coatings were carried out using gluconate bath and they were characterized by employing techniques like XRD, FESEM, DSC and XPS. Broad XRD lines demonstrate the amorphous nature of Co – P coatings. Spherical and rough nodules are observed on the surface of coatings as seen from FESEM images. Three exothermic peaks around 290, 342 and 390°C in DSC profiles of Co – P coatings could be attributed to the crystallization and formation of Co 2 P phase in the coatings. As-deposited coatings consist of Co metal and oxidized Co species as revealed by XPS studies. Bulk alloy P ( P δ-) as well as oxidized P ( P 5+) are present on the surface of coatings. Concentrations of Co metal and P δ- increase with successive sputtering of the coating. Observed microhardness value is 1005 HK when Co – P coating obtained from 10 g L-1 NaH 2 PO 2 is heated at 400°C that is comparable with hard chromium coatings.