DIMITAR STOYCHEV, NADEZHDA KOTEVA, MARIA STOYCHEVA, ELENA VELKOVA, DIMITAR DOBREV CHEMICAL COBALT COATING OF POLYETHYLENETEREPHTHALATE The role of the concentration of the components of the alkaline electrolyte for chemical (electroless) coating of cobalt has been investigated with respect to the rate of their deposition on flexible organic support (polyterephthalate). It has been proved that with the increase in the concentration of Co2+ ions in the solution the rate of deposition is growing up. The influence of the concentration of NaH2PO2, used as a reducing agent, has been studied in regard to the kinetics of deposition and with respect to the morphology of the cobalt coating, as well as the effect on the quantity of the phosphorus co-deposited in the coating. In the course of the study on the influence of the buffering components (NH4Cl and H3BO3) in the working electrolyte, preventing the undesired liberation of cobalt hydroxide, on the kinetics of reduction of the cobalt ions, their optimal concentrations have been ascertained. It has been found that the increase in pH and in the temperature of the studied electrolyte determined an increase in the rate of reduction of the cobalt ions, whereupon the optimal values have been selected.
Keywords: chemical deposition, cobalt, coating, organic substrate