Preparation of Amerphous Alloys in Cobalt with Lanthanum, Cerium by Electrodeposition and Its Crystallization Kinetics

Rare-earth elements (La, Ce) have lower standard equilibrium potential than hydrogen and are very difficult to electrodeposition from aqueous solution. Co-La, Co-La-P, Co-Ce, Co-Ce-P and Co-P alloys deposits having amorphous structure were obtained from aqueous solutions by using optimized electroplaing solutions and process conditions. The crystallization kinetics of these amorphous alloy coatings was investigated. The crystallization activation energy and kinetics equation of five kinds amorphous coatings were determined by DSC method. The results indicate that the crystallization activation energy of Co-P, Co-La, Co-Ce, Co-La-P, Co-Ce-P amorphous coatings are 185.7,386.5, 383.0, 587.3, 535.5kJ·mol-1 respectively. The crystallization mechamism of four kinds amorphous coatings may be expressed by kinetics equation: