Abstract
The carbon contents in Cr-C deposits obtained from Cr (III) sulfate-ammonium oxalate baths changed from 0.8wt% up to 3.2wt% with increases in the oxalate concentration in the bath. The structure of the deposits changed from crystalline to amorphous at a carbon content of about 1.4wt%. With the heating of amorphous Cr-C alloy two exothermic reactions occurred-one at 250∼350°C due to crystallization of metallic Cr from the amorphous alloy, and the other at 610∼630°C due to the deposition of Cr7C3 in the Cr metal matrix. The Cr-C deposition and the evolution of hydrocarbon at cathode seem to be brought about by the reduction of oxalate to carbon on the electrode surface during Cr electrodeposition.
