Corrosion and wear properties of electrodeposited amorphous chrome

Amorphous chrome was electrodeposited onto AISI 1025 steel substrates in a modified Sargent bath containing formic acid after electropolished in several electrolytic solutions. The average carbon content of the deposited layer was 2.0 wt %, which is higher than the carbon content of a chrome layer deposited in the modified Sargent bath. The hardness and wear resistance of the amorphous chrome layer are improved by annealing up to about 600 degrees C due to the precipitation hardening effect resulting from the formation of chromium carbide. The chrome layers electropolished in a modified Sargent bath for 2 min showed the longest neutral salt spray life amongst the chrome layers prepared in the same solution. Electropolishing in the modified Faust solution also improved the neutral salt spray life of chrome plated steel more than did the electropolishing in the plating bath. A chrome layer electropolished in the modified Faust solution for 2 min at a current density of 0.6 Acm(-2) and 53 degrees C showed the highest corrosion resistance amongst the samples prepared in this study. The contamination of the plating bath with a modified Faust solution reduces the cathodic current efficiency.