Abstract:
The tarnishing of cooper in aqueous solutions of thiourea and alkaline potassium polysulphide has been examined by coulometric reduction, weight-change techniques and scanning electron microscopy. Potentiodynamic reduction indicated the presence of up to six constituents but most tarnish films contained only two main sulphide components and one oxide. Simultaneous dissolution occurred in thiourea solutions only, the threshold concentration depending upon the degree of agitation employed. In polysulphide solutions no dissolutions of the sulphide film was detected.
Referência:
WOLYNEC, Stephan. Film dissolution during sulphide tarnishing of copper in aqueous solutions of thiourea and alkaline polysulphide. Corros. Sci., v. 12, n. 5, p. 437-50, may, 1972.
The tarnishing of cooper in aqueous solutions of thiourea and alkaline potassium polysulphide has been examined by coulometric reduction, weight-change techniques and scanning electron microscopy. Potentiodynamic reduction indicated the presence of up to six constituents but most tarnish films contained only two main sulphide components and one oxide. Simultaneous dissolution occurred in thiourea solutions only, the threshold concentration depending upon the degree of agitation employed. In polysulphide solutions no dissolutions of the sulphide film was detected.
Referência:
WOLYNEC, Stephan. Film dissolution during sulphide tarnishing of copper in aqueous solutions of thiourea and alkaline polysulphide. Corros. Sci., v. 12, n. 5, p. 437-50, may, 1972.
