Sulfide Induced Corrosion of Copper Nickel Alloys

Abstract

The susceptibility of Cu-Ni alloys to accelerated corrosion in sea water containing low sulfide concentrations has been investigated. Test alloys included wrought 90/10 Cu-Ni, 70/30 Cu-Ni and Ni-Cu, plus cast 70/30 Cu-Ni. Sheet type specimen exposures were performed in fresh flowing sea water at a test velocity of 2.4 m/s (8 ft/s), and simultaneous polarization resistance cell exposures were conducted at a test velocity of 1.2 m/s (4 ft/s). Sulfide concentrations included 0.01, 0.05, and 0.2 ppm from addition of Na2S to flowing sea water. The test sequence included continuous sulfide exposures ranging from 1 to 1 5 days, followed by 60 days exposure in natural sea water. Gravimetric corrosion rates, depth of attack, corrosion potentials, and instantaneous corrosion rate data were developed. Results showed that wrought 90/10 Cu-Ni was susceptible to accelerated attack in sea water containing 0.01 ppm sulfides and is attacked vigorously after exposure to 0.2 ppm sulfides in sea water. Wrought 70/30 Cu-Ni is similarly susceptible to sulfide induced pitting, but appears to require higher sulfide concentration to trigger attack. Cast 70/30 Cu-Ni and Ni-Cu are susceptible to accelerated corrosion in sulfide modified sea water, but modes of attack differ from wrought 90/10 and 70/30 Cu-Ni. Interaction of exposure (or system operating) variables is seen as a key factor in assessing susceptibility of Cu-Ni alloys to sulfide induced corrosion.

A review of the effects of benzotriazole on the corrosion of copper and copper alloys in clean and polluted environments

“…There is a large number of variables, e.g., composition of the material, concentration of pollutants, environments… etc. In spite of the high corrosion resistance of these alloys, they suffered from severe corrosion in media polluted by sulfide ions [18,20,[69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84]. This is a problem of considerable significance in view of the fact that many industrial water streams and indeed some natural water bodies are polluted by dissolved sulfides.…”

Copper and Copper Alloys

“…Doping a passivating cuprous oxide corrosion product layer by sulfide may lead to very high rates of corrosion once the material is exposed to aerated conditions [253,254].…”

Effect of sulfide pollution on the stability of the protective film of benzotriazole on copper

“…In www.elsevier.com/locate/apsusc Applied Surface Science 253 (2007) 8986-8991 such environments, these metallic components serve in media that are inhibited by BTAH and polluted with sulfide ions. Sulfide ions are known to promote the corrosion of copper [27][28][29][30][31][32][33][34][35][36][37]. The process involves an adsorption step, that is,…”