Investigation of corrosion behavior of CuAlMn alloy in chloride and sulfate electrolytes : diploma thesis

U radu je provedeno ispitivanje elektrokemijskog ponašanja CuAlMn legure u 0.5 mol dm -3 NaCl otopini bez i u prisustvu 0.1, 0.3 i 0.5 mol dm -3 Na 2 SO 4 pri T = 20 o C i pH = 7. Primijenjene su elektrokemijske tehnike kao što su mjerenje potencijala otvorenog strujnog kruga, metode linearne i potenciodinamičke polarizacije. Rezultati ispitivanja su pokazali da prisustvo sulfata u otopini klorida dovodi do smanjenja gustoće korozijske struje i do povećanja vrijednosti polarizacijskog otpora. Kod viših anodnih potencijala, dobivene su veće anodne gustoće struje kod mjerenja u prisustvu sulfatnih iona zbog veće topljivosti bakrova sulfata, koji nastaje na površini elektroda. Utjecaj vremena izlaganja legure elektrolitu 0.5 mol dm -3 NaCl i 0.5 mol dm -3 NaCl + 0.5 mol dm -3 Na 2 SO 4 ispitan je mjerenjem metodom linearne polarizacije u vremenskom periodu od 24 sata, pri čemu su vrijednosti polarizacijskog otpora rasle s vremenom i u NaCl i u NaCl+Na 2 SO 4 otopini, s time što su u otopini sa sulfatnim ionima ove vrijednosti bile značajno više. Nakon elektrokemijskih mjerenja, korodirane površine elektroda ispitane su optičkim i elektronskim mikroskopom.The electrochemical behavior of CuAlMn alloy in 0.5 mol dm -3 NaCl solution without and in the presence of 0.1, 0.3 and 0.5 mol dm -3 Na 2 SO 4 at T = 20 o C and pH = 7 was investigated. Conventional electrochemical techniques including open circuit potential measurements, linear and potentiodynamic polarization method were used. After electrochemical measurements, the corroded electrode surfaces were examined with an optical and electron microscope. The results showed that the presence of sulfate in the chloride solution leads to a decrease in corrosion current density values and to an increase in polarization resistance values. At higher anode potentials, higher anodic current densities were obtained in the presence of sulfate ions, due to the higher solubility of copper sulfate, which is formed on the electrode surface. The effect of electrolyte exposure time on 0.5 mol dm -3 NaCl and 0.5 mol dm -3 NaCl + 0.5 mol dm -3 Na 2 SO 4 was examined by measuring with linear polarization method over a period of 24 hours, with the polarization resistance values increasing with time in both NaCl and NaCl + Na 2 SO 4 solution, and these values being significantly higher in the solution with sulfate ions. After electrochemical measurements, the corroded electrode surfaces were examined with an optical and electron microscope