Yang, Gong and Yuan Materials and Corrosion 2012. 63. No. 1 Fe 2p3 oIs c Is Ti 2p3 Binding Energy (ev) Figure 8. XPS results of the inside wall near the rupture on tube A demonstrated in Equation(7). As for the initiation temperature, maybe it is true for sole crevice corrosion to take place on titanium ever corrosion was also accompanied by galvanic corrosion, which a)10000 would probably help to decrease the initial barrier potential for Hr crevice corrosion to occur on titanium. as a result, the threshold temperature is accordingly decreased, at least around 35-40C. Anode:Ti→Ti++4e Total reaction:T4C+4H2O→T(OH)4+4HC⑦) Cathode: O+2H20+4e- 4OH galvanic corrosion and crevice corrosion, metal cations as ferrous ions and titanium ions were continuously produced. Besides forming the corrosion products, these two cations would also hydrolyze in the desalinated water to generate hydrogen ions H Time(s) 1500 When contacting negative electrons, such hydrogen ions will be b)100 1000 000 00 10 20 MMMM- Time(s) 26/° Figure 9. SIMS results of the areas near the rupture on tube A:(a) outside wall, (b)inside wall Figure 10. XRD results of the area near the rupture on tube a o 2012 WILEY-VCH Verlag Gmbh Co KGaA, Weinheim www.matcorr.comdemonstrated in Equation (7). As for the initiation temperature, maybe it is true for sole crevice corrosion to take place on titanium at temperatures above 70 8C, however in our event, crevice corrosion was also accompanied by galvanic corrosion, which would probably help to decrease the initial barrier potential for crevice corrosion to occur on titanium. As a result, the threshold temperature is accordingly decreased, at least around 35–40 8C. Anode : Ti ! Ti4þ þ 4e Cathode : O2 þ 2H2O þ 4e ! 4OH Total reaction : Ti4þ4Clþ4H2O ! TiðOHÞ4þ4HþCl (7) Then, it is easy to infer that, with the progress of both galvanic corrosion and crevice corrosion, metal cations as ferrous ions and titanium ions were continuously produced. Besides forming the corrosion products, these two cations would also hydrolyze in the desalinated water to generate hydrogen ions Hþ. When contacting negative electrons, such hydrogen ions will be 14 Yang, Gong and Yuan Materials and Corrosion 2012, 63, No. 1 Figure 8. XPS results of the inside wall near the rupture on tube A Figure 9. SIMS results of the areas near the rupture on tube A: (a) outside wall, (b) inside wall Figure 10. XRD results of the area near the rupture on tube A
2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.matcorr.com