[en] A study has been made in order to determine corrosion protection performance of alkoxy titanate modified iron in a 3% NaCl solution. The effectiveness of alkoxy titanates as corrosion retarders for chloride environments is confirmed by both stepped potential sweep technique and electrochemical impedance spectroscopy (EIS). Ion microanalysis (IMA) depth profiles are used to elucidate the corrosion inhibitive action of different alkoxy titanate. (orig.)

[en] Highlights: • The tailings can be used for ironmaking, black ceramic pigments and TiO₂ production. • The mass concentration ratio of V/Fe in the leachate reaches 18.34. • Cr₂O₃ addition can reduce the leaching of Fe. • The leaching rate of V and Fe reach 91% and 1.39%, respectively. -- Abstract: A new comprehensive utilization of vanadium slag (VS) method focusing on inhibiting leaching of iron (Fe) during the leaching of vanadium (V) using sulfuric acid (SA) was proposed. In this process, Cr₂O₃ was added to VS to conjugate with Fe in the VS to form (Fe_x,Cr_1-x)₂O₃ which is insoluble in SA, resulting in the decrease of leaching ratio (LR) of Fe to avoid the subsequent separation difficulty of V in leachate. The phase evolutions of VS during the roasting and SA leaching process, and the influences of roasting temperature, roasting time, and addition of Cr₂O₃ on the LR of V, Fe and chromium (Cr) from VS were studied. When the addition of Cr₂O₃ is 12 wt.%, the mass concentration of V in the leachate is 1 order magnitude higher than Fe and the mass ratio of V to Fe reaches 18.34. The LR of V, Fe and Cr are 91% 1.39% and 0.28%, respectively. The leaching residue can be reused as ironmaking raw material. More importantly, the (Fe_x,Cr_1-x)₂O₃ and Fe₂TiO₅ can be separated from the leaching residue and recycled as raw materials for black ceramic pigments and titanium dioxide production by mineral processing technology, respectively.

[en] The effect of bicarbonate on biodegradation of pure magnesium in a simulated body fluid is investigated by means of X-ray diffraction, X-ray photoelectron spectroscopy, polarization curve and electrochemical impedance spectroscopy. The results show that magnesium biodegrades rapidly and non-uniformly during 27 h of immersion in four simulated body fluid solutions containing different concentrations of bicarbonate. The biodegradation rate first decreases and then increases with time. A small amount of bicarbonate in simulated body fluid has an inhibition effect on the Mg dissolution, while an overdose of bicarbonate addition activates the magnesium surface in the simulated body fluid. The interesting phenomena can be interpreted by a surface film model involving precipitation of calcium carbonate and further ionization of bicarbonate in the simulated body fluids, incorporation of calcium, carbonate and phosphate compounds in the surface film, and development of chloride-induced pitting corrosion damage on the magnesium with time

[en] Highlights: • Passivity degradation of UNS N08800 in thiosulphate solution is investigated. • Thiosulphate can be reduced on a passive surface. • Elemental sulphur particles are found on the passive film. • Pitting potentials evolve substantially due to competitive adsorption of thiosulphate and chloride ions. • Sulphur ions can incorporate into the outer layer of the passive film. - Abstract: Reduced sulphur induced corrosion of steam generator (SG) tubing in pressurized water reactor (PWR) is assumed to occur at low temperature. Corrosion of UNS N08800 in chloride and thiosulphate solutions at 20, 40 and 90 $\mathrm{℃}$ is systemically investigated by using polarization technique, electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). It is concluded that thiosulphate can be reduced to S°, S₂²⁻ and S²⁻, and incorporate into the passive film, which significantly depends on temperature. The evolution on pitting potentials in chloride + thiosulphate solution can be ascribed to the competitive adsorption of these two ions on the passive surface.