The effect of the addition of graphite nanoparticles into the electrolyte used to produce plasma electrolytic oxidation（PEO） coatings on AZ91 and AZ80 magnesium alloys was studied. The corrosion and wear resistances...The effect of the addition of graphite nanoparticles into the electrolyte used to produce plasma electrolytic oxidation（PEO） coatings on AZ91 and AZ80 magnesium alloys was studied. The corrosion and wear resistances of the obtained coatings were investigated. A solution that contained both phosphates and silicates was used as electrolyte. Moreover, two different PEO treatment times were studied. The corrosion resistance was analyzed with potentiodynamic polarization and EIS tests; the wear resistance was investigated with a flat on ring tribometer. The results were related to the morphology, microstructure, elemental composition and thickness evaluated with SEM analysis. The presence of the graphite nanoparticles increased the thickness, produced a densification of the coating and sealed the pores on the surface, thus improving both the corrosion and wear resistance. The increase in the corrosion and wear resistances was more evident for AZ91 than for AZ80 due to the higher aluminum content.展开更多
In this work, an ultrasound-assisted leaching process was studied for the recovery of zinc from electric arc furnace （EAF） dust, in which zinc was mainly present in the form of franklinite （60%）. HydrometaUurgy is...In this work, an ultrasound-assisted leaching process was studied for the recovery of zinc from electric arc furnace （EAF） dust, in which zinc was mainly present in the form of franklinite （60%）. HydrometaUurgy is emerging as a preferred process for the recovery of a va- riety of metals, and the use of ultrasound could offer advantages over the conventional leaching process, especially for the dissolution of franklinite. Franklinite is a refractory phase that is difficult to leach and represents the main obstacle in conventional hydrometallurgy proc- essing. Atmospheric leaching with different sulfuric acid concentrations （0.2-2.0 M） at two temperatures （323 and 353 K） was performed. The tests were conducted using both conventional and ultrasound-assisted leaching. After the leaching tests, the solid residues were charac- terized by scanning electron microscopy （SEM） and X-ray diffraction （XRD） techniques, whereas the leach liquor was analyzed by induc- tively coupled plasma spectroscopy OCP）. The use of ultrasound facilitated the dissolution of franklinite at low acid concentrations and re- suited in a greater zinc recovery under all of the investigated operating conditions.展开更多
文摘The effect of the addition of graphite nanoparticles into the electrolyte used to produce plasma electrolytic oxidation（PEO） coatings on AZ91 and AZ80 magnesium alloys was studied. The corrosion and wear resistances of the obtained coatings were investigated. A solution that contained both phosphates and silicates was used as electrolyte. Moreover, two different PEO treatment times were studied. The corrosion resistance was analyzed with potentiodynamic polarization and EIS tests; the wear resistance was investigated with a flat on ring tribometer. The results were related to the morphology, microstructure, elemental composition and thickness evaluated with SEM analysis. The presence of the graphite nanoparticles increased the thickness, produced a densification of the coating and sealed the pores on the surface, thus improving both the corrosion and wear resistance. The increase in the corrosion and wear resistances was more evident for AZ91 than for AZ80 due to the higher aluminum content.
基金supported by a Senior Research Grant 2011, University of Padua (Protocol GRIC13VPE5)
文摘In this work, an ultrasound-assisted leaching process was studied for the recovery of zinc from electric arc furnace （EAF） dust, in which zinc was mainly present in the form of franklinite （60%）. HydrometaUurgy is emerging as a preferred process for the recovery of a va- riety of metals, and the use of ultrasound could offer advantages over the conventional leaching process, especially for the dissolution of franklinite. Franklinite is a refractory phase that is difficult to leach and represents the main obstacle in conventional hydrometallurgy proc- essing. Atmospheric leaching with different sulfuric acid concentrations （0.2-2.0 M） at two temperatures （323 and 353 K） was performed. The tests were conducted using both conventional and ultrasound-assisted leaching. After the leaching tests, the solid residues were charac- terized by scanning electron microscopy （SEM） and X-ray diffraction （XRD） techniques, whereas the leach liquor was analyzed by induc- tively coupled plasma spectroscopy OCP）. The use of ultrasound facilitated the dissolution of franklinite at low acid concentrations and re- suited in a greater zinc recovery under all of the investigated operating conditions.
