The feasibility was investigated to substitute chrome-free passivation treatment of electrodeposited zinc in a titanium bath for chromate passivation treatment. The formation mechanism of the chrome-free passivation f...The feasibility was investigated to substitute chrome-free passivation treatment of electrodeposited zinc in a titanium bath for chromate passivation treatment. The formation mechanism of the chrome-free passivation film was further analyzed. The surface mor- phologies and the elemental compositions of the treated samples with varied immersion times were observed by scanning electron mi- croscopy （SEM） and determined by energy dispersion spectrometry （EDS）, respectively. The electrode potential of the sample surface was recorded in the film formation process. The changes of the electrode potential are in accordance with that of SEM and EDS of the sample surface. The results of X-ray photoelectron spectroscopy （XPS） show the chrome-free passivation film composed ofZnO, SiO2, TiO2, Zn4Si207（OH）2, and SrF2. The anode zinc dissolution and the local pH value increase due to the cathode hydrogen ion reduction process result in the formation of the chrome-free passivation film. The macro-images of the chrome-free passivation films formed on electrodeposited zinc show that the color of the film changes from blue to iridescence with the increase of the immersion times.展开更多
Nano-sized growth of zinc electrodeposit on the ferrite substrate has been studied by means of in situ scanning tunnel microscopy (STM) and atomic force micoscopy (AFM). It is found that the morphology of zinc electro...Nano-sized growth of zinc electrodeposit on the ferrite substrate has been studied by means of in situ scanning tunnel microscopy (STM) and atomic force micoscopy (AFM). It is found that the morphology of zinc electrodeposit varies from initial about 30nm granular crystals to layered platelet crystals with increasing deposition time by using in situ STM. With AFM, the results show that the platelet crystals are hexagonal in shape and the hexagonal platelet crystals form steps perpendicular to the growth direction by side-by-side stacking along the (0001)η surface. The mechanism of morphological change is discussed in details. It is proposed that these steps grow laterally as a result of the embedment of zinc ion clusters.展开更多
文摘The feasibility was investigated to substitute chrome-free passivation treatment of electrodeposited zinc in a titanium bath for chromate passivation treatment. The formation mechanism of the chrome-free passivation film was further analyzed. The surface mor- phologies and the elemental compositions of the treated samples with varied immersion times were observed by scanning electron mi- croscopy （SEM） and determined by energy dispersion spectrometry （EDS）, respectively. The electrode potential of the sample surface was recorded in the film formation process. The changes of the electrode potential are in accordance with that of SEM and EDS of the sample surface. The results of X-ray photoelectron spectroscopy （XPS） show the chrome-free passivation film composed ofZnO, SiO2, TiO2, Zn4Si207（OH）2, and SrF2. The anode zinc dissolution and the local pH value increase due to the cathode hydrogen ion reduction process result in the formation of the chrome-free passivation film. The macro-images of the chrome-free passivation films formed on electrodeposited zinc show that the color of the film changes from blue to iridescence with the increase of the immersion times.
基金This research was supported by the collaboration program between Nippon Steel Corporation and University of Science and Technology Beijing and the National Natural Science Foundation of China(No.571014569).
文摘Nano-sized growth of zinc electrodeposit on the ferrite substrate has been studied by means of in situ scanning tunnel microscopy (STM) and atomic force micoscopy (AFM). It is found that the morphology of zinc electrodeposit varies from initial about 30nm granular crystals to layered platelet crystals with increasing deposition time by using in situ STM. With AFM, the results show that the platelet crystals are hexagonal in shape and the hexagonal platelet crystals form steps perpendicular to the growth direction by side-by-side stacking along the (0001)η surface. The mechanism of morphological change is discussed in details. It is proposed that these steps grow laterally as a result of the embedment of zinc ion clusters.
