Titanium based IrO2 +Ta2O5 oxide anodes with different compositions and pyrolysis temperatures were prepared by termodecompoisition method. By using X-ray diffraction (XRD), the structure and texture coefficient of th...Titanium based IrO2 +Ta2O5 oxide anodes with different compositions and pyrolysis temperatures were prepared by termodecompoisition method. By using X-ray diffraction (XRD), the structure and texture coefficient of the coatings, TC(hkl), of IrO2 rutile crystal have been tested. It showed that, the crystallization processes of IrO2 and Ta2O5 in xIrO2 +(100-x) Ta2 O5 (x is in mol%) films affected and confined each other.In the mixed system, IrO2 rutile phase existed as a solid solution with Ta, and attained the maximum solubility when x=70mol%, i.e. for the coating of 70% IrO2 +Ta2O5.For the coatings of low iridium content or at low preparing tem pemture, (110) and (101) pwtered orientations were dominant. However, preferred growth of IrO2 weakened with increasing either iridium content or temperature. Three typical surface morphologies were observed by using scanning electron tnicroscopy(SEM). The crystallite size of the mixed oxide coatings were finest for the the film of 70%IrO2 +30%Ta2O5,and decreased with the pyrolysis tempemture. As the results of the finest crystallite segregating on sudece and the maxitnum solid solubility of Ir and Ta component in deposits, the coatings with the composition of 70%IrO2 +Ta2O5 prepared at 450℃ presented the mdrimutn electrocatalgtic activitg for O2 evolution in 0. 5M H2SO4 solution.UP to 550℃, Ti base suffered to oxidation resulting in decreasing anode conductivity,therefore, coatings performed a low activity.展开更多
Anodic oxide coatings on aluminum alloys are used for space environment applications. These provide specific thermo-optical properties to spacecraft surface. Fragments of these coatings lead to generate the contaminat...Anodic oxide coatings on aluminum alloys are used for space environment applications. These provide specific thermo-optical properties to spacecraft surface. Fragments of these coatings lead to generate the contamination in satellites and affect the mission lifetime. The current work concerns studying of the anodic processes applied on aluminum and different groups of aluminum alloys as Al7075, Al2024 and Al6061. Experimental procedures are performed using sulfuric acid at different values of current density (1 - 2 A/dm2). The influence of the parameters of anodic film formation on the coating characteristics and layer thickness of aluminum alloys has been investigated. Reflectance and optical properties of the anodized aluminum alloy coatings are determined and found to be dependent on the alloying elements. Changes in anodic coating weight and film thickness of aluminium alloys with the process parameters as current density, temperature, time duration, acid concentration, and sealing system have been studied. Moreover, morphology and surface structure of the considered samples are carried out in attempt to understand the physical characteristics. The obtained results are compared and briefly outlined.展开更多
The aim of this work was to investigate the effects of calcination/acid-activation on the composition, structure, and photocatalytic （PC） reduction property of an anodic oxidation TiO2/Ti film catalyst. The surface ...The aim of this work was to investigate the effects of calcination/acid-activation on the composition, structure, and photocatalytic （PC） reduction property of an anodic oxidation TiO2/Ti film catalyst. The surface morphology and phase composition were examined by scanning electron microscopy and X-ray diffraction. The catalytic property of the film catalysts was evaluated through the removal rate of potassium chromate during the PC reduction process. The results showed that the film catalysts were composed of anatase and rutile TiO2 with a micro-porous surface structure. The calcination treatment increased the content of TiO2 in the film, changed the relative ratio of anatase and rutile TiO2, and decreased the size of the micro pores of the film catalysts. The removal rate of potassium chromate was related to the technique parameters of calcination/acid-activation treatment. When the anodic oxidation TiO2/Ti film catalyst was calcined at 873 K for 30 min and then acid-activated in the concentrated H2SO4 for 60 min, it presented the highest catalytic property, with the removal rate of potassium chromate of 96.3% during the PC reduction process under the experimental conditions.展开更多
文摘Titanium based IrO2 +Ta2O5 oxide anodes with different compositions and pyrolysis temperatures were prepared by termodecompoisition method. By using X-ray diffraction (XRD), the structure and texture coefficient of the coatings, TC(hkl), of IrO2 rutile crystal have been tested. It showed that, the crystallization processes of IrO2 and Ta2O5 in xIrO2 +(100-x) Ta2 O5 (x is in mol%) films affected and confined each other.In the mixed system, IrO2 rutile phase existed as a solid solution with Ta, and attained the maximum solubility when x=70mol%, i.e. for the coating of 70% IrO2 +Ta2O5.For the coatings of low iridium content or at low preparing tem pemture, (110) and (101) pwtered orientations were dominant. However, preferred growth of IrO2 weakened with increasing either iridium content or temperature. Three typical surface morphologies were observed by using scanning electron tnicroscopy(SEM). The crystallite size of the mixed oxide coatings were finest for the the film of 70%IrO2 +30%Ta2O5,and decreased with the pyrolysis tempemture. As the results of the finest crystallite segregating on sudece and the maxitnum solid solubility of Ir and Ta component in deposits, the coatings with the composition of 70%IrO2 +Ta2O5 prepared at 450℃ presented the mdrimutn electrocatalgtic activitg for O2 evolution in 0. 5M H2SO4 solution.UP to 550℃, Ti base suffered to oxidation resulting in decreasing anode conductivity,therefore, coatings performed a low activity.
文摘Anodic oxide coatings on aluminum alloys are used for space environment applications. These provide specific thermo-optical properties to spacecraft surface. Fragments of these coatings lead to generate the contamination in satellites and affect the mission lifetime. The current work concerns studying of the anodic processes applied on aluminum and different groups of aluminum alloys as Al7075, Al2024 and Al6061. Experimental procedures are performed using sulfuric acid at different values of current density (1 - 2 A/dm2). The influence of the parameters of anodic film formation on the coating characteristics and layer thickness of aluminum alloys has been investigated. Reflectance and optical properties of the anodized aluminum alloy coatings are determined and found to be dependent on the alloying elements. Changes in anodic coating weight and film thickness of aluminium alloys with the process parameters as current density, temperature, time duration, acid concentration, and sealing system have been studied. Moreover, morphology and surface structure of the considered samples are carried out in attempt to understand the physical characteristics. The obtained results are compared and briefly outlined.
基金supported by the National High Technology Research and Development Program of China (No. 2007AA03Z337)the Harbin Special Creation Foundation for Science and Technology of Fellow in China (No. 2006RFQXG032)
文摘The aim of this work was to investigate the effects of calcination/acid-activation on the composition, structure, and photocatalytic （PC） reduction property of an anodic oxidation TiO2/Ti film catalyst. The surface morphology and phase composition were examined by scanning electron microscopy and X-ray diffraction. The catalytic property of the film catalysts was evaluated through the removal rate of potassium chromate during the PC reduction process. The results showed that the film catalysts were composed of anatase and rutile TiO2 with a micro-porous surface structure. The calcination treatment increased the content of TiO2 in the film, changed the relative ratio of anatase and rutile TiO2, and decreased the size of the micro pores of the film catalysts. The removal rate of potassium chromate was related to the technique parameters of calcination/acid-activation treatment. When the anodic oxidation TiO2/Ti film catalyst was calcined at 873 K for 30 min and then acid-activated in the concentrated H2SO4 for 60 min, it presented the highest catalytic property, with the removal rate of potassium chromate of 96.3% during the PC reduction process under the experimental conditions.
