The oxalate coating formed on AZ91D magnesium alloy by chemical conversion treatment methods in oxalate salt solutions was investigated.The surface morphologies and chemical composition of coating were examined using ...The oxalate coating formed on AZ91D magnesium alloy by chemical conversion treatment methods in oxalate salt solutions was investigated.The surface morphologies and chemical composition of coating were examined using scanning electron microscopy(SEM)equipped with energy dispersive analysis of X-ray(EDX).Electrochemical impedance spectroscopy(EIS), potentiodynamic polarization curves and salt spray tests were employed to evaluate corrosion protection of the coating to substrate in 5%NaCl solution.The mechanism of coating formations was also considered in details.The results indicate that a compact and dense surface morphology with fine particle clusters of the oxalate coating on magnesium alloy is presented,which mainly consists of oxide or/and organic of Mg,Al and Zn.And the anti-corrosion of the magnesium after oxalate conversion treatment is better than that of the magnesium substrate.The results of salt spray test for oxalate coating is evaluated as Grade 9 according to ASTM B117. The electric resistance of oxalate chemical conversion coating to substrate is below 0.1Ω.展开更多
Silver-ceramics (Ag2MO2)(M=Co, Ni, or Cu) were prepared through thermal decompositionof coprecipitated oxalates. Pellets of these materials were annealed at 350℃ for different timeperiods up to 5 h. The effect of ann...Silver-ceramics (Ag2MO2)(M=Co, Ni, or Cu) were prepared through thermal decompositionof coprecipitated oxalates. Pellets of these materials were annealed at 350℃ for different timeperiods up to 5 h. The effect of annealing time on the transport properties was studied. IR andX-ray spectra were also studied.展开更多
Oxychloride titanium oxide precursor material is one of the key substances produced by the giant electrorheological effect. In this paper, tetrabutyl titanate and oxalic acid and anhydrous ethanol are used to prepare ...Oxychloride titanium oxide precursor material is one of the key substances produced by the giant electrorheological effect. In this paper, tetrabutyl titanate and oxalic acid and anhydrous ethanol are used to prepare porous titanyl oxalate precursor powder by precipitation method. The materials, morphology and grain size were analyzed by X-ray diffraction and electron microscope method. Conductivity was measured by a four-probe method, and then the infiltration property of water and silicone oil on the surface of the powder was investigated. The results show that Oxychloride titanium oxide precursor has good wettability to water and silicone oil. The wettability has little to do with the bath temperature and the pH of the solution. The contact angle of water on oxychloride titanium oxide precursor surface does not change greatly with the change of the bath temperature and pH, ranging from 26.8? to 31.1?. Similarly, the contact angle of silicone oil on the surface of the sample ranges from 9.5? to 11.5?. So, silicone oil has better wettability on the surface of the sample than water. Porous titanium oxalate is an insulating material having a resistivity more than 1 GΩ?cm. Oxychloride titanium oxide precursor is poor thermal stability, and it breaks down to generate TiO2 when the temperature is higher than 70?C.展开更多
基金Project(20070420821)supported by the China Postdoctoral Science FoundationProject supported by the Special Project for Postdoctoral Scientific Research of Hunan Provincial Scientific and Technology Department of ChinaProject supported by the Postdoctoral Foundation of Central South University,China
文摘The oxalate coating formed on AZ91D magnesium alloy by chemical conversion treatment methods in oxalate salt solutions was investigated.The surface morphologies and chemical composition of coating were examined using scanning electron microscopy(SEM)equipped with energy dispersive analysis of X-ray(EDX).Electrochemical impedance spectroscopy(EIS), potentiodynamic polarization curves and salt spray tests were employed to evaluate corrosion protection of the coating to substrate in 5%NaCl solution.The mechanism of coating formations was also considered in details.The results indicate that a compact and dense surface morphology with fine particle clusters of the oxalate coating on magnesium alloy is presented,which mainly consists of oxide or/and organic of Mg,Al and Zn.And the anti-corrosion of the magnesium after oxalate conversion treatment is better than that of the magnesium substrate.The results of salt spray test for oxalate coating is evaluated as Grade 9 according to ASTM B117. The electric resistance of oxalate chemical conversion coating to substrate is below 0.1Ω.
文摘Silver-ceramics (Ag2MO2)(M=Co, Ni, or Cu) were prepared through thermal decompositionof coprecipitated oxalates. Pellets of these materials were annealed at 350℃ for different timeperiods up to 5 h. The effect of annealing time on the transport properties was studied. IR andX-ray spectra were also studied.
文摘Oxychloride titanium oxide precursor material is one of the key substances produced by the giant electrorheological effect. In this paper, tetrabutyl titanate and oxalic acid and anhydrous ethanol are used to prepare porous titanyl oxalate precursor powder by precipitation method. The materials, morphology and grain size were analyzed by X-ray diffraction and electron microscope method. Conductivity was measured by a four-probe method, and then the infiltration property of water and silicone oil on the surface of the powder was investigated. The results show that Oxychloride titanium oxide precursor has good wettability to water and silicone oil. The wettability has little to do with the bath temperature and the pH of the solution. The contact angle of water on oxychloride titanium oxide precursor surface does not change greatly with the change of the bath temperature and pH, ranging from 26.8? to 31.1?. Similarly, the contact angle of silicone oil on the surface of the sample ranges from 9.5? to 11.5?. So, silicone oil has better wettability on the surface of the sample than water. Porous titanium oxalate is an insulating material having a resistivity more than 1 GΩ?cm. Oxychloride titanium oxide precursor is poor thermal stability, and it breaks down to generate TiO2 when the temperature is higher than 70?C.
