NiFe2O4-10NiO-based cermet inert anodes for aluminium electrolysis were prepared and their properties were investigated in a lab-scale electrolysis cell. The results show that the inert anodes exhibit good performance...NiFe2O4-10NiO-based cermet inert anodes for aluminium electrolysis were prepared and their properties were investigated in a lab-scale electrolysis cell. The results show that the inert anodes exhibit good performance during electrolysis in molten salt cryolite at 960 °C, but according to the analyses of phase compositions and microstructures through XRD, SEM/EDX and metallographic analysis, the metal in the anodes is preferentially corroded and many pores are produced on the anode surface after electrolysis. The preferential dissolution of Fe in the NiFe2O4 phase may lead to the non-uniform corrosion of NiFe2O4 grains. Moreover, a dense protective layer of NiFe2O4-NiAl2O4-FeAl2O4 is formed on the anode surface, which originates from the reaction of Al2O3 dissolved in the electrolyte with NiO or FeO, the annexation of NiFe2O4-NiAl2O4-FeAl2O4 to NiO and volume expansion. Thus, the dense NiFe2O4-NiAl2O4-FeAl2O4 layer inhibits the metal loss and ceramic-phase corrosion on the surface of the cermet inert anodes.展开更多
To explore the corrosion properties of magnesium alloys, the chemical behavior of a high strength Mg_(97)Zn_(1)Y_(2)-1 wt.%Si C alloy in different corrosion environments was studied. Three solutions of 0.2 mol·L^...To explore the corrosion properties of magnesium alloys, the chemical behavior of a high strength Mg_(97)Zn_(1)Y_(2)-1 wt.%Si C alloy in different corrosion environments was studied. Three solutions of 0.2 mol·L^(-1) NaCl, Na_(2)SO_(4) and NaNO_(3) were selected as corrosion solutions. The microstructures, corrosion rate, corrosion potential, and mechanism were investigated qualitatively and quantitatively by optical microscopy(OM), scanning electron microscopy(SEM), immersion testing experiment, and electrochemical test. Microstructure observation shows that the Mg_(97) Zn_(1)Y_(2)-1 wt.%Si C alloy is composed of α-Mg matrix, LPSO(Mg_(12) ZnY) phase and Si C phase. The hydrogen evolution and electrochemical test results reflect that the Mg_(97)Zn_(1)Y_(2)-1 wt.%SiC in 0.2 mol·L^(-1) Na Cl solution has the fastest corrosion rate, followed by Na_(2)SO_(4) and NaNO_(3) solutions, and that the charge-transfer resistance presents the contrary trend and decreases in turn.展开更多
The corrosion behavior of BFe10-1-1 alloy with different rare earth （RE） contents in simulated flowing marine water was investigated by X-ray diffractometer and scanning electron microscope （SEM）. It was demonstra...The corrosion behavior of BFe10-1-1 alloy with different rare earth （RE） contents in simulated flowing marine water was investigated by X-ray diffractometer and scanning electron microscope （SEM）. It was demonstrated that the corrosion rate of BFel0-1-1 alloy with the same chemical compositions in faster flow velocity of marine water was higher than that in a lower flow velocity of marine water. Fixing the flow velocity, BFe 10-1-1 alloy had the best flushing corrosion resistance when the RE content was 0.04wt.%. The consequence of such good corrosion resistance was attributed to the formation of compact protective film on alloy surface containing RE phase such as CeNis. The RE-contained film combines with other corrosion products firmly, which was difficult to fall off from the alloy surface in the flowing marine water. Additionally, SEM analysis confirmed that pitting mechanism, which would be transformed to spalling mechanism gradually with further increasing RE content, was the prevalent mechanism when the alloy contained 0.04wt.%RE.展开更多
The influence of chloride or sulphur dioxide on the corrosion behavior of copper tube in the air-conditioning system was studied using scanning electron microscope (SEM), energy dispersion spectrometer (EDS) and cycli...The influence of chloride or sulphur dioxide on the corrosion behavior of copper tube in the air-conditioning system was studied using scanning electron microscope (SEM), energy dispersion spectrometer (EDS) and cyclic polarization techniques. The results showed that the corrosion of copper tube are mainly caused by the SO42- and Cl- ions in the circulating water, and the former is mainly responsible for the general corrosion of the copper tube whilst the latter for the pitting corrosion. The different influences of SG42- and Cl- ions on the corrosion type of copper tube may be attributed to that the radius of SO42- ion is much larger than that of Cl- ion. Meanwhile the results also indicated that SO42- inhibits the pitting corrosion caused by Cl- and Cl- inhibits the general corrosion initiated by SO42- due to their competitive adsorption on the copper matrix.展开更多
The CaO-doped Cu/（NiFe2O4-10NiO） cermet inert anodes were prepared by the cold isostatie pressing-sintering process, and their corrosion resistance to Na3AlF6-K3AlF6-Al203 melt was studied. The results show that the...The CaO-doped Cu/（NiFe2O4-10NiO） cermet inert anodes were prepared by the cold isostatie pressing-sintering process, and their corrosion resistance to Na3AlF6-K3AlF6-Al203 melt was studied. The results show that the relative density of 5Cu/（NiFe2O4-10NiO） cermet sintered at 1 200 ℃ increases from 82.83% to 97.63% when 2% CaO （mass fraction） is added. During the electrolysis, the relative density of cermet inert anode descends owing to the chemical dissolution of additive CaO at ceramic grain boundary, which accelerates the penetration of electrolyte. Thus, the corrosion resistance to melts of Cu/（NiFe2O4-10NiO） cermet inert anode is reduced. To improve the corrosion resistance of the cermet inert anode, the content of CaO doped should be decreased and the technology of cleaning the ceramic grain boundary should be applied.展开更多
Effects of FeO content （0, 5%, 10%, and 15% in mass, respectively ） in lab-synthesized smelting redttc- tion slag with iron bath and test temperature （1 450, 1 500, 1550, anti 1 600 ℃ ） on corrosion am,amount and...Effects of FeO content （0, 5%, 10%, and 15% in mass, respectively ） in lab-synthesized smelting redttc- tion slag with iron bath and test temperature （1 450, 1 500, 1550, anti 1 600 ℃ ） on corrosion am,amount and microstructure of fused rebonded magnesia - chrome brick with 26.02 massqc of Cr2O3 were researched by rotary cylinder method. The results show that ： （ 1 ） the corro- sion amolult of magnesia -chrome brick by slag without FeO is higher than that by the slag with 5% FeO, and the vorrosion amount increases when FeO content increa- ses from 5% to 15% ; （2） the test temperature is one of the important factors affecting the slag corrosion resist- ance of magnesia - chrome brick, and the corrosion of smelting reduction slag to brick increases with the temperature rising.展开更多
Corrosion of metal components constitutes a major challenge in many engineering systems, with appropriate design, proper material selection, and heat treatment as commonly used control strategies. In this study, the c...Corrosion of metal components constitutes a major challenge in many engineering systems, with appropriate design, proper material selection, and heat treatment as commonly used control strategies. In this study, the corrosion behaviour of heat-treated (annealed, normalised, hardened, and tempered) NST 37-2 steel in three concentrations (1.0, 1.5 and 2.0 M) of hydrochloric acid solution was investigated using weight loss and electrode-potential methods. Results showed that corrosion rate increased with increase in acid concentration. The decreasing order of corrosion resistance was Tempered > Annealed > Normalised > Hardened > Untreated. The surface pictures of the heat-treated and untreated samples showed uniform and pitting corrosion with the latter becoming more pronounced as concentration increased.展开更多
7-(2-ethyltiophenyl) theophylline was used as copper corrosion inhibitor in 1M HNO3 solution. The study was performed using mass loss, scanning electron microscopy (SEM) and Density Functional Theory (DFT) methods. Th...7-(2-ethyltiophenyl) theophylline was used as copper corrosion inhibitor in 1M HNO3 solution. The study was performed using mass loss, scanning electron microscopy (SEM) and Density Functional Theory (DFT) methods. The results show that the inhibition efficiency increases up to 91.29% with increase of the inhibitor concentration (from 0.05 to 5 mM) but decreases with raising temperature of the solution. Copper dissolution was found to be temperature and 7-(2-ethyltiophenyl) theophylline concentration dependent. The thermodynamic functions related to the adsorption of the molecule on the copper surface and that of the metal dissolution were determined. The results point out a spontaneous adsorption and an endothermic dissolution processes. Adsorption models including Langmuir, El-Awady and Flory-Huggins isotherms were examined. The results also suggest spontaneous and predominant physical adsorption of 7-(2-ethyltiophenyl) theophylline on the metal surface which obeys Langmuir isotherm model. Further investigation on the morphology using scanning electron microscopy (SEM) has confirmed the existence of a protective film of inhibitor molecules on copper surface. Furthermore, the global and local reactivity parameters of the studied molecule were analyzed. Experimental and theoretical results were found to be in good agreement.展开更多
基金Project (2012FJ6123) supported by the Project of Science and Technology of Hunan Province,ChinaProject supported by Post-Doctoral Foundation of Central South University,China+1 种基金Project (CL12100) supported the Undergraduate Innovative Training of Central South University,ChinaProject (2282013bkso13) supported by Free Exploration Plan of Central South University,China
文摘NiFe2O4-10NiO-based cermet inert anodes for aluminium electrolysis were prepared and their properties were investigated in a lab-scale electrolysis cell. The results show that the inert anodes exhibit good performance during electrolysis in molten salt cryolite at 960 °C, but according to the analyses of phase compositions and microstructures through XRD, SEM/EDX and metallographic analysis, the metal in the anodes is preferentially corroded and many pores are produced on the anode surface after electrolysis. The preferential dissolution of Fe in the NiFe2O4 phase may lead to the non-uniform corrosion of NiFe2O4 grains. Moreover, a dense protective layer of NiFe2O4-NiAl2O4-FeAl2O4 is formed on the anode surface, which originates from the reaction of Al2O3 dissolved in the electrolyte with NiO or FeO, the annexation of NiFe2O4-NiAl2O4-FeAl2O4 to NiO and volume expansion. Thus, the dense NiFe2O4-NiAl2O4-FeAl2O4 layer inhibits the metal loss and ceramic-phase corrosion on the surface of the cermet inert anodes.
基金Financially supported by the National Natural Science Foundation of China (51665012)the Jiangxi Province Science Foundation for Outstanding Scholarship (20171BCB23061,2018ACB21020)the Primary Research & Development Plan of Jiangxi Province (20192BBEL50019)。
文摘To explore the corrosion properties of magnesium alloys, the chemical behavior of a high strength Mg_(97)Zn_(1)Y_(2)-1 wt.%Si C alloy in different corrosion environments was studied. Three solutions of 0.2 mol·L^(-1) NaCl, Na_(2)SO_(4) and NaNO_(3) were selected as corrosion solutions. The microstructures, corrosion rate, corrosion potential, and mechanism were investigated qualitatively and quantitatively by optical microscopy(OM), scanning electron microscopy(SEM), immersion testing experiment, and electrochemical test. Microstructure observation shows that the Mg_(97) Zn_(1)Y_(2)-1 wt.%Si C alloy is composed of α-Mg matrix, LPSO(Mg_(12) ZnY) phase and Si C phase. The hydrogen evolution and electrochemical test results reflect that the Mg_(97)Zn_(1)Y_(2)-1 wt.%SiC in 0.2 mol·L^(-1) Na Cl solution has the fastest corrosion rate, followed by Na_(2)SO_(4) and NaNO_(3) solutions, and that the charge-transfer resistance presents the contrary trend and decreases in turn.
基金supported by the Science and Technology Payoffs Transformation Program of Jiangsu Province (DA2006034)the Program of National College Student Creative Experiment (081053309)
文摘The corrosion behavior of BFe10-1-1 alloy with different rare earth （RE） contents in simulated flowing marine water was investigated by X-ray diffractometer and scanning electron microscope （SEM）. It was demonstrated that the corrosion rate of BFel0-1-1 alloy with the same chemical compositions in faster flow velocity of marine water was higher than that in a lower flow velocity of marine water. Fixing the flow velocity, BFe 10-1-1 alloy had the best flushing corrosion resistance when the RE content was 0.04wt.%. The consequence of such good corrosion resistance was attributed to the formation of compact protective film on alloy surface containing RE phase such as CeNis. The RE-contained film combines with other corrosion products firmly, which was difficult to fall off from the alloy surface in the flowing marine water. Additionally, SEM analysis confirmed that pitting mechanism, which would be transformed to spalling mechanism gradually with further increasing RE content, was the prevalent mechanism when the alloy contained 0.04wt.%RE.
文摘The influence of chloride or sulphur dioxide on the corrosion behavior of copper tube in the air-conditioning system was studied using scanning electron microscope (SEM), energy dispersion spectrometer (EDS) and cyclic polarization techniques. The results showed that the corrosion of copper tube are mainly caused by the SO42- and Cl- ions in the circulating water, and the former is mainly responsible for the general corrosion of the copper tube whilst the latter for the pitting corrosion. The different influences of SG42- and Cl- ions on the corrosion type of copper tube may be attributed to that the radius of SO42- ion is much larger than that of Cl- ion. Meanwhile the results also indicated that SO42- inhibits the pitting corrosion caused by Cl- and Cl- inhibits the general corrosion initiated by SO42- due to their competitive adsorption on the copper matrix.
基金Project(2005CB623703) supported by the Major State Basic Research and Development Program of ChinaProject(2008AA030503) supported by Hi-Tech Research and Development Program of China
文摘The CaO-doped Cu/（NiFe2O4-10NiO） cermet inert anodes were prepared by the cold isostatie pressing-sintering process, and their corrosion resistance to Na3AlF6-K3AlF6-Al203 melt was studied. The results show that the relative density of 5Cu/（NiFe2O4-10NiO） cermet sintered at 1 200 ℃ increases from 82.83% to 97.63% when 2% CaO （mass fraction） is added. During the electrolysis, the relative density of cermet inert anode descends owing to the chemical dissolution of additive CaO at ceramic grain boundary, which accelerates the penetration of electrolyte. Thus, the corrosion resistance to melts of Cu/（NiFe2O4-10NiO） cermet inert anode is reduced. To improve the corrosion resistance of the cermet inert anode, the content of CaO doped should be decreased and the technology of cleaning the ceramic grain boundary should be applied.
文摘Effects of FeO content （0, 5%, 10%, and 15% in mass, respectively ） in lab-synthesized smelting redttc- tion slag with iron bath and test temperature （1 450, 1 500, 1550, anti 1 600 ℃ ） on corrosion am,amount and microstructure of fused rebonded magnesia - chrome brick with 26.02 massqc of Cr2O3 were researched by rotary cylinder method. The results show that ： （ 1 ） the corro- sion amolult of magnesia -chrome brick by slag without FeO is higher than that by the slag with 5% FeO, and the vorrosion amount increases when FeO content increa- ses from 5% to 15% ; （2） the test temperature is one of the important factors affecting the slag corrosion resist- ance of magnesia - chrome brick, and the corrosion of smelting reduction slag to brick increases with the temperature rising.
文摘Corrosion of metal components constitutes a major challenge in many engineering systems, with appropriate design, proper material selection, and heat treatment as commonly used control strategies. In this study, the corrosion behaviour of heat-treated (annealed, normalised, hardened, and tempered) NST 37-2 steel in three concentrations (1.0, 1.5 and 2.0 M) of hydrochloric acid solution was investigated using weight loss and electrode-potential methods. Results showed that corrosion rate increased with increase in acid concentration. The decreasing order of corrosion resistance was Tempered > Annealed > Normalised > Hardened > Untreated. The surface pictures of the heat-treated and untreated samples showed uniform and pitting corrosion with the latter becoming more pronounced as concentration increased.
文摘7-(2-ethyltiophenyl) theophylline was used as copper corrosion inhibitor in 1M HNO3 solution. The study was performed using mass loss, scanning electron microscopy (SEM) and Density Functional Theory (DFT) methods. The results show that the inhibition efficiency increases up to 91.29% with increase of the inhibitor concentration (from 0.05 to 5 mM) but decreases with raising temperature of the solution. Copper dissolution was found to be temperature and 7-(2-ethyltiophenyl) theophylline concentration dependent. The thermodynamic functions related to the adsorption of the molecule on the copper surface and that of the metal dissolution were determined. The results point out a spontaneous adsorption and an endothermic dissolution processes. Adsorption models including Langmuir, El-Awady and Flory-Huggins isotherms were examined. The results also suggest spontaneous and predominant physical adsorption of 7-(2-ethyltiophenyl) theophylline on the metal surface which obeys Langmuir isotherm model. Further investigation on the morphology using scanning electron microscopy (SEM) has confirmed the existence of a protective film of inhibitor molecules on copper surface. Furthermore, the global and local reactivity parameters of the studied molecule were analyzed. Experimental and theoretical results were found to be in good agreement.
