The polarization curves of mild steel in de-aerated 0.5 mol NaHCO 3+0.5 mol Na 2CO 3 solution with and without erodent particles of 300 g/L of 100 μm alumina have been measured using a rotating cylinder electrode (RC...The polarization curves of mild steel in de-aerated 0.5 mol NaHCO 3+0.5 mol Na 2CO 3 solution with and without erodent particles of 300 g/L of 100 μm alumina have been measured using a rotating cylinder electrode (RCE) apparatus over the range of rotation speeds from 0 to 4 000 r/min. The results show that the mild steel in the de-aerated slurry exhibits classical active/passive polarization behavior. The speed of cylinder rotation has a great effect in the presence of particles on the active dissolution current density. The erosion-corrosion process is severely erosion-dominated for the mild steel. However, the poor corrosion resistance of the mild steel in such turbulent slurries is also significant, especially at lower than 4 m/s.展开更多
研究对称起爆加载下金属样品内激波斜碰的早期动态力学行为,对分析其后续的动态演化与失效机制有着重要的意义。结合激波极曲线理论和数值模拟方法,开展两点侧面对称起爆加载下金属铅(Lead,Pb)、无氧铜(Oxygen-free high conductive cop...研究对称起爆加载下金属样品内激波斜碰的早期动态力学行为,对分析其后续的动态演化与失效机制有着重要的意义。结合激波极曲线理论和数值模拟方法,开展两点侧面对称起爆加载下金属铅(Lead,Pb)、无氧铜(Oxygen-free high conductive copper,Cu-OFHC)和钨合金(W-Ni-Fe alloy,W4Ni2Fe)的动态行为研究。利用激波极曲线方法和Hugoniot状态方程,得到3种金属激波反射形式发生转变时入射角和入射压力临界值之间的关系,并基于此结果分析仿真中3种金属内激波的对称斜碰特征。模拟结果显示3种金属都发生了马赫反射,吻合理论预测。通过对比3种金属内部横向同一区域的压力剖面发现:Pb的马赫杆宽度远大于Cu-OFHC和W4Ni2Fe;Pb中由入射激波、马赫杆和反射激波形成的三波加载区域也大于后两者,分析认为主要原因是Pb中的声速远小于后两者,造成碰撞区内激波相互作用的差异。基于自由面的速度历史剖面和判定准则估算这3种金属中最终形成的马赫杆宽度并讨论碰撞区的动态演化特征。结合对金属内部压力及自由面速度剖面的分析建立斜激波对称碰撞动态演化模型,为深入认识碰撞区的动态力学行为提供了理论支持。展开更多
The Ti-5Al-2Sn-4Zr-4Mo-2Cr-1Fe(β-CEZ)alloy is considered as a potential structural material in the aviation industry due to its outstanding strength and corrosion resistance.Electrochemical machining(ECM)is an effici...The Ti-5Al-2Sn-4Zr-4Mo-2Cr-1Fe(β-CEZ)alloy is considered as a potential structural material in the aviation industry due to its outstanding strength and corrosion resistance.Electrochemical machining(ECM)is an efficient and low-cost technology for manufacturing theβ-CEZ alloy.In ECM,the machining parameter selection and tool design are based on the electrochemical dissolution behavior of the materials.In this study,the electrochemical dissolution behaviors of theβ-CEZ and Ti-6Al-4V(TC4)alloys in NaNO3solution are discussed.The open circuit potential(OCP),Tafel polarization,potentiodynamic polarization,electrochemical impedance spectroscopy(EIS),and current efficiency curves of theβ-CEZ and TC4 alloys are analyzed.The results show that,compared to the TC4 alloy,the passivation film structure is denser and the charge transfer resistance in the dissolution process is greater for theβ-CEZ alloy.Moreover,the dissolved surface morphology of the two titanium-based alloys under different current densities are analyzed.Under low current densities,theβ-CEZ alloy surface comprises dissolution pits and dissolved products,while the TC4 alloy surface comprises a porous honeycomb structure.Under high current densities,the surface waviness of both the alloys improves and the TC4 alloy surface is flatter and smoother than theβ-CEZ alloy surface.Finally,the electrochemical dissolution models ofβ-CEZ and TC4 alloys are proposed.展开更多
Double-layered microcapsule corrosion inhibitors were developed by sodium monofluorophosphate as the core material,polymethyl methacrylate as the inner wall material,and polyvinyl alcohol as the outer wall material co...Double-layered microcapsule corrosion inhibitors were developed by sodium monofluorophosphate as the core material,polymethyl methacrylate as the inner wall material,and polyvinyl alcohol as the outer wall material combining the solvent evaporation method and spray drying method.The protection by the outer capsule wall was used to prolong the service life of the corrosion inhibitor.The dispersion,encapsulation,thermal stability of microcapsules,and the degradation rate of capsule wall in concrete pore solution were analyzed by ultra-deep field microscopy,scanning electron microscopy,thermal analyzer,and sodium ion release rate analysis.The microcapsules were incorporated into mortar samples containing steel reinforcement,and the effects of double-layered microcapsule corrosion inhibitors on the performance of the cement matrix and the actual corrosion-inhibiting effect were analyzed.The experimental results show that the double-layered microcapsules have a moderate particle size and uniform distribution,and the capsules were completely wrapped.The microcapsules as a whole have good thermal stability below 230 ℃.The monolayer membrane structure microcapsules completely broke within 1 day in the simulated concrete pore solution,and the double-layer membrane structure prolonged the service life of the microcapsules to 80 days in the simulated concrete pore solution before the core material was completely released.The mortar samples containing steel reinforcement incorporated with the double-layered microcapsule corrosion inhibitors still maintained a higher corrosion potential than the monolayer microcapsule corrosion inhibitors control group at 60 days.The incorporation of double-layered microcapsules into the cement matrix has no significant adverse effect on the setting time and early strength.展开更多
文摘The polarization curves of mild steel in de-aerated 0.5 mol NaHCO 3+0.5 mol Na 2CO 3 solution with and without erodent particles of 300 g/L of 100 μm alumina have been measured using a rotating cylinder electrode (RCE) apparatus over the range of rotation speeds from 0 to 4 000 r/min. The results show that the mild steel in the de-aerated slurry exhibits classical active/passive polarization behavior. The speed of cylinder rotation has a great effect in the presence of particles on the active dissolution current density. The erosion-corrosion process is severely erosion-dominated for the mild steel. However, the poor corrosion resistance of the mild steel in such turbulent slurries is also significant, especially at lower than 4 m/s.
文摘研究对称起爆加载下金属样品内激波斜碰的早期动态力学行为,对分析其后续的动态演化与失效机制有着重要的意义。结合激波极曲线理论和数值模拟方法,开展两点侧面对称起爆加载下金属铅(Lead,Pb)、无氧铜(Oxygen-free high conductive copper,Cu-OFHC)和钨合金(W-Ni-Fe alloy,W4Ni2Fe)的动态行为研究。利用激波极曲线方法和Hugoniot状态方程,得到3种金属激波反射形式发生转变时入射角和入射压力临界值之间的关系,并基于此结果分析仿真中3种金属内激波的对称斜碰特征。模拟结果显示3种金属都发生了马赫反射,吻合理论预测。通过对比3种金属内部横向同一区域的压力剖面发现:Pb的马赫杆宽度远大于Cu-OFHC和W4Ni2Fe;Pb中由入射激波、马赫杆和反射激波形成的三波加载区域也大于后两者,分析认为主要原因是Pb中的声速远小于后两者,造成碰撞区内激波相互作用的差异。基于自由面的速度历史剖面和判定准则估算这3种金属中最终形成的马赫杆宽度并讨论碰撞区的动态演化特征。结合对金属内部压力及自由面速度剖面的分析建立斜激波对称碰撞动态演化模型,为深入认识碰撞区的动态力学行为提供了理论支持。
基金supported by the National Natural Science Foundation of China(No.92160301)the Industrial Technology Development Program,China(No.JCKY2021605 B026)。
文摘The Ti-5Al-2Sn-4Zr-4Mo-2Cr-1Fe(β-CEZ)alloy is considered as a potential structural material in the aviation industry due to its outstanding strength and corrosion resistance.Electrochemical machining(ECM)is an efficient and low-cost technology for manufacturing theβ-CEZ alloy.In ECM,the machining parameter selection and tool design are based on the electrochemical dissolution behavior of the materials.In this study,the electrochemical dissolution behaviors of theβ-CEZ and Ti-6Al-4V(TC4)alloys in NaNO3solution are discussed.The open circuit potential(OCP),Tafel polarization,potentiodynamic polarization,electrochemical impedance spectroscopy(EIS),and current efficiency curves of theβ-CEZ and TC4 alloys are analyzed.The results show that,compared to the TC4 alloy,the passivation film structure is denser and the charge transfer resistance in the dissolution process is greater for theβ-CEZ alloy.Moreover,the dissolved surface morphology of the two titanium-based alloys under different current densities are analyzed.Under low current densities,theβ-CEZ alloy surface comprises dissolution pits and dissolved products,while the TC4 alloy surface comprises a porous honeycomb structure.Under high current densities,the surface waviness of both the alloys improves and the TC4 alloy surface is flatter and smoother than theβ-CEZ alloy surface.Finally,the electrochemical dissolution models ofβ-CEZ and TC4 alloys are proposed.
基金Fund by the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (No.2018YFD1101002-03)。
文摘Double-layered microcapsule corrosion inhibitors were developed by sodium monofluorophosphate as the core material,polymethyl methacrylate as the inner wall material,and polyvinyl alcohol as the outer wall material combining the solvent evaporation method and spray drying method.The protection by the outer capsule wall was used to prolong the service life of the corrosion inhibitor.The dispersion,encapsulation,thermal stability of microcapsules,and the degradation rate of capsule wall in concrete pore solution were analyzed by ultra-deep field microscopy,scanning electron microscopy,thermal analyzer,and sodium ion release rate analysis.The microcapsules were incorporated into mortar samples containing steel reinforcement,and the effects of double-layered microcapsule corrosion inhibitors on the performance of the cement matrix and the actual corrosion-inhibiting effect were analyzed.The experimental results show that the double-layered microcapsules have a moderate particle size and uniform distribution,and the capsules were completely wrapped.The microcapsules as a whole have good thermal stability below 230 ℃.The monolayer membrane structure microcapsules completely broke within 1 day in the simulated concrete pore solution,and the double-layer membrane structure prolonged the service life of the microcapsules to 80 days in the simulated concrete pore solution before the core material was completely released.The mortar samples containing steel reinforcement incorporated with the double-layered microcapsule corrosion inhibitors still maintained a higher corrosion potential than the monolayer microcapsule corrosion inhibitors control group at 60 days.The incorporation of double-layered microcapsules into the cement matrix has no significant adverse effect on the setting time and early strength.
