邻胺基苯酚在Al-Ga-Sn-Mg/KOH环境中的抑氢作用

通过恒电流集气、稳态极化曲线、交流阻抗等电化学方法探讨了邻胺基苯酚在4 mol/L KOH溶液中对Al-0.2Ga-0.1Sn-1Mg的自腐蚀抑氢作用,分析了其作用机理.结果表明：铝合金在强碱性介质中的自腐蚀析氢呈现出典型的正差异效应,自腐蚀严重.由于苯环、胺基、羟基等基团的存在使得邻胺基苯酚易在金属的表面吸附,减少了OH-与金属表面接触的机会,析氢量降低,自腐蚀程度减轻,但铝阳极的活性没有降低,正差异效应的规律也没有改变,是碱性介质中铝阳极的良好添加剂.     

氨络合物体系中Ti基IrO2涂层阳极的析氮过程

采用线性扫描技术研究了氯盐氨络合物体系中Ti基IrO2涂层阳极的析氮过程,对3种含有不同氧化物涂层电极的析氮电催化性能进行了比较,并结合扫描电镜(SEM)及能谱(EDX)探讨了不同析氮电催化活性的原因.研究结果表明:当电极电位低于1.1 V(vs SCE)时,Ti基IrO2涂层阳极析气反应主要为析氮反应,氮气的产生主要是由于氨水在电极上发生电化学氧化引起的;Ti基含PdRuTi的IrO2涂层阳极具有最佳的析氮电催化活性,其可能原因是金属元素PdRuTi的存在导致该电极表面特征裂纹最宽且最深,氧化物涂层总析氮面积增多,电催化活性增加.     

溶胶凝胶法制备Ru-Ir-Sn-Ti阳极涂层及其电化学性能研究

采用溶胶凝胶法制备Ru-Ir-Sn-Ti阳极涂层,对涂层进行析氯电位、析氧电位、极化曲线、循环伏安曲线、电化学交流阻抗等电化学测试以及强化电解寿命测试,并与热分解法制备的阳极涂层进行对比。结果表明:与热分解法制备的阳极涂层相比,溶胶凝胶法制备的Ru-Ir-Sn-Ti阳极涂层具有较低的析氯电位、较高的析氧电位、良好的电催化活性和较长的强化电解寿命。     

Nd对锌电积用Pb-Ag合金阳极性能的影响

采用恒流极化、失重法和抗拉强度测试研究不同含量Nd的加入对锌电积用铅银合金阳极主要性能(稳定阳极电位、耐腐蚀性能及力学性能)的影响,并在此基础上采用循环伏安(CV)和计时电位(CP)等电化学手段对恒流极化条件下Nd的作用机理进行研究。结果表明:0.03%Nd(质量分数)加入可以将Pb-Ag合金的抗拉强度提高21.8%;锌电积条件下,铅阳极表面腐蚀膜主要成分为PbO2及PbSO4,Nd加入可以抑制PbSO4的形成,从而明显降低阳极腐蚀速率;由于Nd能降低析氧过电位,且对高阻抗PbSO4的生成具有抑制作用,使得Pb-Ag合金的阳极电位亦有一定程度的下降。Nd对锌电积阳极主要性能均有较大程度的改进作用,是很好的锌电积阳极改性剂,具有较好的工业应用前景。     

金属高温塑性成形微观组织演变研究进展

金属在热加工过程中微观组织发生动态、静态回复以及再结晶、晶粒长大等一系列复杂的演化,材料内部微观结构的改变,会直接影响成形后金属的成形质量和力学性能。文章阐述了金属高温塑性成形时微观组织预测模拟的主要研究方法,即直接模拟法、相场法和有限元法;并分别评述了各方法目前在国内外的研究概况、特点以及缺点和适用范围;重点介绍了基于物理本质多尺度耦合的微观组织内变量有限元模型方法。研究结果表明,基于内变量法的微观组织物理模型相对其他方法,最适合用于多尺度微观组织预测数值模拟,模拟结果与实际更为相符,而且最能解释说明各变量演变的物理机制,具有广阔的应用前景。     

The durability of different elements doped manganese dioxide-coated anodes for oxygen evolution in seawater electrolysis

Manganese-molybdenum (Mn-Mo), manganese-molybdenum-vanadium (Mn-Mo-V), manganese-molybdenum-iron (Mn-Mo-Fe) and manganese-iron-vanadium (Mn-Fe-V) anodes were prepared by anodic electrodeposition on iridium oxide-coated titanium substrates for oxygen evolution in seawater electrolysis. XRD, FESEM, EDX and oxygen evolution efficient analysis revealed that the prepared anodes had a γ-MnO₂ structure and show a unique mesh-like nanostructure. Oxygen evolution efficiencies were all measured to be more than 99%. The durability tests were performed at 1000 A·m^− 2 in 3.5 wt% NaCl solution at pH 12 and 90 °C. The Mn-Fe-V anode was the most stable electrode during the sea water electrolysis, and maintained an oxygen evolution efficiency of 87.96% even after 500 h. It has been found that the main reason for the eventual decrease in oxygen evolution efficiency was partly because of the peeling and electrochemical dissolution of the oxide layer after electrolysis. Also, it was found that the addition of iron and vanadium would maintain a high level of oxygen evolution efficiency during electrolysis.     

Microstructure evolution in the local loading forming of TA15 titanium alloy under non-isothermal condition

In this paper, the microstructure evolution and processing–microstructure relationship in the non-isothermal local loading forming of TA15 titanium alloy were studied through an analog experiment. Some new microstructural mechanisms are found, which are different from those under isothermal local loading forming. In the non-isothermal local loading forming, the tri-modal microstructure consisted of equiaxed primary α, lamellar α and β transformed matrix is achieved. The lamellar α, not produced under isothermal condition, is generated by β → α transformation due to the decrease of component temperature. With the same processing parameters, the volume fraction and grain size of primary α are both greater than those processed isothermally. The content of lamellar α decreases with heating temperature decreasing and little lamellar α can be found when the heating temperature drops to 930 °C. Under small deformation degree, the lamellar α distributes randomly in each feature region. As deformation increases, the lamellar α in transitional region and second-loading region present a preferred orientation perpendicular to the compression direction. The primary α content almost decreases linearly with heating temperature, which is different from the regular that under isothermal condition. Non-isothermal local loading forming with a higher heating temperature (near-β region) offers a cost-efficient way for the manufacture of TA15 titanium alloy large-scale integral components.     

Performance of supercritical carbon dioxide sprays as coolants and lubricants in representative metalworking operations

This paper investigates the cooling and lubrication properties of supercritical carbon dioxide (scCO₂) sprays as potential substitutes for aqueous emulsions and straight oils used in the metalworking industry today. Sprays of rapidly expanding scCO₂ act to cool and lubricate machining and forming processes by delivering a mixture of dry ice and lubricant deep into the cutting/forming zone. In this work, experiments with turning, milling, drilling, thread cutting, and thread forming were performed with scCO₂ and other metalworking fluids (MWFs) to evaluate their relative performance with respect to tool wear and machining torque. Observations reveal that scCO₂–MWFs are more effective in removing heat from the tool-workpiece interface than conventionally delivered (flood) aqueous MWFs as well as other gas-based MWF sprays. In addition, scCO₂–MWFs delivered in lubricant-expanded phase, where scCO₂ is used to increase volume of lubricant in the spray field, are shown to provide better lubricity than straight oils and oil-in-air minimum quantity lubrication (MQL) sprays. As a result, scCO₂–MWFs can reduce tool wear and improve machining productivity in a wide range of manufacturing operations leading to appreciable improvements in the economics of manufacturing. Also given that CO₂ is a recovered waste gas that is non-toxic, scCO₂–MWFs can improve the environmental and worker health performance of manufacturing operations.     

电化学阻抗谱研究负向电压对AZ31B镁合金微弧氧化陶瓷层致密性的影响

采用单极性和双极性脉冲,分别改变几种不同正向电压时的负向电压,在AZ31B镁合金表面制备了微弧氧化膜。利用电化学阻抗谱和扫描电镜研究氧化膜的等效电路元件值以及微观结构的变化,从而分析负向电压对镁合金微弧氧化膜致密性的影响。结果表明：负向电压对于微弧氧化陶瓷膜致密性具有至关重要的作用,适当的负向电压可以有效地提高膜层致密性。并且,不同的正向电压下形成致密氧化膜的负向电压都约为30 V,不随正向电压变化而变化。     

Review and application of closed-loop systems in flow-induced corrosion

Various closed-loop systems have been developed in recent years to investigate flow-induced corrosion. Because of different parameters and techniques used by investigators, interpretation of results is often confusing and complicated. This paper presents a review of important techniques employed and interpretation of corrosion data.