氨基酸复配酸洗缓蚀剂的研究

目的氨基酸对环境无毒无害,生产成本低,可生物降解且水溶性较高,是一种极具发展潜力的新型绿色酸洗缓蚀剂。探究在盐酸介质中,氨基酸及复配缓蚀剂对Q235钢的缓蚀作用。方法采用失重法,利用电子分析天平精确称量浸入腐蚀介质前后金属试样的质量来确定金属的腐蚀速率。研究了L-半胱氨酸及其复配缓蚀剂在1 mol/L盐酸介质中对Q235钢的缓蚀性能,借助等温吸附模型对其缓蚀机理进行了探讨。结果单独使用L-半胱氨酸缓蚀效率较低。当质量浓度为800 mg/L时,L-半胱氨酸的缓蚀效率达到最大值,为65.57%。复配合成缓蚀剂能降低经济成本,并提高缓蚀效率。通过三元复配实验得出L-半光氨酸、KI和抗坏血酸的最佳复配比,当L-半胱氨酸、KI、抗坏血酸的质量浓度分别为20、30、250 mg/L时,其缓蚀效率可达96.37%,且成本较低,是较理想的复配缓蚀剂。复配缓蚀剂在Q235钢表面的吸附符合Langmuir吸附等温模型。结论在盐酸介质中,L-半胱氨酸三元复配缓蚀剂整体用量适中,价格合理,证明复配缓蚀剂是一种能够得到良好应用的绿色缓蚀剂。     

硫酸介质中氨基酸对钢的缓蚀性能

通过自腐蚀电位、极化曲线和阻抗谱等电化学测试方法,研究了半胱氨酸、蛋氨酸两种氨基酸作为缓蚀剂在0.5 mol/L硫酸介质中对X65钢的缓蚀性能.研究结果表明:该缓蚀剂在较低的浓度具有良好的缓蚀效果,缓蚀效率随着浓度的增加而提高;同浓度比较,半胱氨酸的缓蚀效率更高.缓蚀原因可能是氨基酸分子或腐蚀产物在金属表面的吸附作用;极化曲线表明是混合型缓蚀剂.     

硫酸体系中氨基酸复合缓蚀剂

采用失重法和扫描电镜法,研究了氨基酸复合缓蚀剂对浸于0.5 mol/L硫酸介质中碳钢的缓蚀作用,并通过试验确定了与氨基酸有较好缓蚀效应的缓蚀剂配方。结果表明:单一半胱氨酸、蛋氨酸对硫酸中碳钢的缓蚀率随着它们浓度的增加而增加,半胱氨酸、蛋氨酸使用浓度为800 mg/L时,缓蚀率分别为74.81%和63.36%,分别用浓度为800 mg/L半胱氨酸、蛋氨酸与碘化钾复配,碘化钾浓度分别达到800 mg/L和500 mg/L时缓蚀率才达到90%左右,且使用成本增加;三元复配缓蚀剂中,蛋氨酸∶HTAB∶KI为20 mg/L∶10 mg/L∶20 mg/L时,缓蚀率可达到98.21%,而且使用成本低。通过热力学和动力学原理探讨了缓蚀机理,扫描电镜图像表明,添加缓蚀剂后金属表面腐蚀轻微,表面光滑,没有明显的点蚀倾向。缓蚀剂对金属表面起到很好的保护作用。     

硫酸盐还原菌对Cu在循环冷却水中腐蚀行为的影响

采用电化学测量方法和表面分析技术研究了硫酸盐还原菌对Cu电极在循环冷却水系统中腐蚀行为的影响,并初步探索了L-半胱氨酸对Cu材料的缓蚀效果。结果表明,有菌体系中Cu电极的极化电阻呈现先增大后减小的趋势,且在有菌环境中浸泡第10 d时Cu电极的极化电阻比在无菌环境中的小25.82 kΩ·cm~2。有菌体系中Cu电极的自腐蚀电流密度先减小后增大,与电化学阻抗谱实验呈现相同的趋势。有菌体系中加入不同浓度的L-半胱氨酸后,Cu电极的阻抗弧半径均有所增大,且自腐蚀电流密度均有不同程度的减小,在浓度为10~(-3)mol/L时缓蚀效果最佳。     

氨基酸对7B50铝合金在1mol/L NaCl+0.1mol/L HCl溶液中缓蚀性能的影响

采用静态失重法与电化学阻抗谱评价4种氨基酸对7B50超高强度铝合金在1 mol/L Na Cl+0.1 mol/L HCl溶液中的缓蚀行为,并通过腐蚀形貌表征氨基酸的缓蚀机理。结果表明:氨基酸浓度越高、温度越低,氨基酸对铝合金的缓蚀效率就越高。添加氨基酸后,溶液中铝合金的表观活化能均增大,其中,半胱氨酸(Cys)和蛋氨酸(Met)的表观活化能最高,这归因于—SH或—SCH3基团对铝合金表面优良的吸附作用。在4种氨基酸中,0.05 mol/L半胱氨酸(Cys)中含—SH基团的缓蚀效率最高,室温下高达94.7%;Met的次之,主要是由于—SCH3的空间位阻效应所致;苯丙氨酸(Phe)的缓蚀性能较差;低浓度的组氨酸(His)缓蚀能力相对不佳,而高浓度的His在较高温下仍保持着较高的缓蚀效率,这说明His的缓蚀效率受温度的影响较小。因此,His相应的表观活化能也较低。浸泡实验后的金相结果表明:添加氨基酸后会不同程度地抑制铝合金的晶间腐蚀和点蚀。     

L-苯丙氨酸对Q235钢在硫酸中的缓蚀作用

采用电化学方法,研究了L-苯丙氨酸对Q235钢在0.5mol/L H2SO4溶液中的缓蚀作用及缓蚀机理,分析了其缓蚀剂类型。结果表明:L-苯丙氨酸的缓蚀效率随浓度的增加而增大,而且随着温度的升高,Q235钢表面单个活性位点上吸附的缓蚀剂分子数量增加,缓蚀效率也增大;L-苯丙氨酸属于混合抑制型缓蚀剂,作用机理为几何覆盖效应,其在Q235钢表面的吸附为单分子吸附,且吸附规律符合El-Awady动力学模型。     

《电镀与精饰》2011年第3期

<正>L半胱氨酸自组装膜对间苯二酚氧化的电催化作用电沉积ZnO薄膜超声处理后结构和缺陷的研究-研究了pH对L-半胱氨酸自组装膜修饰电极的影响,发现该膜对间苯二酚的电化学氧化具有明显的催化作用。在pH=6.86的L-半胱氨酸溶液中制得的膜最致密。在pH=5的醋酸钠-醋酸缓冲溶液中,间苯二酚在L-半胱氨酸自组装膜修饰电极上产生一灵敏的氧化峰,且峰电流与间苯二酚浓度在0.1～0.6mmol/L范围内呈良好的线性关系     

2-巯基苯并咪唑与L-半胱氨酸在HCl 中对Q235 钢的协同缓蚀效应

目的 探究2-巯基苯并咪唑（MBI）、L-半胱氨酸（L-cysteine）以及两者的混合体系在1 mol/L HCl溶液中对Q235钢的缓蚀性能。方法 通过静态失重法、电化学阻抗谱以及极化曲线研究MBI与L-cysteine的最佳复配条件,并借助原子力显微镜（AFM）以及X射线光电子能谱仪（XPS）分析探究MBI、L-cysteine单独以及复配后在碳钢表面的作用机理。结果 当在HCl溶液中加入5×10?3 mol/L的MBI时,缓蚀效率达到88.01%,而相同浓度下,L-cysteine的缓蚀效率仅达60.19%,缓蚀作用有限。当MBI和L-cysteine复配时,二者的混合体系在HCl介质中具有很好的缓蚀效果,特别是当浓度为1×10?3 mol/L、复配比为9∶1时,缓蚀效果达到最佳,协同效应也最明显。电化学法所得结果和失重法保持一致,且进一步表明MBI和L-cysteine的混合体系同时抑制腐蚀反应的阴、阳极过程,其中抑制阴极的效果最显著。AFM形貌图以及XPS谱图分别表明浸泡在含有MBI-L-cysteine（浓度为1×10?3 mol/L,复配比为9∶1）溶液中的Q235钢表面更加平整,MBI-L-cysteine在Q235钢上通过吸附形成的保护膜可以显著增强Q235钢的耐酸性。结论 MBI与L-cysteine（浓度为1×10?3 mol/L,复配比为9∶1）在1 mol/L HCl溶液中对Q235钢有显著的协同缓蚀性能,但协同效应会随着L-cysteine的增多而逐渐消失。     

电化学法研究硝酸体系中聚天冬氨酸对碳钢的缓蚀作用

利用极化曲线和电化学阻抗法研究了0.1 mol/L硝酸溶液中聚天冬氨酸(PASP)对碳钢的缓蚀作用。结果表明,20℃时,在试验范围内,随着PASP浓度增大缓蚀效率增大,当体系中添加0.5 g/L PASP时,缓蚀效率达到85.3%,聚天冬氨酸对碳钢是以抑制阴极反应为主的混合型缓蚀剂;根据电化学阻抗数据,利用EQUIVCRT软件拟合的等效电路为R(RC)((RW)Q)。     

吐温-40 与植酸复配对碳钢的缓蚀作用

目的提高0.5 mol/L HCl中植酸对热轧碳钢(HRCS)的缓蚀性能。方法用失重法和电化学阻抗法测试植酸、吐温-40以及复配缓蚀剂的缓蚀效率,从热力学和动力学方面分析复配缓蚀剂的作用机制。结果失重法测试表明,植酸和吐温均对热轧碳钢有一定缓蚀作用。当293 K,植酸质量浓度为0.3g/L时,缓蚀效率达到69.1%,在质量浓度为0.8 g/L时缓蚀效率下降为9.6%;吐温-40的缓蚀效率随着质量浓度的增大而增大,0.8 g/L时达到73.4%。在0.5 mol/L盐酸中加入0.05 g/L吐温-40后,复配缓蚀剂的缓蚀效率随着质量浓度的增加而增大,且优于植酸和吐温-40单独使用,表现出协同效应。电化学测试得到了相同的结论,表明复配缓蚀剂在碳钢表面产生自发的Langmuir吸附,使碳钢腐蚀反应的活化能增大,是熵减少的放热过程。结论吐温-40和植酸在盐酸中对热轧碳钢的腐蚀有缓蚀协同作用。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.