静磁场下硫酸盐还原菌对HSn70-1铜合金的腐蚀行为

采用失重法、电化学测量和表面分析技术研究了有、无静磁场环境下,在含有硫酸盐还原菌(SRB)的培养基中HSn70-1铜合金的腐蚀行为。结果表明:SRB条件下,HSn70-1铜合金腐蚀质量损失最大,无磁场下的腐蚀电流密度远大于有磁场条件下的,磁场的加入可以有效地减缓HSn70-1铜合金的腐蚀。SEM,EDS,XRD和XPS实验分析表明,静磁场下HSn70-1铜合金表面腐蚀产物膜均匀致密,腐蚀产物为金属硫化物,Cu的化合价以一价(Cu+)为主;而无磁场时腐蚀产物疏松,腐蚀产物硫化物中Cu主要为二价(Cu2+)。静磁场条件下所形成的致密的Cu2S腐蚀产物层阻碍腐蚀的发生,有效地减缓了HSn70-1铜合金的腐蚀。     

用原子力显微镜研究铜合金微生物的腐蚀行为

用原子力显微镜(AFM)研究了HSn70-1A、HSn70-1B和HSn70-1AB等3种铜合金在硫酸盐还原菌(SRB)菌液中的微生物腐蚀行为.结果表明,3种铜合金表面形成的生物膜形貌各不相同.HSn70-1AB合金表面生物膜的粗糙度大于其余两种合金,表明其生物膜最不均匀.去除生物膜后,3种样品的腐蚀形貌也小相同,粗糙度均有所增加,这是微生物腐蚀作用的结果.研究证实,AFM的定量分析能力是研究材料微生物腐蚀的重要手段.     

硫酸盐还原菌生物膜对HSn70－1AB铜合金电极界面的影响

测试了硫酸盐还原菌(sulfate reducing bacteria,SRB)的生长规律,浸泡初期(前 3d)SRB处于对数增长期,浸泡后期(4 d后)SRB进入稳定生长期.利用AFM技术和EIS电化学方法研究了SRB生物膜对HSn70-1AB铜合金电极界面的影响.AFM分析表明,浸泡后期合金表面生物膜粗糙度较前期有所下降.EIS结果表明,浸泡前3 d,合金表面氧化膜层较为稳定,氧化膜层电容值变化不明显.浸泡7 d后,合金表面氧化膜遭受局部腐蚀,开始出现微孔,粗糙度增加,氧化膜层电容值增大.     

原子力显微镜在微生物腐蚀研究中的应用

利用原子力显微镜(Atomic Force Microscopy,AFM)研究硫酸盐还原菌(Sulfate Reducing Bacteria,SRB)、微生物膜和腐蚀前后铜合金材料BFe30-1-1的表面形貌,得到了高分辨率的表面形貌图,测得SRB的大小、点蚀坑的深度和直径,分析了腐蚀后BFe30-1-1的表面粗糙度参数.结合电化学参数说明,浸蚀14d的铜合金表面形成了不均匀的微生物膜,加速了试片表面的局部腐蚀.AFM作为一种具有纳米级分辨成像能力的工具,是观察材料的表面特征和腐蚀形貌及测量材料表面纳米粗糙度的理想仪器.     

硫酸盐还原菌对 HSn70-1A铜合金电化学腐蚀行为的影响

用电化学、微生物学和表面分析方法研究了培养基中硫酸盐还原菌 (SRB) 对HSn70-1A 铜合金的电化学腐蚀行为,探讨了硫酸盐还原菌生物膜下介质的流动状态及材料表面状态对铜合金腐蚀的影响.结果表明,SRB的存在使电极自腐蚀电位快速负移,腐蚀速率显著增加,细菌生长后期极化电阻显著降低.扫描电子显微分析(SEM) 表明,在 SRB 作用下铜合金发生严重点蚀.介质的流动状态对细菌的附着、生长具有一定的影响,加剧了腐蚀的形成和发展.铜合金在2-巯基苯并噻唑 (MBT) 与1,2,3-苯并三氮唑 (BTA) 复配缓蚀剂中预镀膜后,耐SRB侵蚀性显著提高.     

HEDP-ATMP-TTA缓蚀剂对HSn70-1A铜合金腐蚀行为的影响

通过静态失重法、极化曲线法、电化学阻抗谱测定了HEDP-ATMP-TTA复配缓蚀剂在循环冷却水介质中硫酸盐还原菌(SRB)作用下对HSn70-1A铜合金的协同缓蚀作用,讨论了缓蚀剂浓度和SRB对铜合金腐蚀行为的影响.结果表明:当循环冷却水介质中加入该缓蚀剂后,可以改善SRB对HSn70-1A铜合金的侵蚀程度;随着缓蚀剂浓度的增加,合金腐蚀速率逐渐下降,缓蚀率逐渐提高.     

铜合金在海洋飞溅区的腐蚀

研究了12种铜合金在青岛海域飞溅区暴露16年的腐蚀结果及其腐蚀行为和规律．铜合金在飞溅区的腐蚀率均较低．在飞溅区短期暴露，铜合金的腐蚀类型为均匀腐蚀，长期暴露的铜合金发生较轻的点蚀和缝隙腐蚀，黄铜有脱锌腐蚀倾向，白铜有脱镍腐蚀倾向．纯铜和青铜的腐蚀率随暴露时间增加而降低．HMn58—2和HSn62-1短期暴露的腐蚀率随暴露时间增加而降低，长期暴露腐蚀率出现上升的趋势．HA177—2和BFe10-1-1的腐蚀率随暴露时间增加而略有增加．长期暴露的HA177—2、BFe10-1-1和BFe30-1-1的耐蚀性比纯铜差．铜合金在飞溅区的腐蚀比全浸区、潮汐区轻，比海洋大气区重．     

再生水中硫酸盐还原菌对铜合金的腐蚀

采用微生物技术、表面分析技术以及电化学测量技术,研究了从再生水环境中分离提纯得到的硫酸盐还原菌(SRB)的形态、生长规律,以及SRB对铜合金HSn701-AB在再生水环境中腐蚀的影响.结果表明,在再生水环境中SRB的生长曲线存在2 d～3 d的停滞期;铜合金HSn701～AB在接种SRB的再生水环境中浸泡3 d时,出现...     

常规水稳剂对HSn70-1A铜合金的腐蚀性能研究

通过旋转挂片失重法来测定几种水质稳定剂HPAA、HPMA、PBTC、HEDP、DTPMP、有机膦磺酸、马来酸-丙烯酸共聚物对HSn70-1A铜合金的腐蚀情况。研究表明，阻垢剂对铜离子有较强的络合作用，使用不当会造成腐蚀；常规使用浓度下，阻垢剂对铜合金HSn70-1A的腐蚀一般都是脱锌腐蚀；造成铜合金腐蚀和溶解的水质稳定剂浓度应视具体环境来确定。     

流体冲刷作用对SRB的腐蚀行为影响研究

采用数值仿真与实验相结合研究了流体冲刷下SRB的腐蚀行为。基于计算流体动力学(CFD)得到的管道腐蚀区域预测云图和粒子运动轨迹图结果，预判管道腐蚀部位，结果表明管道底部较顶部腐蚀、管道出口处腐蚀较入口处严重；在预判管道腐蚀部位布置研究电极，运用电化学方法以及表面分析方法探究了流体冲刷下SRB的腐蚀规律。结果表明，SRB在金属表面未形成生物膜时(未进行预膜处理)，冲刷腐蚀占主导地位，金属表面有明显的冲刷腐蚀特点，腐蚀产物主要以Fe的氧化物为主。当SRB在金属表面预先形成致密生物膜时(进行预膜处理)，SRB腐蚀占主导地位，生物膜会减缓冲刷腐蚀，但膜下SRB的生命活动会与金属基体发生电子交换，从而发生SRB腐蚀，腐蚀产物主要以硫铁化合物为主。     

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.     

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.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

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.