THE KINETICS OF REACTION OF MOLTEN CUPROUS SULPHIDE WITH HYDROGEN

本文研究了在1150℃,1200℃和1250℃下熔锍Cu_2S与氢反应的动力学。动力学方程式为: 单相熔体 u_(S％)=d(S％)/dτ=k_S(S％-a)~2P_(H_2)~(1/2) 分层区 u_S％=d(S％)/dτ=AP_(H_2)~(1/2) 通过测定反应速度与硫浓度状态曲线的转折点,验证了Cu-S系相图分层的数据,此数据含硫成分为: ℃ 1150 1200 1250 ％ 19.805 19.73 19.61 研究了温度对反应速度的影响,测得反应活化能E和反应速率常数k: E=11000卡/克分子Cu_2S k_(1150℃)=3.27×10~(-2)/分·S％·大气压1/2 k_(1200℃)=3.76×10~(-2)/分·S％·大气压1/2 k_(1250℃)=4.12×10~(-2)/分·S％·大气压1/2 实验数据表明,反应速度受温度的影响是不大的。 还讨论了Cu-S系相图与反应速度的关系。     

熔锍Cu_2S与氢反应的动力学

本文研究了在1150℃,1200℃和1250℃下熔锍Cu_2S与氢反应的动力学。动力学方程式为: 单相熔体 u_(S％)=d(S％)/dτ=k_S(S％-a)~2P_(H_2)~(1/2) 分层区 u_S％=d(S％)/dτ=AP_(H_2)~(1/2) 通过测定反应速度与硫浓度状态曲线的转折点,验证了Cu-S系相图分层的数据,此数据含硫成分为: ℃ 1150 1200 1250 ％ 19.805 19.73 19.61 研究了温度对反应速度的影响,测得反应活化能E和反应速率常数k: E=11000卡/克分子Cu_2S k_(1150℃)=3.27×10~(-2)/分·S％·大气压1/2 k_(1200℃)=3.76×10~(-2)/分·S％·大气压1/2 k_(1250℃)=4.12×10~(-2)/分·S％·大气压1/2 实验数据表明,反应速度受温度的影响是不大的。还讨论了Cu-S系相图与反应速度的关系。     

溶解氧对BNS管线钢H_2S腐蚀行为的影响

基于两阶段式腐蚀浸泡试验,研究了溶解氧对BNS管线钢H_2S腐蚀行为的影响规律及机理。结果表明:在H_2S环境中,O_2的混入对BNS管线钢的均匀腐蚀具有显著的促进作用,这主要与O_2和H_2S反应生成SO_4~(2-)、S_2O_3~(2-)以及单质硫有关;与单一H_2S环境相比,O_2/H_2S共存环境中BNS管线钢表面腐蚀产物覆盖增多且更为疏松;O_2的混入促使BNS管线钢局部腐蚀敏感性增加,溶解氧、由H_2S和O_2反应生成的单质硫及S_2O_3~(2-)对局部腐蚀发展均有贡献。     

铁在含H2S在撤酸溶液中的腐蚀机制研究

应用动电位极化曲线和交流阻方法，研究了铁在含Ｈ２Ｓ的硫酸溶液中的腐蚀电化学行为，得出阴，阳极反应的动力学方程，并结合ＣＮＤＯ／２量化计算结果，提出了相应的腐蚀反应机制。结果表明，Ｈ２Ｓ可大大促进铁阳极溶解反应，且低极化时反应较快，相应动力不参数为：ｖＨ＋＝－０．８３，ｖＨＳ－＝０．３５，ｂａ≈４０ｍＶ；Ｈ２Ｓ对阴极反应的促进程度较小，且不随Ｈ２Ｓ浓度改变，相应动力学参数为：ｖＨ＋＝１．１９，ｖＨ２     

模拟油田CO_2/H_2S环境15Cr油管腐蚀行为研究

利用电化学动电位测试技术和高温高压失重法研究了15Cr合金油管在CO_2以及与H_2S共存环境下的腐蚀行为和变化趋势,分析了H_2S与CO_2不同时间间隔共存后对材料腐蚀性能的影响。结果表明:在实验溶液中先加入CO_2,当腐蚀电位稳定后再加入H_2S腐蚀介质时,材料阳极钝化区不稳定;当先加入CO_2且时间间隔10 min后加入H_2S介质时,材料阳极钝化区域呈现相对较稳定的状态,维钝电流密度相对减小。材料在应力状态下的腐蚀电位相对非应力状态明显下降,并且腐蚀电流密度右移,耐蚀性相对下降。高温高压实验结果表明,应力的存在促进了腐蚀程度的加剧,平均腐蚀速率明显增大。材料在加载80%σs应力且当H_2S浓度达1 MPa时,试样表面出现明显的点蚀坑,试样发生应力腐蚀断裂。     

抗硫碳钢在CO2／H2S溶液中的腐蚀电化学行为

通过失重法、动电位极化扫描、交流阻抗测试等方法研究抗硫碳钢在CO2/H2S共存的3%NaCl溶液中的腐蚀电化学行为.结果表明:在30℃时,溶液的pH值愈小,硫化膜在电极表面上的沉积量愈少,阴、阳极极化的程度越低;溶液的pH值降低,硫化膜由富S型转变为保护性较弱的富Fe型,且Cr(OH)3和Cr2O3含量的降低,在一定程度上降低了硫化膜的保护作用.溶液的pH=4和H2S浓度>100 mg/L时,H2S对抗硫碳钢的阳极过程无促进作用;溶液的pH=2时,随H2S浓度的增大,电极反应为H+的自催化反应.     

H_2S对碳钢在模拟罐底水中腐蚀行为的影响

利用腐蚀失重法、电化学测试、扫描电镜(SEM)和X射线衍射(XRD)研究了Q235碳钢在含H_2S的模拟罐底水中的腐蚀行为。结果表明:增加H_2S含量,可以促进碳钢表面的析氢反应,从而增大了碳钢的腐蚀速率;碳钢表面形成由四方硫化亚铁组成的疏松、多孔的腐蚀产物膜;碳钢先后在含H_2S溶液、无H_2S且含溶解氧的溶液中进行二次腐蚀后,其腐蚀产物分为两层,内层主要组成依然是四方硫化亚铁,外层为氧化产物,其中氧化产物的生成导致硫化亚铁膜的破裂与脱落;硫化亚铁膜的存在,对碳钢在含H_2S溶液中的保护性大于其在含溶解氧溶液中的。     

H_2S/CO_2共存体系中钢界面反应的暂态研究

采用电化学电位阶跃技术研究了H_2S/CO_2共存溶液中钢界面反应过程,提出了界面反应过程的模型,并建立了相应的数学描述。运用数学模型分析了界面物质吸附、脱附以及氢吸收的反应规律,得出:当η=50mV阶跃时,氢吸附过程控制整个界面反应;η50 mV阶跃时,预吸附物脱附过程在整个阶跃期间控制整个界面反应,在各实验η阶跃条件下,CO_2提高吸收态氢对i_(total)的贡献,促进了氢吸收。     

地热开发中的材料腐蚀问题

地热是洁净、廉价的新兴能源。但由于地热水中含有 O_2、H_2S、Cl~-、SO_4~(2-)、NH_3,以及温度和pH 等因素,构成对设备的腐蚀。类型有:均匀、溃疡、电偶、磨蚀、断裂、缝隙等腐蚀。阳极反应为铁的溶解,阴极反应为氧或 H_2S 中的氢去极化。腐蚀二次产物用 X 射线分析为铁的氧化物和硫化物。北京城区现场动态试验结果表明:碳钢与低合金钢在气相(0.3mm/y)、半浸(0.2mm/y)、间浸(0.5mm/y)和全浸(0.05mm/y)中有相似的腐蚀率,线性极化测定结果亦相同。2Cr13腐蚀率极低,但在半浸水线处点蚀严重。铜合金因氧和 H_2S 共同作用腐蚀率增加。铝合金有严重点蚀.现有设备中异金属接触使用基本安全。地面设备用的镀锌管有良好的耐蚀性。     

Cu_2S-Cu系熔体与氢反应的动力学

1.本文分别研究了在1150,1200,1250和1300℃时,Cu-S 系熔体与氢反应的动力学.得到如下动力学方程式:富硫单相区 u_S=0.717 exp[-(53.137)/(RT)](S%-α)~2p_(H_2)~(1/2) 常数不熔合分层区 u_S=0.531 exp[-(67.259)/(RT)]p_(H_2)~(1/2)富铜单相区 u_S=44.6 exp[-(146.720)/(RT)]p_(H_2)~(1/2)·S% 常数Cu-S 系和氢的脱硫速度主要取决于熔体中硫的浓度,但不熔合分层区除外.在一定的温度和氢分压下,反应速度大小的次序为:u_S(h)>u_S(m)>u_S(l)2.脱硫反应和 Cu-S 相图结构关系中 S 和 Cu 的活度数学模型方程式为:富硫单相区：熔合分层区(b=1.2-19.8%S富铜单相区(0相似文献   

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.