CO2分压对20#钢在CO2/H2O气液两相塞状流中腐蚀行为的影响

利用失重法、SEM、EDS、XRD和 XPS等分析方法在自主设计的动态腐蚀实验装置上研究了 CO2分压对20#钢在CO2/H2O 气液两相塞状流中腐蚀行为的影响,对腐蚀试样进行了腐蚀速率分析、腐蚀形貌特征观察以及腐蚀产物成分与膜层结构特征分析.结果表明:随CO2分压的增加腐蚀速率增加,0.04 MPa、0.28 MPa下分别达到腐蚀速率最小值(1.1609 mm/a)和最大值(1.8988 mm/a);上管壁腐蚀产物随着CO2分压的增加最终形成颗粒较大的节瘤状产物,下管壁腐蚀产物由球形颗粒形成初始致密的单层膜逐渐转变为由致密的内层膜和具有网状连通裂纹的片状疏松外层膜构成;经 EDS元素分析可知上下壁面的腐蚀产物均由Fe、C、O 三种元素构成,XPS分峰图谱显示C 1 s、O 1 s和Fe 2 p均出现了三个拟合峰位,结合XRD分析可知腐蚀产物的主要组成相有 Fe3C、FeCO3、Fe2O3、Fe3O4、FeOOH.     

CO2分压对20#钢在CO2/H2O气液两相塞状流中腐蚀行为的影响

利用失重法、SEM、EDS、XRD和XPS等分析方法在自主设计的动态腐蚀实验装置上研究了CO_2分压对20#钢在CO_2/H_2O气液两相塞状流中腐蚀行为的影响,对腐蚀试样进行了腐蚀速率分析、腐蚀形貌特征观察以及腐蚀产物成分与膜层结构特征分析。结果表明:随CO_2分压的增加腐蚀速率增加,0.04 MPa、0.28 MPa下分别达到腐蚀速率最小值(1.160 9 mm/a)和最大值(1.898 8mm/a);上管壁腐蚀产物随着CO_2分压的增加最终形成颗粒较大的节瘤状产物,下管壁腐蚀产物由球形颗粒形成初始致密的单层膜逐渐转变为由致密的内层膜和具有网状连通裂纹的片状疏松外层膜构成;经EDS元素分析可知上下壁面的腐蚀产物均由Fe、C、O三种元素构成,XPS分峰图谱显示C 1s、O 1s和Fe 2p均出现了三个拟合峰位,结合XRD分析可知腐蚀产物的主要组成相有Fe_3C、FeCO_3、Fe_2O_3、Fe_3O_4、FeOOH。     

过渡层对含氢非晶碳膜生长的影响

本文利用射频等离子体增强化学气相沉积（RFPECVD）工艺在不锈钢基底上制备了含氢非晶碳膜（a-C：H膜）。在沉积碳膜之前，首先在基底表面预先沉积了Ti／TiC、Ti／TiN和Ti／TiN／TiC等过渡层以提高膜基结合力。利用激光Raman光谱分析了过渡层对a-C：H膜生长过程及膜中sp^3含量的影响。实验结果表明，采用Ti／TiN／TiC过渡层时所制备的a-C：H膜中sp^3含量最多，同时膜基结合力最大。     

模拟油田H2S/CO2环境中N80钢的腐蚀及影响因素研究

模拟实际含H2S／CO2高温高压井下多相腐蚀环境，研究了不同腐蚀影响因素对N80钢的作用规律。结果表明：在所研究的参数范围内，材料表现出较高的均匀腐蚀速率，且伴有不同程度的局部腐蚀。当其他条件保持相同时，随H2S含量的增加，材料的腐蚀速率先增加后降低；当介质中CO2含量增加时，腐蚀速率则呈单调增大趋势；Ca^2 、Mg^2 的影响与CO2类似，而Cl^-的影响则与H2S具有基本相似的规律。在H2S／CO2混合介质中，N80钢的腐蚀行为受各因素的交互影响，且影响程度不同，各因素作用由大到小依次是：H2S含量、Ca^2 、Mg^2 含量、Cl^-浓度和CO2含量。     

H2S薄层液膜下16Mn钢腐蚀的电化学研究

利用自行设计的测量金属在薄层液膜下腐蚀的三电极电化学电池,通过极化曲线和交流阻抗技术(EIS)研究了16Mn钢在含H2S薄层液膜下的电化学行为,并与之在大量H2S电解质溶液中的电化学行为进行了比较.结果表明:H2S促进了16Mn钢腐蚀的阴阳极过程;随着H2S浓度的升高,16Mn钢的自腐蚀电位(Ecorr)正移,腐蚀速率逐渐增加,但C(H2S)＞2 mmol/L后腐蚀速率不再增加;随薄层液膜酸度增加,Ecorr负移,自腐蚀电流(Jcorr)增大,但pH＜4.4后腐蚀速度与酸度无关.16Mn钢在H2S薄层液膜下与在全浸状态下的腐蚀机理可能不同.     

Ag—MgF2复合纳米金属陶瓷薄膜的微粒尺寸效应

本文用Maxwell-Gamett有效介质理论计算了不同体积成分比的Ag-MgF2复合纳米金属陶瓷薄膜在250nm-830nm波段的光学常数，考虑了由于金属颗粒尺寸对其内部传导电子平均自由程的限制而产生的尺寸效应。同时讨论了Ag-MgF2复合薄膜中的Ag微粒表面等离子体共振吸收峰的峰强、峰位、半高宽以及由于金属微粒的尺寸效应而引起的峰位移动的情况，并将考虑尺寸效应后所得到光学常数的理论值和实验结果进行了比较。     

PAN原丝在预氧化及碳化石墨化过程中微观结构的变化研究

利用拉曼光谱和X射线衍射对聚丙烯腈原丝在预氧化以及碳化石墨化阶段的微观结构进行研究,分析了纤维的石墨结构有序性、晶态结构在不同处理阶段的变化规律。结果表明,240℃开始出现明显的拉曼特征峰;在碳化过程中,逐渐形成碳基平面,G峰峰强不断增强,有序性提高;石墨化过程中,D、G峰的半高宽(FWHM)和R值迅速减小,并出现G′峰,有序性进一步提高。在碳化石墨化阶段,随着处理温度的提高,产生乱层石墨结构,晶面间距d002减小,微晶尺寸La、Lc增加,C—C原子键距不断增大并接近SP2杂化碳原子间距。     

纯Cr在O2-ZnCl2混合气中的高温腐蚀

利用SEM／EDX和XRD等手段，用热重法对纯Cr于650～850℃在含有少量气态ZnCl2的氧气中的腐蚀行为进行了研究，并从热力学角度探讨了腐蚀机理．结果表明，随着试验温度的升高和混合气氛中ZnCl2体积分数的增加，Cr的腐蚀明显加剧；本文试验条件下试样皆生成疏松的表面腐蚀产物膜；ZnCl2与表面Cr2O3发生反应，不但破坏了试样表面氧化膜的完整性，而且释放出Cl2导致“活化氧化”。     

H2S／CO2环境中碳钢的腐蚀电化学行为研究

采用电化学测试方法,结合SEM、EDS等分析技术,研究了在H2S／CO2环境中服役和未服役的碳钢弯管的电化学行为。结果表明：在H2S／CO2环境中服役后的弯管耐H2S／CO2腐蚀性能降低。在CO2体系中,电化学阻抗谱由高频容抗弧和低频感抗弧组成,金属表面局部覆盖疏松多孔且保护性差的FeCO3膜。当腐蚀体系中存在H2S时,低频感抗弧消失,金属表面形成均匀致密的FeS膜,可以显著降低弯管的腐蚀速率。     

Ag-MgF2复合纳米金属陶瓷薄膜的微粒尺寸效应

本文用Maxwell-Gamett有效介质理论计算了不同体积成分比的Ag-MgF2复合纳米金属陶瓷薄膜在2.50 nm-830 nm波段的光学常数,考虑了由于金属颗粒尺寸对其内部传导电子平均自由程的限制而产生的尺寸效应。同时讨论了Ag-MgF2复合薄膜中的Ag微粒表面等离子体共振吸收峰的峰强、峰位、半高宽以及由于金属微粒的尺寸效应而引起的峰位移动的情况,并将考虑尺寸效应后所得到光学常数的理论值和实验结果进行了比较。     

Supercooling of liquid H2 and the possible production of superfluid H2

We discuss the extent to which it may be possible to supercool liquid H₂ below its normal freezing temperature. We show that there is a significant prospect that H₂ could be supercooled to arbitrarily low temperatures, and that in this way superfluid H₂ might be produced. A brief discussion is given of the properties of the anticipated superfluid phase.     

Analysis of C2H4 in C2H6 and C2H5D with VUV absorption spectroscopy and a method to remove C2H4 from C2H6 and C2H5D

The photoabsorption cross section of C2H4 was measured in the spectral region 107-183 nm and those of C2H6 and C2H5D were accurately determined in the spectral region 107-162 nm using radiation from a synchrotron as source of VUV light. Typically, C2H4 present as a minor impurity in samples of C2H6 and C2H5D distorted the absorption cross section in curves of C2H6 and C2H5D in the onset region. We completely eliminated C2H4 from C2H6 and C2H5D using adsorption on activated Pd/charcoal at 195 K. By this means, we detected no C2H4 in samples of C2H6 and C2H5D according to their absorption spectra. The detection limit of C2H4 in C2H6 and C2H5D is less than 0.03 ppm with VUV absorption spectroscopy.     

Precise Pore Engineering of fcu-Type Y-MOFs for One-Step C2H4 Purification from Ternary C2H6/C2H4/C2H2 Mixtures

The purification of C₂H₄ from C₂H₆/C₂H₄/C₂H₂ mixtures is of great significance in the chemical industry for C₂H₄ production but remains a daunting task. Guided by powerful reticular chemistry principles, herein a systematic study is carried out to engineer pore dimensions and pore functionality of fcu-type Y-based metal–organic frameworks (Y-MOFs) through the construction of a series of eight new structures using linear dicarboxylate linkers with different length and functional groups. This study illustrates how delicate changes in pore size and pore surface chemistry can effectively influence the adsorption preference of C₂H₆, C₂H₄, and C₂H₂ by the MOFs. Importantly, clear relations between pore size/pore surface polarity and C₂ adsorption selectivities of this series of MOFs are established. In particular, HIAM-326 built on a linker decorated with trifluoromethoxy group shows notably preferential adsorption of C₂H₆ and C₂H₂ over C₂H₄, with balanced C₂H₂/C₂H₄ and C₂H₆/C₂H₄ selectivities. This endows the compound with the capability of one-step purification of C₂H₄ from C₂H₆/C₂H₄/C₂H₂ ternary mixtures, which is validated by breakthrough measurements where high purity C₂H₄ (99.9%+) can be obtained directly from the separation column. Its adsorption thermodynamics and underlying selective adsorption mechanisms are further revealed by ab initio calculations.     

Thermal diffusion in binary mixtures H2-CCl2F2 and H2-CHClF2

Thermal diffusion coefficients were measured in two gaseous mixtures, in which one component was close to the critical temperature, in the pressure range (19.6–127.4)·10⁴ N/m² and at a freon concentration of 0.25–0.8.     

Specific Features of Anodic Dissolution of Copper in H2SO4 + H2O and H2SO4 + CuSO4 + H2O Systems

We investigate anodic dissolution of copper in H₂SO₄ + H₂O and H₂SO₄ + H₂O + CuSO₄ systems, which model solutions for the electrochemical production of copper (+2) sulfate. Ultimate densities of anodic current in the temperature range 20–80°C for a voltage up to 8 V were found. We show that a concentration of copper ions ( Cu²⁺) of 1.5–2.0 moles/liter in the anolyte is the limiting one in the electrochemical production of solutions of copper (+2) sulfate.     

Phase diagram of the Na2CO3 · 10H2O-Na2S2O3 · 5H2O system

Using thermal analysis, we have constructed the phase diagram of the crystalline hydrate system Na₂CO₃ · 10H₂O-Na₂S₂O₃ · 5H₂O, which has been shown to have eutectic phase relationships. The eutectic composition is 27 wt % Na₂CO₃ · 10H₂O + 73 wt % Na₂S₂O₃ · 5H₂O, and the eutectic temperature is T _e = ?0.92°C. We have determined the enthalpy of fusion of the alloys in this system and evaluated the activities of their components both at the liquidus temperatures and in metastable regions. The composition dependences of the above thermodynamic characteristics are shown to correlate with each other and to have extreme values at the eutectic composition. The results obtained lead us to recommend the eutectic mixture of the crystalline hydrates in this system as a heat storage material.     

硫酸-草酸混合法硬质阳极氧化溶液的分析

1　前　言　　混合酸阳极氧化法是指用含有两种或以上的无机酸或有机酸的混合水溶液对工件进行的阳极氧化。它适用于硬质氧化膜和自然着色法的有机酸电解着色 ,与单一酸阳极氧化法相比有如下优点 :(1)在 10～ 2 0℃下电解 ,能获得耐磨性好的氧化膜和高着色率 ;(2 )实行高电流密度的混合酸电解 ,可防止氧化膜溶解 ,并可在较高温度下有效地形成硬质氧化膜 ;(3)可在较高的温度下实施 ,降低生产成本 ,有利于生产。该法获得的膜层的性能与溶液的成分密切相关 ,因而要求对溶液实行监控分析。然而 ,目前的分析基本上都是沿用单一酸电解液法进行 ,其…     

Synthesis and structural study of new potassium uranyl selenates K2(H5O2)(H3O)[(UO2)2(SeO4)4(H2O)2](H2O)4 and K3(H3O)[(UO2)2(SeO4)4(H2O)2](H2O)5

Single crystals of new uranyl selenates K₂(H₅O₂)(H₃O)[(UO₂)₂(SeO₄)₄(H₂O)₂](H₂O)₄ (1) and K₃(H₃O)[(UO₂)₂(SeO₄)₄(H₂O)₂](H₂O)₅ (2) were prepared by isothermal evaporation at room temperature. The crystal structure of 1 was solved by the direct method [C2/c, a = 17.879(5), b = 8.152(5), c = 17.872(5) Å, β = 96.943(5)°, V = 2585.7(19) ų, Z = 4] and refined to R ₁ = 0.0449 (wR ₂ = 0.0952) for 2600 reflections with |F _o| ≥ 4σ _F . The structure of 2 was solved by the direct method [P2₁/c, a = 17.8377(5), b = 8.1478(5), c = 23.696(1) Å, β = 131.622(2)°, V = 2574.5(2) ų, Z = 4] and refined to R ₁ = 0.0516 (wR ₂ = 0.1233) for 4075 reflections with |F _o| ≥ 4σ _F . The structures of 1 and 2 are based on [(UO₂)₂(SeO₄)₄(H₂O)₂]^4? layers. The charge of the inorganic layer is compensated by potassium and oxonium ions arranged in the interlayer space. Each K ion is surrounded by seven O atoms belonging to uranyl selenate layers and water molecules, so that it binds with each other the adjacent uranyl selenate structural elements.     

The controlled reduction of copper tungstate in H2O/H2 mixtures

The controlled reductions of copper tungstate, copper tungstate plus blue tungsten oxide and CuO plus WO₃ have been studied at temperatures of 500, 600 and 700C using H₂/H₂O mixtures in a glass thermobalance. The copper-tungsten oxide composite powder products have been characterized by X-ray diffraction analysis and scanning electron microscopy. The morphologies of the copper-tungsten oxide products have been related to the morphologies of copper-tungsten powders obtained by dry hydrogen reduction. It is shown that widely varying copper-tungsten oxide morphologies may be obtained as precursors for metal powder production by control of the H₂/H₂O ratio in the reducing gas mixture.     

Influence of Treatment Conditions on the Chemical Oxidative Activity of H2SO4/H2O2 Mixtures for Modulating the Topography of Titanium

Host‐tissue integration of medical implants is governed by their surface properties. The capacity to rationally design the surface physico‐chemical cues of implantable materials is thus a fundamental prerequisite to confer enhanced biocompatibility. Our previous work demonstrated that different cellular processes are elicited by the nanotexture generated on titanium (cpTi) and Ti6Al4V alloy by chemical oxidation with a H₂SO₄/H₂O₂ mixture. Here, we illustrate that by varying the etching parameters such as temperature, concentration, and treatment time, we can create a variety of surface features on titanium which are expected to impact its biological response. The modified submicron and nanotextured surfaces were characterized by scanning electron (SEM) and atomic force (AFM) microscopies. Contact angle measurements revealed the higher hydrophilicity of the modified surfaces compared to untreated samples and Fourier transform infrared spectroscopy (FT‐IR) established that the etching generated a TiO₂ layer with a thickness in the 40–60 nm range.