Ni-xCr-10Al合金于700-800℃的氧化-硫化腐蚀

研究了Ni-10Al和Ni-xCr-10Al (x=3,5,10)合金在700-800℃的H2-H2S-CO2混合气氛中的腐蚀行为.结果表明,添加Cr可降低Ni-10Al合金的腐蚀速率;在700℃,Ni-10Al合金氧化动力学曲线遵循直线规律,而Ni-xCr-10Al合金的氧化动力学曲线则为多段抛物线;在800℃,所有...     

Sulfidation behavior of a binary Fe-Mn alloy

An Fe-27 w/o (weight %) Mn alloy was sulfidized at temperatures of 973, 1073, and 1173 K inflowing H₂/H₂S/N₂ atmospheres corresponding to equilibrium sulfur pressures of 8 Pa. Steady-state parabolic kinetics were always observed after an initial period during which the instantaneous parabolic rate constant increased with time. Product scales were compact and consisted of a layer of Fe(Mn)_1–x S over an inner layer of -Mn(Fe)S. Preoxidation led to a diminution in the subsequent sulfidation rate. Conflicts between differing reports in the literature of the kinetics of this reaction are resolved, and it is concluded that the protective effect expected of an -MnS layer is in fact possible.     

Sulfidation properties of an Fe-26.6 at.% Cr alloy at temperatures of 973–1173 K in H2S-H2 atmospheres at sulfur Pressures 104–10−6 Pa

An investigation is reported on the sulfidation properties of an Fe-26.6 at. % Cr alloy at 973, 1073, and 1173 K in H₂S-H₂ atmospheres at sulfur pressures 10⁴ 10^–6 Pa. The sulfidation kinetics when plotted according to a parabolic relationship usually exhibited an early slow transient period before onset of parabolic kinetics. Scales contained up to three layers. A triplex (CrFe)S_x/(CrFe)₃S₄/-(FeCr)S_x scale was formed at high sulfur pressures (range I), a single-phase (FeCr)S_x or a duplex (CrFe)S_x/(FeCr)S scale at intermediate sulfur pressures (range II), and a single-phase (CrFe)S_x scale at low sulfur pressures (range III). These pressure ranges at 973 K were: range I = 10^–2Pa, 10^–2 > (range II) 10^–5 Pa, and range III .     

菱锌矿表面强化硫化技术及机理研究

本文以主要氧化锌矿物菱锌矿作为研究对象,研究了硫化温度、铜离子活化、低pH条件硫化等多种方式对菱锌矿硫化程度的影响,并揭示了水洗除去表面的过量的高浓度硫化钠对氧化锌矿硫化浮选效果的影响。在以上基础上,利用分析检测手段对氧化锌矿强化硫化反应机理进行了探究。论文得到的主要结论：（1）硫化时加入铜离子可以改善菱锌矿纯矿物的回收率;（2）以用量为1×10-3mol/L的硫化钠作为硫化剂时,在没有除去溶液中过量硫化钠时,菱锌矿几乎没有得到有效浮选,表明溶液中残存的高浓度硫化钠对浮选过程起抑制作用,水洗除去溶液中过量硫化钠后可以提高菱锌矿回收率;（3）酸性条件下进行氧化锌矿硫化有助于提高氧化锌矿浮选回收率,在弱酸性条件下强于强酸性条件;（4）提高硫化温度可以提高菱锌矿硫化效果。通过XRD分析表明,硫化反应生成物结晶度很低,XPS分析表明加入硫化钠硫化时有硫化锌生成,并且随着温度升高菱锌矿表面硫化锌含量增加。红外光谱分析表明,铜离子强化了丁基黄药与菱锌矿的吸附作用。     

Avoiding artefacts during electron microscopy of silver nanomaterials exposed to biological environments

Electron microscopy has been applied widely to study the interaction of nanomaterials with proteins, cells and tissues at nanometre scale. Biological material is most commonly embedded in thermoset resins to make it compatible with the high vacuum in the electron microscope. Room temperature sample preparation protocols developed over decades provide contrast by staining cell organelles, and aim to preserve the native cell structure. However, the effect of these complex protocols on the nanomaterials in the system is seldom considered. Any artefacts generated during sample preparation may ultimately interfere with the accurate prediction of the stability and reactivity of the nanomaterials. As a case study, we review steps in the room temperature preparation of cells exposed to silver nanomaterials (AgNMs) for transmission electron microscopy imaging and analysis. In particular, embedding and staining protocols, which can alter the physicochemical properties of AgNMs and introduce artefacts thereby leading to a misinterpretation of silver bioreactivity, are scrutinized. Recommendations are given for the application of cryogenic sample preparation protocols, which simultaneously fix both particles and diffusible ions. By being aware of the advantages and limitations of different sample preparation methods, compromises or selection of different correlative techniques can be made to draw more accurate conclusions about the data.     

Fe-Si合金在600℃不同气氛中的腐蚀

研究了Fe-5Si,Fe-9Si和Fe-13Si合金在600℃下H2-CO2和H2-CO2-H2S两种气氛中的腐蚀行为。结果表明:在两种气氛中,3种合金的腐蚀均遵循近似抛物线规律;并且合金在含S和不含S气氛中的抛物线速率常数数量级分别为10-8和10-10g2·cm-4·s-1。在H2-CO2气氛中合金氧化膜由Fe的氧化物外层、Fe与Si的混合氧化物内层及Si的内氧化区组成;在H2-CO2-H2S气氛中则由层状的FeS外层和FeS+SiO2混合内层组成。两种气氛中合金均没有生成连续的SiO2外氧化膜。气氛中S的加入使合金表面生成了大量的FeS,FeS中较高的离子缺陷浓度为Fe2+向外扩散提供了通道,从而明显增大了合金的腐蚀速率。Si氧化物的生成提高了Fe在两种气氛中的耐腐蚀性。     

FV(520)B 不锈钢高温高压条件下硫化腐蚀初始阶段机理研究

目的研究高温高压条件下FV(520)B不锈钢硫化初始阶段的腐蚀机理。方法在573 K,H2S分压为1.5 MPa条件下制备硫化腐蚀试样,利用XPS,SEM等分析硫化膜成分、元素含量及分布。结果硫化膜为双层膜结构,外层成分为Fe7S8,Fe S2和Ni(1-x)S,内层成分为Fe7S8,Fe S2,Ni(1-x)S和Cr2S3。XPS数据显示Fe7S8,Fe S2中存在Fe2+和Fe3+,且Fe3+平均原子数分数分别为36.53%和35.78%,Ni(1-x)S硫化物中存在Ni2+,Ni3+,且Ni3+的平均质量分数约为32.08%。结论铁镍硫化物的主要缺陷为阳离子缺陷,且缺陷浓度较高,内层中Cr2S3抑制Fe,Ni离子向外迁移,但硫化初期阶段Cr2S3的含量少,抑制作用不明显。     

炼厂的环烷酸腐蚀问题及最新研究动态

回顾了高酸原油加工防腐经验。加工高酸值原油是炼油企业控制成本、提高赢利空间的重要手段,但同时要面临设备腐蚀加剧问题,如高于230℃的高温部位、减压塔内器件、过流部件等腐蚀严重。各炼油企业普遍采取装置适应性改造、材质升级、加强在线腐蚀监测、高温缓蚀剂等技术手段应对高酸值原油腐蚀问题,然而设备腐蚀风险并没有得到彻底控制,由于腐蚀严重而导致的非计划停工仍难以杜绝,因此许多学者持续开展了高温环烷酸腐蚀研究。通过在模拟介质中的实验研究掌握了温度、总酸值、硫含量等因素对高温环烷酸腐蚀的影响,发现硫腐蚀可以部分抑制环烷酸腐蚀。近年来,实际馏分中环烷酸腐蚀和硫腐蚀交互作用得到了更多关注,重点是研究硫腐蚀产物膜在环烷酸腐蚀环境中的作用和机理。发展了旋转圆环实验装置、喷射式实验装置、流经式迷你高压釜、常温高速双相流模拟装置等,从不同角度模拟工况条件,使之更加接近工业生产实际工况。发展了预成膜-后腐蚀的"Challenge(挑战)"实验,用于研究钝化膜在高温环烷酸腐蚀中的行为和特性。环烷酸在馏分中的分布以及对腐蚀的影响也得到了广泛关注。基于机理或者经验数据的腐蚀预测模型已经成为各种炼厂设备完整性管理技术的基础。