三价铬钝化的研究进展

六价铬钝化毒性大,对环境污染严重,而三价铬钝化最有可能成为六价铬钝化的替代品.综述了三价铬钝化的机理及钝化液的主要组成成分,介绍了一些典型的三价铬钝化配方,提出今后三价铬钝化应该在增强耐腐蚀性和色度上进行重点研究.     

钢领镀铬故障处理一例

由于钢领形状复杂,曾长期使用象形阳极,在镀铬过程中出现了毛刺、发花、局部无镀层,镀层不均等质量问题.通过去掉象形阳极并改善挂具设计等手段,使产品成品率由40%提高到95%.     

Preparation of hexagonal and amorphous chromium oxyhydroxides by facile hydrolysis of KxCrOy

The hydrolysis process and mechanisms of unique as-prepared KCrO₂ and K₃CrO₄ were systematically investigated. The characterization results of XRD, IR and SEM show that the hydrolysis reaction can be realized at a low reaction temperature of 80 °C and a reaction time of 24 h. Moreover, the greyish-green α-CrOOH with a hexagonal plate-like morphology and a large size of 10 μm is formed via the hydrolysis of the single-phase hexagonal KCrO₂, while the green sol−gel of amorphous Cr(OH)₃ with a lumpy aggregate morphology is generated through the hydrolysis of a cubic K₃CrO₄. It is a facile and rapid method to synthesize pure-phase chromium oxyhydroxide via the above hydrolysis.     

聚合物驱用复合离子调剖剂HN-3性能研究

为了抑制聚合物驱过程中聚合物的窜流,研制了一种用于河南油田聚合物驱技术的复合离子调剖剂HN-3(由400~800 mg/L复合离子聚合物ZN930和40~80 mg/L有机铬交联剂DT862组成),考察了ZN930与聚合物驱用聚合物的配伍性和成胶性差异,研究了ZN930浓度、DT862浓度和剪切等因素对成胶性能的影响,以及HN-3在多孔介质中的注入性和封堵性。结果表明,ZN930与聚合物驱单元用聚合物配伍性好,混合后油藏温度下(50℃)放置90 d未发生分层或沉淀,且老化后的黏度略高于混合初始黏度;同等聚合物浓度下成胶性能优于相当或略高相对分子质量的部分水解聚丙烯酰胺(HPAM);油藏条件下浓度为400~800 mg/L的ZN930和40~80 mg/L的DT862复配能形成性能良好的凝胶并在180 d以上不破胶,说明调剖剂成胶后具有良好的稳定性;随着注入速率的增加,交联体系初始黏度和成胶黏度均有不同程度的下降,且成胶时间有所延长;当注入速率达1200 m L/h时,剪切后的体系几乎不能成胶,故在现场应用中应尽量控制地面设备对交联体系的剪切。与相同浓度(1000 mg/L)的聚合物3630S、MO-4000、1285溶液相比,在相同注入速率下HN-3具有良好的注入性,且在多孔介质中封堵效率大于90%,成胶黏度40~1500 m Pa·s可控。     

前驱体碳化等离子熔覆高铬铁基涂层的耐空蚀性

利用前驱体碳化复合技术制备的粉末在中碳钢表面制得等离子熔覆高铬铁基涂层,采用光学显微镜(OM)、X射线衍射仪(XRD)、扫描电镜(SEM)、显微硬度计、超声振荡磁致伸缩仪等研究了涂层的组织形态和耐空蚀性能,并对腐蚀破坏过程进行分析.结果表明,涂层具有较高的显微硬度,经时间44h空蚀试验后累积的质量损失量为0Cr13M6Mo不锈钢的0.497倍,具有一定的耐空蚀性能.硬质相晶界对7相塑性变形的阻碍以及应力诱发γ相向马氏体组织转变是高铬铁基涂层具有良好耐空蚀性能的主要原因.     

Simultaneous phenol removal and biological reduction of hexavalent chromium in a packed‐bed reactor

BACKGROUND: Phenol and hexavalent chromium are considered industrial pollutants that pose severe threats to human health and the environment. The two pollutants can be found together in aquatic environments originating from mixed discharges of many industrial processes, or from a single industry discharge. The main objective of this work was to study the feasibility of using phenol as an electron donor for Cr(VI) reduction, thus achieving the simultaneous biological removal/reduction of the two pollutants in a packed‐bed reactor. RESULTS: A pilot‐scale packed‐bed reactor was used to estimate phenol removal with simultaneous Cr(VI) reduction through biological mechanisms, using a new mixed bacterial culture originated from Cr(VI)‐reducing and phenol‐degrading bacteria, operated in draw–fill mode with recirculation. Experiments were performed for feed Cr(VI) concentration of about 5.5 mg L^?1, while phenol concentration ranged from 350 to 1500 mg L^?1. The maximum reduction/removal rates achieved were 0.062 g Cr(VI) L^?1 d^?1 and 3.574 g phenol L^?1 d^?1, for a phenol concentration of 500 mg L^?1. CONCLUSION: Phenol removal with simultaneous biological Cr(VI) reduction is feasible in a packed‐bed attached growth bioreactor. Phenol was found to inhibit Cr(VI) reduction, while phenol removal was rather unaffected by Cr(VI) concentration increase. However, the recorded removal rates of phenol and Cr(VI) were found to be much lower than those obtained from previous research, where the two pollutants were examined separately. Copyright © 2008 Society of Chemical Industry     

加氢换热器热电偶套管泄漏失效分析

采用化学成分分析、金相分析、宏观与微观断口分析以及有限元分析等方法，对某石化厂重整车间加氢换热器热电偶套管接管处的泄漏原因进行了分析和研究。分析结果表明，由于接管材料的含碳量过高，在进行焊接加工时，焊接热影响区过饱和的碳从奥氏体中析出而形成碳化铬，碳化铬的形成使得很多晶界处成了极端贫铬区，这些区域在一定的介质条件下发生了晶间腐蚀，产生了微观孔洞。在工作压力的作用下，这些孔洞发生沿晶扩展，当这些孔洞相互连接、内外贯通后，就发生了泄漏。针对泄漏发生的原因，采取了相应的处理措施，抑制了换热器的腐蚀。     

Effect of Annealing on Structure Formation in Cr - V Layered Composites

We have analyzed the structural transformations occurring in a Cr - V layered composite as a result of deformation followed by heat treatment in the temperature range 1073–1573 K. We have shown that the structural changes and mechanical properties of the composite are sensitive to the thickness of the layers.__________Translated from Poroshkovaya Metallurgiya, Nos. 3–4(442), pp. 80–86, March–April, 2005.     

Cr12白口铸铁热处理工艺性分析

通过分析研究，绘制出Ｃｒ１２白口铸铁的ＣＣＴ曲线及淬硬性图，并探讨了工艺参数对白口铸铁热处理工艺性的影响     

On texture formation of chromium electrodeposits

The microstructure, texture and hardness of electrodeposited hard, direct current (DC) chromium and pulsed reversed chromium has been investigated. These investigations suggest that the growth and texture of hard chromium is controlled by inhibition processes and reactions. Further, it has been established that codeposition of Cr2O3 nanoparticles is a general feature of DC chromium electrodeposition.