Electrochemical pitting behaviour of type 321 stainless steel in sulfide-containing chloride solutions

The pitting behaviour of type 321 stainless steel in sulfide-containing chloride aqueous environments was studied using cyclic potentiodynamic polarization. A well-established correlation between H₂S and Na₂S₂O₃ in the study of corrosion was applied, that is, H₂S was simulated by Na₂S₂O₃. The major factors affecting the pitting corrosion of type 321 stainless steel are the Cl^- concentration, solution pH and temperature. The results clearly indicate that both E_pit and E _pp decrease with increasing Cl^- concentration and temperature, while I _pass is more sensitive to temperature variation. E _pit decreased with decreasing pH in the range 2 < pH < 7.5. The surface morphology and chemistry of the corroded type 321 stainless steel resulting from anodic polarization in 0.01 M S₂O ₃ ^2- -containing Cl^- solution were analysed by XRD, SEM and EPMA. A higher concentration of sulfur was found in the pits, and the dark surface film was mainly composed of FeS and -Fe₂O₃. The results describe the pitting behaviour of type 321 stainless steel in sulfide-containing Cl^- aqueous environments.     

硝酸钠卤水沸点变化理论计算

根椐已有的文献与数据,采用数学模型方法,研究了硝酸钠卤水沸点在不同组成、不同压力条件下的变化关系,确定了硝酸钠卤水沸点与质量分数及压力的数学方程式;根椐硝酸钠卤水压力与组成,可以计算出硝酸钠卤水的沸点值,为新疆都善县库木塔格硝酸钠矿大规模生产硝酸钠提供了重要设计依据.     

3,5-二羟基苯甲醇的简便合成方法

以３，５ 二羟基苯甲酸为原料，经酯化、酰化、硼氢化锂还原等改进步骤合成了３，５ 二羟基苯甲醇，总收率达７５％，提供了一条较为简便的适合于工业化生产的合成方法。     

美洛西林钠的合成

美洛西林钠是一种新型半合成青霉素。在以往的文献中其合成过程中都要使用剧毒品光气作为反应物。今以2-咪唑烷酮为起始原料，经甲磺酰化、酰化等四步反应，合成了酰脲类青霉素美洛西林钠。在合成过程中用氯甲酸三氯甲酯替代光气对其重要中间体l-氯甲酰基-3-甲磺酰基-2-咪唑烷酮的合成工艺进行了改进，不仅避免了使用光气，而且收率也从文献值70％提高到75％。     

新型阻垢剂IA-SSS-MA聚合物的合成与表征

以衣康酸(IA)、苯乙烯磺酸钠(SSS)和马来酸酐(MA)为单体,以水为溶剂,过硫酸铵作引发剂,合成了衣康酸-苯乙烯磺酸钠-马来酸酐(IA-SSS-MA)三元聚合物阻垢剂,考察了单体配比、反应温度、引发剂量、滴加时间等对聚合物阻碳酸钙垢效果的影响,结果表明:当单体配比为IA∶SSS∶MA=5∶1∶0.25(摩尔比),反应温度100℃,引发剂量占单体总量13%,滴加时间为5 h,阻碳酸钙垢效果最好,阻垢率达到98.11%。     

国外过氧化氢在化学合成中应用研究进展

介绍了近期国外过氧化氢在部分化学品合成中应用研究新进展 ,产品包括过碳酸钠、过碳酰胺、4Na2 SO4·2H2 O2 ·NaCl加合物、叔胺氧化物、水合肼、二羟基苯、季铵盐过氧化氢和甲乙酮肟。内容涉及产品质量 (纯度、安定性、溶解速率、外观等 )、产品收率、催化剂、工艺过程等方面改进。主要介绍专利技术。     

（Nb_yTi_（1－y））C_x单晶体制备及其结构研究

用熔剂法制备了（Ｎｂ＿ｙ．Ｔｉ＿（１－ｙ））Ｃ＿ｒ单晶体，用Ｄｅｂｙｅ照相法及四圆衍射仪对其晶体结构进行了研究。实验结果表明，（Ｎｂ＿ｙＴｉ￣（１－ｙ）Ｃ＿ｘ中存在类似于作化学计量化合物ＴｉＣ＿ｘ及ＮｂＣ＿ｘ的有序一无序转变现象，转变温度随其化学成份改变在１１７５～１２８０Ｋ范围内变化。高温型（Ｎｂ＿ｙＴｉ￣（１－ｙ））Ｃ＿ｘ的晶体结构属ＮａＣｌ型结构，碳空位呈随机分布；低温型（Ｎｂ＿ｙＴｉ￣（１－ｙ））Ｃ＿ｘ的晶体中碳空位呈短程有序分布，可用Ｖ＿６Ｃ＿５晶体结构模型进行描述。     

硫氰酸钠法明胶改性腈纶的研究

采用丙烯腈对明胶接枝改性 ,然后与聚丙烯腈共混纺丝的方法 ,制备了明胶改性腈纶 ,研究了改性比 (明胶 /丙烯腈 ,质量比 )和明胶含量对明胶改性腈纶机械性能、吸湿保水性能的影响。研究结果表明 ,当改性比为 0 .7～ 2 .0 ,明胶含量不超过 5 .0 %时 ,改性腈纶具有良好的机械性能 (断裂强度大于 3 .1c N/dtex) ,可以满足后纺加工的需要 ;改性腈纶纤维亲水性能良好 ,随着改性比的减小、明胶含量的增加 ,其回潮率和保水率都逐渐增大。     

Paired electrooxidation IV. Decarboxylation of sodium gluconate to D-arabinose

A paired electrooxidative method has been developed to synthesize D-arabinose in a divided cell. D-arabinose is a material which has an important role in the production of vitamin B2 and DNA. Sodium gluconate was directly oxidized at the anode and indirectly oxidized in the catholyte by bubbling oxygen which was reduced to H₂O₂ and OH free radicals. In the catholyte, indirect oxidation of sodium gluconate was mediated by Fe³⁺ and OH free radicals. The optimal current efficiencies for D-arabinose production in the anolyte and catholyte were found to be 88.37% and 39.12%, respectively, and the total current efficiency of the paired electrooxidation was 127.49%. The paired electrosynthesis of D-arabinose is more economical in terms of power consumption than electrosynthesis that employ a single anode or cathode as the working electrode. The influence of cathodic/anodic CV and I/E curves, redox mediators and the amount of charge passed were also examined.     

铬酸酐副产物硫酸氢钠的利用

对生产铬酸酐时副产的含铬硫酸氢钠的利用作了评论，介绍了8种方法，即，化学沉淀法、磷酸沉淀法、铬酸铬法、电解氧化法、过硫酸钠氧化法、制商品硫酸氢钠、酸泥制碱式硫酸铬、硫酸氢钠制碱式硫酸铬，其中以化学沉淀法、磷酸沉淀法和铬酸铬法应用最广。