聚酯粉末涂层在工业污染环境中的腐蚀行为研究

采用金相显微镜和交流阻抗谱研究了涂层缺陷以及不同前处理工艺对建筑铝合金6063在0.04 mol/LNa2SO4溶液(pH=3.0)中的腐蚀行为。研究结果表明:未经铬酸钝化处理的铝合金缺陷粉末涂层在0.04 mol/L Na2SO4(pH=3.0)溶液中浸泡50 d后,其划痕处堆积满腐蚀产物,划痕两侧局部出现明显翘起和气泡;浸泡相同时间的经铬酸钝化处理的铝合金粉末涂层其腐蚀速率低约1个数量级,铝合金钝化膜能延缓腐蚀,提高缺陷涂层和完整涂层的阻抗。     

也谈镀锌层银白钝化工艺

0 前言 传统银白钝化膜是镀锌件经高铬彩色钝化后,不经老化处理直接在不含硫酸根的高铬溶液中漂白而成.此时,锌表面彩色钝化膜很快脱落.由于六 价铬在酸性溶液中是强氧化剂,使锌表面很快氧化而产生透明氧化膜,附着于锌层表面.因此,一般认为银白钝化膜实际是一层很薄氧化膜.当然其中还含有极微量六价铬.基于这一看法,锌层经硝酸出光后,直接浸铬酸溶液,同样可获得与铬酸漂白效果相同的白色保护膜.     

钛盐钝化在锡镀层和黄铜带上的应用

在电镀行业中,通常用铬酸对锡镀层和黄铜带进行钝化。钝化后,大量污水流入江河,造成严重污染,而且操作时危害人体健康。采用无毒材料硫酸氧钛制成钝化液,钝化后形成的钝化膜质量、性能等方面都达到铬酸钝化膜的指标,本文对钝化液配方、钝化膜的性能等进行了探讨。     

铁阳极钝化对高铁酸盐电化合成工艺的影响

使用浓度跟踪分析法和恒电流电解曲线对铁网阳极在浓氢氧化钠溶液中电化合成Fe(VI)工艺及阳极钝化行为进行了研究.结果表明,用Fe(VI)表观电化合成速率、理论电化合成速率和分解速率可以定量描述电解过程中阳极钝化程度,其数学表达式为:θ=1-[r(FeO42-)app-r(FeO42-)d]/r(FeO42-);铁阳极在某种条件下可以明显避免钝化的影响,从而长时间保持较高的Fe(VI)电流效率.具体条件:温度35℃、电流密度≤6.1 mA/cm2和氢氧化钠浓度≥14.5 mol/L.据此可成功电化合成出浓度高于0.78 mol/L高铁酸钠溶液,相应平均电流效率47%.     

铬酸洗液中Cr(Ⅵ）萃取回收研究

针对铬酸洗液的排放,为解决其对环境环境污染和资源浪费问题,以三辛胺(TOA)为萃取剂,采用萃取法对铬酸洗液中的Cr(Ⅵ)进行回收。研究了稀释剂在高酸、强氧化性条件下的选择、硫酸和Cr(Ⅵ)浓度对萃取率的影响以及Cr(Ⅵ)的反萃取实验。结果表明,以TOA为萃取剂,以1,2-二氯乙烷为稀释剂,当硫酸浓度为92 g/L,萃取率最高,可达到96.3%;以4 mol/L的氢氧化钠溶液为反萃剂,反萃取率为100%。采用溶剂萃取法回收铬酸洗液中的Cr(Ⅵ),不仅有益于环境保护与资源节约,而且为铬酸洗液资源化利用提供新途径。     

化工装置的化学清洗程序

化学清洗,要根据垢样的分析结果,选择合适的溶剂和相应的缓冲剂来配制清洗剂。清洗前,设备通常用1％～2％的氢氧化钠溶液进行脱油脂的预处理。在某些场合也用1％的热铬酸作为氧化剂来协助除去某种硫化物。金属设备酸洗除垢后,需注意冲洗、中和及钝化,防止设备再生锈。钝化的药剂有:硝酸钠、纯碱、联氨、磷酸盐等。     

三价铬对测定退铬溶液中氢氧化钠的影响

在氢氧化钠溶液中用电解法退铬,退镀液中产生亚铬酸钠。用酸碱滴定法以酚酞作指示剂测定氢氧化钠,亚铬酸钠影响测定结果。在生产过程中发现,用传统的酸碱滴定法测定氢氧化钠误差很大。通过实验改进了氢氧化钠的测定方法,用氯化钡沉淀亚铬酸钠等,以酚酞作指示剂,用盐酸滴定氢氧化钠的质量浓度。     

铝锌合金镀层镀板（带）再保护膜处理工艺的研究

含铝量55%的铝锌合金镀层很难采用常规的铬酸钝化液钝化,为给覆以这种镀层的钢板(带)提供再保护膜,本文提供一种新型的铬酸钝化工艺,其溶液中含有一种具有润湿、活化、氧化、封孔等综合效果的表面处理剂,能在这种铝锌合金表面形成致密的保护膜.     

镀锡板铬酸钝化工艺研究

采用铬酸溶液对镀锡板进行钝化,对钝化液组成、阴极电流密度、温度等工艺条件进行研究,通过宏观表面质量、钝化膜的组成、漆膜附着力评价等方面对钝化膜的性能进行考察.结果表明:在50 g/L CrO3+0.5 g/L H2SO4的钝化液中,阴极钝化电流密度控制在6～10 A/dm2、温度保持在50～60℃较为合适;在此条件下得...     

低铬酸彩色钝化液的快速调整

镀锌层的钝化工艺对镀锌层的质量有至关重要的影响，镀锌层在低铬酸溶液中钝化，不仅由于化学作用产生一层光亮美丽的彩虹色钝化膜，而且这层钝化膜使镀锌层的防护性能成倍地大幅提高。我厂采用的是低铬酸彩色钝化工艺，低铬酸钝化工艺配方及操作条件为：铬酐工业品４～６...     

化学镀镍层无铬钝化工艺的研究

探讨了氢氧化钠、碳酸钠、磷酸钠和硅酸钠单独或协同作用对化学镀镍层钝化的影响,并以正交设计试验确定了上述四种组成的最佳浓度。为增强钝化效果,研究了高锰酸钾质量浓度、钝化温度和时间对钝化效果的影响。结果表明,钝化液的最佳组成为10g/L氢氧化钠,15g/L碳酸钠,50 g/L磷酸钠,5 g/L硅酸钠,1 g/L高锰酸钾,θ为80℃,t为20 min。化学镀镍层经无铬钝化液处理后,镀层抗腐蚀能力显著提高。     

Durability of geopolymer materials in sodium and magnesium sulfate solutions

This paper presents an investigation into the durability of geopolymer materials manufactured using class F fly ash and alkaline activators when exposed to a sulfate environment. Three tests were used to determine resistance of geopolymer materials. The tests involved immersions for a period of 5 months into 5% solutions of sodium sulfate and magnesium sulfate, and a solution of 5% sodium sulfate+5% magnesium sulfate. The evolution of weight, compressive strength, products of degradation and microstructural changes were studied.In the sodium sulfate solution, significant fluctuations of strength occurred with strength reduction 18% in the 8FASS material prepared with sodium silicate and 65% in the 8FAK material prepared with a mixture of sodium hydroxide and potassium hydroxide as activators, while 4% strength increase was measured in the 8FA specimens activated by sodium hydroxide. In the magnesium sulfate solution, 12% and 35% strength increase was measured in the 8FA and 8FAK specimens, respectively; and 24% strength decline was measured in the 8FASS samples. The most significant deterioration was observed in the sodium sulfate solution and it appeared to be connected to migration of alkalies into solution. In the magnesium sulfate solution, migration of alkalies into the solution and diffusion of magnesium and calcium to the subsurface areas was observed in the specimens prepared using sodium silicate and a mixture of sodium and potassium hydroxides as activators. The least strength changes were found in the solution of 5% sodium sulfate+5% magnesium sulfate. The material prepared using sodium hydroxide had the best performance, which was attributed to its stable cross-linked aluminosilicate polymer structure.     

纯三水铝石在NaOH溶液中溶出过程最可机函数和动力学参数(英文)

Determination of probable mechanism function and kinetic parameters is important to hydrometallurgical kinetics.In this work,the most probable mechanism function and kinetic parameters of gibbsite dissolution in NaOH solution are studied.The sample,the mixture of synthetic gibbsite and sodium hydroxide solution,was scanned in high-pressure differential scanning calorimetry(DSC) equipment with the heating rate of 10 K·min-1. Integral equation and differential equation of non-isothermal kinetics were solved to fit the data related to DSC curve.According to the calculation results,the most probable mechanism function for pure synthetic gibbsite dissolution in sodium hydroxide solution is presented based on the optimum procedure in the database of the mechanism function.The apparent activation energy obtained is(75±1) kJ·mol-1,the frequency factor is 10 8±1mol·s-1,and the reaction is a second order reaction.     

碳酸钠溶液吸收硫化氢富液的直接电解工艺

在电解碳酸钠吸收硫化氢的富液过程中,为了降低阳极钝化,提高负二价硫向零价硫的转化率和电流效率,采用板框式电解槽直接电解法回收硫黄和氢气,其中石墨电极为阳极,碳酸钠溶液吸收硫化氢富液为阳极液,钛网电极为阴极,氢氧化钠溶液为阴极液。实验考察了温度、pH值、初始溶液浓度、电流密度等因素对电解过程阳极反应的影响。结果表明:溶液中S^2-的转化率随温度和初始溶液中Na₂S浓度的增大而增大,而随电流密度的增大而降低。确定了适宜的电解条件为电解温度75℃,初始硫化钠溶液浓度在0.5mol/L以上,电流密度10~20mA/cm²,且初始阳极液中不加氢氧化钠为佳,此时阳极液中S^2-的转化率可达85%以上。对回收硫黄的XRD、SEM表征结果表明,所生成的硫黄以斜方硫的形式存在,且硫黄颗粒粒径变大,有利于固液分离。     

Electroless copper plating on acrylonitrile butadiene styrene material surfaces without chromic acid etching and a palladium catalyst

Hydrolysis modification of nitrile groups on acrylonitrile butadiene styrene (ABS) plate surfaces into carboxylic acid groups was investigated to find a new recipe for electroless copper plating of ABS plate surfaces without etching reactions using chromic acid and also without a palladium catalyst. Hydrolysis modification of nitrile groups was successfully conducted in an aqueous sodium hydroxide (NaOH) solution (70 wt %) at 80°C for more than 72 h, and nitrile groups were modified into carboxylic acid groups. The hydrolysis modification was accelerated by the addition of dioxane as a supplement to the aqueous NaOH solution. The modification, when an aqueous mixture solution of NaOH (35 wt %) and dioxane (10 wt %) was used as a reagent, was accomplished at 65°C in 30 min. The hydrolyzed ABS plate surfaces were successfully metalized by electroless copper plating. A silver catalyst, instead of a palladium catalyst, was usable in the electroless copper‐plating process. Adhesion between the deposited copper metal and ABS plate surface was perfect for the Scotch tape test. Consequently, we propose a new recipe for an electroless copper‐plating process without an etching process using chromic acid and without a palladium catalyst. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

镀锌层墨绿色钝化膜的X-射线能谱分析

在铬酐、磷酸、硝酸和硫酸溶液中加入稳定剂及调色剂,对镀锌钢板进行墨绿色钝化处理.用扫描电子显微镜观察了钝化膜的微观形貌;用能谱仪测定了钝化膜的元素成分及其质量分数.扫描电子显微镜观察表明,钝化膜表面较为均匀平整.X-射线能谱分析显示,钝化膜主要由 Cr、O、P、S、N和Zn元素组成,另外膜中还含有少量的Fe.     

A sodium hydroxide anodize surface pretreatment for the adhesive bonding of titanium alloys

The development of a sodium hydroxide anodize prebond treatment for titanium alloys, which results in excellent durability of adhesive-bonded joints when assessed by wedge specimens exposed to 50°C and 96% relative humidity, is described. Crack growth data are reported which show that the process resulted in better durability than the 10V chromic acid-fluoride anodize process developed in the USA, and that alkaline hydrogen peroxide etch pretreatments resulted in lower durability than the two anodize processes. Other important advantages of the sodium hydroxide anodize process, including easy process control, are indicated.     

从高苛性比铝酸钠溶液中制取氢氧化铝的实验研究

霞石经高压水化学法处理,得到高苛性比铝酸钠溶液加入CaO,生成水合铝酸三钙,溶解于碳酸氢钠溶液中,得到低苛性比铝酸钠溶液,经除杂碳分后,可制得符合国家二级标准(GB/T4294—1997)的氢氧化铝制品。实验结果表明,在水合铝酸三钙形成过程中,影响因素大小的顺序为:CaO/Al2O3>温度>时间;在氧化铝溶出过程中,影响因素大小的顺序为:温度>时间>碳酸氢钠加入量。实验所采用的工艺路线,对于解决从高硅原料中提取氧化铝的问题,具有重要的意义和实际应用价值。     

Stimulation of the passivation of iron by tungstate,molybdate and chromate ions

The effects of tungstate, molybdate and chromate ions on the passivation of iron were investigated, and these oxyanions stimulated the passivation especially at lower pH.The results were rationalized by the dissolution-precipitation mechanism of iron passivation.In order to bring about the passivity of iron, it was required that iron first dissolves into solution, and then a ferric hydroxide or a ferric complex with oxyanion should be produced on the metal surface, which was followed by the dyhydration or the condensation reaction of these compounds to form ferric oxide.     

N-酰基肌氨酸钠的合成工艺现状

综述了N-酰基肌氨酸钠的合成工艺及产品分析检测方法。重点介绍了N-酰基肌氨酸钠的间接合成法(即肖顿-鲍曼(Schotten-Baumann)缩合反应方法),该方法根据反应条件可分为:水相滴加脂肪酰氯和氢氧化钠溶液法、有机溶剂-水混合相滴加脂肪酰氯和氢氧化钠溶液法和一次加入氢氧化钠溶液水相滴加脂肪酰氯法,对比讨论了3种合成方法的优缺点。同时对N-酰基肌氨酸钠产品的质量分析方法进行了比较。