镀锌层单宁酸钝化膜的耐蚀性

为提高镀锌层的耐蚀性,以氟钛酸钾、双氧水、硝酸为辅助成分,制备了单宁酸钝化液,并对低碳钢上的碱性镀锌层进行了钝化处理.通过质量分数为5%的NaCl溶液浸泡试验,确定了最佳钝化液组成和钝化工艺条件为:单宁酸40 g/L,HNO3 5 mL/L,氟钛酸钾10g/L,H2O2 60 mL/L,温度25℃,时间20～30 s....     

四酸型镀锌层军绿色钝化工艺

提出了一种镀锌层四酸型军绿色钝化工艺。研究了钝化液中4种酸的含量和钝化时间对钝化膜外观和耐蚀性的影响。确定最佳工艺条件为:CrO36g/L,H3PO42mL/L,H2SO42mL/L,H3NO33mL/L,温度25℃,pH1.5,钝化时间100s。所得钝化膜为光亮的军绿色,耐蚀性较镀锌层好。     

镀锌低铬钝化故障处理

0前言 镀锌低铬钝化从上世纪70年代中期起,由180g/L、40 g/L高铬二次钝化基础上降到2～5 g/L低铬钝化新工艺,并且钝化膜的耐蚀性基本上可达到高铬钝化的耐蚀性,初步解决了环境污染问题.本文将低铬彩钝化和白钝化常见的膜层缺陷、产生原因及处理方法,汇总如下.     

稀土钕对镀锌层三价铬蓝白钝化膜耐蚀性的影响

在三价铬钝化液中添加稀土钕,以提高三价铬蓝白钝化膜的耐蚀性。研究了钝化温度、pH、时间以及钝化液中稀土钕含量对钝化膜耐蚀性的影响,得到镀锌层三价铬蓝白钝化的最优工艺条件为:Cr2(SO4)3 18.9 g/L,Nd(NO3)3·6H2O 4 g/L,NaNO32.2 g/L,C6H8O7·H2O 0.7 g/L,CoSO4·7H2O 7 g/L,NaH2PO2·H2O3.4 g/L,NH4HF2 0.2 g/L,温度30°C,pH 1.9,时间30 s。钝化液中添加稀土钕可有效提高钝化膜的耐蚀性。在最佳工艺条件下,钝化膜在3.5%NaCl溶液中的腐蚀电位、腐蚀电流密度和交流阻抗分别为-1.231 V、0.568μA/cm2和1 937?·cm2,中性盐雾试验出现白锈的时间为93 h。     

高耐蚀性镀锌层三价铬蓝白色钝化工艺

开发了一种环保的镀锌层三价铬蓝白色钝化工艺。研究了钝化液中CrCl3·6H2O、Na3C6H5O7、NaNO3、钴盐等成分及pH和温度等工艺参数对钝化膜外观和耐蚀性的影响。蓝白钝化的最佳工艺条件为:CrCl3·6H2O 48g/L,NaNO3 20g/L,Na3C6H5O7 18g/L,钴盐18g/L,室温,pH1.5,钝化时间8s。采用最佳工艺所得钝化膜为光亮、均匀的蓝白色,表面平整、致密,耐蚀性优于镀锌层。     

电镀锌层无铬钝化工艺的研究

开发一种绿色无铬的钝化工艺,所得钝化膜的性能接近铬酸盐钝化膜的。研究了电镀锌层在钛磷硅钼复合体系中的钝化工艺,并采用扫描电子显微镜、硫酸铜点滴实验和中性盐雾实验等方法测试了钝化膜的形貌和耐蚀性。通过正交实验确定了钝化液的最优配方为:三氯化钛10mL/L,磷酸1.8mL/L,硅酸钠18g/L,钼酸钠0.85g/L。其中硅酸钠的质量浓度对钝化膜的表面形貌及耐蚀性的影响最大。采用二次钝化工艺能有效提高钝化膜的耐蚀性。采用上述配方和工艺能够得到一种淡蓝色的无铬钝化膜,其耐蚀性优于三价铬钝化膜的,硫酸铜点滴时间能达到80s,中性盐雾实验的变色时间为72h。     

镀锌层高耐蚀三价铬黑色钝化工艺

采用正交试验优化镀锌层三价铬黑色钝化液的各个组分,在此基础上考察各种工艺条件对钝化膜的外观、耐蚀性和附着力的影响,确定了三价铬黑色钝化工艺的配方及工艺参数。三价铬黑色钝化工艺为:7.5 g/L Cr~(3+),21 g/L络合剂,22 g/L磷酸二氢钠,15 g/L过渡金属盐,0.4 mL/L有机硫化物,0.4 mL/L纳米硅溶胶,pH为2.0,θ为50℃,钝化t为45 s。该钝化工艺得到的钝化膜均匀黑亮,附着力良好,在未加封闭的情况下,耐蚀性达到中性盐雾60 h以上。     

新型氯化钾镀锌三价铬钝化剂和膜层耐蚀性

通过测定Tafel极化曲线、交流阻抗谱和进行盐雾试验,研究了新型三价铬彩色钝化剂SF-571和蓝白钝化剂SF-572对镀锌层耐蚀性能的影响,并与进口钝化剂进行对比。氯化钾镀锌工艺为:KCl200g/L,ZnCl250g/L,H3BO335g/L,柔软剂30mL/L,光亮剂1.5mL/L,25°C,25min,电流密度2A/dm2。电化学分析表明,所有镀锌层钝化膜在1%NaCl溶液中均存在钝化现象,采用自制钝化剂SF-571和SF-572所得膜层的耐腐蚀性能达到或优于用进口钝化剂所得膜层。对比膜层的表面形貌可知,自制钝化剂钝化所得膜层表面更平整、致密。     

无钴硫酸体系三价铬黑色钝化工艺

以过渡金属硫化物M替代钴(镍)盐作发黑剂,在镀锌层表面得到黑色钝化膜。钝化液的配方与工艺为:Cr2(SO4)335g/L,有机羧酸X6g/L,柠檬酸32g/L,过渡金属硫化物M2g/L,FeSO410g/L,NaNO37g/L,NaH2PO415g/L,pH=2.0,室温,时间30s。钝化膜层乌黑均匀、附着力合格;经封闭后的三价铬黑色钝化膜,其耐蚀性等级高于市售含钴盐发黑剂的三价铬黑色钝化膜,且达到六价铬钝化的耐蚀等级;钝化膜中不含六价铬;钝化液性能稳定。     

镀锌层硅酸盐钝化膜的现状及展望

针对钝化膜的研究现状,从工艺改进、联合添加剂以及无机有机复合钝化三个方面详细介绍了国内外提高镀锌层硅酸盐钝化膜耐蚀性的具体方法,并对镀锌层的腐蚀机理进行了初步探讨。最后指出提高硅酸盐钝化膜耐蚀性仍是今后研究的重点。     

含固溶体三元体系K_2SO_4-(NH4)_2SO_4-H_2O和KCl-NH_4Cl-H_2O溶解度的计算

含固溶体三元体系Ｋ２ＳＯ４－（ＮＨ４）２ＳＯ４－Ｈ２Ｏ和ＫＣｌ－ＮＨ４Ｃｌ－Ｈ２Ｏ溶解度的计算樊彩梅舒兰余华瑞石炎福（四川联合大学化工系,成都６１００６５）关键词固溶体电解质溶液溶解度１前言自１９７３年以来,美国物理化学家Ｋ．Ｓ．Ｐｉｔｚｅｒ在总结...     

CaCl2对聚间二苯砜对苯二甲酰胺/DMF溶液特性的影响

为了研究CaCl₂对聚间二苯砜对苯二甲酰胺(mt-PSA)在DMF中分子构象和形态的影响,采用流变仪测定了mt-PSA/DMF/CaCl₂浓溶液的流变行为,并通过乌氏黏度计和激光光散射研究其稀溶液的溶液黏度和高分子形态尺寸。结果表明:CaCl₂的加入增大了大分子与溶剂在mt-PSA/DMF/CaCl₂浓溶液和其稀溶液中的相互作用,同时CaCl₂使大分子链段得到舒展。但大分子的重均分子量没有发生明显的变化,说明CaCl₂未使mt-PSA高分子链段发生聚集或者坍塌。     

固溶体补强增韧的机理

本文主要对无机非金属材料晶体因固溶外来离子而对晶体强度和韧性的贡献进行阐述。本文从固溶类型、点阵畸变、畸变应力着手进行讨论。     

本菲尔脱碳工艺的系统改造

介绍用自行开发的技术对脱碳系统实行节能,扩容,环保改造的原理和效益。     

非水溶液法制备二氧化氯纯水溶液

介绍通过二氧化氯非水溶液制备二氧化氯纯水溶液———一种优良、高效广谱杀菌消毒剂的生产方法 ,该法避免了二氧化氯气体在生产中带来的不安全因素     

浮法联合车间一层方案和二层方案的技术经济分析

以江门900 t/d浮法联合车间为例,用一系列数据对一层方案和二层方案的经济性和实用性作了分析比较.     

草酸-酸亚硅钼蓝光度法检测钢铁及合金中硅的含量

试样用稀酸溶解,在微酸性溶液中,硅酸与钼酸铵生成硅钼杂多酸,在草酸存在下,用硫酸亚铁铵还原成硅钼蓝,测其吸光度.与钼酸盐形成杂多酸的硅必须以正硅酸状态存在,所以在试样溶解过程中必须避免硅酸的聚合.在溶液中硅酸较易于聚合,其聚合程度与溶液的酸度、溶解时加热的程度和时间以及最终溶液中正硅酸离子的浓度有关     

新型缔合聚合物ADH溶液性能研究

研究了疏水缔合水溶性聚合物稀溶液的盐增粘性、抗温性、pH值效应,分析了溶液中聚合物与外加表面活性剂的相互作用,并初步研究了剪切速率对聚合物溶液粘度的影响。     

Viscoelasticity of concentrated polyacrylonitrile solutions: effects of solution composition and temperature

The effects of solution composition and temperature on the viscoelasticity of concentrated polyacrylonitrile (PAN) solutions were studied using a variety of rheological measurements, such as steady‐state shearing, dynamic stress sweep and transient rheological tests. The first normal stress difference N₁ and the shear stress τ were found to increase with decreasing temperature and increasing PAN concentration and water content in the solutions. The crossover point of N₁ and τ, denoting the equal contribution of viscosity and elasticity to the viscoelasticity of the solutions, moved to lower shear rates at lower temperature, higher PAN concentration and higher water content. The values of the relaxation time (λ) were larger at 70 °C than at 40 °C. In addition, the changes of λ with PAN concentration and water content were different at the two temperatures, ascribed to the different states of the solutions. The PAN solutions were in the linear viscoelastic regime in the temperature range 40–70 °C when the shear stress was below 300 Pa. The creep compliance recovery rate decreased with increasing temperature, but increased with increasing PAN concentration and water content. Thixotropic tests showed that the thixotropy of the solutions was also affected by the solution composition and temperature. Gelation was found to influence the way the solution composition and temperature affected the viscoelastic properties of the PAN solutions. Copyright © 2011 Society of Chemical Industry     

Improvement of Zeolite T Membrane via Clear Solution Gel in Dehydration of Methanol,Ethanol, and 2-Propanol

Using of clear gel solution on synthesis of zeolite membrane can potentially have many benefits. In this research, zeolite T membrane on home-made α-Alumina disc-shaped MF support was successfully synthesized in 120°C for 24 h via secondary growth hydrothermal method using high alkalinity clear gel solution in molar ratio formulation (SiO₂:Al₂O₃:Na₂O:K₂O:H₂O = 55:1:122.7:42.3:2000). The synthesized membrane showed elevated selectivity in dehydration of ethanol/water and 2-propanol/water solutions (between 1000 to more than 10000) and high-water permeation fluxes (between 1.2 to 2.4 kg/m²h at 40°C for 10 wt.% water content). The synthesized MF alumina supports, zeolite T membranes, and crystals used for seeding were characterized by XRD and SEM analyses. These analyses indicated 10 μm dense and defect-free well-intergrowth zeolite T as active layers were formed on the porous media support.