镀镍层针孔和麻点的故障及其排除方法

镀镍层针孔和麻点大都是由于空气或氢气泡附着在被镀工件表面所引起的。总结了生产实践中可能引起针孔和麻点的原因有：机械加工处理所造成的基材表面缺陷,镀前除油、清洗不充分,镀液含有无机、有机杂质,镀镍润湿剂用量不足,镀液pH值、电流密度太高,操作温度、硼酸含量太低等。详细介绍了镀镍层针孔和麻点的排除方法,并提供了相关的工厂实例。     

萃取分离法比色测定镀镍液中铁的含量

铁杂质是镀镍液中最常见的金属杂质,它来源于某些化工材料的不纯及钢铁件在镀液中的化学溶解。当槽液中的铁杂质含量达到一定浓度时,会造成镀层粗糙、产生针孔,槽液pH值高时还会形成Fe(OH)_3沉淀并夹杂在镀层中产生脆性、脱皮等疵病。可见定量测定铁含量在电镀工艺管理中是很有必要的。     

一次三镍故障的排除

我厂1993年6月新改建了一条年加工100万套自行车把的三镍铬电镀自动线。正式投产几个月来,产品质量一直稳定。可是进入1993年12月中旬以来突然发生故障,零件上面出现细小的针孔麻点,给产品外观和内在质量带来一定影响。 1、初步分析造成的原因可能是:①工件去油不彻底,②半亮镍、高硫镍及光亮镍镀液的润湿性能不够,③镀液中有机杂质或机械杂质过量,④pH值不当,⑤各槽成分不当。     

基于阴极高速平动的电铸实验研究

设计了一种新型的电铸阴极平动机构,并将其应用于阴极平动电铸实验中。结果表明:此新型阴极平动机构能实现电铸阴极大平动量、高速率的运动;电铸阴极高速平动有助于提高电铸层的质量,在一定程度上消除由于析氢产生的针孔、麻点等缺陷,提高了电铸层的显微硬度。     

电铸镍在激光全息防伪中的应用

电铸镍是激光全息防伪中的一个重要工序。简要介绍了全息图的拍摄原理和生产工艺，详细论述了电铸镍工艺在激光全息防伪中的应用，并对电铸槽液中各成分的作用进行了分析。最后列举了电铸过程中出现的几种问题，如厚度不匀，硬度不够，应力过大等，并对问题原因进行了剖析，同时提出了相应的解决方案。     

浅析阴极电泳针孔产生的原因及解决措施

通过在实验室内进行槽液调整试验,分析阴极电泳后电泳漆膜出现针孔的原因,提出了在实际施工过程中通过调整部分工艺参数解决针孔的方法。     

丙烯酸阳极电泳涂料的电泳涂装工艺研究

针对铝型材丙烯酸阳极电泳涂料,探讨了槽液固体含量、电泳电压、电泳时间、槽液pH等因素对漆膜外观和厚度的影响,确定了电泳涂装的最佳工艺参数:固体分5%～6%,电压120 V,电泳时间80～100 s,电泳槽液pH 7.6～8.1。     

毛刺与麻点

镀层上产生“毛刺”“麻点”是电镀中常见的问题。发生故障的原因,一般认为:前者是镀液中含有的机械杂质造成,后者除基体上原有的缺陷外,主要是阴极上有滞留的气泡造成“麻点”或者含有大量可溶性杂质,如在亮镍镀液中、有机杂质过多,铁杂质超量,都会形成“麻点”。     

手表轴类零件碱性化学镀镍

本文阐述了手表轴类零件(以下简称轴件)的化学镀镍,采用碱性槽液比酸性槽液更优越。还阐述了影响沉积过程的各种因素。指出轴件化学镀镍层最常见毛病的成因及其克服方法。建议采用含适量焦磷酸钠的碱液、煤油、四氯化碳、酒精的混合物作清洗液,以超声波清洗取代常规的化学除油和电解除油工艺。并指出超声波揽拌或利用反应生成的氢气泡揽拌镀液,能显著减少镀层的麻点和针孔。本文的结论是:轴件采用碱性化学镀镍,能满足产品的技术要求。     

光亮镀镍溶液的净化处理

对于光亮镀镍来说,杂质的影响很大.在镀槽中存在无机杂质、有机杂质和气泡,可使镀层粗糙、产生脆性、麻点、裂纹、脱皮和高的内应力.口所以新配的镀液要经过净化处理,才能获得良好的镀层.工作一定时间的镀液,也需要清除有害杂质,才能维.     

乙苯,苯乙烯的生产及合成乙苯,苯乙烯催化剂的研究进展

苯乙烯是重要的石油化工原料。本文介绍了国内外苯乙烯生产的发展概况，合成乙苯，苯乙烯所用的催化剂种类，并就苯乙烯生产及催化剂的发展趋势提出了自己的观点。     

生物质气化及生物质与煤共气化技术的研发与应用

总结了生物质原料的特点及生物质单独气化的缺点;介绍了国内外生物质气化技术及生物质与煤共气化技术的研发与应用现状;分析了在此领域国内外的发展趋势与前景;概括了开展生物质与煤共气化技术研发的意义。     

责任和责任心的涵义与结构

责任是人应主动承担的角色义务和对其因过失所造成后果应承担的责罚.有两层涵义:一是义务;二是后果.责任心是个体自觉做好分内事务和履行道德义务的心理倾向,是个性心理品质成分中自我特征维度上的重要内容.责任心具有两个方面的涵义:一是角色分内职责;二是角色道德义务.责任心是一种通过责任认知、责任个性和责任适应的动态形式表现出来的静态品质,责任心是责任心过程结构与责任心关系结构相互制约、相互影响的统一体.     

Kinetics and Mechanism of Oxidation of Mono- and Polyacetals

Abstract

Kinetics and mechanisms of oxidation of 6 acetals by molecular oxygen and ozone in liquid phase have been studied. Reaction with molecular oxygen (70°C, 15–16 hr) leads to the formation monoethers of the corresponding glycols with 68–90% selectivity. Salts of metals and complexes with crown-ethers have increased the reaction rate significally. Ozone have reacted with acetals with formation similar products. The mechanisms of intermediate stages have been proposed.     

医药和农药纳米剂型研究和应用

系统介绍了医药和农药纳米剂型研究进展和应用前景。医药微乳剂和纳米悬浮剂可显著改善药物的悬浮性和分散性,提高生物利用度。载药纳米微粒具有缓释功能,延长药物在体内的半衰期,并可实现药物的靶向定位给药。农药微乳剂具有增溶和渗透作用,提高农药的传递效率和使用安全性。农药纳米悬浮剂和载药纳米粒均可显著提高药效。纳米技术为医药和农药剂型的研究提供了新机遇,具有广阔的应用前景。     

Electronic structures and reactivities of monometallic and bimetallic clusters of Au and Cu

The variation of the Au 4f binding energy of Au clusters with the cluster size has been established by measuring the binding energies of clusters whose size distributions were independently determined by HREM and STM. The binding energy increases significantly when the cluster size is less than 2 nm. Au-Cu bimetallic clusters of the composition Cu₃Au have been deposited for the first time on carbon substrates. The shifts in the core level binding energies of the bimetallic clusters show the effect of alloying in the case of large clusters, but show effects of both alloying and cluster size in the case of the small clusters. The interaction of CO with Cu₃Au clusters is stronger than with a bulk Cu metal. The interaction of CO with small Cu clusters also seems to be stronger than with bulk Cu or with large Cu clusters.     

塑料挤出机螺杆,机筒耐磨损,耐腐蚀的强化与应用

对塑料挤出机,注塑机螺杆,机筒的磨损,腐蚀原因及提高螺杆,机筒耐磨损,耐腐蚀的方法、制造与应用作了较详尽的介绍。     

Modelling and simulation of batch and semi-batch emulsion copolymerization of styrene and butyl acrylate

This work deals with modelling of emulsion polymerization processes using batch and semi-batch reactors. Specific attention is paid to copolymerization of the system styrene/butyl acrylate.The main key parameters of the model are identified on the basis of batch experimental data in order to describe the complete sketch of emulsion polymerization. The model is then used to simulate, under several operating conditions, the polymerization rate, the global monomers conversion, the number and weight average molecular weights as well as the particle size distribution and the glass transition temperature. Then, the model is generalized to the use of semi-batch processes and validated for this application.     

甘油锌和光稳定剂NBC、BZ的光稳定作用测试与评价

对用甘油锌作光稳定剂的光稳定作用进行了测试，并与光稳定剂NBC，BZ进行了比较。研究了甘油锌，NBC和BZ与双酚A的复配效果。研究结果表明，甘油锌是一种性能优良的光稳定剂。     

Structure Elucidation and Evaluation of Antioxidant and Tyrosinase Inhibitory Effect and Mechanism of Proanthocyanidins from Leaf and Fruit of Leucaena Leucocephala

This study aimed to investigate the structural features, antioxidant activity, tyrosinase inhibitory effect, and mechanism of proanthocyanidins from leaf and fruit of Leucaena leucocephala. MALDI-TOF-MS, thiolysis coupled with HPLC-ESI-MS, and ¹³C-NMR confirmed that these proanthocyanidins were complex mixtures of propelargonidins, procyanidins, and prodelphinidins. (Epi)catechin, (epi)gallocatechin, (epi)catechin gallate, and (epi)gallocatechin gallate were the main constitutive units. The findings obtained from enzyme analysis revealed that the proanthocyanidins had inhibitory effects on both monophenolase and diphenolase of tyrosinase. The IC₅₀ values of leaf and fruit proanthocyanidins were 73.5?±?2.7 and 52.3?±?3.5 µg/mL for monophenolase activity, and 27.2?±?1.4 and 16.1?±?1.1 µg/mL for diphenolase activity, respectively. The inhibition of diphenolase by proanthocyanidins were proved to be reversible and mixed type. In addition, it was also found from various antioxidant methods that the proanthocyanidins in leaf and fruit possessed potent DPPH radical scavenging activity with IC₅₀ values of 103.4?±?0.8 and 87.8?±?1.1 µg/mL, ABTS radical scavenging activity with IC₅₀ values of 72.9?±?0.4 and 65.7?±?0.9 µg/mL, and ferric reducing antioxidant power with FRAP values of 3.74?±?0.03 and 4.02?±?0.15?mmol AAE/g, respectively. The results obtained suggested that the proanthocyanidins from leaf and fruit of L. leucocephala might have the potential to be exploited as natural tyrosinase inhibitors and antioxidants.