铜及铜合金钝化膜发黄故障的解决

继电器部分基材为铜及铜合金零件,要求具有一定的防护性能和钎焊性能,采用酸洗铬酸钝化工艺,经一段时间的生产发现零件表面经常有发黄现象产生,影响其防护性能和钎焊性能.经过多次试验,深入分析,进行工艺改进,成功地解决了铜及铜合金钝化膜发黄的问题.     

铜合金元件的苯骈三氮唑钝化处理

前言铜合金元件及零件的钝化处理,普遍采用铬酸或重铬酸盐溶液。6价铬是剧毒物质。含Cr废水严重污染水源,毒害生物。因此,排放水前必须妥善处理。目前,国内对含Cr废水的净化处理与Cr的回收,比较有效的方法是:还原沉淀法;离子交换法和电解处理法。但是采用这些处理方法,均需一笔相当数量的投资,而且操作、管理均较复杂。这对于只进行铜合金件的酸洗、钝化处理的非电镀生产,废水的净化处理从经济上来说还是颇费资金的。近几年来,有关行业的工程技术人员在积极地探讨铜合金件的新的钝化途径,企图从根本上革除铜及其合金件的铬酸钝化工艺。苯骄三氮唑水溶液是一种效果比较好的铜合金钝化     

铜合金表面硝酸镧稀土钝化膜的性能研究

为了提高铜及其合金的耐蚀性能,研究了一种含硝酸镧的新型钝化工艺,处理后的铜合金表面形成了金黄色的稀土钝化膜.采用硝酸点滴、湿热试验及盐雾试验等方法对钝化膜的耐蚀性进行了表征.结果表明,最佳钝化工艺为:23 g/L有机羧酸,16 g/L苯并三氮唑(BTA),4 g/L硝酸镧,1 g/L促进剂,温度60℃,钝化时间3 min.稀土盐的加入使其耐硝酸点滴及湿热试验的时间均延长了3倍多;在5%NaCl溶液的腐蚀速率降低6倍,在扫描电镜下可以明显观察到加入稀土盐后合金表面结构变得均匀致密;电子探针分析表明,稀土钝化膜的La,O等元素都均匀分布在膜层表面.     

铜和铜合金的低浓度钠盐钝化工艺

本文介绍一种新型的铜和铜合金低浓度钠盐钝化工艺,其重铬酸钠浓度可大幅度降低:重铬酸钠12～18g/升,而传统配方为100～150g/升。钝化膜的耐蚀性,耐磨性和装饰性都达到规定指标。该工艺已经过一年多的生产性考验。本文除介绍有关工艺试验外,还结合仪表零(组)件生产,介绍该工艺的工作条件和工艺流程,并对影响钝化膜质量的各种因素进行讨论。     

镀锌层硅酸盐彩色钝化工艺

镀锌层无铬彩色钝化已成为重要的研究方向。研究了硅酸盐无铬彩色钝化工艺条件对钝化膜性能的影响,确定了最佳钝化工艺:30.0 g/L Na2SiO3,25.0 g/L H2SO4,25.0 g/L H2O2,0.1 g/L CuSO4,pH值1.5～2.5,钝化时间10～100 s。最佳工艺条件下,分别对酸性和碱性镀锌件进行硅酸盐彩色钝化,并与六价铬盐钝化层的性能进行了对比。结果表明:镀锌层硅酸盐钝化可以在表面获得彩色、光亮、均匀的钝化膜,膜层的颜色是由膜的化学组成和光的干涉共同作用的显现;耐蚀性能与六价铬盐钝化膜相当,耐中性盐雾腐蚀可达到200 h,且用于碱性镀锌的钝化效果明显优于酸性镀锌;该工艺成本低,无污染,有望代替传统铬酸盐彩色钝化工艺。     

镀锌及锌合金层低毒、无毒钝化工艺

综述了国内外镀锌及锌合金层主要的低毒无毒钝化工艺.介绍了镀锌及锌合金层钝化原理和钝化体系.讨论了镀锌及锌合金层无六价铬钝化工艺的特点,包括三价铬盐钝化、钼酸盐钝化、稀土钝化、钛盐钝化、硅酸盐钝化、钨酸盐钝化和有机物钝化等,并针对各种钝化工艺的特点提出了有待完善的方面.通过分析讨论镀锌及锌合金层低毒、无毒钝化工艺,从成本和性能两个因素比较得出三价铬钝化技术是最有可能被接受的六价铬替代品,其次为钼酸盐钝化.指出了六价铬钝化工艺的替代势在必行,以及无毒或低毒、高耐蚀性和低成本的镀锌及锌合金层钝化工艺是今后的研究方向.     

钝化工艺参数对镀锌钛盐钝化膜色泽的影响

对代替铬酸盐溶液的镀锌钛盐钝化技术进行了研究,并借助扫描电镜、电子能谱仪考察了钝化工艺对钝化膜色泽的影响情况.结果表明,在钛盐钝化液中,镀锌层表面可获得黄、蓝、金黄、紫、绿等色泽的钝化膜;钝化工艺参数(钝化时间、钝化温度、钝化液pH值、干澡温度等)对镀锌层钝化膜的色泽有很大影响;镀锌钛盐钝化膜的微观形貌、表面成分与不同钝化工艺条件下获得的钝化色泽具有一定的对应关系.初步探讨了镀锌层在钛盐钝化液中成膜产生色泽的原因.     

镀锌层墨绿色钝化工艺的优化

现有的镀锌墨绿色钝化工艺性能不稳定,不便使用.在四酸溶液体系中,加入稳定剂及调色剂,对镀锌钢板进行墨绿色钝化处理.研究了溶液组分、温度、pH值、钝化时间等因素对钝化膜性能的影响,确定了最优工艺参数.结果表明,钝化液组分最佳范围:20～30 g/L铬酐,10～13 mL/L磷酸,2～6 mL/L硫酸,3～5 mL/L硝酸,3～5 mL/L稳定剂,2～10 mL/L调色剂;最佳工艺条件:溶液pH值1.0～1.5,钝化温度20～30℃,钝化时间40-60 s.经最优工艺处理的钝化试样外观呈墨绿色,色泽均匀,光度柔和,耐中性盐雾达400 h,附着力测试擦拭次数达100次,超过国家标准10次擦拭次数的要求.本工艺在实际生产中取得了很好的效果.     

镀锌层军绿色钝化工艺

介绍了镀锌军绿色钝化工艺，研究并讨论了钝化液的成分及操作条件对钝化膜的影响，用中性盐雾实验和５％氯化钠溶液浸泡实验评定了膜层的耐蚀性。结果表明，本钝化工艺得到的镀锌层军绿色钝化膜均匀，膜层耐蚀性比彩色钝化的好。     

热浸镀锌层有机物-无机物复合钝化工艺优选及其性能

为了进一步提高热浸镀锌层钝化膜的耐蚀性能,针对目前无铬钝化多为独立体系的有机物钝化或无机物钝化的情况,运用有机物与无机物进行复合钝化。通过正交试验法确立了热浸镀锌层无色钝化工艺,采用单因素变量法、点滴试验、中性盐雾腐蚀试验及电化学测试技术,研究了复合钝化工艺参数对钝化膜外观和耐蚀性的影响。结果表明:最佳复合钝化工艺为40 g/L丙烯酸树脂,20 g/L硝酸钠,40 g/L硅酸钠,15 m L/L过氧化氢;p H值11,钝化时间30 s,温度30℃,恒温烘干;钝化膜的耐蚀性能接近于三价铬钝化。     

检定和校准证书的异同与应用

本文介绍了检定和校准以及证书的两点相同、五点不同之处,说明了对检定证书和校准证书的正确应用。     

Heat and Mass Transfer and Modeling and Prediction of Environmental Catastrophes

Basic definitions and concepts of the physicomathematical theory of natural catastrophes are given. Possibilities of mathematical modeling of natural and technogenic catastrophes are discussed in the context of the theory of heat and mass transfer and the mechanics of reacting media. The importance of taking into account conjugate heat and mass exchange in modeling catastrophes is emphasized. A formula for evaluating the probability of a collisional catastrophe is given.     

Multi-ferroic and magnetoelectric materials and interfaces

The existence of multiple ferroic orders in the same material and the coupling between them have been known for decades. However, these phenomena have mostly remained the theoretical domain owing to the fact that in single-phase materials such couplings are rare and weak. This situation has changed dramatically recently for at least two reasons: first, advances in materials fabrication have made it possible to manufacture these materials in structures of lower dimensionality, such as thin films or wires, or in compound structures such as laminates and epitaxial-layered heterostructures. In these designed materials, new degrees of freedom are accessible in which the coupling between ferroic orders can be greatly enhanced. Second, the miniaturization trend in conventional electronics is approaching the limits beyond which the reduction of the electronic element is becoming more and more difficult. One way to continue the current trends in computer power and storage increase, without further size reduction, is to use multi-functional materials that would enable new device capabilities. Here, we review the field of multi-ferroic (MF) and magnetoelectric (ME) materials, putting the emphasis on electronic effects at ME interfaces and MF tunnel junctions.     

CellML and associated tools and techniques

We have, in the last few years, witnessed the development and availability of an ever increasing number of computer models that describe complex biological structures and processes. The multi-scale and multi-physics nature of these models makes their development particularly challenging, not only from a biological or biophysical viewpoint but also from a mathematical and computational perspective. In addition, the issue of sharing and reusing such models has proved to be particularly problematic, with the published models often lacking information that is required to accurately reproduce the published results. The International Union of Physiological Sciences Physiome Project was launched in 1997 with the aim of tackling the aforementioned issues by providing a framework for the modelling of the human body. As part of this initiative, the specifications of the CellML mark-up language were released in 2001. Now, more than 7 years later, the time has come to assess the situation, in particular with regard to the tools and techniques that are now available to the modelling community. Thus, after introducing CellML, we review and discuss existing editors, validators, online repository, code generators and simulation environments, as well as the CellML Application Program Interface. We also address possible future directions including the need for additional mark-up languages.     

Synthesis and luminescent properties of alkali-metal and ammonium fluorosulfatozirconates and fluorosulfatohafnates

We have synthesized a variety of alkali-metal and ammonium fluorosulfatometallates (titanates, zirconates, and hafnates). The alkali fluorosulfatozirconates and fluorosulfatohafnates have been shown to exhibit efficient roentgenoluminescence (RL) in the UV through visible spectral region, with a maximum at 390–440 nm. Their RL spectra depend significantly on their composition (cation, anion, and water content), coordination of KF and K₂SO₄, and relative amounts of fluorine and SO₄ groups. We have examined the effect of heat treatment on the RL of these compounds. The rubidium and cesium fluorosulfatozirconates Rb₃Zr₂F₉SO₄ · 2H₂O, Cs₂ZrF₂(SO₄)₂ · 2H₂O, Cs₈Zr₄F₂(SO₄)₁₁ · 16H₂O, and Cs₂ZrF₄SO₄ offer the most efficient RL.     

热交换器的分类及优缺点分析

热交换器是将不同温度介质之间的热量通过热传导的形式,由高温介质传递给低温介质,使介质达到生产所需温度的工艺设备,也可作为一种节能设备使用.通过对不同热交换器的结构分析,总结不同热交换器的优缺点、适用环境,为生产工艺设计人员及设备制造单位在选择可降低能耗、提高效率的设备上提供参考.     

凝固科学技术与材料

从凝固科学与实践发展的角度介绍了当前凝固材料体系的基本框架和凝固科学主要发展阶段的基本理论。作为材料科学与工程的基本组成，凝固科学技术正在现代科学理论的基础上针对传统材料的改性提高和新材料的发展需求，以控形、控构、控性为目标开展优质铸件的定向、晶体生长、快凝、深过冷及各种新型和超常领域凝固过程的研究，并介绍了其中某些方面和展望了可能的发展趋势。