化学镀法制备纳米Cu/Al复合粉末

为了改善超细铝粉的表面易氧化问题和微米级铝粉对推进剂的热分解催化作用不明显现象,以对推进剂具有良好催化作用的纳米Cu包覆金属Al表面.采用化学镀铜法对微米级铝粉表面进行镀覆,制备出纳米Cu粒子在超细Al颗粒表面包覆完整的Al-Cu核壳式复合粉末,并利用正交实验优化镀液组分及镀覆工艺条件.利用XRD、SEM、EDX等仪器,对复合粉末的形貌、物相结构及表面成分进行分析,结果表明铝粉表面包覆一层致密的纳米铜层,这种纳米层是由粒度约为18.83nm的晶态析出的纳米铜组成.     

钼粉表面化学镀铜工艺研究

采用化学镀方法对平均粒径3 μm的Mo粉末进行化学镀铜,探讨了工艺条件对化学镀铜的影响.利用扫描电镜(SEM)对钼粉镀覆前后形貌进行观察;X射线衍射(XRD)对所得复合粉末相组成进行了分析.结果表明:采用化学镀的方法可以成功地获得铜含量(质量分数)为15%～85%的Mo/Cu复合粉末,复合粉末中无Cu2O,表面平滑,但有团聚现象;化学镀铜过程中,pH值的临界值为12,随着pH值增加,镀速加快,但是pH值过高会引起甲醛分解,镀液中pH值的最佳范围在12～13之间;随着温度和甲醛含量的升高,镀速加快,镀液稳定性降低,镀液中甲醛含量和温度最佳范围分别为22～26 mL/L,60～70℃.     

纳米Al2O3化学镀铜粉杂质对烧结致密化的影响

用化学镀铜方法制备了纳米Al2O3化学镀铜复合粉末,并用常规粉末冶金方法对粉末的烧结特性进行了研究.纳米Al2O3化学镀铜复合粉末具有异常的粉末烧结特性和难于烧结的特点.通过对粉末清洗、热重分析(TG)、粉末及烧结试样的场发射扫描电镜(FT-SEM)及能谱(EDS)的观察分析,发现纳米Al2O3化学镀铜粉末表面吸附了化学镀溶液的杂质.这些杂质在粉末高温还原及烧结过程中发生热解,并在铜的表面沉积碳,影响了纳米Al2O3化学镀铜粉的烧结.     

化学镀铜法制备Mo-Cu复合粉体的研究

采用化学镀技术对平均粒度为3μm的Mo粉末进行化学镀铜，探讨了镀液组成及工艺条件对Mo粉末化学镀铜的影响，利用X射线衍射、SEM对所得粉末进行了分析。结果表明：以TEA为主络合剂，EDTA为辅助络合剂，并加入2，2′-联吡啶和聚乙二醇作为稳定剂，可以成功地在Mo粉上镀铜，复合粉末铜含量为15％～85％（wt）。化学镀铜过程中pH的最佳值在12-13之间，甲醛浓度的最佳值在22-26mL／L之间。     

硅粉表面化学镀铜工艺研究

研究了化学镀法对硅粉进行化学镀铜过程,探讨了甲醛含量、pH值、温度对化学镀铜反应时间及复合粉体颜色的影响和镀层的微观形貌及结构。结果表明：在镀液中,pH值增大、温度升高、甲醛含量增加,可以缩短反应时间,提高镀速。得出最佳工艺条件：甲醛为60～72ml／L,pH值为12～12．5,60℃。所得复合粉体镀覆均匀,晶形良好,没有Cu2O的存在。     

氮化硅超细粉的钴磷合金镀

用超声波低温化学镀法在纳米Si3N4粉末表面沉积了均匀的钴磷合金镀层，在平行对比实验的基础上，提出了获得良好钴磷合金镀层的最佳镀液组成和操作条件，并对复合粉末进行了能谱成分、XRD相、TEM形貌以及衍射分析。     

均匀设计法在Al2O3粉末超声化学镀铜工艺中的应用

用均匀设计法设计实验方案,采用在超声辐照下的化学沉积法制备了一种新型的Cu/Al2O3I粉末复合材料,探索了该技术中各种囚素对镀铜质量的影响规律,找到了表征这些规律的数学方程及化学镀铜的最佳工艺,化学镀铜的最佳工艺为:化学镀液的组成是CuSO4·5H2O 0.104mol/L、NaOH 0.541mol/L、酒石酸钾钠0.152mol/L、CH2O(37%)O.158mol/L(镀前现加).镀铜时间20min.     

纳米SiC表面化学镀铜研究

采用化学镀方法在超声辐照下对50 nm的SiC进行了化学镀铜,并探讨了孕育期的存在机制以及施镀工艺对化学镀铜的影响.利用XRD、场发射扫描电镜、EDS对粉体镀覆前后成分进行了物相、形貌、成分分析.结果表明:孕育期的存在机理在于镀液中配位剂对活化后粉体表面胶体层的去除;采用双配位剂工艺,配位剂的协同效应能大大提高镀液中Cu2 的利用率,本试验中铜的利用率最低高达89.5%,从而减少了镀后废液的污染;在试验所取温度范围内,随着温度的提高,镀速逐渐升高;通过控制装载量可以实现不同含铜量的复合粉体的制备.     

化学镀法制备纳米Ni-B包覆Al复合粉末

以硼氢化钾(KBH4)为还原剂,采用化学镀法制备了纳米Ni-B包覆Al复合粉末,研究了镀液组分及工艺对包覆效果的影响,获得了制备复合粉末的优化条件。采用SEM,XRD,ICP和BET对复合粉末的表面形貌、物相结构、元素组成和比表面积进行了表征分析。结果表明:纳米Ni-B在Al表面包覆连续、均匀,且纳米Ni-B呈非晶态,粒径80~100nm,化学组成约为Ni72B28,纳米Ni-B/Al复合粉末比表面积达到了26.21m2.g-1。     

石墨表面化学镀铜新方法

在石墨粉表面预包覆一层铜可以大大提高铜-石墨复合材料的力学和电学性能.研究了一种在石墨粉表面化学镀铜的新方法--利用还原铁粉作还原剂的化学镀法.通过大量试验和差热分析仪确定了最佳镀覆工艺条件,并用扫描电镜分析了镀覆效果.研究表明,使用十二烷基磺酸钠、十二烷基苯磺酸钠和磷酸钠混合表面活性剂对石墨粉清洗、润湿和活化预处理后,用还原铁粉作还原剂、饱和硫酸铜溶液作镀液,在pH值为1.5～2.0、40～60 ℃温度下搅拌施镀,C6H5N3钝化后在红外干燥箱内48～50 ℃干燥可得镀覆效果良好的镀铜石墨粉末.该方法解决了常用铁粉作还原剂时出现的问题.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.