低密度磁性粉末的制备

采用化学镀的方法,在密度为0.6g/cm3的空心玻璃微珠表面镀覆具有磁性的金属Co层,制备低密度的磁粉。研究结果表明:通过改变镀覆工艺参数,可以得到密度在0.62～1.88g/cm3的表面包覆Co的空心玻璃微珠。单位体积镀液中空心微珠的量(装载量)增加,粉末的密度下降,粉末表面Co包覆的均匀程度增加。当装载量为3g/L、化学镀温度为80℃时,包Co微珠密度为0.98g/cm3。所得粉体的矫顽力约为Hc=39789A/m,饱和磁化强度43A·m2/kg,剩磁12A·m2/kg。     

空心玻璃微球表面化学镀银工艺研究

研究了以甲醛为还原剂的空心玻璃微球表面化学镀银工艺,探讨了微球预处理、反应速度、微球装载量、pH值及加料方式等因素对镀覆结果的影响,采用显微分析、X射线衍射等分析方法对样品进行了分析和比较.结果表明,控制微球装载量、缓慢滴加银液、适当降低反应温度可以减缓镀覆速率,能得到镀层均匀致密、结合牢固、体积电阻小的镀银空心玻璃微球.     

空心微珠表面化学沉积Co—P合金研究

利用化学镀工艺在粉煤灰空心微珠表面均匀、完整地包覆磁性Co-P合金层,成功制备出新型轻质的复合导电粉体.使用XRD、EDS、SEM和镶嵌金相的方法对样品进行形貌观察和分析表征,并讨论了镀液温度、pH值和稳定剂浓度对沉积效率的影响.结果表明,空心微珠经过敏化-活化的表面预处理后,利用化学镀方法可以得到均匀、包覆完整的Co-P合金层,并且出现了新的晶化相α-Co单质.T=90℃、pH=10.2和加入适量的硫脲是使反应良好进行的最佳工艺参数.     

化学镀法制备Ag/Al复合粉末

通过化学镀的方法在铝粉表面包覆银,研究了铝粉化学镀银的原理,探讨了氨水、银氨离子、稳定剂、温度和pH对化学镀银的影响。结果表明氨水可以增加镀液稳定性,改善镀层形貌;银氨离子浓度对镀层银含量以及粉末电阻率影响明显;少量稳定剂可以增强镀液稳定性,过量导致镀层疏松多孔;温度和pH的提高可以增加银的析出量,但也会导致镀液的分解。     

铝镀银微珠/有机硅导电压敏胶的制备及性能研究

以107硅橡胶和甲基乙烯基硅树脂为原料制备了有机硅压敏胶,傅里叶变换红外光谱分析表明反应生成物具有典型的甲基聚硅氧烷结构;采用有机溶剂化学镀法制备出铝镀银微珠,采用扫描电子显微镜、X射线衍射仪、能谱分析仪对铝镀银微珠及铝镀银微珠/有机硅导电压敏胶的形貌、微观结构及元素含量进行分析和测试,结果表明铝镀银微珠表面被致密银层包覆且银质量分数大于95%,铝镀银微珠/有机硅导电压敏胶与导电橡胶板具有有效电连接。电性能与力学性能测试结果表明,当铝镀银微珠体积分数为5%时,铝镀银微珠/有机硅导电压敏胶综合性能最优。     

空心玻璃微珠表面无钯活化化学镀镍工艺研究

空心玻璃微珠表面进行金属化处理后, 可以作为复合导电填料用于制备电磁屏蔽材料或吸波材料.采用无钯活化工艺在空心玻璃微珠表面实施了化学镀镍磷合金, 对影响镀速和镀液稳定性的因素进行了讨论,并利用环境扫描电子显微镜、X射线能量色散谱仪和X射线衍射对施镀前后空心玻璃微珠的表观形貌、成分和晶形变化进行了表征.结果表明,利用无钯活化法可以得到均匀的非晶态的镍磷合金镀层, 镀层光亮、包覆完整.还对空心玻璃微珠表面化学镀镍活化机理进行了分析.     

空心玻璃微珠无钯活化化学镀银的研究

采用一种特殊的空心玻璃微珠表面前处理方法,在化学镀银前进行碱洗、双氧水洗和γ-氨丙基三乙氧基硅烷(KH-550)偶联3步处理,使其表面同时达到较好的粗化、羟基化与氨基化效果,再对处理后的玻璃微珠实施化学镀银得到镀银空心玻璃微珠。借助扫描电子显微镜(SEM)、X射线能谱(EDS)和X射线衍射(XRD)测试手段对所得复合粉体的活化及偶联改性效果、镀层表面形貌和结构进行了表征。结果表明:与传统胶体钯活化法化学镀银相比,空心玻璃微珠经活化、偶联表面改性后化学镀银的镀层更为均匀、致密、导电性好。     

空心玻璃微珠表面处理微观分析

用硅烷偶联剂对空心玻璃微珠的表面进行了处理.用红外,热分析,电镜对空心玻璃微珠进行了观测.未经偶联剂处理的空心玻璃微珠表面的OH键含量少.未经偶联剂处理的空心玻璃微珠含水量非常微小.通过电镜观察,偶联剂剂提高了环氧树脂与空心玻璃微珠的结合程度.     

镀银铝粉的制备及其机理分析

通过置换反应法制备镀银铝粉时所得到的银层不够致密,为了提升银镀层对铝粉的包覆效果,本文利用扫描电子显微镜、X射线衍射仪观察镀银铝粉的包覆效果和微观结构,并采用电化学工作站对反应过程中铝基体电位的变化进行分析.结果 表明,在活化的铝粉表面依靠铝银之间的置换反应可以使银沉积,但由于电化学微电偶电池效应的存在,仅通过置换反应无法得到致密的镀银层.进一步研究发现,通过添加合适的还原剂来降低置换反应中的微电偶电池效应的影响,可以改善银颗粒的沉积形貌并提高镀银层的致密性,从而降低镀银铝粉的压片电阻.     

pH值对涤纶织物化学镀银的影响

研究了用葡萄糖作还原剂、氨水作络合剂在平纹涤纶织物上的化学镀银。分别采用场发射电镜(FE-SEM)、电子能谱(EDS)和X射线衍射(XRD)表征化学镀银层的表面形貌、镀层成分及结晶情况。考察了pH值对化学镀银镀液稳定性、镀层表面形貌、化学成分、结晶情况、镀银速率、增重率、表面电阻以及电磁屏蔽效能的影响。结果表明:pH值对化学镀银有非常重要的影响,pH值越高,溶液稳定性越差,镀银速率越快;随着pH值的升高,银的晶粒尺寸先增大后减小,晶面(111)的择优取向降低,晶面(220),(311)的择优取向升高。当pH值为12.8时,镀层堆积紧密、结晶性和电磁屏蔽效能较好。     

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.