前处理工艺对涤纶纤维化学镀银的影响

采用化学法在涤纶纤维表面镀银制备涤纶导电纤维,探讨了前处理工艺对涤纶纤维表面形貌及性能的影响。通过扫描电镜对经过粗化、敏化和活化工序后的纤维表面形貌进行分析,重点研究了敏化、活化工艺中各因素对镀银涤纶纤维导电性能及增重率的影响,并确定了涤纶纤维化学镀银的最佳前处理工艺参数。结果表明,前处理工艺对纤维化学镀银效果有着显著的影响,经过最佳前处理工艺制备的涤纶纤维化学镀银后的电阻率仅为1.6×10-2Ω·cm,导电性能优于未经前处理工艺的镀银涤纶纤维。     

无活化化学镀银涤纶纤维的制备及性能研究

采用不经活化处理步骤的无活化化学镀方法制备镀银涤纶纤维,分别用X射线衍射(XRD)、扫描电镜(SEM)及傅里叶红外光谱(FT-IR)对纤维镀层及成分进行表征分析。探讨了化学反应的可能机理并测试了镀银纤维的导电性能。结果表明,无活化预处理的化学镀方法适用于涤纶纤维化学镀银,能够快速催化化学镀银反应;通过测试分析,发现制得镀银导电纤维的表面形成了一层致密均匀的金属银层,使得纤维具有良好的导电性能。     

芳纶纤维表面银金属化的性能

用Na OH粗化处理芳纶纤维,然后用化学镀方法实现了芳纶纤维表面Ag金属化。使用扫描电子显微镜(SEM)、原子力显微镜(AFM)和X射线光电子能谱仪(XPS)等手段对纤维的表面形貌和元素组成进行了表征,使用X射线衍射仪(XRD)分析了镀银前后纤维的晶体结构变化,使用纤维强伸度仪和热重分析仪(TG)测量了芳纶纤维在镀银前后的力学性能和热稳定性,用万用表测试了镀层的导电性能。结果表明:Ag金属层均匀致密地包裹在纤维的表面,结合牢固度较高。镀银使纤维的热稳定性有所提高,对力学性能的影响较小,电阻达到0.52Ω/cm,在冷热水循环和盐水环境下银层的稳定性较好。     

芳纶纤维表面化学镀Ni/Sn研究

采用化学镀技术制备Ni/Sn双镀层芳纶纤维,实现了芳纶纤维表面金属化,应用SEM、EDS和XRD分析研究芳纶纤维在不同处理阶段表面形貌、镀层成分和物相的变化,并对镀层进行耐腐蚀性、结合强度和导电性能测试。结果表明,芳纶纤维经过适当的前处理获得了适合于化学镀的洁净催化过渡表面;在实验中观察到,镀液pH值为6,施镀时间为120 min时,镀镍层均匀、连续地覆盖于芳纶纤维表面,厚度达到了752 nm;镀液pH值为0.8~1.2,施镀温度为150 min时,镀锡层与镀镍芳纶纤维结合良好,双镀层厚度达到1.4μm;镍锡镀层与芳纶纤维结合致密且牢固,镀层耐腐蚀性、结合强度和导电性能良好。     

碳纤维表面化学镀银工艺研究

为了制备新型无源干扰材料,并简化碳纤维表面化学镀银的工艺流程,以葡萄糖＋酒石酸为还原剂,采用直接法对碳纤维表面进行了化学镀银。考察了碳纤维预处理及镀液配制工艺等因素对镀层质量的影响,采用SEM及X射线能谱分析仪分析了镀银碳纤维结构,并对镀银碳纤维的导电性能进行了测试。结果表明,采用该方法得到的镀银碳纤维具有均匀致密、结合强度高、体积电阻率小等特点。     

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。     

基于微生物模板复合化学镀的轻质导电颗粒制造及其表征

以两种典型的生物微粒(硅藻土和螺旋藻)作为成形模板,采用化学镀工艺在其表面包覆Cu@Ag层,来制备生物型核壳式导电微粒。通过光学显微镜、扫描电子显微镜、能谱仪及SZT-2A型四探针测试仪对化学镀Cu@Ag后生物微粒的外观形态、表面形貌、镀层成分及导电性进行研究。结果表明,通过调节化学镀铜液和化学镀银液的使用比例,可以获得表面镀层质量优异的生物型导电微粒;与纯金属粉相比,生物型导电微粒的比重显著降低,是一种轻质导电微粒。     

石墨纤维表面镀铜工艺及性能研究

采用化学镀铜方法,以SnCl_2为敏化剂、银氨溶液为活化剂及甲醛为还原剂,并利用正交实验方法在石墨纤维表面镀铜,成功制备了铜基复合材料用石墨纤维增强体。研究了石墨纤维表面化学镀铜的最优工艺参数。实验结果表明,通过优化的正交试验参数,可以在石墨纤维表面获得质量良好,厚度均一的铜镀层,其最佳工艺参数为15g CuSO_4·5H_2O、30g EDTA-2Na、10mL甲醛、温度60℃;实验得到镀铜反应的最佳pH值为12.4;制备过程中,气流搅拌方法的引入使得所获镀层稳定性和均匀性更佳。采用优化后的工艺对镀铜后的纤维进行导电性能测试,结果表明纤维电导率大大提升。     

Kevlar织物化学镀掺钨镀银层

应用“非刻蚀-无钯活化”法对Kevlar织物进行表面改性,化学镀制备掺钨镀银层。采用多种表征方法测试掺钨镀银层的结构、形貌和成分,分别用四探针法、Na₂S全浸及超声实验研究掺钨镀银层Kevlar织物的导电性能、抗硫变色性能以及银层/纤维结合性能。研究结果表明:纳米尺寸银颗粒均匀镶嵌在Kevlar纤维表层,形成活化中心;随后,均匀且致密的掺钨镀银层被制备,该镀层显示晶态结构,W以WO₃和Ag₂WO₄的形式存在,该镀层呈现优异的导电性能和结合力。与纯银镀层相比,掺钨镀银层具有更优异的抗硫变色性能。     

镀铜导电聚酰亚胺纤维的制备及其性能研究

采用化学镀方法在聚酰亚胺纤维表面进行镀铜,实现聚酰亚胺纤维表面金属化。通过场发射扫描电子显微镜、能谱仪、微电子测试仪等测试手段对所制备的样品进行表征。讨论了工艺条件对镀铜纤维镀层厚度和表面电阻的影响,确定了最佳的施镀时间和温度,并对镀层的形貌、成分、结合强度和导电性能进行了分析。实验结果表明,在时间为10min,温度为33℃条件下化学镀铜处理后,聚酰亚胺纤维表面的镀层覆盖均匀、致密,晶粒细致,厚度约为0.75μm,与纤维结合力好,导电性能优越。     

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.