Repair of Pd/α-Al_2O_3 composite membrane with defects

A palladium composite membrane with a large number of defects was repaired using the electroless plating combined with the technique of osmosis. The loose structure of palladium film prepared by the conventional electroless plating was densified. Defects were repaired. Hydrogen selectivity was thus significantly increased without significantly increasing palladium film thickness and reducing hydrogen permeability.     

Preparation of palladium composite membranes by modified electroless plating procedure

A thin palladium composite membrane was produced by modified electroless plating procedure. Compared with the conventional electroless plating procedure, the modified electroless plating procedure consists of the activation of a ceramic substrate by the sol–gel process of a Pd(II)-modified boehmite sol. Additionally, the infiltration of an electroless plating solution to a porous substrate during the deposition of palladium was employed with the filter device to improve adherence of a palladium layer to a substrate. The resulting membrane with a thickness of about 1 μm has a high compactness. The membrane shows a hydrogen selectivity of 20–130 for H₂/N₂, and a hydrogen flux of 1.8–87 m³/m²·h, depending on operation conditions.     

Repair of Pd/α-Al2O3 composite membrane with defects

A palladium composite membrane with a large number of defects was repaired using the electroless plating combined with the technique of osmosis. The loose structure of palladium film prepared by the conventional electroless plating was densified. Defects were repaired. Hydrogen selectivity was thus significantly increased without significantly increasing palladium film thickness and reducing hydrogen permeability. Project supported by the Chinese Academy of Sciences (Grant No. KJ951-A1-508) and the National Natural Science Foundation of China (Grant No. 29392003).     

Palladium coated porous anodic alumina membranes for gas reforming processes

Nanostructured ceramic membranes with ultrathin coatings of palladium metal have been demonstrated to separate hydrogen gas from a gas mixture containing nitrogen with 10% carbon dioxide and 10% hydrogen at temperatures up to 550 °C. The mechanically robust and thermally durable membranes were fabricated using a combination of conventional and high-efficiency anodisation processes on high purity aluminium foils. A pH-neutral plating solution has also been developed to enable electroless deposition of palladium metal on templates which were normally prone to chemical corrosion in strong acid or base environment. Activation and thus seeding of palladium nuclei on the surface of the template were essential to ensure uniform and fast deposition, and the thickness of the metal film was controlled by time of deposition. The palladium coated membranes showed improved hydrogen selectivity with increased temperature as well as after prolonged exposure to hydrogen, demonstrating excellent potential for gas separation technologies.     

自组装技术在电磁屏蔽织物加工中的应用

尼龙织物经功能性高分子壳聚糖(CS)预处理后,应用分子自组装技术于其表面自组装钯膜(镀镍前活化).该膜钯微粒为纳米级,比表面较大,催化活性较高.将成膜后的织物化学镀镍磷合金,即可得到屏蔽性能优异的电磁屏蔽织物.正交试验及单因素试验得出CS预处理的最佳工艺条件.SPM、SEM表征活化前后及施镀前后织物表面的形态变化.根据Schelkunoff理论,计算织物的电磁辐射屏蔽效能,其值高于30 dB,相当于屏蔽掉了96.0%以上的电磁波.     

Unsupported palladium alloy foil membranes fabricated by electroless plating

It is desirable to create thin (<25 μm), unsupported, defect-free palladium and palladium alloy foils in a cost-effective manner in order to study intrinsic material properties exclusive of support effects. We have developed a novel technique for producing unsupported palladium films by electroless plating upon mirror-finished stainless steel supports followed by mechanical removal. High quality pure palladium films as thin as 7.2 μm were produced. Single gas steady state permeation experiments were performed using hydrogen and nitrogen to examine permeability and selectivity. The pure palladium membranes showed hydrogen permeabilities comparable to cold-rolled unsupported foils, and high H₂/N₂ selectivity. Palladium-copper membranes were prepared by sequential electroless plating of copper onto palladium foils followed by in situ annealing. The annealing process produces films of desired composition with permeabilities comparable to those in the literature. The annealing process does not appear to produce defects in the film, and the membranes thus produced have performed 15 days without increased leak rates.     

A New Activation Method for Electroless Metal Plating：Palladium Laden via Bonding with Self—Assembly Monolayers

A new activation method has been developed for electroless copper plating on silicon wafer based on palladium chemisorption on SAMs of APTS without SnCl2 sensitization and roughening condition.A closely packed electroless copper film with strong adhesion is successfully formed by AFM observation.XPS study indicates that palladium chemisorption occurred via palladium chloride bonding to the pendant amino group of the SAMs.     

碳纳米管表面的无钯活化化学镀镍研究

本文提出碳纳米管表面无钯活化的化学镀镍方法.碳纳米管经硝酸氧化和碱中和后表面生成羧基,利用羧基吸附镍离子,之后吸附的镍离子被化学还原为镍的纳米微粒并成为化学镀镍的催化活性中心.红外吸收光谱和电子显微镜观察等证实了上述活化过程的机理.实验表明,新的活化方法对碳纳米管表面化学镀是切实可行的,文中同时对化学沉积层的不同形貌进行讨论.     

陶瓷表面无敏化活化法微细化学镀铜

本文提出一种新的化学镀铜工艺,与激光微细刻蚀技术相结合可在Al2O3基底上实现无敏化活化化学镀铜,获得光亮致密、分辨率较高(40μm),导电性良好的化学镀层.     

Preparation of palladium nanoparticles–titanium electrodes as a new anode for direct methanol fuel cells

Pd nanoparticle/Ti electrodes are prepared by electroless plating of palladium on titanium plates. The morphology and surface analysis of Pd nanoparticle/Ti electrodes are investigated using scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. The results indicate that palladium nanoparticles are homogeneously deposited on the surface of titanium plates. The electro-catalytic activity of Pd nanoparticle/Ti electrodes in the methanol electro-oxidation is studied by cyclic voltammetry and chronoamperometry methods. The results show that the electro-catalytic oxidation of methanol on the Pd nanoparticle/Ti electrode improved compare to pure palladium electrode and confirmed the better electro-catalytic activity and stability of these new electrodes.     

表面活性剂对陶瓷基底化学镀镍的作用机理及镀层性能的影响

采用酸性化学镀技术在Al₂O₃陶瓷片表面沉积Ni-P镀层,通过电感耦合等离子体发射光谱,X射线衍射光谱和扫描电子显微镜等分析测试,对镀层的成分、物相和形貌进行了表征,考察了表面活性剂种类、掺量等因素对镀层表面性貌和性能的影响。结果表明,当添加5 mg·L^-1 SDS时,镀速从14 μm·h^-1增加到17 μm·h^-1,随表面活性剂添加量继续增加,镀速呈减少趋势。添加表面活性剂能够不同程度的消除化学镀Ni-P镀层固有的胞状组织,提高表面致密性和平整性;镀层自腐蚀电流密度从43 μA·cm^-2减小至3.5 μA·cm^-2,镀层的耐腐蚀性能显著提高。根据电化学理论和实验规律,探讨了表面活性剂在化学镀镍磷合金反应过程的影响机理。     

Effect of plating bath hydrodynamic on the morphology of palladium layer electrolessly deposited on porous ceramic support

The present work was focused on the preliminary stage of palladium composite membrane preparation through electroless plating and the effects of bath hydrodynamic properties on the deposited layer morphology. Eight samples of palladium composite membrane were prepared which were different in terms of plating time, solution stirring rate and bath agitating mode. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used for characterization of deposited layer. In comparison with the support rotating mode, the support fixing and the magnet rotating mode, which are caused running the solution toward the support, were led to a deposited layer with better quality, larger grains of deposited layer, more compacted plating and higher plating efficiency.     

Creating a Catalytically Active Phase on Dielectric Surfaces Prior to Electroless Copper Plating

Several promising schemes of activation of dielectric surfaces prior to electroless plating are considered. The schemes are based on such reducing agents as sodium borohydride and formaldehyde and use no palladium.     

Area-selective microscale metallization on porous anodic oxide film of aluminium

A new method for micropatterning of metallic patterns on porous anodic oxide film of aluminium is described. The porous anodic oxide film was impregnated with organic dye and palladium ions before the hydrothermal pore-sealing. The surface layers formed during the pore-sealing, i.e. outer acicular hydroxide layer and a compact intermediate sub-layer trap the palladium ion underneath the layers. Exposing the palladium enriched area by the help of laser beam followed by electroless nickel deposition results the deposition of nickel on the laser-exposed part. Thickness of the deposits can be up to about 2–3 μm, after about the 20 min of immersion in electroless nickel plating bath. The metallic micropatterns, formed by the method are crack free, smooth and uniform over extended length.     

Synthesis of new chitosan derivatives and combination with biodegradable polymer

New chitosan derivatives are synthesized by the reductive N‐alkylation reaction of chitosan with various aldehydes, such as 2,4‐dihydroxybenzaldehyde, cholesteryl 4‐formylbenzoate, and N‐dehydroabietyl‐4‐formylbenzamide. The palladium‐adsorption ability of the newly synthesized derivatives is found to be as good as that of chitosan. A blend of chitosan and other biodegradable polymers is also found to exhibit palladium‐adsorption ability. In comparison to the starting chitosan, the chitosan derivative having dehydroabietyl‐type side chains exhibited an improved solubility in methanol. The chitosan derivatives are successfully applied as plastic coating materials for electroless plating. Copyright © 2003 John Wiley & Sons, Ltd.     

Influence of electroless nickel plating of hydrogen-absorbing alloys on cycle characteristics of nickel-metal hydride batteries

The effects of electroless nickel plating of a hydrogen-absorbing alloy on the cycle characteristics of a nickel-metal hydride battery were investigated. The cycle life was improved by employing an electroless nickel-plated hydrogen-absorbing alloy for the negative electrode, which retained the same high-rate level and low-temperature characteristics compared to a cell using a non-plated hydrogen-absorbing alloy. The electroless nickel-plated hydrogen-absorbing alloy provided better electrochemical characteristics when its surface was partly and tightly covered by nickel particles under optimal electroless plating conditions.     

超薄铜膜包覆的金刚石纳米复合粉体制备与表征

在氯化亚锡敏化、氯化钯活化的条件下,通过化学镀方法,成功地在纳米金刚石粉体表面制备了超薄铜膜.用X射线粉末衍射(XRD)和傅立叶红外吸收光谱(FTIR)表征了该Cu-金刚石纳米复合材料.此种复合材料在无水乙醇中超声分散5 min后的溶胶可稳定存放半年之久而不见沉降.     

溶胶-凝胶技术在织物化学镀活化预处理中的应用

以γ-氨丙基三乙氧基硅烷(KH-550)为先驱体,应用溶胶-凝胶技术在织物表面形成一层凝胶薄膜.由于该薄膜含有氨基和羟基等活性基团,能与钯离子起配位络合作用,阻止钯粒子的团聚,使钯以较高的活性完成织物化学镀.扫描探针显微镜(SPM)及扫描电子显微镜(SEM)观察了施镀前后织物的表面形态.与传统的前处理相比,无需SnCl2敏化,减少污染,缩短工艺流程,降低钯盐用量.     

自组装膜吸附钯的化学镀前活化研究

提出了一种无需氯化亚锡敏化、基于分子自组装膜（SAMs）吸附钯的活化方法,成功地引发了在氧化铝粉末表面的化学镀铜.用XPS、AES、FTIR研究了钯的吸附机理,认为是由于氯化钯与SAMs上向外突出的氨基形成了化学键,并提出了相应的活化机理.金属化产物经XRD、FTIR、剖面金相显微表征分析与压片电阻率测定,示为金属铜完全包覆氧化铝的复合材料.该活化工艺具有活性引发层厚度薄、寿命长和与基底结合力强等优点,也可应用于其它表面富羟基的基底材料.     

Sputtered,electroless, and rolled palladium–ceramic membranes

Three techniques were used to produce palladium–ceramic (Pd–ceramic) composite membranes for hydrogen separation and production. They are sputtering, electroless deposition and rolling of thin Pd alloy films over ceramic porous tubes.After studying and developing the three coating techniques, an extensive testing and characterizing work was carried out on these thin film composite membranes. The results show that in the sputtered (0.5–5 μm) and electroless (2.5–20 μm) composite membranes, the thermal cycling of the hydrogenated metallic layer produces membrane failures. Such failures are characterized by crack formation and metal film peeling. This fact has been explained by an evaluation of the shear stresses at the metal–ceramic interface due to the differential elongation between the palladium (Pd) coating and the ceramic support under thermal cycling and hydrogen loading. The rolled membranes (50–70 μm), however, because of the particular coating solution, have shown a complete hydrogen selectivity and good chemical and physical stability in long-term tests.