Electrochemical studies of titanium in fluoride-chloride molten salts

The interaction between titanium and Ti⁴⁺ ions (K₂TiF₆), the electroreduction reaction of Ti⁴⁺ ions and the anodic reaction of Ti in KCl–NaCl–KF melts with K₂TiF₆ at 973 K were studied by means of electrochemical and physical measurements. It was found that the fluoride ions played a very important role in these reactionsIn KCl–NaCl-3 wt % K₂TiF₆ molten salts with less than 3 wt % KF, the interaction reaction was considered to proceed as Ti⁴⁺+Ti=2Ti²⁺. If the bath contained more than 10 wt% KF, the reaction 3Ti⁴⁺+Ti=4Ti³⁺ occurred.The electrochemical reduction of Ti⁴⁺ (K₂TiF₆) ions in the molten salts with less fluoride ions was observed to proceed according to three reaction steps, i.e. Ti⁴⁺+e=Ti³⁺, Ti³⁺+e=Ti²⁺, Ti²⁺+2e=Ti. In the case of the fluoride ion concentration being higher, two reduction steps, i.e. Ti⁴⁺+e=Ti³⁺, Ti³⁺+3e=Ti were suggested.     

Direct conversion of CO2 with diols,aminoalcohols and diamines to cyclic carbonates,cyclic carbamates and cyclic ureas using heterogeneous catalysts

CO₂ has a large effect on global warming by greenhouse gases, and development of an effective technique for the reduction of CO₂ is a crucial and urgent issue. From the chemical viewpoint, CO₂ is regarded as a stable, safe and abundant C1 resource, and the transformation of CO₂ to valuable chemicals is promising not only for reduction of CO₂ but also for production of useful chemicals. This mini‐review focuses on the direct conversion of CO₂ with diols, aminoalcohols and diamines to cyclic compounds such as cyclic carbonates, cyclic carbamates and cyclic ureas, and in particular discusses the mechanisms for these reactions over heterogeneous catalysts. © 2013 Society of Chemical Industry     

Mechanical reliability in electronic packaging

The dramatic increase in the number of devices and functionality of the latest ultra large scale integration designs have resulted in increasing chip size. Concurrently, to achieve higher circuit board component densities, package dimensions have been shrinking. These two competing trends are leading to ever more rigorous requirements on the mechanical characteristics of the packaging technology. The dominant issue in component level reliability is delamination and cracks initiated at the interface between dissimilar materials. In board level reliability, solder joint reliability is a primary issue. This paper describes the methodology of prediction and the explanation for interfacial delamination, cracks at the top of the interfaces and the edge of corner, and also solder joint reliability. This paper furthermore presents the role of the chip backside contamination affecting interfacial delamination, the surface characterizations and an explanation of the interface chemistry, and the strength of solders with a variety of plating materials for Sn–Ag-based lead free solders.     

DISSOLUTION THEORY OF GOLD IN ALKALINE THIOUREA SOLUTION(Ⅱ)——Electrochemical Study on Au-Fe Mix Anode in Alkaline Thiourea Solution Containing Na_2SO_3

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A new method for preparing hydrophobic nano-copper powders

A novel chemical process for producing hydrophobic nano-copper particles with satisfied anti-oxidation property is described here. The resultant particles have been characterized by X-ray diffraction, size distribution analysis and SEM, TEM observation. Well-dispersed nano-copper particles with c.a. 30 nm in diameter were obtained from the water/organic solution containing 0.2M Cu²⁺ ion, glucose as the first reductant, ascorbic acid as the second reductant. In this process, oleic acid acted as both a phase-transfer agent and a particle protector coordinating their carboxyl end groups on the new generated copper particles surface, the hydrophobic carbon tails of the oleic acids were pointed outwards from the surface of the synthesized particles. This organic film seems to play an important role for prevent the new generated copper particles from oxidation. In addition, this process also adopting two-step reduction method can lead compulsively disconnect nucleation and nucleation growth, and weaken conventional eruptible nucleation. By controlling the first reduction product’s size, this process is more convenient for delaying the nuclei processes and for controlling the ultimate copper particles size.     

Allergen inactivation with colloidal silica

We evaluated the allergen inactivating effect of colloidal silica by performing enzyme-liked immunosorbent assay (ELISA) whose wells were coated with 150 ng/mL of Japanese cedar pollen allergen (Cry j 1) or mite allergen (Der f 2). The allergens were almost 100% inactivated by 100 microg/mL of colloidal silica having a particle size 5 nm, and the inactivating effect was increased by aluminum binding to the surface of the colloidal silica. The results show that colloidal silica is a promising material for allergen inactivation. Since colloidal silica forms an insoluble nondispersive solid when dried, it is expected that airborne allergens can be reduced by binding them to colloidal silica.     

NaBH_4的水性还原法制备纳米铜颗粒(英文)

在碱性溶液中用NaBH4还原Cu2+制备纳米铜颗粒,研究NaBH4浓度和滴加速率对Cu纳米颗粒制备的影响。反应的最佳条件是:0.2mol/LCu2+,溶液pH12,温度313K,1%明胶作为分散剂,将0.4mol/LNaBH4溶液以50mL/min的速率加入CuSO4溶液中。氨水是最佳的络合剂。采用一系列实验研究不同时间点的反应进程。     

通过水性还原法用NaBH4制备纳米铜颗粒过程中反应参数对制备过程的影响（英文）

通过水溶液还原法制备纳米铜颗粒,研究了不同反应条件对制备纳米铜的影响。制备纳米铜的最优条件是:当溶液 pH为12、温度为 313K、1%的明胶作为分散剂时,将0.4mol/L NaBH4加入含有 1.2mol/L 氨水的0.2mol/L CuSO4溶液中。此外,进行了一系列实验来模拟反应进程。结果表明,氨水能改变反应进程。当溶液 pH为10时,氨水将Cu2+转化为铜氨络合物,然后被 NaBH4还原为铜颗粒。当溶液pH为12时,氨水将Cu2+转化为氢氧化铜,然后被 NaBH4还原为铜颗粒。     

Electroless coating of Fe3Si on steel in the molten salt

The corrosion‐resistive intermetallic compound Fe₃Si could non‐electrolytically coat pure iron and mild steel. The disproportional reaction between Si and Si⁴⁺ ions deposited the homogeneous Fe₃Si layer on the Fe substrates, by using solid silicon and the molten salt composed of NaCl‐KCl‐NaF‐Na₂SiF6‐SiO₂. SiF₄ gas evaporation prevented from continuous siliconization, when only Na₂SiF₆ was used as Si⁴⁺ ion source. By adding SiO₂ into the salt as another source, the molten salt became endurable for repeated usage in air. The layer of Fe₃Si single phase with silicon mole fractions of 24 ± 1 % grew thicker than 200 μm by immersing for a few hours at 973 – 1173K.