Surface Analysis of Chemical Stripping Titanium Alloy Oxide Films

The chemical stripping method of titanium alloy oxide films was studied. An environment friendly solution hydrogen peroxide and sodium hydroxide without hydrofluoric acid or fluoride were used to strip the oxide films. The morphologies of the surface and cross-section of the oxide films before and after the films stripping were characterized by using scanning electron microscopy （SEM）. The microstructure and chemical compositions of the oxide films before and after the films stripping were investigated by using Raman spectroscopy （Raman） and X-ray photoelectron spectroscopy （XPS）. It was shown that the thickness of the oxide film was in the range of 5-6 μm. The oxide films were stripped for 2 to 8 min in the solution. Moreover, the effect of the stripping time on the efficiency of the film stripping was investigated, and the optimum stripping time was between 6-8 min. When the stripping solution completely dissolved the whole film, the α/β microstructure of the titanium alloy Ti-10V-2Fe-3Al was partly revealed. The stripping mechanism was discussed in terms of the dissolution of film delamination. The hydrogen peroxide had a significant effect on the dissolution of the titanium alloy anodic oxide film. The feasibility of the dissolution reaction also was evaluated.

Repassivation Behaviour of UNS S32101 and UNS S30403 Stainless Steels after Cathodic Stripping of the Native Passive Film in a CO₂-Saturated Oilfield Brine

Repassivation behaviour of the passive film formed on lean duplex stainless steel UNS S32101 and austenitic stainless steel UNS S30403 in a CO2-saturated oilfield environment has been studied. The native passive film on the alloys was thinned/removed by stepping the potential of the alloy to ﹣850 mV/Ag/AgCl for 30 minutes. Potentiostatic measurements were then taken at potentials of ﹣200, ﹣100, 0, 100 and 200 mV versus Ag/AgCl. Results show that the passive film repassivates at potentials of ﹣200 and ﹣100 mV and 0 mV for both alloys at 50°C. The current density however continues to rise for potentials of 100 and 200 mV. This shows that both alloys are susceptible to pitting at potentials above 100 mV at the test temperature of 50°C.

Molten Salts as Stripping Media for Radioactive Superficial Decontamination

The main practical difficulty associated to the task of the dismantling and decommissioning of the IPEN＇s old nuclear fuel cycle facilities has been the big amount of radioactive waste generated in the dismantling operations. The waste is mainly in the form of contaminated carbon steel structures. In the IPEN, the presence of contamination in the equipments, structures and buildings, although restricted to low and medium activity levels, constituted an important concern due, on one hand, to the great volume of radioactive wastes generated during the operations. On the other hand, it should be outstanding that the capacity of radioactive wastes stockpiling in IPEN found been exhausted. In function of the large waste volume generated in the dismantling operations, the main concems and focuses of research and technological development in the IPEN＇s Chemical and Environmental Center--CQMA have been the effluent and waste treatment subjects, besides the development of some special decontamination techniques, since most old nuclear fuel cycle facilities are installed in the CQMA＇s area. The reduction of the radioactive waste volume has a significant impact in the decommissioning costs and in the amount of material to be stored. The mentioned steel structures, during the operations and after ten or twelve years after the facilities shut down, have presented severe corrosion. In the past, to protect them, several layers of paint were applied. Traditional decontamination methods were tried, such as acid pickling, alkaline washing and ultrasonic baths. Nevertheless, these methods have failed to reach effective decontamination. In this paper, we described some aspects and problems in decommissioning of IPEN＇s nuclear fuel cycle facilities and it is presented an innovative method for radioactive superficial decontamination of steel structures using different molten salt compositions and temperatures as stripping media.

Determination of the Antiretroviral Drug Zidovudine in Diluted Alkaline Electrolyte by Adsorptive Stripping Voltammetry at the Mercury Film Electrode

This paper describes a stripping method for the determination of zidovudine at the submicromolar concentration levels. This method is based on the controlled adsorptive accumulation of zidovudine at the thin-film mercury electrode, followed by a linear-sweep stripping voltammetry measurement of the surface species. Optimal experimental conditions include a NaOH solution of 2.0 × 10–3 mol●L–1 (sup-porting electrolyte), an accumulation potential of –0.30 V and a scan rate of 100 mV?s–1. The response of zidovudine is linear over the concentration range 0.01 - 0.08 ppm. After an accumulation time of 5 minutes, the detection limit was found to be 0.67 ppb (2.5 × 10–9 mol●L–1). More convenient methods to measure zidovudine concentration in the presence of the didanosine, acyclovir, nevirapine, lamivudine, and efavirenz, were also investigated. The presence of zidovudine together with ATP or ssDNA demonstrates the utility of this method.

Effect of phosphorus content on interfacial heat transfer and film deposition behavior during the high-temperature simulation of strip casting

The interfacial wettability and heat transfer behavior are crucial in the strip casting of high phosphorus-containing steel.A hightemperature simulation of strip casting was conducted using the droplet solidification technique with the aims to reveal the effects of phosphorus content on interfacial wettability,deposited film,and interfacial heat transfer behavior.Results showed that when the phosphorus content increased from 0.014wt%to 0.406wt%,the mushy zone enlarged,the complete solidification temperature delayed from1518.3 to 1459.4℃,the final contact angle decreased from 118.4°to 102.8°,indicating improved interfacial contact,and the maximum heat flux increased from 6.9 to 9.2 MW/m2.Increasing the phosphorus content from 0.081wt%to 0.406wt%also accelerated the film deposition rate from 1.57 to 1.73μm per test,resulting in a thickened naturally deposited film with increased thermal resistance that advanced the transition point of heat transfer from the fifth experiment to the third experiment.

Electrochemical Characteristics and Applications of Boron-Doped Polycrystalline Diamond Film Electrodes

The elcetrochemical characteristics of boron doped polycrystalline diamond thin film (BDF) electrode 4×4 mm 2 in size were studied using cyclic voltammetry and potentiostatic method. The diamond electrode exhibits adequate electrochemical activity and its response current changes linearly with K 3Fe(CN) 6 concentrations. The response current is proportional to the square root of the scan rate, reflecting mass transport controlled by planar diffusion. Stable mass transport can be quickly established within 4s. The BDF electrode provides good resolving power for the determination of lead and cadmium and gives satisfactory results in the analysis of pure water sample.

Preparation of dendritic bismuth film electrodes and their application for detection of trace Pb(Ⅱ)and Cd(Ⅱ)

In this paper,dendritic Bi film electrodes with porous structure had successfully been prepared on glassy carbon electrode using a constant current electrolysis method based on hydrogen bubble dynamic templates.The electrode prepared using a large applied current density showed an increased internal electroactive area and a significantly improved electrochemical performance.The analytical utility of the prepared dendritic Bi film electrodes for the determination of Pb(Ⅱ)and Cd(Ⅱ)in the range of 5–50 μg·L^(-1)were presented in combination with square wave stripping voltammetry in model solution.Compared with non-porous Bi film electrode,the dendritic Bi film electrode exhibited higher sensitivity and lower detection limit.The prepared Bi film electrode with dendritic structure was also successfully applied to real water sample analysis.

Green Fabrication of Freestanding Piezoceramic Films for Energy Harvesting and Virus Detection

Most electronics such as sensors,actuators and energy harvesters need piezoceramic films to interconvert mechanical and electrical energy.Transferring the ceramic films from their growth substrates for assembling electronic devices commonly requires chemical or physical etching,which comes at the sacrifice of the substrate materials,film cracks,and environmental contamination.Here,we introduce a van der Waals stripping method to fabricate large-area and freestanding piezoceramic thin films in a simple,green,and cost-effective manner.The introduction of the quasi van der Waals epitaxial platinum layer enables the capillary force of water to drive the separation process of the film and substrate interface.The fabricated lead-free film,Ba_(0.85)Ca_(0.15)Zr_(0.1)Ti_(0.9)O_(3)(BCZT),shows a high piezoelectric coefficient d_(33)=209±10 pm V−1 and outstanding flexibility of maximum strain 2%.The freestanding feature enables a wide application scenario,including micro energy harvesting,and covid-19 spike protein detection.We further conduct a life cycle analysis and quantify the low energy consumption and low pollution of the water-based stripping film method.

Experimental research on breakup of 2D power law liquid film

On account of limited knowledge of the breakup of power law liquid film, the process of its disintegration and atomization was studied by using a planar liquid film. A linear stability analysis was adopted to predict the breakup characteristics of the power law film. The predicting formulas of stripping breakup length and diameter of ligament were put forward presently. Through high-speed photography and laser light sheet illumination,different breakup characteristics of flat power law film under different conditions were derived. The characteristic dimension of breakup regimes were defined and extracted. The effects of several parameters(injection pressure,ambient pressure, nozzle structure and fluid property) on the stripping breakup length and spray angle were investigated. The results revealed that increasing both the velocity of liquid film and the ambient pressure facilitated the breakup of film, reduced the stripping breakup length and enlarged the spray angle in different extents. The comparison between theoretical and experimental results was conducted to validate the feasibility of the linear stability theory.

Optical and electronic performances of CVD diamond film andits applications in radiation detectors

The outstanding properties of CVD diamond film such as electronic, optical, thermal and mechanical and the high radiation hardness have made it an ideal candidate material for radiation detectors in severe environments. Fabrication of ＇detector grade＇ CVD diamond films and development of CVD diamond detectors have been leading edge subjects. Micro-strip gas chamber （MSGC） fabricated on CVD diamond substrate would overcome the charge-up effect and the substrate instability, which has been a hotspot in the research of gas detectors.

Determination of Hypoxanthine in the Presence of Copper by Adsorptive Stripping Voltammetry

A stripping method for the determination of hypoxanthine in the presence of copper at the submicromolar concentration levels is described. The method is based on controlled adsorptive accumulation of hypoxanthine-copper at the thin-film mercury electrode followed by a fast linear scan voltammetric measurement of the surface species. Optimum experimental conditions were found to be the use of 1.0 × 10﹣3 mol·L﹣1 NaOH solution as electrolyte supporting, an accumulation potential of ﹣0.50 V and a linear scan rate of 200 mV·s﹣1. The response of hypoxanthine-copper is linear over the concentration ranges of 10 - 60 ppb. For an accumulation time of 30 minutes, the detection limit was found to be 250 ppt (1.8 × 10﹣9 mol·L﹣1). Adequate conditions for measuring the hypoxanthine in the presence of metal ions, xanthine, uric acid and other nitrogenated bases were also investigated. The utility of the method is demonstrated by the presence of hypoxanthine associated in ATP or ssDNA.

Highly stabilized and lowly polarized Li anodes using a hybrid surface film with inner Li–Zn nucleation sites and outer LiF-rich protection texture

Lithium(Li)metal is the most promising anode for improving the energy density of currently commercialized Li-ion batteries.However,its practical application is limited due to its high reactivity to electrolytes,which induces severe electrolyte decomposition and Li-dendrite growth.Interphases are usually constructed on Li anode to address the above issue.Meanwhile,it is a big challenge to balance the stability and plating/stripping overpotential of Li anode.In this work,we report a novel strategy for constructing a highly stable and lowly polarized surface film on Li anode.A chemically and structurally unique film is formed by simply dropping a zinc trifluoromethanesulfonate[Zn(OTF)_(2)]and fluoroethylene carbonate(FEC)-containing solution onto Li anode.This unique film consists of inner nucleation sites and outer protection textures,mainly containing Li–Zn alloy and LiF/polymer,respectively.The former results from the preferential reduction of Zn(OTF)_(2),providing nucleation sites with low polarization for Li plating/stripping.In contrast,the latter arises from the subsequent reduction of FEC,providing protection for the underneath Li–Zn alloy and Li metal and ensuring the stability of Li anode.The Li anode with such a unique surface film exhibits excellent cycling stability and low plating/stripping overpotentials,which have been demonstrated using Li//Li symmetric and Li//LiFePO_(4)full cells.

Determination of trace Pb(II), Cd(II) and Zn(II) using differential pulse stripping voltammetry without Hg modification

In this work,we reported a simultaneous determination approach for Pb(II),Cd(II)and Zn(II)atμg L 1concentration levels using differential pulse stripping voltammetry on a bismuth film electrode(BiFE).The BiFE could be prepared in situ when the sample solution contained a suitable amount of Bi(NO)3,and its analytical performance was evaluated for the simultaneous determination of Pb(II),Cd(II)and Zn(II)in solutions.The determination limits were found to be 0.19μg L 1for Zn(II),and0.28μg L 1for Pb(II)and Cd(II),with a preconcentration time of 300 s.The BiFE approach was successfully applied to determine Pb(II),Cd(II)and Zn(II)in tea leaf and infusion samples,and the results were in agreement with those obtained using an atomic absorption spectrometry approach.Without Hg usage,the in situ preparation for BiFE supplied a green and acceptability sensitive method for the determination of the heavy metal ions.

Enhanced optical transmission through a nanoslit by coupling light between periodic strips and metal film

Surface plasmon resonance （SPR） is obtained by exciting the surface plasmon （SP） at the metal and dielectric interface, which can greatly enhance the extraordinary optical transmission （EOT） through a nanoslit milled in the metal film. We present a structure with a 50-nm-wide silver nanoslit for EOT by coupling light into the dielectric interlayer between periodic strips and a metal film. When the period of the metallic strips is equal to the wavelength of the SPR, the transmission efficiency of 187.6 through the nanoslit is enhanced. The metallic strip width over the nanoslit is optimized to improve transmission efficiency, and the maximal efficiency of 204.3 is achieved.

Design and experiment of nail tooth picking up device for strip type residual film recycling and baling machine

In order to solve the problem of residual film pollution caused by large area of cotton mulched planting in Xinjiang,a strip type residual film recycling and baling machine was designed,which can complete mulching film picking up,impurities separation,baling and other operations.The picking up device,as the key part of residual film recycling machine,was designed and analyzed.The kinematics of the pick-up nail tooth was analyzed,and its motion equation,motion trajectory and the conditions for completing the film pick-up were determined.And the key parameters were determined by analyzing the conditions of no missing picking and the stress of the residual film.According to the Box-Benhnken test design principle,field experiments were carried out with the forward speed of machine,the pickup speed ratio and the number of auxiliary film removing mechanisms as the key experimental factors,and the residual film pickup rate,the cotton stalk content and the residual film winding rate as the operation performance indexes of the picking up device.The mathematical models between the experimental factors and indexes were established,and the effect of each factor was analyzed.Through multi-objective parameter optimization and field experiment,the optimal combination of operation parameters was obtained as follows:the forward speed of machine of 1.67 m/s,the pickup speed ratio of 1.13,and the number of auxiliary film removing mechanisms of 6.Under this parameter combination,the pickup rate of residual film was 88.9%,the cotton stalk content in recycled residual film of 3.9%,and the residual film winding rate of 1.5%.The absolute error with the theoretical value was less than 0.6%.The research results show that the picking up device has stable operation performance and good residual film recycling effect,which meets the design and practical operation requirements.

In-plane Uniaxial Anisotropy and Magnetization Reversal Mechanism of FeCo Films by Strip Pattern

Strip-like Fe Co films were patterned by a traditional lithograph process from intrinsically isotropic continuous Fe Co films. The strip-patterned Fe Co film shows a strong in-plane uniaxial magnetic anisotropy with easy axis along the length direction of the strip. The angular dependences of remanence ratio, switching field, and coercivity indicate that the magnetization reversal mechanism of the strip-patterned Fe Co film is coherent rotation and domain wall depinning when the applied field is near the hard axis and easy axis, respectively. The consistency of the experimental hysteresis loops of the strip-patterned Fe Co film and calculated hysteresis loops with a simple in-plane uniaxial anisotropy model indicates that the strip-patterned Fe Co film behaves as a single domain. The absence of the domain wall and the strong in-plane anisotropy field make the strip-patterned Fe Co films have much potential for high-frequency application.

抗镀金褪膜药水对封装基板镀层品质影响研究

研究A、B、C这3种不同体系褪膜药水对封装基板电镀镍金表面处理镀层和铜面的品质影响。通过研究发现:A系列会导致铜面污染异物,影响打线,出现铜面外观异色、金面外观异色等品质问题;B系列和C系列与干膜反应过程中,仅产生蓝色片状干膜屑,与验证板完全脱离,对验证板品质无影响。通过对褪膜反应原理和药水展开分析,猜测其为A系列褪膜药水中的有机碱与羧酸产生黏性物质沉淀,黏性物质反粘在验证板铜面,产生验证板铜面外观不易检出的透明异物。通过研究,改善现有产品抗镀金去膜后镀层外观和功能性问题,并为后续封装基板抗镀金干膜和褪膜药水组合搭配时,镀层产品品质影响的评价项目和方法提供参考。

印刷线路板环保型退膜液的设计开发及性能研究

为了提高印刷线路板退膜液的环保性,通过试验研究确定了以无机碱为主体的环保型退膜液配方:无机碱NaOH 0.5 mol/L,碎膜剂二乙二醇单丁醚10 mL/L,表面活性剂醇类R 5 mL/L,护锡剂柠檬酸钾1 g/L,其余为纯水。该退膜液无色透明,状态稳定,在温度50℃的条件下进行退膜,退膜时间在50~70 s以内,膜碎大小为5~10 mm,锡厚变量均值低于0.5μm,氨氮值为4.632 mg/L。将该退膜液与同产线产品进行对比,发现两者退膜性能极为接近,而环保型退膜液具有更低的氨氮值和化学需氧量(COD)值,在满足生产需求的同时也能有很好的环保性,从而降低了退膜废液的处理成本。

马来酸酐接枝聚乙烯对多层共挤薄膜的影响

对于以PA6为阻断层的多层共挤膜而言,通过马来酸酐(MA)接枝改性的聚乙烯是一种良好的黏合树脂,利用双螺杆挤出机制备马来酸酐接枝聚乙烯,作为五层共挤薄膜的结合层,从晶体数量、拉伸强度、剥离强度等角度,考察马来酸酐接枝聚乙烯对五层共挤薄膜的影响。经实验发现,随着马来酸酐添加量的增加,对五层共挤吹膜晶点的影响先增大后减少,对五层共挤膜的纵向拉伸强度和横向拉伸强度的影响都是先升高后降低,但是剥离强度逐步升高,氧气透过率先降低后升高,透光率逐步降低。在五层共挤薄膜的生产过程中,需要结合马来酸酐对五层共挤薄膜的拉伸强度、剥离强度、氧气透过率、透光率的影响,综合考虑马来酸酐的添加量。

覆盖栽培对旱地春玉米耗水特性的影响

【目的】探讨覆盖方式对旱地春玉米产量及耗水特性的影响,以期为半干旱区玉米高效及绿色生产提供理论支撑。【方法】在陇中旱作区设置秸秆带状覆盖(SM)、白膜双垄沟覆盖(BM)和黑膜双垄沟覆盖(HM)和露地平作(CK)4种栽培方式。【结果】与CK相比,SM、BM和HM处理下春玉米播种~成熟期0~200 cm土壤水分增加2.6%~20.9%;各生育时期间,增墒幅度SM以抽雄吐丝期最大,BM和HM均以苗期最大;不同土层间,SM、BM和HM增墒幅度分别以60~120、60~120和120~200 cm土层最大。覆盖处理较对照降低了春玉米全生育期耗水量5.1%,其中SM处理均降低了春玉米生育前期(播种期-拔节期)、中期(拔节期-灌浆期)和后期(灌浆期-收获期)耗水,降幅为2.4%~50.0%,而地膜覆盖(BM和HM)降低了生育前期和后期的耗水量,而增加了中期的耗水。与CK相比,覆盖均能显著增加春玉米籽粒产量22.9%~34.9%和水分利用效率33.1%~39.7%,增幅分别以BM和SM处理最大。相关分析发现,春玉米籽粒产量与穗粒数(r=0.922**)和百粒质量(r=0.833**)高度相关。【结论】在西北旱作区,应用秸秆带状覆盖能明显增墒、增产,显著降低耗水而增加水分利用效率,是适宜旱地玉米生产的可行措施。