Reliable fabrication method of transferable micron scale metal pattern for poly(dimethylsiloxane) metallization

We have developed a reliable fabrication method of forming micron scale metal patterns on poly(dimethylsiloxane) (PDMS) using a pattern transfer process. A metal stack layer consisting of Au-Ti-Au layers, providing a weak but reliable adhesion, was deposited on a silicon wafer. The metal stack layer was then transferred to a PDMS substrate using serial and selective etching. We demonstrate that features as small as 2 microm were reliably transferred on to the PDMS substrate for use as interconnects and electrodes for biosensors and flexible electronics application.     

Radiological chronometry of uranium metal samples

Radiological chronometry is an important tool in nuclear forensics that uses several methods to determine the length of time that has elapsed since a material was last purified. One of the chronometers used in determining the age of metallic uranium involves measuring the fractional ingrowth of ²³⁰Th from its parent ²³⁴U with the assumption that the uranium metal contained no impurities, especially thorium, when it was purified. The affects of different etching procedures were evaluated for the removal of surface oxidation with three different types of uranium metal samples to determine whether the etching procedure affects the radiological age. The sample treated with a rigorous etching procedure had exhibited the most reliable radiological age while less rigorous etching yields a radiological age from 15 years to hundreds of years older than the known age. Any excess thorium on the surface of a uranium metal sample presents a bias in age determination and the sample will appear older than the true age. Although this research demonstrates the need for rigorous surface etching, a bias in the radiological age could have arisen if the uranium in the metal was heterogeneously distributed.     

Single etch patterning of stacked silver and molybdenum alloy layers on glass using microcontact wave printing

Stacked thin layers of silver alloy (AgPdCu) and MoCr layers on 10 x 15 cm2 glass substrates were patterned by microcontact wave printing and etching. Patterns of etch-resistant octadecanethiol self-assembled monolayers (SAMs) were wave printed with regular backplane stabilized PDMS stamps. Pattern development was achieved by etching both metal layers in a single step, employing a nitric acid-based etching bath. Trifluoroacetic acid and a nitrite salt were identified as essential bath components for a homogeneous etching process. Etch defects could be eliminated by the addition of a decanesulfonate, which stabilizes the SAM resist via a defect healing mechanism.     

Corrosion activity of carbon plastics and protection of metal power structures in contact with carbon plastics

Methods for assessing the corrosion activity of carbon plastics against metal materials and development of complex anticorrosive protection of load-bearing units of structures including carbon plastics in contact with metal materials are considered. Data on the electrochemically measured corrosion rates in carbon plastic-metal contact pairs and on the efficiency of separating layers (sealants, glass fabrics) are presented. Recommendations on corrosion protection of carbon plastic-metal joints are given.     

Electroplating of Plastics in Theory and Practice

Electroplated plastics combine many advantages of plastics and of metals; they have the low weight and ease of shaping of plastics, together with the luster, hardness, and electrical conductivity of metals. An important part of any process for the electroplating of plastics is a pretreatment to ensure good adhesion of the metal film. Etch activation in the straight-through method requires only six steps for pretreatment.     

Simple and rapid methods for the fabrication of polymeric and glass chips for using in analytical chemistry

This paper describes simple and rapid methods for the fabrication of glass and polymeric chips for routine analytical applications. The methods are easily interfaced to the general laboratory environment and do not require special clean room facilities or expensive instruments. Glass microchips were fabricated by etching with HF solution. Microfluidic channels were designed with CAD program and transferred onto a sheet of commercial polymeric self-adhesive (PSA) film by a cutter plotter. The PSA film was used as a mask for etching process. The etching rate was about 7 μm min⁻¹. A cover glass plate was sealed on the top of etched substrate by using polycellulose (cellophane). Polymeric microchips were fabricated by sawing with a jigsaw. Commercial polycarbonate (PC) was used as a substrate and two iron sheets were used as leader masks. While this restricts us to the fabrication of straight channels, it is however, much faster and less complicated than the other methods. The chip comprised three polymeric plates and the channels were created in the middle plate. Thermal bonding was used to bond three layers of the microfluidic chip. With this method, we could achieve simple channels with the width of about 200 μm. The channel depth depends on the polymeric plate thickness. Fabricated channels were accurate without any sinuosity or sideshow.     

Influence of master fabrication techniques on the characteristics of embossed microfluidic channels

We describe protocols for the fabrication of microfluidic devices in plastics using a number of different embossing masters. Masters were fabricated by deep reactive ion etching (DRIE) of silicon (100), wet etching of silicon (100) and (110), and SU-8 processing. Structures embossed into a cyclo-olefin polymer were characterized in terms of the quality of pattern transfer as well as of the surface roughness. High quality pattern transfer was achieved with masters containing structures with angled sidewalls. Pattern distortions occurring during de-embossing were minimized by using masters consisting of SU-8 (which has a thermal expansion coefficient close to that of the substrates). Structures embossed with SU-8 masters also exhibited the lowest surface roughness. However, due to structural deformation, the reusability of the masters prepared for this study extended to only five embossing experiments. Masters fabricated on silicon, on the other hand, were more robust, but were subject to breakage during the de-embossing phase of the experiment. The results of this study will guide researchers in choosing master fabrication methods that will provide profile and surface characteristics of embossed microfluidic channels that are advantageous to their specific application.     

胶粉/热塑性塑料共混材料的研究

以胶粉及通用塑料PP和LLDPE为原料,研究了原料种类、相容剂等对胶粉/热塑性塑料共混材料性能的影响,制得了性能较好的共混材料。通过热分析和扫描电镜对制得的共混材料进行分析表征,表明胶粉和LLDPE有较好的相容性及较强的结合力。     

借助液体透射电镜原位分析钯纳米棒的可控性氧化刻蚀

借助原位液体透射电镜,我们观察并研究了钯纳米棒溶液环境下的氧化刻蚀的微观行为及机理。通过改变钯纳米棒所处的液体环境,有效地控制了钯纳米棒的氧化刻蚀行为。由于端部具有较高的反应活性,钯纳米棒在氯化铁溶液中的氧化刻蚀会选择沿着轴向进行,具有明显的各向异性。当反应在超薄液层进行时,钯纳米棒的氧化刻蚀会变为准各向同性。这种行为是由于超薄溶液中溶解产物以及氧化物的扩散被抑制,在纳米棒端部选择性发生的氧化刻蚀会受到阻碍。最后,我们发现在钯纳米棒端部选择性沉积金,可以保护纳米棒的端部不受氧化,从而能控制刻蚀沿着钯纳米棒的径向进行。本文的研究结果对贵金属纳米晶的结构参数的精确调控以利于实际应用具有重要的意义。     

The Nanoparticle Size Effect in Graphene Cutting: A “Pac‐Man” Mechanism

Metal‐nanoparticle‐catalyzed cutting is a promising way to produce graphene nanostructures with smooth and well‐aligned edges. Using a multiscale simulation approach, we unambiguously identified a “Pac‐Man” cutting mechanism, characterized by the metal nanoparticle “biting off” edge carbon atoms through a synergetic effect of multiple metal atoms. By comparing the reaction rates at different types of edge sites, we found that etching of an entire edge carbon row could be triggered by a single zigzag‐site etching event, which explains the puzzling linear dependence of the overall carbon‐atom etching rate on the nanoparticle surface area observed experimentally. With incorporation of the nanoparticle size effect, the mechanisms revealed herein open a new avenue to improve controllability in graphene cutting.     

金属纳米结构的氧化刻蚀调控与催化性能优化

金属纳米结构的可控合成,对其性能优化和高效应用至为关键．氧化刻蚀作为金属纳米晶可控合成中的新兴有效调控手段之一,受到越来越多的关注．本文以本课题组近期的研究工作为例,说明了氧化刻蚀对金属纳米晶的形貌、尺寸、结构及组成等合成参数的有效调控作用．由此总结认为,在金属纳米晶可控合成的一般过程,尤其是成核和生长过程中,氧化刻蚀的本质是有效调控“两个速率”和“两个力学”,即减缓原子的生成速率与晶种的形成速率、选择性接受反应热力学和反应动力学的控制作用．我们将通过氧化刻蚀法调控合成得到的具有独特结构的Pd,Pt纳米晶,用于氧活化和电催化这两个重要的催化体系,获得了理想的催化结果,表明氧化刻蚀在金属纳米晶的功能改性和应用拓展方面,具有令人称奇的广阔应用前景．     

Sacrificial adhesion promotion layers for copper metallization of device structures

The adhesion of copper films to adjacent device layers including TiN, Ta, and TaN diffusion barriers is a crucial reliability issue for integrated circuits. We report that ultrathin layers of poly(acrylic acid) (PAA) prepared on barrier surfaces or on the native oxide of Si wafers dramatically increase the interfacial adhesion of Cu films deposited by the H2 assisted reduction of bis(2,2,7-trimethyloctane-3,5-dionato)copper in supercritical carbon dioxide. Similar improvements were achieved on Si wafers using a simple vapor phase exposure of the substrate to acrylic acid prior to metallization. The deposited films and the substrate/Cu interfaces were analyzed by X-ray photoelectron spectroscopy (XPS), electron microscopy, atomic force microscopy, and variable-angle spectroscopic ellipsometry. No trace of the adhesion layer was detected at the interface, indicating it was sacrificial at the deposition conditions used. Moreover, the presence and subsequent decomposition of the PAA layer during deposition substantially reduced or eliminated metal oxides at the substrate interface. For depositions on PAA-treated Si wafers, copper was present primarily as Cu0 at the interface and Si was present only as Si0. On PAA-treated Ta substrates, XPS analysis indicated Ta was present primarily as Ta0 at the metallized interface whereas Ta2O5 dominated the interface of samples prepared without the adhesion layers. The technique can be extended to patterned substrates using adsorption of acrylic acid or thermal/UV polymerization of acrylic acid.     

Study on pyrolysis behavior and kinetics of waste plastics with spent FCC catalyst

Pyrolysis is the most promising method for treating plastic waste since it can convert waste plastics into high value-added products, which have significant application potential. In this study, kinetic and thermodynamic analyses of spent fluid catalytic cracking (FCC) catalysts were performed for testing their applicability in catalytic cracking of mixed plastics. Thermogravimetric analysis data were obtained at different heating rates under an inert atmosphere, and the synergistic effect between the mixed plastics and activation energy reduction before and after pretreatment of the spent FCC catalysts was discussed. Through a variety of model-free methods (Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, Starink, and Kissinger methods), it is proved that the spent FCC catalyst facilitates the reduction in activation energy required for the pyrolysis of plastics, which is reduced by approximately 13% from 278 to 242 kJ/mol. The catalytic performance of spent FCC catalyst was improved after pretreatment, while its activation energy decreased by approximately 21% from 278 to 220 kJ/mol. The Friedman-Reich-Levi method was used to fit the curve, and the number of mechanism functions in plastic pyrolysis was determined according to the slope of the fitting curve. The C-R method was used in combination with the Malek method to determine the optimal mechanism function. Moreover, kinetic parameters of the spent FCC catalyst for catalytic cracking of plastics were obtained via kinetic studies on the pyrolysis of mixed plastics, which provided theoretical guidance for industrialization of plastic pyrolysis.     

Effect of AA2024‐T3 surface pretreatment on the physicochemical properties and the anticorrosion performance of poly(γ‐glycidoxypropyltrimethoxysilane) sol‐gel coating

This study investigated the dependence of the anticorrosion performance of a poly(γ‐glycidoxypropyltrimethoxysilane) (poly(γ‐GPTMS)) sol‐gel coating on AA2024‐T3 aluminum alloy surface state. Two different AA2024‐T3 surface pretreatment procedures were tested: a degreasing with acetone and a chemical multistep etching process (industrial chemical etching pretreatment). Poly(γ‐GPTMS) coatings were deposited onto both pretreated surfaces using the dip‐coating technique. Surfaces were characterized principally by scanning electron microscopy, X‐ray photoelectron spectroscopy, Fourier transform infrared attenuated total reflectance, contact angles, and roughness measurements. Moreover, for the coated AA2024‐T3 surfaces, a pull‐off test was used to evaluate the poly(γ‐GPTMS) adhesion to the pretreated surface. Bare surface properties depended on the applied pretreatment. The chemically etched surface was the roughest and the most concentrated in hydroxyl groups. In addition, comparatively to the degreased surface, it has a more hydrophobic character. Poly(γ‐GPTMS) coating revealed an uneven nature and a poor adhesion once it was deposited onto the degreased surface. Coatings anticorrosion performances were evaluated using electrochemical impedance spectroscopy measurements (EIS). Electrochemical impedance spectroscopy data proved that the sol‐gel coating applied onto the chemically etched surface had better anticorrosion performance.     

电沉积种子层化学控制生长氧化锌纳米棒和纳米管

采用水溶液法在电沉积的ZnO种子层上制备了高度取向的ZnO纳米棒阵列,并通过碱溶液化学腐蚀法获得了ZnO纳米管。对ZnO纳米棒和纳米管的溶液生长和腐蚀过程进行了分析。结果表明,种子层的结构和性能对ZnO纳米棒有着重要的影响,在-700 mV电位下沉积的种子层薄膜均匀性好,生长的纳米棒密度大、与基底垂直性好;碱溶液对纳米棒的腐蚀具有选择性,通过控制腐蚀液的浓度和时间,可获得中空的ZnO纳米管。     

Biomimetic core-shell fibril for enhanced adhesion

Fibrillar adhesive structures in nature are usually terminated by compliant plate-like elements that are critically important. We have fabricated a simple, model, core-shell fibrillar structure by coating an aluminum wire with (poly)dimethylsiloxane (PDMS). By partially etching the core metal, we obtain a compliant annular terminus. Measurements of the force required for this structure to detach from and slide against a glass substrate show that sliding is accommodated by a stick-slip mechanism and that substantial enhancement of adhesion can be achieved. A simple theoretical model, which is in good agreement with experimental data, shows that during the sticking phase the contact reduces in size and the mechanics of this process is controlled by the balance of energy release from the stretched PDMS and adhesion between it and the substrate.     

Fabrication of a sensor chip containing Au and Ag electrodes and its application for sensitive Hg(II) determination using chronocoulometry

In this work, we explored a novel fabrication method to construct Au and Ag electrodes on chip, utilizing the different solubility of gold and silver in different etching solutions. KI-I₂ etching solution and 50% HNO₃ were chosen to dissolve the metal layers alternatively. Planar electrodes with gold and silver could be simultaneously and accurately patterned on chip using photolithographic technique. The as-prepared electrode could be directly served as integrated three-electrode system for electrochemical measurement. Based on it, a sensing strategy has been carried out using home-made electrochemical sensing (ECS) chip, which depended on the competition of double strand DNA and Hg(II)-mediated T–T base pairs (T-Hg(II)-T). Actually, a mercury specific oligonucleotide (MSO) was immobilized onto the thus-fabricated gold working electrode and employed as the sensing element. Chronocoulometry (CC) was chosen to monitor the differences of surface charge volume and quantify the concentrations of Hg(II) ions with a low detection limit down to 1 nM. Therefore, a facile method to fabricate Au and Ag electrodes has been demonstrated to simplify the production of ECS chip. The ECS chip was finally used for constructing an effective sensing platform for sensitive Hg(II) determination, which held promising potential for designing ECS chip in lab-on-a-chip device or point-of-care diagnosis.     

提高PBO纤维/环氧树脂复合材料界面结合的研究

本文采用表面化学蚀刻与溶胀法结合、化学偶联法与氩气低温等离子体表面处理技术结合的方法对聚苯撑苯并二。唑（PBO）纤维进行表面改性。探讨了不同改性方法对纤维表面性能的影响。同时，采用FTIR和SEM等方法对处理前后纤维表面化学结构及形态进行了表征。     

Untersuchungen zur atomspektroskopischen spurenanalyse in AIIIBV-halbleiter-mikroproben—III: Untersuchungen zur schichtabtrennung und zur spurenanalyse in dünnen GaAs schichten

Three methods for stripping thin layers of GaAs have been compared with regard to depth of layer and reproducibility. They are (1) chemical etching with methanolic bromine solution, (2) mechanical separation with a microtome, (3) chemical etching after a preliminary amperostatic anodic oxidation. Conditions were optimized. The depth of strip was 0.4 μm for chemical etching, 1 μm for the mechanical separation and 0.02 μm for the anodic oxidation method. Thus the anodic oxidation is specially suitable for profile analysis, and the mechanical method for investigation of thicker layers; chemical etching lies between them. The trace elements in the micro samples thus obtained were determined by d.c. are atomic-emission spectrography (AES) and atomic-absorption spectrometry with electrothermal atomization in a graphite tube (AAS). The absolute and relative detection limits of AAS for the 0.1–0.2 mg micro samples were on average better by an order of magnitude than those of AES. The advantage of AES lies in the possibility of simultaneous determination of several elements. in der Möglichkeit der Simultanbestimmung mehrerer Elemente.     

SEM-EDS Investigation of Scale Formation on Low Carbon, Low Alloy Steel

 This paper summarises an experimental work performed at the Dunaferr Research Institute, Hungary. Low carbon and low alloy steels with different silicon and nickel contents were heat treated under industrial conditions, i.e. in the reheating furnace of the hot rolling mill. Other sets of samples were heat treated in a laboratory furnace in air atmosphere. Scales formed in both cases were examined by different chemical and physical methods. The speed of dissolution was measured by etching the samples in a special agent and measuring the mass of the sample as a function of the etching time. The main investigations, however, were performed using a scanning electron microscope equipped with an ED analyser. EDS investigations showed that with increasing Si content of the base material the scale was more rigid and could easier be removed, while increasing Ni-content caused the scale/metal interface to be more rough. The latter was observed in the case of laboratory samples as well.