Influence of Cure Conditions on the Adhesion of Rubber Compound to Brass-plated Steel Cord. Part I. Cure Temperature

The effect of the cure temperature of rubber compound on the adhesion with brass-plated steel cord was investigated in conjunction with the formation, growth and degradation of the adhesion interphase formed between the rubber compound and brass-plated steel cord. With increasing cure temperature from 130°C to 190°C, the pull-out force after cure decreased linearly. This decrease in adhesion force at higher temperature may be explained by the limitation of the mass transfer of vulcanizing agents into the adhesion interphase and/or rubber compound near the adhesion interphase, resulting in a deficiency of sulfur due to the fast cure of the rubber compound which significantly retards the diffusion of vulcanizing chemicals. Also, at a high temperature, an adhesion interphase with a ZnS-rich layer, which may act as a barrier to copper diffusion for the formation of the adhesion interphase of copper sulfide, was formed. After thermal aging of the adhesion samples, the pull-out force decreased in comparison with that of the unaged. The decrease of pull-out force after thermal aging stemmed mainly from the decline of the tensile properties after thermal aging. The adhesion property after humidity aging was completely different from that after thermal aging. With increase in the cure temperature to 160°C, the pull-out force increased. But further increase in the cure temperature caused a decline in pull-out force. This phenomenon can be explained by the degradation of the adhesion interphase. At lower cure temperatures, a severe growth of copper sulfide and a large extent of dezincification were observed in the adhesion interphase. At higher cure temperatures, a significant growth of copper sulfide in the adhesion interphase appeared. The proper formation of the adhesion interphase and good physical properties of the rubber compound at a moderate cure temperature can result in high retention of adhesion properties.     

Fabrication of superhydrophilic surface on copper substrate by electrochemical deposition and sintering process

Superhydrophilic surfaces were fabricated on copper substrates by an electrochemical deposition and sintering process. Superhydrophobic surfaces were prepared by constructing micro/nano-structure on copper substrates through an electrochemical deposition method. Conversion from superhydrophobic to superhydrophilic was ob-tained via a suitable sintering process. After reduction sintering, the contact angle of the superhydrophilic sur-faces changed from 155° to 0°. The scanning electron microscope (SEM) images show that the morphology of superhydrophobic and superhydrophilic surfaces looks like corals and cells respectively. The chemical composi-tion and crystal structure of these surfaces were examined using energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). The results show that the main components on superhydrophobic surfaces are Cu, Cu2O and CuO, while the superhydrophilic surfaces are composed of Cu merely. The crystal structure is more inerratic and the grain size becomes bigger after the sintering. The interfacial strength of the superhydrophilic surfaces was investigated, showing that the interfacial strength between superhydrophilic layer and copper substrate is considerably high.     

Over 95% of large-scale length uniformity in template-assisted electrodeposited nanowires by subzero-temperature electrodeposition

In this work, we report highly uniform growth of template-assisted electrodeposited copper nanowires on a large area by lowering the deposition temperature down to subzero centigrade. Even with highly disordered commercial porous anodic aluminum oxide template and conventional potentiostatic electrodeposition, length uniformity over 95% can be achieved when the deposition temperature is lowered down to -2.4°C. Decreased diffusion coefficient and ion concentration gradient due to the lowered deposition temperature effectively reduces ion diffusion rate, thereby favors uniform nanowire growth. Moreover, by varying the deposition temperature, we show that also the pore nucleation and the crystallinity can be controlled.     

Influence of Cure Conditions on the Adhesion of Rubber Compound to Brass-plated Steel Cord. Part I. Cure Temperature

The effect of the cure temperature of rubber compound on the adhesion with brass-plated steel cord was investigated in conjunction with the formation, growth and degradation of the adhesion interphase formed between the rubber compound and brass-plated steel cord. With increasing cure temperature from 130°C to 190°C, the pull-out force after cure decreased linearly. This decrease in adhesion force at higher temperature may be explained by the limitation of the mass transfer of vulcanizing agents into the adhesion interphase and/or rubber compound near the adhesion interphase, resulting in a deficiency of sulfur due to the fast cure of the rubber compound which significantly retards the diffusion of vulcanizing chemicals. Also, at a high temperature, an adhesion interphase with a ZnS-rich layer, which may act as a barrier to copper diffusion for the formation of the adhesion interphase of copper sulfide, was formed. After thermal aging of the adhesion samples, the pull-out force decreased in comparison with that of the unaged. The decrease of pull-out force after thermal aging stemmed mainly from the decline of the tensile properties after thermal aging. The adhesion property after humidity aging was completely different from that after thermal aging. With increase in the cure temperature to 160°C, the pull-out force increased. But further increase in the cure temperature caused a decline in pull-out force. This phenomenon can be explained by the degradation of the adhesion interphase. At lower cure temperatures, a severe growth of copper sulfide and a large extent of dezincification were observed in the adhesion interphase. At higher cure temperatures, a significant growth of copper sulfide in the adhesion interphase appeared. The proper formation of the adhesion interphase and good physical properties of the rubber compound at a moderate cure temperature can result in high retention of adhesion properties.     

Sulphate-activated growth of bamboo-like carbon nanotubes over copper catalysts

A sulphate-activated mechanism is proposed to describe the growth of bamboo-like carbon nanotubes (CNTs) over copper catalysts using chemical vapour deposition with helium-diluted ethylene. Sulphate-assisted copper catalysts afford a high-yield growth of bamboo-like CNTs at a mild temperature, 800 °C; however, non-sulphate-assisted copper catalysts, e.g., copper acetate and copper nitrate prepared catalysts, were inert to CNT growth and only gave amorphous carbons (a-C) surrounding copper nanoparticles under the same conditions. Nevertheless, the addition of sulphate ions in the preparation step for the two inert catalysts can activate their abilities for CNT growth with remarkable yields. Furthermore, Raman spectra analysis demonstrates a linear dependence between the concentration of sulphate ions in copper catalysts and the ratio of CNT-a-C in the as-grown carbon soot. The sulphate-activated effect on CNT growth over copper catalysts could be related to a three-way interaction of sulphate ions, copper nanoparticles and support. In situ TEM images of an as-grown CNT irradiated by electron beams without the inlet of carbon sources reveal a new pathway of carbon diffusion through the bulk of copper nanoparticles and an enlarged inner-wall thickness of the on-site CNT. This carbon diffusion model over copper catalysts can provide new insights into the CNT growth mechanism over non-magnetic metal catalysts.     

乙醛酸化学镀铜工艺

研究了以乙醛酸为还原剂的化学镀铜工艺、镀层结构和形貌。其镀液组成和操作条件为:28.0 g/L CuSO4.5H2O,44.0 g/L EDTA-2Na,10.0 mg/Lα,α’-联吡啶,10.0 mg/L亚铁氰化钾,9.2 g/L乙醛酸,pH为11.5～12.5,θ为40～50℃。实验结果表明,化学镀铜溶液较稳定;镀液温度和硫酸铜质量浓度提高,铜沉积速率增大;较高的镀液温度下,化学镀铜反应的活化能较低,镀液稳定性下降;镀液pH在11.5～12.5可获得较好的铜镀层;随乙醛酸和络合剂质量浓度提高,铜沉积速率变化不大,但过量的乙醛酸导致镀液的稳定性降低;铜镀层为面心立方混晶结构,呈光亮的粉红色块状形貌,有较高的韧性。     

Comparative study of homoepitaxial single crystal diamond growth at continuous and pulsed mode of MPACVD reactor operation

Homoepitaxial growth of single crystal diamond by microwave plasma chemical vapor deposition in pulsed regime of a 2.45 GHz MPACVD reactor operation at pulse repetition rates of 150 and 250 Hz was investigated. The high quality CVD diamond layers were deposited in the H₂-CH₄ gas mixture containing 4% and 8% of methane, gas pressures of 250 and 260 Torr and substrate temperature of 900 °C without any nitrogen addition. The (100) HPHT single crystal diamond seeds 2.5 × 2.5 × 0.3 mm (type Ib) were used as substrates. At pulse repetition rate 150 Hz the high quality single crystal diamond was grown with growth rate of 22 μm/h. The comparison of the single crystal diamond growth rates in CW and pulsed wave regimes of MPACVD reactor operation at microwave power density 200 W/cm³ was made. It was found that at equal power density, the growth rate in pulsed wave regime was higher than in CW regime. Differences in single crystal diamond growth for two sets of experiments (with continuous and pulsed wave regimes) were explained.     

The effect of temperature on nascent morphology of polyethylene polymerized over solution-phase flat model catalysts

The structure and morphology of polyethylene (PE) produced during solution polymerization using bis(imino)pyridyl metal catalysts supported by flat SiO₂/Si(100) wafers were investigated by atomic force microscopy (AFM) and electron diffraction. Depending on the polymerization temperature, ranging from RT to 85 °C, different morphologies of the nascent PE have been observed. “Sea weed” like supermolecular structures are the predominant nascent morphologies of the PE polymerized at low temperatures. This should be associated with the high PE yield and high nucleation rate at low temperature; the catalyst is highly active and the PE macromolecules have low solubility in toluene and nucleate immediately after formation. With increasing polymerization temperature, e.g. at 60 or 70 °C, larger single crystals with roughly a lozenge shape but saw-tooth-like facets have been created. The multilayer overgrowth of the PE crystals demonstrates that the generated PE materials exceed what is required for single layer crystal growth. At 85 °C, decreasing crystal growth rate results in the formation of small PE single crystals. At the same time, the high solubility of the PE in toluene results in continuous diffusion of the macromolecules to the existing PE crystals and therefore single crystals in regular truncated lozenge shape have been formed. Electron diffraction indicates that in the whole temperature range, PE crystallizes in flat-on crystals in chain-folded structure with different chain folding stem length.     

SrTiO3薄膜的自组装生长

利用激光分子束外延技术在LaAlO3(100)单晶基片表面生长SrTiO3(STO)薄膜。通过反射式高能电子衍射原位实时监测STO薄膜自组装生长过程，采用原子力显微镜分析自组装生长演化过程，并利用X射线衍射分析薄膜结构及其生长方向。对不同生长条件下薄膜的生长的研究发现：在较低生长温度时，STO薄膜在(200)方向上以三维岛状模式进行生长，小岛在单位原胞尺度呈波浪状周期性排列，即出现自组装生长；而在较高的生长温度时，薄膜以层状模式进行生长自组装行为被抑止。并据此讨论了STO多元氧化物薄膜自组装生长条件及生长机理。     

Epitaxial Ir layers on SrTiO3 as substrates for diamond nucleation: deposition of the films and modification in the CVD environment

Iridium films on SrTiO₃(001) have recently proven to be a superior substrate material for the heteroepitaxy of diamond thin films by chemical vapour deposition in the effort towards the realization of single crystal diamond films. In this paper we report on the growth and structural properties of iridium (Ir) films deposited by electron-beam evaporation on SrTiO₃(001) surfaces varying the deposition temperature between 280 and 950°C. The films were studied by scanning electron microscopy, atomic force microscopy and X-ray diffraction. At the highest temperature film growth proceeds via three-dimensional nucleation, coalescence and subsequent layer-by-layer growth. The resulting films show a cube-on-cube orientation relationship with the substrate and a minimum mosaic spread of 0.15°. Towards lower deposition temperatures the orientation spread increases only slightly down to ∼500°C while the surface roughness, after passing through a maximum at ∼860°C, decreases significantly. For the lowest temperatures (below 500°C) the mosaic spread rises accompanied by the occurrence of twins until the epitaxial order is lost. Plasma treatment in the diamond deposition reactor at high temperature (920°C) yields low nucleation densities and modifies the Ir surface. At the same time {111} facets show a significantly higher structural stability as compared with {001} facets. Nucleation at 700°C results in highly aligned diamond grains with low mosaic spread and a vanishing fraction of randomly oriented grains, proving the superior properties of Ir films on SrTiO₃ for diamond nucleation as compared with pure silicon substrates.     

Electrochemical and thermal behavior of copper coated type MAG-20 natural graphite

Natural graphite powders, type MAG-20, were modified by electroless deposition of copper onto the graphite surface. The scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) of the modified graphite showed that almost all the copper covered the edge plane of graphite particles and the copper content increased from 6 to 17 at.% depending upon the plating time. Thermal gravimetric analysis (TGA) confirmed the copper composition obtained using EDS. TGA carried out under oxygen atmosphere showed that the combustion temperature decreased by 200 °C for a copper content from 0 to 16 at.%. Cycling the modified graphite at a C/10 rate showed that the initial large irreversible capacity typically present in untreated natural graphite was significantly reduced when the modified graphite contained 6-17 at.% copper coatings. A differential scanning calorimetry (DSC) comparison between fully lithiated copper coated MAG-20 with fully lithiated MCMB showed that the major exothermic peak for the MAG-20 modified graphite is lower in magnitude and is shifted to higher temperatures. However, both MAG-20 and MCMB types of lithiated graphite gave the same amount of total heat generation up to 350 °C.     

文昌13-1/2油田液化石油气铜腐超标治理方法的研究及应用

文昌13-1/2油田液化石油气(LPG)回收项目是中海石油(中国)有限公司湛江分公司首个海上LPG回收项目。近年来文昌油田LPG产品时而会发生铜腐测试不合格情况,本文通过对LPG系统硫化氢检测,LPG气样总硫含量测试以及铜片腐蚀产物的能谱测试,发现文昌油田LPG气样铜腐超标和硫含量超标有关。根据海上油田生产环境特点,拟采取湿法脱硫技术,直接加注脱硫剂的方法治理铜腐不合格问题。现场试验加药点选在进口压缩机进口,这样既可以给脱硫剂与硫化氢反应提供空间和时间,又可以在LPG系统较前端将硫化氢治理到较低水平,防止了硫化氢在LPG系统中的扩散。液化气脱硫剂以加注量50mL/min,在现场实践应用的一个月的时间里,可以有效地将铜腐指标从2a降低到1a,确保LPG产品符合国标标准要求。     

Influence of substrate temperature on formation of ultrananocrystalline diamond films deposited by HFCVD argon-rich gas mixture

The influence of the substrate temperature on the formation of ultrananocrystalline diamond (UNCD) thin films, prepared by an argon-based hot filament chemical vapor deposition (HFCVD), is discussed in this work. The gas mixture used for diamond growth was 1 vol.% methane, 9 vol.% hydrogen and 90 vol.% argon at a total flow rate of 200 sccm and at a total pressure of 30 Torr. The substrate temperature range was from 550 to 850 °C at deposition time of 8 h. Mass growth rate was determined at different deposition temperatures. The activation energy for UNCD growth, determined from the Arrhenius plot, was lower (5.7 kcal/mol) than the values found for standard diamond deposition (around 11 kcal/mol). In this work, we suggest that the activation energy was lower because the growth of these films occurs at conditions that there is a high growth competition between diamond phase and sp² phases. To support this hypothesis, systematic characterization studies based on Raman scattering spectroscopy, high-resolution X-ray diffractometry and high-resolution scanning electron microscopy were performed.     

Growth of single and multi-layer graphene on Ir(1 0 0)

We report on the high temperature chemical vapor deposition of ethylene on Ir(1 0 0) and the resulting development of single and multi-layer graphene films. By employing X-ray photoemission electron spectromicroscopy, low energy electron microscopy and related microprobe methods, we investigate nucleation and growth of graphene as a function of the concentration of the chemisorbed carbon lattice gas. Further, we characterize the morphology and crystal structure of graphene as a function of temperature, revealing subtle changes in bonding occurring upon cooling from growth to room temperature. We also identify conditions to grow multi-layer flakes. Their thickness, unambiguously determined through the analysis of the intensity of the Ir 4f and C 1s emission, is correlated to the electron reflectivity at very low kinetic energy. The effective attenuation length of electrons in few-layer graphene is estimated to be 4.4 and 8.4 Å at kinetic energies of 116 and 338 eV, respectively.     

硅酸镓镧结构的新型压电晶体的研究进展

新型压电晶体La3Ga5SiO14因其低声速、零温度切向和良好的高温稳定性受到关注，但是昂贵的Ga2O3原料阻碍了它的工业应用。通过离子置换可获得具有langasite结构的多种新型压电晶体。综述介绍了置换La，Ga，Si形成的新型压电晶体的最新研究进展，比较分析了不同晶体的优势及其存在的问题。在这些新晶体中，由于Sr3Ga2Ge4O14（SGG)具有熔点较低、性能较高的综合优势，它有可能成为新一代表面波器件的重要候选材料。与提拉法相比，采用增蜗密封的下降法生长SGG单晶；可以显著提高晶体产率，降低成本。     

Diamond nanowire - a challenge from extremes

Crystalline diamond nanowires have been grown in a chemical vapor deposition (CVD) process under 900 °C and atmospheric pressure - an extraordinary find in diamond growth. These diamond nanowires are straight, thin and long, and uniform in diameter (60-90 nm) over their entire lengths of tens of microns. Extensive characterizations including electron microscopy and Raman spectroscopy were performed to confirm that the diamond nanowire has highly crystalline cubic diamond structure encased inside a graphitic or carbonaceous shell. Such a core-shell structure suggests a potential formation mechanism in the framework of an effectively lowered Gibbs free energy due to nano-capillary and surface charge pressure. The capillary pressure (inversely proportional to the wire radius) can be sufficiently high to allow the diamond phase to be thermodynamically favorable in the inner core while the outer shell takes on the graphitic phase. The properties of diamond can manifest themselves differently in the nanowire morphology. Examples include single-photon emission of nitrogen-vacancy and electron field-emission. Whereas the former has received much attention in the literature, the latter turned out to be just as impressive and is show-cased here for the first time.     

十六烷基三甲基溴化铵对氢气泡模板法电沉积多孔铜薄膜的影响

以阴极析出的氢气泡为模板电沉积制得三维多孔铜薄膜,电解液的组成和工艺条件为:CuSO450g/L,H2SO4147g/L,Na2SO470.2g/L,HCHO30g/L,HCl0.25mL/L,聚乙二醇0.25mL/L,十六烷基三甲基溴化铵(CTAB)0～9.75g/L,温度25°C,电流密度3A/cm2,时间10～20s。研究了电沉积时间及CTAB用量对薄膜结构的影响。结果表明,随沉积时间的延长,镀层的主孔径增大,孔壁变厚。镀液中CTAB的存在会影响铜离子的沉积和结晶取向,随着镀液中CTAB质量浓度的增大,多孔铜薄膜的孔径先减小后增大。     

含有蒽酰亚胺的铜(I)配合物的合成、结构及光谱研究

合成了两个含蒽酰亚胺基团的新配体N-(2-(6-氨基吡啶))-9-蒽酰亚胺(L1)和N,N′-(2,6-吡啶基)-二(9-蒽酰亚胺)(L2),以及L1的铜(I)配合物[CuL1(PPh3)2](BF4)(1),并研究了它们的结构和光谱性质.理论计算表明配体L1配位前为反式构象,配合物1的晶体结构显示L1配位后发生结构扭曲呈顺式构象,羰基氧原子与铜(I)离子配位.光谱研究表明配体L1和配合物1都表现出蒽的特征吸收和发射峰.     

Growth and characterization of highly oriented CuBr thin films through room temperature electrochemical route

A simple electrochemical process has been demonstrated to grow highly oriented copper(I) bromide thin films on indium-doped tin oxide (ITO) glass through reducing CuBr₂ in aqueous solutions at room temperature. The copper(I) bromide thin films grow preferential orientation along the 〈1 1 1〉 crystal axis from the X-ray diffraction patterns. The orientation growth of the CuBr thin films is little affected by the solution pH and applied potentials. The possible mechanism of the orientation growth has been discussed, and the surface energy of different crystal plane of CuBr crystal is believed to play an important role to control the orientation growth of the CuBr thin films. The oriented films exhibit intense free-exciton photoluminescence at room temperature.     

Overpotential deposition of copper on an iodine-modified Au(1 1 1) electrode

Cyclic voltammetry, chronoamperometry and in situ electrochemical scanning tunneling microscopy were used to study the kinetics of nucleation and crystal growth during the initial stages of copper overpotential deposition (OPD) on a previously iodine-modified Au(1 1 1) electrode, from an aqueous solution 10⁻³ M CuSO₄ in 0.05 M H₂SO₄. The starting potential during step experiments was chosen in the region where the gold electrode was completely free of the copper deposit. The recorded current transients for copper deposition onto the iodine-modified Au(1 1 1) electrode surface appear to be very complex, with the unusual presence of two or more current maxima. A new method was used for quantitative evaluation of current transients that involves the transition UPD-OPD, developed by our group [M. Palomar-Pardavé, I. González, N. Batina, J. Phys. Chem. B 104 (2000) 3545], was used for the quantitative interpretation. Our results show that, within a single current transient, copper adsorption and two types of nucleation process: two-dimensional (2D) and three-dimensional (3D) limited by lattice incorporation of copper adatoms and diffusion of Cu(II) ion, respectively, take place simultaneously. STM images revealed the enhanced growth of 3D copper on edge of I-Au(1 1 1) during the early stages of deposition. Moreover, our results strongly suggest that the iodine adlayer is constantly present, even after the striping Cu that was overpotential deposited.