Application results of a prototype ultrasonic liquid film sensor to a 7 MPa steam–water two-phase flow experiment

A prototype ultrasonic liquid film sensor was applied to a high-temperature steam–water two-phase flow experiment. The liquid film sensor was vertically installed in a loop which was connected to HUSTLE, a multi-purpose steam source test facility. The hydraulic diameter of the measurement section was 9.4 mm. The output waveforms of the sensor were acquired with a digital oscilloscope. The fluid temperature and system pressure were kept at 288 °C and 7.2 MPa, respectively, during the experiment. The pulse-echo method was used to calculate the liquid film thickness. The cross-correlation calculation was utilized to determine the time difference between the pulse reflected at the sensor surface and the pulse reflected at the liquid film surface. The time-averaged liquid film thicknesses were less than 0.055 mm in the annular flow condition. The increase of the time-averaged thickness was small with the change of the gas momentum flux. The film thicknesses measured with the sensor were compared with the past experimental results; the former were smaller than one-fourth of the thickness estimated as the mean film thickness. The comparison results suggested that the continuous liquid sublayer thickness was measured with the liquid film sensor.     

Morphologies and Influential Factors of Forsterite Film in Grain-Oriented Silicon Steel

The product quality of grain-oriented silicon steel may be affected by each process because of its complicated production technology. Morphologies, compositions and structures of forsterite film formed in different conditions on the samples subjected to high temperature annealing were measured by using a scanning electron microscope, an energy disperse spectroscope, an X-ray diffractometer and Fourier transform infrared technique respectively. The morphologies and influential factors of forsterite film were investigated. The results showed that the major component of forsterite film composed of light-gray spherical particles was Mg₂SiO₄, and the minor was MgAl₂O₄. If the amount of MgO coated on the surface of the steel was less, bare holes or even large-scale bare grains for forsterite film appeared. The higher temperature of water bath during decarburization annealing led to gaps of strips in forsterite film. Moreover, MgO coating method had great influence on forsterite film. Roller coating method was beneficial to increase compactness and smoothness of forsterite film, but was disadvantageous to its thickness.     

The role of the electrode configuration on the electrical properties of small-molecule semiconductor thin-films

This paper presents a systematic analysis of the electrode configuration influence on the electrical properties of organic semiconductor (OSC) thin-film devices. We have fabricated and electrically characterized a set of planar two-terminal devices. The differences in I-V characteristics between the top and bottom contact structures are presented and analyzed. Top-contact configurations have a linear current vs. electric field behavior, while the bottom-electrode devices display a transition from ohmic to space-charge-limited conduction regime. The transition is temperature- and thickness-dependent. Finite-element calculations show that when the OSC film is connected using top electrodes, the current flows through the OSC bulk region. On the other hand, the bottom-electrode configuration allows most of the current to flow near the OSC/substrate interface. The current probes interfacial states resulting in a space-charge conduction regime. The results shed some light on the so-called “contact effects” commonly observed in organic thin-film transistors. The findings presented here have implications for both the understanding of the charge transport in OSC films and the design of organic semiconductor devices.     

Preparation and characterization of CoFe2O4 powders and films via the sol-gel method

The CoFe₂O₄ (CFO) starting precursor solutions were prepared by two sol-gel methods. The XRD results show that the second sol-gel method is a better method to obtain CFO materials with high purity. The CFO precursor solutions prepared by the second sol-gel method were spin-coated onto the Pt/Ti/SiO₂/Si substrate to obtain CFO films. With the increase of annealing temperature, the relative amounts of secondary phases in CFO films are decreased. When annealed at 700 °C, CFO films are almost composed of the main phase and the substrate phase without secondary phases. The CFO film is crack-free and has compact structure without any pore. The thickness of CFO film is about 49 nm. The starting precursor solution with the concentration of 0.15 mol L⁻¹ is better for preparing CFO films. The CFO films with nano-scaled film thicknesses have better magnetic properties than the CFO powders.     

双向拉伸聚酯薄膜生产线的技术创新

综述了国内外双向拉伸聚酯薄膜(BOPET)生产线技术水平的差异。并在现有的生产线配套系统上,进行了技术改进和创新,并取得了较好的效果。     

Direct structuring of C60 thin film transistors by photo-lithography under ambient conditions

Direct structuring techniques are an indispensable need for future low-cost applications of organic semiconductor materials in e.g. active matrix displays or integrated circuits. We demonstrate direct structuring of a small molecule organic semiconductor by a photo-lithography lift off process under ambient conditions. To show compatibility of this process, we fabricate organic thin film transistors (OTFT) containing the benchmark electron transporting semiconductor C60 as active material in a top-contact geometry. C60 as electron transporting semiconductor serves as good indicator for contamination and degradation caused by the structuring procedure. To disclose influences of structuring, we discuss the OTFT performance for different channel lengths from 100 μm down to 2.7 μm. In particular, we show that lithography processing gives rise to increased contact resistances. Apart from that, mobility of C60 as material parameter is only weakly affected which underlines the compatibility of the suggested structuring procedure. The potential of this structuring procedure for future integration of driving transistors in active matrix displays is demonstrated.     

A study on the characteristics and pervaporation performance of polyamide thin‐film composite membranes with modified polyacrylonitrile as substrate for bioethanol dehydration

To improve the pervaporation performance in separating an aqueous ethanol solution, polyamide thin‐film composite (TFC) membranes (m‐tolidine‐H‐TMC/mPAN) were prepared through the interfacial polymerization reaction between trimesoyl chloride (TMC) and 2,2'‐dimethylbenzidine hydrochloride (m‐tolidine‐H) on the surface of a modified polyacrylonitrile (mPAN) membrane. The effects of the feed ethanol concentration on the pervaporation performance and the durability of m‐tolidine‐H‐TMC/mPAN TFC membranes were investigated. To choose the optimal mPAN membrane as the TFC substrate, the effect of hydrolysis time on the chemical properties and separation performance of an mPAN substrate was also studied. An appropriate hydrolysis time of 15 min was chosen to obtain the mPAN substrate due to the corresponding high permeation flux. The m‐tolidine‐H‐TMC/mPAN TFC membrane exhibited a high pervaporation performance for ethanol dehydration. A positron annihilation lifetime spectroscopy experiment was used to estimate the mean free‐volume radius of the m‐tolidine‐H‐TMC polyamide selective layer, which lay between the radii of the water and ethanol molecules. © 2013 Society of Chemical Industry     

Microwear mechanism of head carbon film during head disk interface sliding contact

Thermomechanical sliding contact of head disk interface (HDI) causes critical wear on the carbon film of a head slider. An improved contact model accounting for both asperity and substrate deformation is applied to analyze the HDI contact behavior, while theories of frictional heat generation and heat transfer are used to investigate the change in HDI temperature. Based on actual HDI design and operation parameters, parametric study of thermomechanical HDI contact has been performed. It was found that severe wear of head carbon film would be significantly attributed to thermal degradation of carbon material during its sliding contact.     

Effect of polyelectrolyte size on multilayer conformation and dynamics at different temperatures and salt concentrations

Polyelectrolyte bilayers, which consist of poly-l-lysine (PLL) and hyaluronic acid (HA) were simulated with lipid membranes at different temperatures and ion concentrations. Starting with the sequential deposition of PLL and HA above the membrane surface, PLL and HA become completely mixed, leading to the formation of stable bilayers. PLL/HA bilayers are thicker at higher salt concentration because of weakened electrostatic interactions between PLLs and membrane lipids, in agreement with experiments. This salt effect decreases as PLL size increases. Also, bilayers become thinner at higher temperature because of the increased surface area of membrane. In particular, regardless of temperature and salt concentration, larger PLLs induce thicker bilayers, although larger PLLs have lower diffusivities than do smaller ones. Bilayers with larger PLLs show larger vacancy (more water) inside the bilayer, indicating that larger PLLs are less densely stacked on membrane surface than do smaller ones and thus form the thicker bilayer. These findings show the lower diffusivity of larger polyelectrolytes, which supports the experimental observation regarding the restricted diffusion of large polymers, and also imply the dependence of bilayer thickness on the polymer size.