简单且大尺寸超疏水硅橡胶涂层的制备

采用疏水气相纳米二氧化硅构建粗糙结构,双组分室温硫化硅橡胶(RTV-2)作为黏合剂增加涂层的机械性能,制备的涂层水接触角达到155.5°,滚动角达到8°。加入硅烷偶联剂(KH-570)对涂层疏水改性后,涂层水接触角达到160.5°,滚动角达到4°。采用自清洁实验、机械性能实验、耐气候老化实验对涂层性能进行了测试,结果表明涂层具有良好的自清洁、机械性能高、耐气候老化等优点。涂层实验步骤简单、药品经济型高、不需要高温固化。室温下2h可以完成涂层制备的全过程,适用于大尺寸制备。实验方案为超疏水涂层商用化提供了一定的思路。

Preparation of amorphous nano-boron powder with high activity by combustion synthesis

The preparation process of amorphous nanometer boron powders through combustion synthesis was investigated, and the effects of the reactant ratio, the heating agent and the milling rate on the activity and particle size of amorphous boron powders were studied. The results show that the boron powders exist in the form of an amorphous phase which has the crystallinity lower than 30.4%, and the panicle size of boron powder decreases with an increase of the high-energy ball milling rate. The purity of amorphous boron powder is 94.8% and panicle sizes are much smaller than 100 nm when the mass ratio of B2O3/Mg/KClO3 is 100：105：17 and the ball milling time is 20 min with the milling rate of 300 r/min. At the same time, the amorphous boron nano-fibers appear in the boron powders.

Low Breakage and Size-controlled Preparation of NiCl2 Immobilized Hollow Polyurea Microcapsules

Polyurea microcapsules containing NiCl2 were prepared by interracial polymerization between diisocyanate and water with triethylamine as a catalyst in water-in-oil emulsion system. The influence of preparation conditions such as the dosage and feed mode of the catalyst, concentration of the encapsulated NiCl2, and concentration and structure of diisocyanates on the breakage of the microcapsules have been evaluated. The results show thatbreakage is strongly dependent on the rate of polymerization and stability of initial emulsion. The improved microcapsules with low breakage have been produced under the optimum conditions. Furthermore, the obtained microcapsules capsules immobilizing NiCl2 as a recyclable catalyst is successfully used in benzaldehyde reduction.

Microstructure and mechanical properties of AZ31 alloy ingot fabricated by semi-continuous casting

The AZ31 alloy ingot with diameter of 110 mm and length of 3500 mm was fabricated successfully. The compositions and microstructure morphologies of the ingot at different locations were performed, which indicated that the chemical composition distributed homogeneously through the whole alloy ingot and the average grain size increased from the surface to the center. The results of the EDS and element face-scanning illustrated that the eutectic compounds mainly consisted of fl-Mg17Al12 and a small amount of fl-Mgl7（AlZn）12. Furthermore, slight improvements of the strength and ductility were observed from the center to the surface along the axial direction of the alloy ingot, while both the strength and elongation to failure of the samples along the radial direction are higher than that along the axial direction. The fine grain strengthening was the main contributors to the strength of the as-casted AZ31 alloy.

多孔莫来石陶瓷的近净尺寸制备及性能

以蓝晶石和Al_(2)O_(3)粉体为原料、PMMA微球为造孔剂、Isobam104为分散胶凝剂,结合凝胶注模工艺与造孔剂法,实现了收缩率可控的多孔莫来石陶瓷的近净尺寸制备。研究了烧结温度对相组成的影响以及固相含量对样品微观结构、相组成、收缩率、气孔率及抗压强度的影响。结果表明:随着固相含量的增加,样品在1 500℃烧结后收缩率先减小后增大,在固相含量为30%(体积分数)、造孔剂含量为30%(质量分数)时,样品的总收缩率接近于0,实现了多孔莫来石陶瓷的近净尺寸制备。多孔莫来石陶瓷呈现出较高的气孔率(60.4%)、较小的平均气孔尺寸(3.75μm)和较高的抗压强度(8.3 MPa)。利用制备过程中的体积膨胀效应,可以有效地控制多孔陶瓷制备过程中的收缩率,实现了多孔莫来石陶瓷的近净尺寸制备,对制备大尺寸复杂形状多孔陶瓷部件、降低加工成本具有重要参考价值。

PREPARATION OF PARTICLE SIZE NARROWLY DISTRIBUTED LOW-DENSITY STYRENE DIVINYLBENZENE COPOLYMER MICROBEADS

In view of the importance of dispersion agent,the amount of the crosslinking monomer and the diluent in suspension polymerization for the production of particle size narrowly distributed low-density stryene divinylbenzene copolymer microbeads(LDPS),their actions are preliminarily investigated in this paper.Experimental results indicate that when both the gelatine and polyvinyl alcohol(PVA)are used dispersion agents,the better effect is achieved,DVB is helpful to the formation of the lower density fine particles,the proportionof the DVB/St should be between 1:1-1.5:1.Compared with toluene,gasoline is the more effective diluent for the above target.

The preparation of high concentration alkaline silica sol with the method of vacuum distillation

High concentration alkaline silica sol has been prepared by the method of vacuum distillation, which shows that the stable and high concentration silica sol can be obtained under conditions as follows： 70℃, vacuum degree of 0.095Mpa and dispersant of SDS. The experimental results show that the sol particles size decreases with mass concentration first and then increase, sol viscosity increases with mass concentration during the concentrating process. The TEM method was used to study the dispersion behavior of sol particles, its result showed that sol particles dispersed more uniformly after concentrating process than before concentrating distinctly. It could be concluded that the disperse degree of alkaline silica sol could be increased by addition of right dispersant. The dispersion mechanism of dispersant in alkaline silica sol was also discussed.

Mg70Ni15Gd10Ag5块体非晶的制备及晶化行为

采用铜模铸造法制备新型块体非晶合金Mg70Ni15Gd10Ag5(at%),其临界制备尺寸不低于5mm,是目前Mg-Ni基非晶合金制备尺寸的最大值。采用差示扫描量热(DSC)法研究非晶合金的晶化行为,发现合金的晶化为多级晶化。随着升温速度的提高,玻璃转变温度Tg、晶化开始温度Tx、熔化前4个放热峰温度(Tp1、Tp2、Tp3、Tp4)、熔化开始温度(Tm)和液相线温度(Tl)均向高温区移动,晶化行为具有显著的动力学特征。利用Kissinger法计算特征温度对应的激活能,其值分别为Eg=188.05kJ/mol、Ex=144.79kJ/mol、Ep1=138kJ/mol、Ep2=142.40kJ/mol、Ep3=119.10kJ/mol、Ep4=72.86kJ/mol。

Controllable preparation of ultrathin 2D BiOBr crystals for high-performance ultraviolet photodetector

Ternary layered compound materials(bismuth oxyhalides and metal phosphorus trichalcogenides)stand out in electronic and optoelectronic fields due to their interesting physical properties.However,few studies focus on the preparation of high-quality two-dimensional(2D)BiOBr crystals with a typical layered structure,let alone their optoelectronic applications.Here,for the first time,high-quality 2D BiOBr crystals with ultrathin thicknesses(less than 10 nm)and large domain sizes(~100μm)were efficiently prepared via a modified space-confined chemical vapor deposition(SCCVD)method.It is demonstrated that a moderate amount of H2O molecules in the SCCVD system greatly promote the formation of high-quality 2D BiOBr crystals because of the strong polarity of H2O molecules.In addition,a linear relationship between the thickness of BiOBr nanosheets and Raman shift of A1g(1)mode was found.Corresponding theoretical calculations were carried out to verify the experimental data.Furthermore,the BiOBr-based photodetector was fabricated,exhibiting excellent performances with a responsivity of 12.4 A W-1 and a detectivity of 1.6×1013 Jones at 365 nm.This study paves the way for controllable preparation of high-quality 2D BiOBr crystals and implies intriguing opportunities of them in optoelectronic applications.

Effects of discharge power on the structural and optical properties of TGZO thin films prepared by RF magnetron sputtering technique

The transparent semiconductors of Ti and Ga-incorporated ZnO(TGZO) thin films were prepared by radio frequency(RF) magnetron sputtering onto glass substrates. The effects of discharge power on the physical properties of thin films are studied. Experimental results show that all nanocrystalline TGZO thin films possess preferential orientation along the(002) plane. The discharge power significantly affects the crystal structure and optical properties of thin films. When the discharge power is 200 W, the TGZO thin film has the optimal crystalline quality and optical properties, with the narrowest full width at half-maximum(FWHM) of 1.76×10^(-3) rad, the largest average grain size of 82.4 nm and the highest average transmittance of 84.3% in the visible range. The optical gaps of thin films are estimated by the Tauc's relation and observed to increase firstly and then decrease with the increase of the discharge power. In addition, the optical parameters, including refractive index, extinction coefficient, dielectric function and dissipation factor of the thin films, are determined by optical characterization methods. The dispersion behavior of the refractive index is also analyzed using the Sellmeier's dispersion model.

Two-photon polymerization fabrication and Raman spectroscopy research of SU-8 photoresist using the femtosecond laser

In this work, a two-photon polymerization(2PP) processing device was built using the femtosecond laser, and femtosecond laser direct writing was performed on SU-8 photoresist. Due to the 2PP effect of the photoresist caused by the femtosecond laser, the polymeric line with size less than the focal spot size is obtained. Based on the Raman spectroscopy characterization of SU-8 polymer before and after 2PP, we research the dynamic process of femtosecond laser induced 2PP. In Raman spectra, some scattering peaks with large intensity variation, such as 1 108 cm^(-1) and 1 183 cm^(-1), indicate that the asymmetric stretching vibration of C-O-C bond in SU-8 polymer is increased. By comparison, we can find that 2PP only affects the light absorption of initiator, but does not affect the monomer polymerization. It is helpful to understand the interaction of photoresist and femtosecond laser, and plays an important role in quantitatively controlling the polymerization degree of SU-8 polymer and improving the processing resolution of 2PP.

Fabrication of quantum-sized Cd S-coated Ti O2 nanotube array with efficient photoelectrochemical performance using modified successive ionic layer absorption and reaction(SILAR) method

Quantum-sized CdS-coated TiO2 nanotube array （Q-CdS-TiO2 NTA） was fabricated by the modified successive ionic layer absorption and reaction method. Scanning electron microscope and transmission electron microscope images showed the regular structure of TiO2 NTA, where quantum-sized CdS （diameter 〈10nm） deposited on both the inside and outside of TiO2 nanotube wall. Fabrication conditions including immersing cycles, calcination temperature and drying process were well optimized, and the Q-CdS-TiO2 NTA and its photoelectrochemical （PEC） properties were characterized by X-ray fluorescence spectrometer, UV-Vis diffuse reflectance spectra and photovoltage. Distinct increases in visible light absorption and photocurrent were observed as the immersing cycle was increased from 5 to 20 times. The additional drying process accelerated the CdS crystal growth rate, and thus, the fabrication time could be shortened accordingly. Calcination temperature influenced the PEC property of Q-CdS-TiO2 NTA deeply, and the optimized calcination temperature was found as 500 ℃. As the Q-CdS-TiO2 NTA was fabricated under such condition, the visible photocurrent density increased to 2.8 mA/cm and the photovoltage between 350 and 480 nm was enhanced by 2.33 times than that without calcination. This study is expected to optimize Q-CdS-TiO2 NTA fabrication conditions for the purpose of improving its PEC performance.

Preparation of nanophase M-type ferrite and its laser-attenuated characteristics

By citrate sol-gel auto-combustion method,the nanophase M-type planar hexagonal ferrite is prepared.The transmission electron microscopy(TEM),X-ray diffraction(XRD) and thermal analysis are used to study the grain size,phase composition,microstructure and crystallization process.The results show that the nanophase M-type Sr-ferrite prepared by this method is single,and its grain size is smaller than 100 nm.Moreover,most of the grains present hexagonal sheet shape.Tests are carried out for its attenuation to 1.06 mm laser.It is found that the extinction capability of the nanophase M-type Sr-ferrite smoke is good,and its mass extinction coefficient is 1.628 m2/g.