Critical and Subcritical Adhesion Measurements of a Model Epoxy Coating Exposed to Moisture Using the Shaft-Loaded Blister Test

The shaft-loaded blister test (SLBT) was used to investigate the adhesion between a model epoxy coating and a silicon oxide surface as a function of relative humidity. Critical and subcritical strain energy release rates were measured using specimens that incorporate reinforcing layers of Kapton® film. A simplified procedure that eliminates the need for video imaging to measure the blister radius and fracture energy was developed. A critical relative humidity level for adhesion loss was observed, in agreement with measurements that have been made previously in a number of polymeric systems. The SLBT was confirmed to be particularly attractive for fracture energy measurements on thin, strongly adhered coatings and films which otherwise tend to be problematic.     

COMBINED NATURAL AND FORCED CONVECTION IN A HORIZONTAL FLOW CHANNEL

The effect of natural convection on forced convection in a horizontal flow was investigated during zinc electrodeposition on a horizontal electrode facing upward in a channel. The previous findings of Tobias and Hickman [1] are confirmed. A secondary flow in the form of roll cells whose axes are parallel to the flow direction is formed at some distance from the leading edge. This distance depends linearly on the flow velocity through the critical Rayleigh number for the onset of natural convection across the diffusion boundary layer. Striated zinc deposits reveal the imprint of the secondary flow on the planar cathode facing upward.     

Hydrodynamic effects on erosion-enhanced corrosion of stainless steel in aqueous slurries

This paper studies the hydrodynamic effects of erosive slurry on corrosion of passive target (type 304 stainless steel). The transient current response to disruption of passive film is investigated using the single particle impingement technique. The transient current density over the damaged surface is approximately independent of the hydrodynamics of fluid when the flowing velocity is in range of 5-10 m/s. It is characterized by a sharp rise caused by disruption of passive film and a slow decay due to repassivation. Therefore, the difference in transient current response is a result of different damaged surface area produced by solid particle impingement. After the kinetic parameters of repassivation are determined, the hydrodynamic effects on average corrosion rates of the passive target are quantitatively predictable with aid of the physical model developed by Lu and Luo.     

离子注入技术改性聚合物薄膜的研究进展

离子注入技术改性聚合物薄膜在电子及电器工程中有着巨大的潜在应用价值。综述了近年来聚合物薄膜经离子注入后在导电性能、光学性能、导磁性能及表面力学机械性能等方面的最新进展。分析了注入离子与聚合物相互作用的物理过程,并指出了该领域存在的问题及发展方向。     

Structural and optical properties of four-hexagonal polytype nanocrystalline silicon carbide films deposited by plasma enhanced chemical vapor deposition technique

Four-hexagonal polytype films of nanocrystalline silicon carbide (4H-nc-SiC) were deposited by plasma enhanced chemical vapor deposition method with more than 3×10⁴ W m⁻² threshold of power density, high hydrogen dilution ratio, and bias pretreatment. The source gases were silane, methane and hydrogen. Our work showed that under conditions similar to those used for the growth of μc-SiC—except a higher power densities over a threshold, a bigger bias pretreatment on substrates, and a moderate bias deposition—nc-SiC films could indeed be achieved. The Raman spectra and transmission electron microscopy diffraction patterns demonstrated that the as-grown films from the H₂-CH₄-SiH₄ plasma consist of amorphous network and phase-pure crystalline silicon carbide which has the 4H polytype structure. The microcolumnar 4H-SiC nanocrystallites of a mean size of approximately 1.6×10⁻⁸ m in diameter are encapsulated by amorphous SiC networks. The photoluminescence spectra of 4H-SiC at room temperature, peaking at 8.10×10⁻⁷ m using a wavelength of 5.145×10⁻⁷ m of argon ion laser, were obtained at room temperature; the luminescence mechanism is thought to be related to transitions in the energy band gap which could be ascribed to the surface states and defects in the structure of 4H-SiC nanocrystalline in these films due to its small size. The as-grown films showed an optical transmittance of 89% at 6.58×10⁻⁷ m. This higher transmittance is believed to be from the small size and amorphous matrix.     

生物传感器法检测葡萄汁中葡萄糖含量

采用葡萄糖氧化酶与过氧化氢电极,在0.2 mol/L的磷酸盐缓冲液（pH 7.2）和1‰的葡萄糖标准溶液反应体系中,建立葡萄汁中葡萄糖含量检测的生物传感器分析方法。结果表明,在葡萄糖质量浓度为0～1 000 mg/L的范围内生物传感器法测定葡萄糖含量的线性良好;线性回归方程为y=0.994 8x-3.081,相关系数R2=0.999 9;稳定性好,相对标准偏差（RSD）=1.63%;加标回收率为96.0%～102.4%;专一性强,只对葡萄糖进行专一性测定。     

Analysis of the stress and interfacial reactions in Pt/Ti/SiO2/Si for use with ferroelectric thin films

The microstructure of the Pt/Ti/SiO₂/Si structure has been investigated by scanning and transmission electron microscopy. Pt films of 100 nm thickness deposited by sputtering or evaporation onto unheated substrates gave complete coverage of the underlying Ti layer and showed a granular and faceted structure with grains ∼20 nm in diameter. They did not exhibit hillocks or surface TiO_x formation. X-ray diffraction was used to examine the film stress through use of the sin²ψ method with bulk values for the elastic constants (v=0.39, E=162 GPa). The as-deposited sputtered film had a compressive stress of ∼540 MPa, while the evaporated films had tensile stresses of ∼630 MPa. The films then received a 400°C rapid thermal anneal (RTA) for 90 s and a subsequent RTA of 650°C for 30s. Further investigation of the film stresses and microstructure were made after each annealing step. After the low temperature anneal, the film stress for the sputtered film became tensile. Plan-view sections examined by transmission electron microscopy (TEM) showed that the as-deposited sputtered films were dense but became porous after annealing. Initially, the evaporated films had a less dense microstructure, but were more stable with annealing. Little change in the stress for the evaporated film was observed after this initial low temperature annealing step. Additional annealing of the evaporated and sputtered samples caused complete consumption of the Ti layer including some TiO_x formation from the underlying SiO₂ layer and marked interaction with the Pt; however, little change in the stress was found. The surface of the Pt film revealed larger grains, but otherwise remained unaffected. The underlying phase changes were minimized once the Ti layer had reacted with the Pt. Due to the ratio of the layers, Pt:Ti of 2:1, the surface of the Pt was unaffected.     

脉冲激光薄膜制备技术

脉冲激光薄膜沉积是近年来受到普遍关注的制膜新技术。简要介绍了脉冲激光薄膜沉积技术的物理原理、独具的特点和研究发展动态,并介绍了采用脉冲激光薄膜沉积技术制备硅基纳米PtSi薄膜的结果     

Bio-based polyurethane films using white dextrins

Several new eco-friendly materials have the potential to replace conventional petroleum-derived materials and monomers. Among them are natural polysaccharides. The use of polysaccharides in polyurethane (PU) synthesis has not yet been studied extensively, even though as multihydroxyl compounds, they can easily serve as crosslinkers in PU synthesis. One naturally occurring (hyper-)branched polymer is amylopectin, a component of starch. In this work, we report the PU synthesis and film-forming capacity using the asymmetric cyclic aliphatic diisocyanate—isophorone diisocyanate (IPDI) with acetylated and pristine partially hydrolyzed amylopectin/white dextrin (AVEDEX W80) as a crosslinker. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47454.     

Structure and electrochemical behaviors of a series of Co-B alloys

A series of Co_xB (x = 1, 2, 3) alloys were prepared by arc melting, the phase structure of the alloys were characterized by X-ray diffraction (XRD). The electrochemical experimental results demonstrated that the Co_xB (x = 1, 2, 3) series alloys showed excellent cycling stability, the capacity retention was 94.2%, 93.6% and 93.8% in the 100th cycle, respectively, as the cobalt content decreased. The CoB alloy electrode showed very good electrochemical reversibility in cyclic voltammetry (CV) curves, the oxidation and reduction peaks resembled the pure cobalt element powder electrode. The electrode mechanism was discussed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), using pure CoB alloy cast electrode. From the SEM, after first and second cycle, the surface became porous and pulverous; also, the oxidation state of Co changed through XPS, after second cycle, the Co of 0 oxidation state could not be found on the surface. Based on the experiment, a proper mechanism was proposed: on this condition, the discharge capacity may due to the Co(OH)₂/Co reaction, which happened on the porous surface as the boron dissolved when the cycle increased.