Papers by Author: Si Rong Yu

Abstract: The complex of 2-amino-4-methylthiazole with silver [Ag (C₄H₆N₂S)₂.(CH₃)₂CO] had been synthesized and characterized by elemental analysis, FT-IR and UV-vis spectra. Crystals of the complex were obtained through solvent diffusion method and the structure had been determined by single crystal X-ray diffraction. The nonlinear optical properties were investigated with the density functional theory method. The calculated results show that the complex has high hyperpolarizability of 316.8×10^-30 esu and the metal irons play an important role for the nonlinear optical properties.

Abstract: The crystal structure of 1, 3-propanediol bis (4-aminobenzoate) has been determined by single crystal X-ray diffraction. The UV-vis spectra have been characterized experimentally. The nonlinear optical properties were investigated with the density functional theory method. The calculated first hyperpolarizability values are 7.69×10^-30, 14.22×10^-30 and 26.66×10^-30 esu for the monomer, dimmer and trimer structure of the compound. The results show that the compound has high hyperpolarizability and the hyperpolarizability multipled along with the increasing number of the molecules.

Abstract: Coiling temperature of hot rolled strip is one of the important parameters which affect performances of hot rolled strip. The control of coiling temperature is highly nonlinear and time-varying. Based on the laminar cooling control system of a hot rolling plant, a coiling temperature prediction model based on BP neural network was established. Many factors which affect coiling temperature control were taken into account, and the BP neural network was trained by actual production data. The simulation was carried out, which indicates that coiling temperature can be predicted precisely, and the BP neural network model has the prospect of online application.

Abstract: The present work focuses on the influence of copper complexes in the MAO electrolyte on the structure and wears resistance of ceramic coating on the surface of titanium alloy. The coatings composition and the morphologies were characterized using X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). It is shown that the working voltage of MAO reaction was lower after adding [Cu (NH₃)₄]²⁺ than adding EDTA-Cu. The color of ceramic coating is black (prepared in the electrolyte with [Cu (NH₃)₄]²⁺) and brown (prepared in the electrolyte with EDTA-Cu). The black coating contained rutile TiO₂, anatase TiO₂ and aluminium titanate (Al₂TiO₅), while the brown coating contained rutile and anatase only. The black coating which contained CuO compound was found to outperform brown coating in wear resistance.

Abstract: According to recent researches, aluminum alloy is an ideal choice for solar energy storage technology. But the erosion nature limits its promotion and application. Therefore, it is particularly important to research the corrosion behavior and the corrosion mechanism. In this paper, the 304 stainless steel was used as the container material. By analyzing the corrosion kinetics curves, the erosion thickness increases and the erosion rate decreases with the erosion time extension. Electron probe, X-Ray Diffraction (XRD) and other instruments were used to research the corrosion behavior and mechanism of erosion products. The results show that the erosion form is uniform corrosion. The erosion phenomenon is due to the diffusion corrosion of Al element. Si, Al_0.5Fe₃Si_0.5 compound and Al₉₅Fe₄Cr compound in the erosion layers can retard the diffusion of Al.

Abstract: Ceramic coatings were prepared on Ti6Al4V alloy surface by applying micro-arc oxidation (MAO) technique. K₂Cr₂O₇ was added into the aluminate-based composite electrolyte for preparing coatings containing Cr. The coatings' morphologies were observed using SEM and their composition was characterized using XRD and EDS. Research shows that the working voltage of MAO reaction was lower after adding K₂Cr₂O₇. The SEM pictures show that the average diameter of micropores decreased while the number increased as the K₂Cr₂O₇ concentration increase. The coatings contain rutile TiO₂, anatase TiO₂, aluminium titanate (Al₂TiO₅) and Cr_0.222Ti_0.778O_1.889 (when adding 1.5g/L K₂Cr₂O₇). The EDS results show that all coatings contained Cr after adding K₂Cr₂O₇ into electrolyte. After immersion test for half year, results show that ceramic coating containing chromium has lower anti-biofouling properties than the substrate.

Abstract: A novel method for preparing oleophobic surface is presented. In this article, an oleophobic surface on X70 pipeline steel was prepared successfully by the combination of shot blasting, hydrochloric acid aqueous solution etching, and modified with low-energy material. The influences of the concentration of hydrochloric acid and chemical etching time on the oleophobicity were analyzed. And the optimal experimental parameters were determined. The surface morphology and chemical composition were observed by the field emission scanning electron microscopy (FESEM) and energy dispersive spectrometer (EDS), and the contact angle was measured by contact angle meter. The results showed that micro-nanocomposite structure on the substrate was formed after shot blasting and chemical etching of hydrochloric acid aqueous solution. After low-energy modified, the specimen obtained the better oleophobicity, and the maximum contact angle between the surface and peanut oil was 140°.

Abstract: The problems such as poor oxidation resistant properties at high temperatures and abated thermal storage capacities after repeated thermal cycles still exist in heat storage alloys. In order to alleviate these problems, orthogonal experiment was used to design nine Al-Si-Mg-Cu alloys in this work. An SII TG/DTA6300 differential thermal analyzer was used to determine the heat storage properties of these alloys. After integrating a series of factors, Al-12Si-2Mg-15Cu alloy was selected as the heat storage alloy. The oxidation test of this alloy at the temperature of 650 °C for 300 h was carried out, and the oxidation kinetics curve was obtained. The results showed that the oxide film was of good protection. This alloy exhibited a good thermal stability in view of the latent heat of fusion decreased 3.53%, the initial phase transition temperature decreased 0.1 °C, and terminated phase transition temperature increased 3.1 °C after 150 times of thermal cycles. The photomicrograph was used to discuss the reasons of the performance changes of this alloy.

Abstract: Commercially available magnesium alloy is extensively used in structural engineering components although, like many magnesium-based materials, it suffers from poor corrosion resistance, particularly in moist environments, which limit wider application. Previously, by reducing the contact area of metal substrate with surrounding water environment and decreasing the risk of corrosion is shown to improve the corrosion resistance of magnesium alloy in humid environments and in the presence of chloride-containing aqueous environments. The objective of this study, without the low-surface-energy materials modification, is to fabricate the superhydrophobic surfaces by wet-chemical methods and to understand how the microstructure influences the surface wettability of unstable materials such as magnesium alloy. The influence of the variety of experiment conditions on the wettability of the substrates was investigated by a contact angle goniometry with water as a probe liquid. Scanning electron microscopy and energy dispersive spectroscopy were used to study the surface chemistry and microstructure at various stages of the multi-wet-chemical process.

Abstract: The metal and nano-ceramic nanocomposite coatings were prepared on gray cast iron surface by electrodepositon. The nickel and cobalt were used as metal matrix of coating, and the nano-Al2O3 was chosen as second-phase particulates, which had good chemical stability, high microhardness and good wear resistance. The morphology of composite coatings was flatter and microstructure was denser than pure nickel and cobalt coatings. The composite coatings were fabricated by different dispersion methods such as high speed mechanical stir, ultrasonic vibration and ultrasonic vibration together with mechanical stir. The result indicated the nano-Al2O3/Ni+Co composite coating with fine and compact microstructure are obtained compared with pure Ni-Co coating. The nanoparticles were dispersion evenly when dispersion style was ultrasonic vibration together with mechanical stir according to composite coatings SEM images of different dispersion style. The concentration of nanoparticulates reached a maximum value when the dispersion style was ultrasonic vibration together with mechanical stir, at the same time the mechanical property such as microhardness reached a maximum value also. The reason was that nano-Al2O3 caused dispersive strengthening and grain refining.