Applied Mechanics and Materials Vols. 423-426

Abstract: To reduce the adhesion of blood cells to the pyrolytic carbon surface of heart valve prosthesis, pyrolytic carbon is utilized as the foundation material for the realization of surface super-hydrophobicity. In this process, 10% PVP in concentration is used as the raw material and netted fiber film is textured on the surface of pyrolytic carbon material via electrostatic spinning method at the voltage of 12KV. The experiment results show that the contact angle of the pyrolytic carbon surface amounts to 154o after electrostatic spinning treatment and many porous structures are formed on the fiber film. The conclusion is thus reached that fiber film featured by super-hydrophobicity is attributable to the inability to fill the fiber meshes of liquid drops, which retain the air beneath and then give rise to this super-hydrophobic feature.

Abstract: The foamed plastics are not bio-degradable and not readily recyclable. How to substitute new foamed buffer materials with lower pollution for foamed plastics became a popular research topic. The paper discussed the effects of microwave power, natural bonding agent, lubricating agent and crosslink agent on foamed buffer material with fibers of old newspaper and inorganic foaming agent. The result showed that increasing of microwave power could be beneficial to decrease the molded time and density of foamed buffer material with fibers of old newspaper. The best foamed properties were achieved with proper dosage of natural bonding agent like wheat flour, glyceryl monostearate sodium borate at the microwave power of 575W.

Abstract: Hemp was treated with guanidine nitrate to impart flame retardance. The thermal degradation of the samples were studied by thermogravimetry (TG) and differential thermal analysis (DTA). The flame retardance was determined by LOI. Morphology of the char structure was studied by SEM to obtain information concerning the thermal degradation mechanism. For hemp treated with guanidine nitrate, which has higher LOI and char yield values, the oxidative decomposition stages include a decomposition stage at lower temperatures (203-240°C) , leading to more carbonaceous residue and small amount of flammable products to get the good flame retardance. The SEM of the chars of hemp treated with guanidine nitrate also indicate the structure of the charring layer may increase heat insulation, and protect inner matrix materials.

Abstract: A copolymer was prepared from itaconic acid (IA) and sodium allysulfonate (SAS). The structure of the IA/SAS copolymer was characterized by the means of FTIR. The performances of scale inhibition, dispersion and biodegradability of the IA/SAS copolymer were studied. The results showed that the IA/SAS copolymer had good scale inhibition and dispersing performance. The scale inhibition rate on calcium carbonate was 93% when the copolymer was 20 mg·L^-1. The scale inhibition rate on calcium phosphate was 92% when the copolymer was 24 mg·L^-1. The copolymer had good biodegradation performance and biodegradation rate could reach 69.5% after 28 days.

Abstract: High temperature solid state reaction has been used to prepare the new red long-lasting phosphorescence (LLP) material ZnGa₂O₄:Cr³⁺ with different doping concentration. The afterglow properties of the samples have been investigated. Our study has shown that ZnGa₂O₄ samples without Cr³⁺ doping have blue-green afterglow. While the blue-green afterglow has disappeared and the red long-lasting phosphorescence according to the Cr³⁺ luminescence center covering 650 nm-750 nm has been observed when Cr³⁺ has been doped. In terms of brightness and decay time of the afterglow, the red afterglow and the blue-green afterglow have been entirely different. In this article the influence on LLP due to different doping concentrations of ZnGa₂O₄:Cr³⁺ has been discussed and the possible LLP mechanism has been proposed.

Abstract: High temperature solid state reaction has been used to prepare Zn₃(PO₄)₂: Mn²⁺. XRD analysis shows that different phases have been generated with different Mn²⁺ doping concentration at the same sintering temperature. Low Mn²⁺ doping concentration is conducive to form α phase, while γ is in favor of high Mn²⁺ doping concentration. In α phase, the emission spectrum of Mn²⁺ is a wide emission band peaking at 542 nm, green fluorescence. In γ phase, the emission spectrum of Mn²⁺ is a wide emission band peaking at 608 nm, red fluorescence. In the both phases, green and red afterglows have been observed. The red afterglow in γ phase has stronger initial brightness and longer afterglow decay time than the green afterglow in α phase, the reason of which lies in the larger trap concentration in γ phase.

Abstract: Spectrally selective AlCr-AlCrON cermet solar absorber coating has been deposited on Cu substrate experimentally by reactive DC magnetron sputtering and heat-treated in air at 300°C for 2h. The spectral properties and thermal stability of the as-synthesized AlCr-AlCrON coatings were characterized. The solar absorptance and thermal emittance of the as-synthesized AlCr-AlCrON coating are 0.926 and 0.065, respectively. In addition, after heat treatment at 300 ° C for 500 h in air, the spectral properties of the as-synthesized AlCr-AlCrON coating is virtually unchanged. The results indicate that the as-synthesized AlCr-AlCrON coating has good spectral properties and thermal stability, which will be a good selective absorbing coating for mid-temperature solar vacuum collector tubes.

Abstract: LiTaO₃: Tm³⁺, Yb³⁺ powders were synthesized by a high-energy ball-milling (HEB) method compared with the conventional solid-state reaction (SSR) method. Under the excitation of 980 nm laser, the strong blue emission (477 nm) band is observed and attributed to ¹G₄- ³H₆ of Tm³⁺. Because of it causing high local temperature and narrow particles size, increasing the contact area between the particles and improved crystallinity of the host, synthesis by high-energy ball milling show higher photoluminescence (PL) intensity compared to the solid state reaction method. In the process of mechanical milling, Tm³⁺, Yb³⁺ co-doped LiTaO₃ phosphors with high photoluminescence property could be achieved at a relatively low reaction temperature.

Abstract: β-NaGdF₄: Yb, Tm/β-NaGdF₄: Eu and β-NaGdF₄: Yb, Tm, Eu particles were successfully synthesized by two different methods, solvothermal method and high-energy ball milling. The properties were measured by X-ray diffraction (XRD), TEM and luminescence spectra. All samples shown the strong photoluminescence intensity under 980 nm light excitation and emission of Eu³⁺ was observed. Finally, two methods are compared in paper.

Abstract: TiO₂ sol was doped with SiO₂ and modified by adding PEG. Using the sol the self-cleaning antireflective films were prepared with dip-pulling method. Field emission scanning electron microscope (FESEM) test results showed that the TiO₂-SiO₂ film surface distributed a large number of pores and grooves. The visible spectrophotometer testing found that the transmittance showed a decreasing trend with the increase of TBTT: TEOS ratio. Meanwhile, the photo-catalytic efficiency showed an increase firstly and then decreased with the TBTT: TEOS ratio increasing. When the ratio of TBTT: TEOS was 1:5, the films transmittance and the photo-catalytic efficiency can reach up to 97.1% and 13.5% respectively. The mechanisms on the transmittance and photo-catalytic activity of PEG-modified TiO₂-SiO₂ films were studied. It was found that PEG-modified TiO₂-SiO₂ films have higher porosity, transmittance and hydrophilicity than pure TiO₂ film. Furthermore, photo-catalytic activity of the TiO₂-SiO₂ film was enhanced.