Advanced Materials Research Vols. 183-185

Abstract: Being the first step of foaming, bubble heterogeneous nucleation of aluminum foam has remarkable effects on the final cell structure of aluminum foam. The bubble heterogeneous nucleation of foaming Al-9Si and T_iH₂ powder compact has been analyzed. The results obtained are given as follows: (1)The remaining T_iH₂ particles act as the nuclei during heterogeneous nucleation. (2)The nucleation rate increases with the increasing of T_iH₂ content, the decrease of T_iH₂ granularity, the elevation of foaming temperature, and the elongation of foaming time. (3) Only about 5‰ bubble nuclei can survive and develop to the final foam cells. (4)The influence of processing parameters on the nucleation rate descends by the following sequence: foaming temperature elevates 20°C, T_iH₂ granularity decreases from 150μm to 26μm, T_iH₂ content increases 0.5%wt., and the time for foaming extends 10s.

Abstract: Al-Si12 alloy foams were fabricated by filtration method, and the Al-Si12 alloy foam core mufflers were made by using the fabricated Al-Si12 alloy foams. The preparation and sound absorption property of Al-Si12 alloy foam core muffler has been studied. The results show that sound absorption property of Al-Si12 alloy foam core muffler increases with the decreasing of pore diameter and the widening of the pore diameter range of Al-Si12 alloy foam core. Being superior to conventional sound-absorbing materials core mufflers, Al-Si12 alloy foam core muffler especially fits in noise control in hot, wet, and open-air environments.

Abstract: Fluorescent whitening agent is relatively small dosage in the coating, but it has great influence on the properties of the coating and ink-jet printing qualities. With the increase of fluorescent whitening agent dosage, the PH of the coating rose but the viscosity was hardly to change. The brightness of coated ink-jet printing paper and color density of the printing image firstly presented the trend of increasing then decreasing. What’s more, when the brightness of the coated paper achieved to the maximum, color density and contact angle properties were the largest. Chromatic aberration property of the image reduced from 1.87 to 1.75, when the addition of fluorescent whitening agent rose from 0.1% to 0.5%. While the dosage was rose to 0.9%, chromatic aberration increased to 2.15. The gloss of coated paper decreased with the dosage of fluorescent whitening agent increasing. In sum, fluorescent whitening agent can enhance the brightness of the coated paper as well as the printing properties. The results show that the best brightness and printing qualities of coated ink-jet printing paper are obtained, when the fluorescent whitening agent is 0.5%( relative to pigment).

Abstract: Based on the basic components of the porous Metal Rubber (MR) materials, all kinds of heat transfer modes were analyzed. Wire helix was considered as the micro-element of Metal Rubber by analyzing the characteristics of processing components of Metal Rubber. According to the acoustoelectric analogy method, the heat transfer model of MR was established on the basis of arrangement of wire helix and Fourier Law. The formula of thermal conductivity coefficient was derived. And the LFA 427 instrument was used to obtain thermal conductivity characteristics of MR experimentally. The results showed that the model had certain application. This model was valuable for the analysis of the thermal properties and the design of Metal Rubber. It provided theoretical support for the further engineering application of Metal Rubber in the field of heat insulation.

Abstract: A novel photoelectrochemical biosensor incorporating nanosized ZnO semiconductor crystals with enzyme to enhance photochemical reaction has been investigated. In this work, the ZnO nanoparticles and acetylcholinesterase (AChE) were immobilized on Pt electrode by chitosan (CHI) via layer-by-layer technique (LbL) to fabricate a biological-inorganic hybrid system. Micrographs of (ZnO/CHI/AChE) films were obtained by scanning electron microscope, and photoelectrochemical properties of the resulting biosensors were measured by a three electrodes system and an ultraviolet lamp. Under ultraviolet light, the photo-effect of the ZnO nanoparticles showed enhancement of the biosensor to detect pesticide. Based on the inhibition of organophosphate pesticides on the AChE activity, using malathion as a model compound, the inhibition of dimethoate was proportional to its concentration ranging from 0.25 to 1.50 and from 1.75 to 10.00 μM, with a detection limit of 10 nM estimated at a signal-to-noise ratio of 3. The developed biosensor exhibited good reproducibility and acceptable stability, thus providing a new promising tool for analysis of enzyme inhibitors.

Abstract: The Fe₃Al intermetallics compounds bulks were fabricated by hot-pressing process in this research. The Fe₃Al intermetallics compounds powders were fabricated by mechanical alloying and heat treatment process. The phase composition and microstructure of the Fe₃Al intermetallics compounds powders produced by mechanical alloying and heat treatment were investigated. The phase composition and microstructure of the Fe₃Al intermetallics compounds bulks produced by hot-pressing process were investigated. The XRD patterns results showed that the Fe-Al intermetallics compounds powders were fabricated by mechanical alloying for 60h. Then the Fe₃Al intermetallics compounds powders were fabricated by heat treatment at 800°C and 1000°C. The microstructure showed that the mean particles sizes of the Fe-Al intermetallics compounds powders produced by mechanical alloying decreased remarkably with the increase of milling time. The microstructure showed that the mean particles size of the Fe₃Al intermetallics compounds powders produced by mechanical alloying for 60h and heat treatment was rather fine and about 4-5μm. The Fe₃Al intermetallics compounds bulks were fabricated by hot-pressing process at 1100°C for 2h under the pressure of 35MPa. The XRD patterns results showed that there existed only Fe₃Al intermetallics compounds phase in the sintered bulks. The Fe₃Al intermetallics compounds bulks exhibited the homogenous and compact microstructure. The mean particles size of the Fe₃Al intermetallics compounds was rather fine and about 2-3μm. The relative density of the Fe₃Al intermetallics compounds sintered bulks was about 99.2%. So the Fe₃Al intermetallics compounds bulks with the high relative density were fabricated by hot-pressing process.

Abstract: Polyaniline was synthesized by the chemical synthesis. Polyaniline as dispersion agent, nano silver / polyaniline composite particles was prepared by In-situ Synthesis in DMF solution. Nano Silver / Polyaniline / PMMA composites were prepared by direct dispersion method. The microstructure and characterization of the sample were studied by UV-Vis absorption spectroscopy infrared spectroscopy and XRD. The composite electrical conductivity was measured by four-probe method, showing that nano silver / polyaniline composite particle size was about 31.0 nm. When the doping concentration of nano-silver reached 0.12%, the electrical conductivity of silver / polyaniline / PMMA composite comparing to the pure PMMA material increased four orders of magnitude.

Abstract: Fine silica particles were synthesized using sodium silicate from the iron ore tailings and ion exchange of ammonium sulfate at room temperature by water-in-oil (w/o) emulsion containing water, nonionic surfactant of Triton X-100, and cyclohexane. The reaction conditions and silica particles properties were investigated by X-ray diffraction (XRD), FT-IR analysis and scanning electron microscopy (SEM). The results showed that the particle size of SiO₂ decreased with increase of reaction time and concentration of surfactant. The preparation conditions were experimentally determined for obtaining the fine silica particles with submicron size, narrow size distribution, sphere in shape, and high purity without sodium contamination.

Abstract: Used RF magnetron sputtering method to prepare SiO₂ thin film on the carbon steel (Q235A) substrate, Films were characterized with the atomic force microscope (AFM) and the X-ray photoelectron spectrum (XPS). Corrosion resistance was compared of SiO₂/ Q235A and Q235A. The results showed that: nano-structured thin film was smooth and dense, The thin film was constituted by compact particles of SiO₂, and there was no Fe in the films. Electrochemical experiments indicated that SiO₂ / Q235A had better corrosion resistant than Q235A in the sea water.

Abstract: The rheological behaviors of nylon610 and nylon610/montmorillonite nanocomposites had been studied by means of HAAKE-Ⅱrheometer. The results showed that nylon610 and nylon610/montmorillonite composites were pseudoplastic fluid. The non-Newtonian indexes, which were in the range of 0.49～0.82 at differern temperatures, decreased with the addition of montmorillonite. What is more, the apparent viscous activation energy decreased, which showed the effect of temperature on apparent viscosity of the nanocomposites was weaker than that of pure nylon610, apparent viscosity increased with the increase of montmorillonite, especially at the lower shear rate.