Advanced Materials Research Vols. 317-319

Abstract: Butyl rubber was synthesis by solution process in hexane-chloromethane mixed solvent using ethylaluminium sesquichloride/water as initiating system The product has comparable properties with BK1675(solution process) and EXXON268（slurry process）in terms of molecular, molecular distribution, unsaturated degree as well as processing properties of Mooney viscosity, vulcanization, tensile properties. The solution method will open up a new way to produce butyl rubber in China.

Abstract: The present paper studied the as-cast structure and macrosegregation of the wedge-shaped castings produced vertical centrifugal casting process at different mould rotating speeds. The element distributions were determined by the secondary electron line scanning in the S-570SEM type scanning electron microscope (SEM) and the grain sizes of the castings were observed by the optical stereoscope. The research results show that the grain sizes increase with increasing of casting wall-thickness, but decrease with increasing of the mold rotational speed. The cooling rate is high and rotational speed is not high enough, therefore, there is slightly macrosegregation trend for the alloy element of Al and V in the wedge-shape castings.

Abstract: This paper is mainly to describe coating method of MgO nano film with about 2nm and Bio-medicine materials on surface the magnetic nanoparticle. The coated composite magnetic nanoparticles of coated were dispersed into ion exchange water, widely known as magnetic fluids for applying to Drug Delivery System(DDS). Through observation of micro-structure of MgO film and the bio-nanopaticles on coating surface, and evaluation of magnetic property, we known that the effectiveness of this coating method of MgO and the bio-medicine coated on surface of magnetic nanoparticles was confirmed.

Abstract: Subdivision technology provides a convenient way to represent smooth surfaces of arbitrary topological structures. The technology is now widely applied in character animation and computer graphics. However, it meets challenges if to be employed in machining. This paper focuses on the problems of surface subdivision in machining applications and the solutions for these problems. The work includes two parts. First, an algorithm of Loop subdivision that can keep sharp surface features is presented. And second, a cross-section method is employed to obtain the NC tool path of the divided surface. The NC tool path of the refined model is verified with the MasterCAM software. The research is valuable for the improvement of the subdivision scheme commonly used in CAD/CAM system.

Abstract: Abstract. In this paper, a novel type of 2-UPU/2-URU asymmetric parallel mechanism is put forward, the degree of freedom and kinematics characteristics of the mechanism is analyzed. Firstly, based on screw theory, the degree of freedom of the mechanism is analyzed by using modified Grübler-Kutzbach formula of Degree of Freedom, the method is ingenious and simple. Then the kinematics analysis is done. Finally, the velocity and acceleration of the mechanism is analyzed by combining kinematic influence coefficient theory with imaginary mechanism method, and draw the velocity and acceleration performance curve of the mechanism with the MATLAB. This paper lays the foundation for further research of the parallel mechanism.

Abstract: Silver nanoparticles (AgNPs) were rapidly synthesized by treating silver ions with the extract of a well-known Traditional Chinese Medicine herb, Flos Sophorae Immaturus, at room temperature. The AgNPs were characterized by UV–vis spectroscopy and zeta potentials analysis. The bactericidal activity of the AgNPs against S. aureus and E. coli was investigated. The results indicated that the AgNPs synthesized by Flos Sophorae Immaturus extract were water-soluble nanoparticles with 30-60 nm size, zeta potential studies showed that the surface charge of the formed nanoparticles was highly negative, and the antibacterial activity of the green prepared AgNPs exhibited potent bactericidal activity on S. aureus and E. coli.

Abstract: The microstructures and properties of 20CrMo steel in rare earth catalysis and conventional carburization have been investigated by using the homemade rare earth energizer. The results show that the diffusion rate of carbon increases due to rare earth catalysis, so the time of carburizing decreases by about 30 %, and the martensite microstructures are refined on the surface layer. Also, the amount of residual austenite decreases obviously, and the hardness of the carburized layer is improved about HV150. At the same time, the depth of the hardened layer increased.

Abstract: In this paper, the first 80MN rapid forging hydraulic press in China was developed. The inclined double-column and pre-stress combined frame structure and the direct Pump-driven technologies were adopted for the first time in the design of this press. The linkage driving with the full-hydraulic orbital manipulator has been realized. A rapid forging frequency of 75~80 /min and a finishing precision of ±1mm for hot-state forgings can be obtained. The three dimensional full-contact solid model of the double-column combined frame structure of the 80 MN rapid forging hydraulic press has been set up. The modal analysis of the pre-tightened frame has been carried out with the FEM analysis software ANSYS. The first five-order inherent frequencies and the corresponding natural modes have been obtained, the mode shapes of various orders have also been analyzed in detail. It is shown from the research results that the inherent frequency of the frame is larger than the impact frequency. Therefore, resonant vibration of the structure will not occur. The analysis results will have an important significance for the understanding of the dynamic performance of the rapid forging hydraulic press, optimization of the structure design of the press and the decrease of vibration and noise pollution.

Abstract: Effects of various amounts of ground limestone on the setting time, fluidity and compressive strength of high alumina cement were described in this paper. Microstructure analyses were performed by SEM. The results indicate that the initial setting time, the final setting time, the fluidity and the compressive strength of the pastes increase first and decrease later with the ground limestone content increasing, all of which reach the maximum when the ground limestone content is 3%. Meanwhile, an increase of the fineness of the ground limestone produces a shorter setting time, the fluidity of the pastes increases when the content of the ground limestone increases, and the compressive strength of the hardened pastes increases with the ground limestone content increasing and decreases with water-binder ratio increasing. The 28d strength of the pure high alumina cement paste is lower than the 3d strength, appearing the strength shrinkage, which can be improved by a proper addition of the ground limestone.

Abstract: This paper used spatial random cutting plane method for modeling the real irregular grain shapes, and method of smoothed particle hydrodynamic (SPH) was used to establish CBN grinding wheel abrasive wear model. In order to research the wear mechanism of CBN abrasive and the relationships between grinding parameters and grinding wheel wear, simulation of the wheel abrasive wear process was simulated by the LS-DYNA explicit dynamics. According to the results obtained by simulation of abrasive wear model which has the same law with the actual wear abrasive, it is has realistic instructive significance to the actual grinding process of vitrified CBN grinding wheel.