Advanced Materials Research Vols. 482-484

Abstract: In this study, phase change microcapsules were prepared by in situ polymerization using paraffin as core material, poly(MMA -co- MAA) as shell material, Tween60/span60 as emulsifier. The surface morphology, thermal properties and particle size distribution of the prepared microcapsules were investigated by using SEM, TGA, DSC and ELS. The effects of paraffin core content and amount of emulsifier on the properties of microcapsules were studied.

Abstract: Thermo-simulated test was conducted to study the effect of cooling rate from 1 °C/s to 15 °C/s on microstructure of V-N microalloying high strength aseismic rebar. Microstructure investigation was done using both optical and scanning electron microscopes. Microstructures in center of the rebar mainly consist of ferrite, pearlite, and bainite. The percentage of bainite increases below 5 °C/s cooling rate and decreases between 5 °C/s and 15 °C/s with the increase in cooling rate. At the cooling rate of 15 °C/s the fraction of bainite is about 7.7%, and the finest ferrite with 5.3 μm was obtained. Higher strength value obtained at the cooling rate 8~10 °C/s is due to the combination of smaller ferrite and about 10 % bainite.

Abstract: In order to facilitate the actual design of the project, we study force performance of FRP tube steel-reinforced concrete columns under axial load. By five FRP tube steel reinforced concrete structures of axial compression, explore the damage characteristics and the force characteristics of the combination of column, and study parameters on performance of the force combination of column such as FRP tube wall thickness, fiber winding angle and loading mode etc. The capacity of combination column increases with the larger of the FRP tube wall thickness; and increases with the smaller of the FRP fiber winding angle; loaded in different ways lead to different capacities. Using superposition method Study and deduce a more reasonable axial compressive bearing capacity formula of FRP tube steel reinforced concrete structure. Theoretical calculation results match well with experimental results.

Abstract: A set of new nitrogen-containing hot work die steels were designed. The best experimental steels and their heat treatment processes were optimized by microstructures, mechanical properties and thermal fatigue tests. The results show that the best compositions of V, Cr, N are 1.0 wt％, 3.75 wt％ and 0.01 wt％, respectively. The optimized heat treatment process is that quenching at 1080°C, first tempering at 550°C and second tempering at 530°C.

Abstract: First, the corn starch was taken as raw material, and then it was broken down by enzymes and fermentation by lactic acid bacteria, and the poly lactic acid was obtained by chemical synthesis. Then the corn starch was taken as raw material again, the dialdehyde starch was obtained by high efficient light-catalytic reactor. Secondly, a certain percentage of dialdehyde starch and urea were mixed together to get urea-formaldehyde resin. Finally, a certain amount of polylactic acid, urea formaldehyde resins and dispersions were put together and mixed in a high-speed stirring to get urea slow release membrane materials. Experimental results showed that it needed 150-300 days degradate completely by 75% poly lactic acid sustained release membrane, while 85% needed 100 -120 days. Single thin membrane absorption test showed that per unit area of the sustained release membrane absorption ability would increase with the poly lactic acid increased, and the absorbent capacity of 85% poly lactic acid of sustained release membrane was 112 times higher than the mass of itself.

Abstract: Based on the observation of fracture surfaces for a low-alloy high strength steel under rotating bending in very high cycle regime, a newly defined method about inspection plane under rotating bending was developed in this paper. By using the statistics of extreme values (SEV) method, the maximum sizes of inclusion and FGA corresponding to the control volume of specimen are evaluated to be about 41.38 μm and 58.51 μm on the basis of this newly defined inspection plane, and the corresponding values of fatigue limit are evaluated to be 690 MPa and 654 MPa, respectively. It should be noted that fatigue design based on former involves a certain amount of risk in very high cycle regime.

Abstract: As a group of environmental-friendly chemicals, galactomannan gums acquired from plant resources demonstrates some distinguishing features such as convenient preparation processes, unique physical-chemical characteristics and bio-chemical properties. Moreover, these attributes can be further improved through modification of chemical and bio-chemical approaches. Therefore, they are found more and more applications in many major industries. This paper introduced the research development in the field of galactomannan gums, including their structure analysis and characterization, chemical and enzymatic modification, as well as applications in some industries.

Abstract: The selection of military equipment supplier is a very complex process. In this paper, based on projection pursuit classification method (PPC), we give the best projection direction and weight coefficients of each evaluation index, the sort of evaluation of each supplier, and consequently, we obtain the selection scheme of supplier. The method has strong objectivity, which provides scientific basis for correct decision.

Abstract: In order to make full use of chaotic mutation genetic algorithm and the chaotic mutation and bee evolution algorithm, the characteristics of the two algorithms, and the combination of chaotic mutation bee evolution algorithm is proposed. The algorithm in bee evolution process, to adapt to the value of group of smaller portions of the variation of individuals to chaos; to adapt to the value of group of large part of the individual, to the best individual as the center, change crossover operation, each generation is the best individual immune evolutionary iterative calculation. Thus, as the iteration, the algorithm not only fast convergence, and can also by a higher accuracy by the global optimal solution.

Abstract: The low carbon high manganese steel (C: 0.07, Mn: 2.0, mass percentage) was deoxidized by Ti and Mg alloys, and its features of inclusion and microstructure were systemically studied. Through the scanning electron microscope (SEM) and Energy Dispersive X-ray Detector (EDX), it can be seen that in inclusions, the element of magnesium always coexists with titanium, and no single-phase oxides of magnesium are observed. After etching in 3Vol% natal solution, it’s found that the Mg-contained and Ti-contained inclusions can act as nucleation sits for the intragranular acicular ferrite. These results imply that besides the pinning effect, the oxide of magnesium can also participate in the nucleation for intragranular acicular ferrite. Thus, it may be used in the oxide metallurgy to refine the ferrite microstructure.