Advanced Materials Research Vols. 557-559

Abstract: It is known that rare-earth elements exhibit high chemical activity and adding trace amount of rare-earth Y in the solder can significantly improve the properties of solder alloy. However, adding excessive rare-earth Y in the solder will result in rapid growth of tin whiskers. The research results show that: if the YSn3 precipitates formed in the interior of Sn3.8Ag0.7Cu1.0Y were exposed to the air, YSn3 precipitates will oxidize and expand in volume, and the tremendous compressive stress produced by the surrounding solder matrix constraining the volume expansion will accelerate the growth of tin whiskers.

Abstract: As an interesting material in large field area, ZnO synthesize has been widely observed. In this research, synthesize was carried out using zinc dross, waste from galvanization process, as starting material by simple heat treatment method. The as-synthesized ZnO obtained were further underwent post-anneal and post-hydrothermal treatment series. From the characterization data, it was found that highest crystallite size was obtained in sample treated with post-hydrothermal treatment at 150oC for 12 hours with value of 1371 nm, which corresponds to its lowest Eg value of 3,086 eV.

Abstract: Mesoporous molecular sieve Ti-MCM-41 was synthesized by means of microwave radiation in domestic microwave oven using cetyltrimethyl ammonium bromide as template and ethyl orthosilicate, tetrabutyl titanate as raw materials, respectively. The sample is indeed Ti-MCM-41 after characterization by XRD, SEM, FT-IR and BET surface area. Compared with the reported synthesis methods, remarkable predominance of this method is that operation is simpler, crystallization time is shorter (only 40 min) and energy consumption is lower.

Abstract: By testing flexural and compressive strength at different ages, the influence of particle size distribution of slag and fly ash on the strength of LCC (low clinker cement) were systematically studied. The SEM (scanning electron microscope) and laser particle size analyzer were used to study the multi-component cementitious and dense-packing effects of LCC. The results show that the strength development of LCC4 with 30% clinker could completely meet the requirements of P.O 42.5R by varying the type, content or fineness of admixtures; based on a higher fly ash and lower clinker dosage, the strength development of LCC9 is also relatively good.

Abstract: PET fiber was preprocessed by means of microwave radiation. Different reaction parameters such as the time, the power and the Ph value of solution were optioned to study the degree of the fiber hydrolysis. The changes of mechanical performance and hygroscopicity of the fiber were analyzed, which showed that the best power of microwave radiation was the 250W, the best reaction time was 5 min, and the Ph value of solution was 9. Compared with the untreated fiber, the fracture strength of treated fiber is 1.686cN/dtex and the moisture regain is 0.58%. The morphology structure were characterized by SEM and the fracture strength were tested by filament electronic strength tester. The results showed that the surface of PET fibers became rough and the quantities of the -OH and -COOH functional groups on the surface increased after etching. Meanwhile the hygroscopicity of the treated fibers had been enhanced obviously and the fiber strength had been reduced.

Abstract: Based on dynamic contact force and FEM, the contact – separation process of collision was investigated. Compared with other methods, the dynamic contact method needn’t modify the general stiffness matrix, and increase any additional iterative computation. So there should be less computation and high efficiency. By building simulation model LECEI(the technique of loading edge cracks by edge impact), the propagation of branching cracks were simulated. Compared with existing research results, the method can be suitable to the impact model such as LECEI.

Abstract: aliphatic ester, aliphatic alcohol, stainless steel, cold rolling oil Abstract: In this paper, the deeply hydrogenated mineral oil 60N was used as base oil. The additives such as mixture of dodecanol and tetradecyl alcohol, hexadecanol alcohol, octadecyl alcohol, ethyl hydride laurate, methyl palmitate and butyl stearate were separately added to the base oil by 10 percent. Evaluate its physical and chemical properties, and cold rolling experiments were carried out on both 202 and 304 stainless steel lubricated by different rolling oil. The results showed that the aliphatic alcohol have better performance in lubricating and volatilizing properties than fatty acid ester. Moreover, the octadecyl alcohol showed the best lubricating properties compared with selected aliphatic alcohol.

Abstract: H13 steel specimens with vapor oxidation surface treatment and without surface treatment, were carried out by thermal fatigue test and melting-loss test to research the effect of vapor oxidation surface treatment in the aluminum alloy die casting. The results show that the vapor-oxidized specimens have better erosion resistance and similar thermal fatigue resistance to those without surface treatment. Compound layer and compact layer form in melting-loss test are mainly Fe₂Si₂Al₈ and Fe₂Al₅, respectively.

Abstract: The microencapsulated phase change material is a kind of functional material with latent heat. It may be used applied heat storage and energy transport systems. Methods of the microcapsule production and four kinds of production process are introduced.

Abstract: Fiber Reinforced Concrete (FRC) is a representative strengthening method adopted to improve the sudden brittle failure of concrete under tension and dynamic loadings and to control the generation and propagation of cracks occurring during the curing process. The strengthening performance provided by the fiber is sensitively influenced by the physical properties of the fiber itself as well as by its volume ratio but is also varying according to the difference in the bond performance at the interface between the fiber and concrete. Even if the fiber exhibits outstanding physical performance, if the bond performance does not reach similar level, the fiber will not be able to develop fully its performance. Currently, the methods improving the fiber bond performance are essentially focusing on the improvement of the mechanical bond performance by changing the longitudinal shape of the fiber such as the application of crimped and hooked fibers. A very few methods intend to improve the bond performance by increasing the bond area of the fiber itself. Therefore, this study increases the surface area of the fiber by changing its section while preserving its volume during the fabrication process, conducts tests on the bond performance between the cement paste and the fiber with changed surface area, and examines the changes in the bond performance according to the increase of the surface area.