Advanced Materials Research Vols. 476-478

Abstract: The copper-aluminum pipe has been widely used in the refrigeration industry. With the increases of the scrap rate in electronic products, the recycle and remanufacturing of Cu-Al brazed joints becomes the focus. In this study, introduced the green welding, which will improve the recycle ability of the Cu-Al brazed joints from technological design source. The experiment results shows that it is possible to improve the remanufacturing and the mechanical properties of Cu-Al brazed joints with the appropriate lap length,and it complies with the green welding design concept when the lap length of Cu-Al brazed joints is 5 mm.

Abstract: A kind of Cobalt ferrite ceramics were successfully prepared by using nanocrystalline powders synthesized by citrate gel method. The relative dielectric constant and loss tangent of the ceramic as a function of frequency (100 Hz - 1 MHz) was investigated at room temperature. Both of them decrease with increase in frequency showing dispersion. Hysteresis loop magnetization was measured and the ceramic show good magnetic characteristics at room temperature.

Abstract: The composites of polypropylene (PP) and wasted PET fabric (WF) were prepared by extrusion blending and injection molding, and then, the interface of the composites was modified by two different types of compatibilizers, i.e., maleic anhydride grafted PP (PP-g-MA) and the mixture of methyl methacrylate (MMA) and styrene (St). The mechanical properties, morphology and thermal stability of these composites were studied.

Abstract: On the principle of alloying modification of the same crystal structure compound, MoSi₂-AlCr₂ quasibinary system alloys were prepared by mechanical activation and hot pressed sintering.The phase composition and crystal structure evolution were investigated by X-ray diffractometer(XRD).The results showed that the main phase composition of alloys were MoSi₂ and Mo(Si,Al)₂,the crystal structure was gradually transformed from tetragonal C11_b MoSi₂ to hexagonal C40 Mo(Si,Al)₂. (Mo,Cr)(Si,Al)₂ phase has not found in alloys.

Abstract: The effects of 2at.% Ga addition on the microstructure and mechanical properties of the TiCu-base nano/ultrafine bimodal structured alloy were investigated systematically through XRD, OM, compressive test and SEM. The results showed that constitutional phases were changed from bcc -Ti(M) to unknown nanostructure + bcc -Ti(M), content of nanostructured matrix is increased, the calculated mean crystalline size was decreased from 12.6 to 11.7nm, and also, the yield and maximum strengths and plasticity were enhanced markedly. The reasons, which caused these phenomenons, were discussed.

Abstract: Porous starch as a kind of high efficiency, non-toxic and safe new organic adsorbents are extensively used in food, medicine, agriculture, cosmetics, paper and other industries. Recently the preparation method is amylase in starch gelatinization temperature of less than hydrolysis. In the conditions of ultrasound (physics) and microwave (electromagnetic fields), we could improve the yield of the traditional method of enzyme hydrolysis corn starch. First, the results show that: the time at 45 min, microwave power 150W, ultrasonic power 400W, temperature 56°C, α-amylase enzyme quantity 8 U/g, glucoamylase and α-amylase ratio 6:1, citric acid buffer liquid pH 5.4, the absorption rate of porous starch is best. Ultrasonic- microwave improves the quality of customary enzymatic hydrolysis starch, by SEM observation, found that: There are a lot of table face holes which are uniform pore density, particle more complete.

Abstract: For a sinusoidal alternating current (AC) external field of finite frequency ω , the local electric field distribution at all harmonics has been investigated by graded cylindrical composites with power-law gradient inclusions. In the dilute limit, the obtained results show that the local electrical field distribution in the cylindrical inclusion region is controllable and the electric field peak’s position inside the cylindrical composites can be confined at its centre by varying the parameters of the graded dielectric profiles.

Abstract: Polypyrrole (PPy) is an intrinsically conducting polymer that has a wide variety of potential applications on electrical devices, sensors, electrode material, anticorrosion and antistatic coatings. Bacterial cellulose (BC), a natural nano-material with outstanding properties, can be used as a template material. In this study, water-wet BC was firstly used to prepare PPy/BC nanocomposite membrane by combining with PPy. The obtained nanocomposite showed excellent performances such as high conductivity, considerable mechanicl behavior and perfect flexibility. Effects of pyrrole concentration and reaction time on the electrical conductivity of the membrane were investigated. Besides, FT-IR, FE-SEM and mechanical properties were studies. The results revealed that it was possible to develop a novel PPy/BC nanocomposite with potential applications on flexible displays or sensors.

Abstract: This essay introduces the PHC pile of vertical bearing capacity, level of capacity, capacity and final pressure values, tensile properties, pile the stress mechanism, and the factors that influence bearing capacity, then the useful suggestions of how to design and construct are given. It has vital significance to direct engineer practice, optimize static-pressed pipe-pile foundation design.

Abstract: The drawing, tenacity and thermal properties of nylon 6 (NY6)/nylon 6 clay (NYC) composite fiber specimens prepared at varying NYC contents and drawing temperatures were investigated. The achievable draw ratio (Dra) values of NY6x(NYC)y as-spun fiber specimens initially increase in conjunction with NYC content, and then approach a maximum value, as their NYC contents and drawing temperature approach the 0.5 wt% and 120 oC, respectively. The percentage crystallinity (Xc) values of NY6x(NYC)y as-spun fiber specimens increased significantly, as their NYC contents increased from 0 to 2 wt%. The thermal property were performed on NY6x(NYC)y resins and/or fiber specimens to determine the optimum NYC content and possible deformation mechanisms accounting for the interesting drawing properties found above.