Advanced Materials Research Vols. 148-149

Abstract: With increasing applications of SPF/DB structural components in the fields of aeronautics and astronautics, a large amount of new products are researched and developed. The traditional manufacture mode depending on experiences can not satisfy the new requirements. In this paper, a method of structure optimization design and manufacturing for multilayer load-carrying parts is proposed. Based on the given outlines of the components and the characteristics of SPF/DB process, the form of internal hollow structures are designed and modeled by CAE software before forming and the result of calculating is used to direct the SPF/DB process. It is verified that the optimized structure can satisfy the requirements of strength, stiffness, light weight of parts, which agrees well with the results of simulation. And it is also showed that this method is effective to decrease the quantity of tests, shorten the development cycle and reduce the development costs.

Abstract: Dye-Sensitized Solar Cells (DSSC) are currently under development worldwide. Photoelectric conversion efficiency cannot yet rival the efficiency levels of commercial silicon solar cells. Nonetheless, due to the advantages of simple production, low cost and accessibility which allows for large-scale production, photoelectric conversion efficiency is still one of the technologies under urgent development in the next stage of new solar energy. Usually, laboratories adopt the method of absorbing dyes on film electrodes by placing the specimen sample in the dye for a lengthy soaking period (12 hours). Such an approach merely yields the result of the dye molecules being absorbed on the TiO2 Nanotube, which does not produce time efficiency conducive to future commercialization. Such an improvement in efficiency could have a major impact on the mass production process. Consequently, this study employs a hot-pressure system on a jack with molding to distinguish pressurization, temperature and heating in the pressurization processes; we discovered from the experimental results that the best performance resulted from the heating process. This process not only sped up the diffusion velocity of the dye molecules being absorbed on the tube but also enhanced the photoelectric efficiency for solar cells. This could thereby lead to substantial time saving in the dye soaking process and greatly enhanced the economic benefits of products.

Abstract: Cement is becoming a principal factor in air pollution because of the creation of CO2 during its manufacturing. The exhaustion of the natural resources needed for Portland cement production is also an issue. Therefore, a substitute material for this type of cement is needed. Nano-scale materials are of great interest due to their unique optical, electrical, and magnetic properties. These properties are strongly dependent on the sizes and shapes of the particles, and, therefore, it is important to be able to develop the construction part which retains the excellent properties of the nano-sized material. The purpose of this study was to synthesize nano-powder as a substitute for cement using a chemical method. This study investigated the compressive strengths of concretes with various compositions. Specimens were tested for compressive strength three, seven, 14, and 28 days after manufacture. In the results of this study, the medium-sized (50% by weight) nano-cement particles created via chemical synthesis were less than 168 nm in size, and the compressive strength of the mortar prepared using these nanoparticles was 53.9 MPa

Abstract: Nanoclay/polylactide(PLA) nanocomposite was produced by the electrospinning process. The influences of nanoclays on the morphology and mechanical properties of the nanocomposite were investigated. The morphology and mechanical property of the nanocomposite were evaluated by scanning electron microscopy (SEM) and microtensile testing. SEM images revealed that submicron scale nanoclay/PLA nanocomposite fibers were fabricated and the introduction of nanoclay reduced the diameter of the nanofibers and improved the uniformity of the fibers. The addition of 1% nanoclay in PLA nanofibers leaded to simultaneous increases in the tensile strength, elongation at break and modulus for the PLA nanocomposite mat.

Abstract: The objective function is the same flow speed of each sub-filed of product section at exit of the extrusion die for the complexity of hollow polymer profile, and design variables are impact on the flow uniformity of the space above the compression, the example based on finite element numerical simulation and based on the CAD/CAE/ERP database system, the result showed the velocity is obviously improved after the optimization, well positioned to meet the requirements of customer.

Abstract: The advantages and disadvantages between the pressing binder of hardmetal in existence are analyzed. A new type of binder named QSD is introduced and a series of properties are studied. The experiments show that QSD has been tested to dissolve in alcohol. The materials of hardmetal are milled in alcohol mixed with QSD, achieving a molecule dispersing slurry. The slurry adapts to spray drying with low viscidity. The mixture of the hardmetal prepared by QSD is fine, and soft with good flowability. They are capable of pressing complex form of products that couldn’t be formed with PEG, paraffin wax binder by comparing the experiments. The compacting force has reduced 20% compared to PEG.. The pressing products are effectively less vices of delamination and crack due to the low brittleness and high weight of compact. The products made by QSD fit continuous sintering and there are few remainder carbon in the sintered products. Microstructural observation reveals that the Co particle distributes homogeneously in the WC particle with the pressing binder QSD. So QSD is one kind of considerably ideal cemented carbide binder that combines the advantages of PEG, SBS.

Abstract: Three different fabrication methods of graphene nanoribbons are discussed. Graphene nanoribbons can be produced through unzipping the carbon nanotubes and also cutting graphene sheets, but with rough edges. Another method is a simple, surface-based bottom-up chemical method without the need for cutting, resulting in high-quality graphene ribbons. The band gap of a graphene ribbon strongly depends on its geometry, particularly its width. The third method creates easily graphene ribbons with different width.

Abstract: Based on the axisymmetric and 3-D finite element models, the axial-load and stress distributions on each thread of the threaded connection have been studied. The effect of helix and the elastic-plastic behavior of the material at the thread roots have been explored. Simulation results indicate that the axial-load and stress distributions obtained from the axisymmetric finite element model show good agreement with the results of 3-D analysis in both elastic and plastic states with the same mesh density. So the axisymmetric model can be used to study the axial-load and the stress distributions of the threaded connection subjected to axial-load. The axial-load and stress distributions in threads are very sensitive to the applied load. With increasing the applied forces, the axial-load and stress distributions over teeth become homogeneous eventually.

Abstract: : The talc with average volume grain of 5.35 µm was modified by the mixture of HDPP as bases, grinding talc as the reinforecing filler and proper quantity of coupling agent. After blending the mixture of coupling agent of 1.7 (wt) %, different mass ratio of talc among 4~14 (wt) % and HDPP, the characteristics of surface modification was performed on electron microscopy and the friction properties grinding against stainless steel was analyzed on abrasion and wear tester of M-2000 type under dry sliding condition. The results show that the friction rate of composites is 1.909*10-5 with lower abrasion proof rate, and the friction coefficient is 0.147 with better friction resisting property when the content of talc is 8%. In this way, it can offer comparable data for fiber and other areas.

Abstract: Mullite precursor was prepared from kaoline when calcined at 1250 °C，when the concentration of sodium hydroxide of 3 mol/l; crystallization temperature of 80 °C; holding time of 3 h and precursor concentration of 0.15 g/ml, the morphology of the prepared mullite nanocomposite appears spherical-like, and it has good crystallization property and low agglomeration, and the average size of the particles is about 60.9 nm. Both the thermodymics and kinetics of mullite precursor have been studied. The results are as follows: the reaction started when the calcine temperature T﹥495°C; mullite precursor formed when the reaction system temperature 1000 °C; the activation energy of precursor Ea=928.3 KJ/mol; the reaction order n=1.33. We have reported our successful experiments to use kaolin to synthesize mullite nanocomposite with satisfying, spherical morphology, relatively homogenous grain average size of 60.9 nm, and little aggregation[1-2]. This paper presents an investigation of the thermodynamics and kinetics of the precursor preparation process.