Advanced Materials Research Vols. 415-417

Abstract: SiCp/Al composites were prepared by vacuum hot pressing and sintering method. Optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) is applied to study the diffusion-homogenization process of various elements of powder, and the effect of the diffusion-homogenization temperature and holding time on the SiCp/Al Composites’ microstructure in state of vacuum hot pressing. The results show that the Enrichment of Cu-phase is existed in the composites organization which is in the state of vacuum hot pressing; Al₂CuMg fully dissolve into the Al matrix, Cu fully diffused and the diffusion of various elements becomes homogeneous with the temperature increased and time extend. The best processing parameters for the diffusion-homogenization is at 500°Cfor 3h.

Abstract: NR/ENR/silica composites with different ENR amount were prepared in an open two-roll laboratory mixing mill at room temperature. Dynamic properties of ENR filled NR/silica were performed by dynamic mechanical thermal analyzer (DMA) and compression fatigue analyzer. DMA and compression fatigue test results showed that the effect of ENR on dynamic properties of NR/silica was significant. DMA displayed the tanδ of NR/ENR/silica composites at 0 °C was increased with increasing ENR amount. Compression fatigue test indicated the presence of ENR decreased the heat produced during compression test and the heat build-up is the least when NR to ENR ratio is 80 to 20. Scanning electron microscopy was used to investigate the morphology of NR/silica filled with ENR. It is found that silica self-aggregation was improved in the presence of ENR and sea-island structure was formed in NR/silica when 30phr ENR added, which maybe the reason of decrement of heat produced during compression.

Abstract: Abstract. This paper presents the outcome of a study on heat assisted end milling of Inconel 718 using inducting heating technique conducted to enhance the machinability of the material. The heating temperature maintained below the phase transformation temperature was aimed at softening the top removable material layers. The experimental results of both conventional and heat assisted machining were compared. The machinability of Inconel 718 under these conditions was evaluated in terms of tool life, tool wear morphology and chatter. The advantages of Induction heating is demonstrated by an longer tool life and lower chatter. The study showed that preheated machining facilitates up to 80% increase of tool life over conventional machining conducted using TiAlN coated carbide inserts.

Abstract: A novel phosphor-nitrogen intumescent flame retardant was prepared by dry method (without adding any solvent) using H₃PO₄, P₂O₅, pentaerythritol and melamine as raw materials. IR analysis found that the synthetic flame retardants had the P=O and P-O-C double-ring structures, the same to phosphate ester melamine salts. The reaction temperature, time and the ratio of raw materials had significant effect on the esterification reaction. The esterification reaction temperature should be controlled between 120°C and 130°C, and the reaction time should be 2.5 hours. The conversion rate of esterification could be improved by adding P₂O₅ to the reaction, and preferential mole rate between H₃PO₄ and P₂O₅ should be 2:1. Thermogravimetric analysis showed that the starting decomposition temperature of the flame retardant was 190°C, and at 700°C, the residual char rate was about 30%. The expansion ratio of the flame retardant after heated was about 30 to 50 times, SEM analysis found that the exteral surface of the expansion char layer was continuous and smooth, and the interior of the expansion char layer was uniformly porous structures, and the aperture size was about 150-200 μm, such porous structures could provide better adiabatic effect.

Abstract: In this paper, tests were carried out with four agricultural mulching films used commonly in Microstructure observations of electron microscope, FTIR spectral analyses, and rice seed growth characteristics testing respectively. PLA non-woven was selected out as the inclusive material for the rice seed tape with the advantages of easy degradation, environmental pollution free, less impact on germination rate and the plant height of rice seed. The results will provide practical significance for the application of the rice direct sowing technology with seed tape.

Abstract: Design methods for medical rapid prototyping (RP) of personalized cranioplasty implants are presented in this paper. RP offers an easier way to design customized implants and manufacture them within a very short period. Computed tomography (CT) scans were acquired on a General Electric CT scanner and converted to solid models using Mimics software from Materialise. Stereo lithography patterns were prototyped using Objet build style on a Eden 250.The models helped the surgeons plan and rehearse the surgery well in advance. RP biomedical model is greatly convenient to diagnosis and treatment planning. It could decrease the operation time and the risk of misinterpretation of the medical problem. A physical biomedical model also facilitates surgery planning and makes the rehearsal and simulation of the operation possibly.

Abstract: The printing and dyeing wastewater was treated by internal electrolysis method. The results show the chromaticity removal rate was up to 98.53 percent and COD removal rate 85.98 percent under the optimum conditions of wastewater pH 4, reaction time 30 minutes, the electric conductivity 1450μm/cm, the value BOD5/COD increases from 0.34 to 0.51. Moreover, the pH, Fe2+ concentration and absorbance of wastewater changed in the process, the mechanism of that was also analyzed.

Abstract: (100-x) LiClO_4-xSiO₂ (x is mol %) solid composite electrolytes in various compositions were synthesized by modified sol-gel process with sintering at 200 °C. The electrical and structural properties of the composites were investigated. The ionic conductivity of the composites increased with mol % of the dispersoid and then decreased. The highest conductivity was obtained for x = 50 mol % with a value of 4.06 × 10^-7 S cm^-1 at room temperature. The enhancement in conductivity was more than two orders of magnitude when compared to the host material. The higher conductivity in the SiO₂ dispersed system was interpreted in terms of space charge layer and percolation theory. The temperature dependence of conductivity of all samples were Arrhenian in nature and exhibited a maximum of 10^-3 S cm^-1 at T = 140 °C for x = 50 mol %. XRD spectra showed presence of heterogeneous phase of LiClO₄-SiO₂ crystalline peaks.

Abstract: The thesis studies the microstructure evolution rule during Cu-Sn alloy preparation and processing process and its influence on material performance, provides necessary theoretical support for industrialization development of Cu-Sn contact wire for high-speed railway.

Abstract: The modified static bending model of microcantilever with monolayer molecules has been established based on energy method, in which the change in neutral layer position caused by adsorption-induced stress has been considered. On this basis, we have analyzed the relationship between the bending curvature radius of a microcantilever with its thickness, Young’s modulus and molecule-molecule distance of adsorbed molecules when it is adsorbed with monolayer water molecules. Additionally, we have investigated the effect of change in neutral layer position on the static behavior of microcantilever sensors and have found that: 1) the bending curvature radius of microcantilever is affected by its Young’s modulus, thickness and distance of adsorbed molecules respectively; 2)the predicted error of bending curvature radius caused by the change in neutral layer position slightly increases with decreasing Young’s modulus and thickness, whereas the effect of distance between adsorbed molecules on the error is significant.