Abstract: An experimental study on drainage of different composite filter material in Wenzhou ultra-soft soils was carried out, to investigate the effects of anti-clogging for these composite material. A new instrument was designed to simulate draining process of the ultra-soft soils under vacuum loadings. Based on the experimental results in the form of pump quantity of water, the average settlement of the sludge, the pumping rate and the water content, a comparison was made among six composite filter material (e.g., PVA-1, PVA-2, SAP, superfine fiber, coral cashmere fiber and bamboo fiber) and a traditional non-woven fabric material. The results demonstrate that, PVA-2 composite material is the best way to keep from clogging in the ultra-soft soils. The effects of the anti-clogging is depended on the characteristics of the water absorbency and retention.
Abstract: The properties of heat resistance and manufacturability of epoxy resin system are contradictory to each other. In order to maintain the balance of both properties, this article studied the heat resistance (testing the glass-transition temperature using differential scanning calorimetry) and the manufacturability (characterizing the variation trend of viscosity at molding temperature using AR2000EX rotational rheometer) of two kinds of epoxy resin systems by means of designing orthogonal table. Studies show that when the mass ratio of hydantoin epoxy resin, MF-4101 epoxy resin, anhydride and accelerant is 100:20:150:1.5, the glass transition temperature of the epoxy resin system can reach over 180°C. What’s more, the initial viscosity of the epoxy resin at 40°C is about 230mPa•s, and the viscosity can maintain no more than 800mPa•s in approximately 3 hours, which meets the requirements of liquid composite molding.
Abstract: Researchon thepreparation of ceria based materialfor electrolyteof solid oxide fuelcellhasbeen conducted. The Sm0.2Ce0.8O1.9(SDC) was prepared by sol-gel method and the layered composites of SDC with Y0.08Zr0.92O3-δwerepreparedbyscreenprintingmethod.This research aims to studythecrystal structure and its conductivitycharacter. XRDmeasurementequippedwithLeBailrefinementshowsthatSDCiscrystallizedin cubic structure with space group of Fm3m.Theaddition ofYSZ into SDC does not changeitscrystal structure. However, the cell parameter of SDC is reduced from 5.434036(2) Å to 5.433(0) Å. At 600 °C, SDC has electronic conductivity that indicates the presence of electrons migration that can promotes short circuit during fuel cell operation. The combination of SDC with YSZ forming a layered composite of SDC-YSZ-SDC could reduce the electronicconductivity,eventhoughitsionicconductivityisalsobecomelowerthansingleSDCatthe same temperature.
Abstract: The aim of this work is the studyof the degradation mechanism of a glass fiber/unsaturated polyester (UP) composite immersed inacidic(H2SO4)and alkaline(NaOH)solutionslike establishing a relation between the chemical and the mechanical behaviors of this material. The gravimetric analyses showed a pseudo fickianbehavior for the samples immersed in H2SO4 and mass losses with a pseudo-stage of saturation as from 64 hours of immersion for the samples immersed in NaOH.The Fourier transform infrared analysis (FT-IR)of the UP resin revealed the presence of chemical degradation phenomenon (hydrolysis).Microscopic observations (SEM) confirmed the fibres/matrix interfacesdegradation. The effect of these degradations has been reflected one the mechanical properties of the materials.
Abstract: An attempt has been made to develop and characterize the Al2219 reinforced with Boron carbide (B4C) and Molybdenum disulfide (MoS2) hybridcomposites. The hybrid composites were prepared by using stir casting technique. Theexperimentalresult evaluates the density,micro hardness test & tensiletest.Themicrostructure shows existence of randomly dispersed reinforcement particles andfine reinforcement particles in prepared hybrid composites.X-Ray powder diffraction (XRD) analysis were conducted this confirms the physical content of constituents present in prepared composites. SEM is used to examine fracture surface of tensile specimens for hybrid composites & this consists of ductile& brittle fracture of mixed mode.The test results revels that, themicro hardness and density is minimum for Al2219 and maximum for Al+3%B4C+5%MoS2. The tensile properties of the material vary according to the percentage of reinforcing material added.
Abstract: The cooling rate depends on the properties of the mold material which has significant influence on the formation of microstructure and in turn on the properties of the cast components. This work is aimed at preparing the Al-B4C composite using different chill materials by gravity die casting and recording the casting temperature during pouring and subsequent solidification to analyze the cooling rate of the casting. The effect of chilling on the microstructure and mechanical properties are determined. The cast specimens are cut and polished by standard metallographic procedure. Optical micrographs are taken at different magnification to reveal the microstructure and B4C particulate distribution. The micro hardness and tensile test results indicate that there is a significant increase in these properties with the increase in B4C content.
Abstract: According to the mechanism of thermal insulation, closed pore perlite, hollow glass microsphere and nanoantimony tin oxide (ATO) powder three different kinds of functional fillers were adopted respectively to prepare obstructive, reflective and radiative thermal insulation coating base on polyvinylidene fluoride emulsion, and how the category and content of functional fillers effect the thermal insulation performance of the fluorocarbon thermal insulation coating (FTIC) was investigate. The test results showed that, all the three functional fillers has an significant effect on the thermal insulation performance of FTIC.
Abstract: In this study, non-isothermal kinetic methods for the decomposition of the adsorbed CO2 on pure sodium hydrogen carbonate (NaHCO3) were investigated by a thermogravimetric analysis (TG) and differential thermogravimetry (DTG). Four different heating rates were measured to calculate the order of reaction (n), the pre-exponential factor (A) and activation energy (Ea) using three different models: Kissinger-Akahira-Sunose Method (KAS), Flynn-Wall-Ozawa (FWO) and analytical method. The results showed that KAS and FWO methods gave similar values due to the approximation of employed equation whereas the analytical method gave different values. The obtained parameters from those three methods then were used to calculate the chemical reaction conversion versus temperature and their R2. The results showed that analytical method provided the most accurate results comparing with KAS and FWO methods.
Abstract: In this study lightweight carbon fiber and multiwalled carbon nanotubes filled hybrid nanocomposite was fabricated for electromagnetic interference (EMI) shielding in spacecraft. Electrical conductivity was conducted to assess the affect of MWCNT addition on composite. EMI shielding effectiveness (SE) was tested in the frequency range of 1-18 GHz. Comparison of SE was also made with AA6061-T6 sheet. Dispersion of nanotubes in the matrix was examined through microscopy. Results indicated that the conductivity was increased with increasing MWCNTs up to 0.25 wt%. Higher loading level of MWCNTs has resulted in decrease in conductivity due to agglomeration in cured samples. Hybrid nanocomposite exhibited improved SE than AA6061-T6 in 1-8 GHz frequency range. Best SE and electrical conductivity was witnessed in 0.25 wt% MWCNT sample. EMI SE in range of-20 dB to-40 dB can be easily achieved in our developed material.