Applied Mechanics and Materials Vols. 300-301

Abstract: In order to choose the rubber material and improve the service life of Progressing Cavity Pump (PCP ) when exploiting offshore crude oil, it is important to analyze friction and wear behaviour of stator and rotor of PCP in the mixture of crude oil with different water content. The friction and wear test about Nitrile -Butadiene Rubber (NBR) and Fluorine Rubber (FKM) were carried on ring-on-block tester, the wear loss was observed by electron microscope, the wear mechanism was also discussed. The results show that: (1) FKM owns better wearing resistance than NBR in the mixture of crude oil with different water content; (2) when the content of water in the mixture is less than 26%, the frictional coefficient of sample is 0.05, due to the oil film between the friction pairs; (3) when the content of water in the mixture is more than 26%, the frictional coefficient increases to 0.4, because of the water film between the friction pairs.

Abstract: (NaPO₃)₆ was added to Na₂SiO₃-KOH electrolyte system ,and in-situ ceramic membranes were prepared on pure aluminum by micro-arc oxidation technique. The composition and structure of the micro-arc oxidation ceramic layer and the influence on the performance of the corrosion resistant to sea water were studied through the scanning electron microscopy,X ray diffraction and electrochemical polarization curve method.The results show that the ceramic membrane formed in electrolyte containing (NaPO₃)₆ indicate a considerable increase in coating compactness and bond strength.The dynamic potential polarization curves in simulation sea water show that adding proper (NaPO₃)₆ can increase the ability to resistant the sea water corrosion.When the mass concentration is 2g/L,the corrosion resistant to sea water is the best.

Abstract: Modern bamboo structural system is a new type of green sustainable building technology, conform with our country’s requirements of developing environment-protecting and energy-saving buildings. This paper presents a new lightweight, high-strength , earthquake-resistant and energy-saving system-steel-bamboo composite structural systems , and given the various structural elements of the composite structural systems of steel-bamboo production methods . This paper also gives the production methods of steel-bamboo composite elements. Steel-bamboo-structural system can per-fectly combine steel and bamboo to bear load together, and it have excellent mechanical properties and broad application prospects.

Abstract: In the experiment of the polarization of light, circularly polarized light can’t be got though all instruments are carefully adjusted and the polarized light we get is generally regarded as elliptically polarized light. We analyzed the process and find the light we get isn’t circularly polarized light or elliptically polarized light as usually thought and deduced the light intensity distribution function and it can fit the experimental results with small errors.

Abstract: Strain Bacillus pumilus AC-6 was separated from the soil, which can produce β-glucosidase. According to the β-glucosidase gene of strain SAFR-032, primers were designed to clone the β-glucosidase gene from AC-6. The sequence of β-glucosidase gene from AC-6 is 1437 bp and encode 478 amino acids. Compared with β-glucosidase gene reported in GenBank, the similarity of the gene sequence is 98%. We cloned β-glucosidase gene into the vector pGEX-4T-1 and transferred it into the competent E. coli DH5α and BL21（DE3）for expression.

Abstract: The flammable vapor pressure inside the combustible liquid storage tanks in the fire environment elevates, and the of the tank wall the yield strength of enduring the heat decreases, which cause the collapse to occur soon, resulting in the happen of BLEVE. BLEVE is an incident form of great harm, and the study of its formation mechanism and hazard model is of great significance for the safety of the chemical enterprise. In this paper, the physical and chemical characteristic of dichloropropane and BLEVE in a dichloropropane tank area is analyzed, and the accident analysis model is built. According to TNT equivalent method, the vapor cloud fire and explosion models and the blast wave overpressure injury criteria, we calculated the accident consequence of BLEVE in different filling levels. The calculation and analysis shows that, if the BLEVE occurred, the entire tank area and adjacent buildings will be severely affected and the affect area will be up to 50.35 meter; the people less than 7.43 meter from the explosion tank will be subject to serious injury or death. Based on the above substance hazardous characteristics analysis in dichloro propane tank storage area and the corresponding qualitative and quantitative analysis, and according to the relevant requirements of the specification, the fire safety prevention and control measures in the tank area should be further strengthened.

Abstract: The combination of Aluminum alloy with lost foam casting (LFC) process is best applied in automotive industry to replace steel components in order to achieve light weight components for reducing fuel consumption and to protect the environment. The LFC process involves process parameters such as the degree of vacuum, foam degradation, expanded polystyrene (EPS) foam density, permeability of foam pattern coatings, pouring temperature, filling velocity, cooling rate, and pressure. The effect of polystyrene foam pattern coating thickness on the porosity and mechanical properties of Aluminum Al-Si LM6 alloy were evaluated experimentally. The coating thickness was controlled by slurry viscosity at range between 18sec to 20sec using Zahn viscosity cup No.5 and the foam pattern was coated up to fifth layer. Aluminum Al-Si (LM6) molten metal was poured into expandable mould and castings were examined to determine porosity distribution, mechanical properties and microscopic observation. Results from X-ray testing reveal the porosity distribution on Aluminum Al-Si LM6 castings is greater at thicker foam pattern coating sample. Meanwhile, the tensile strength of casting decreases when foam pattern coating thickness increases. Microscope observation portray the present of porosity on the casting which shows more gas defects present at thicker foam pattern coating sample. The source of porosity in LFC process is due to air entrainment or the entraining gases from polystyrene foam decomposition during pouring of molten metal. As a conclusion, mechanical strength has inverse relationship with porosity.

Abstract: An AlGaN/AlN ultraviolet photodetector with metal-semiconductor-metal structure is fabricated on n type 4H-SiC substrate, which is conventionally epitaxial by metal-organic chemical vapor deposition (MOCVD). The MSM structure is composed of two interdigitated fingers usually formed by Schottky contact which deposited metal with high work function metal by e-beam metallization and thermal evaporator on high resistance layers. This type of MSM has potential advantages, including ultra low dark current because of its rectifying contacts. The current Characteristics are revealed in this paper. A reference sample of AlGaN/GaN heterostructure with two-dimensional electron gas (2DEG) is also fabricated for comparision.

Abstract: magnesium hydroxide whiskers; ABS; mechanical properties Abstract: The magnesium hydroxide (MH) whiskers/ABS composites were prepared by melt-extrusion with whiskers as fillers. Zinc stearate was used as modifier to improve the compatibility of the composites. The mechanical properties of ABS enhanced by different cotents of magnesium hydroxide whiskers were tested by the RGT-10 universal testing machine. When the content of whiskers was 10%, The comprehensive mechanical properties of the composites were the best, the max load was 0.30KN, the elastic modulus was 0.16Gpa, the tensile strength was 20.11Mpa, the total elongation was 10.24%, the fracture strength was 2.05Mpa. The fracture morphology of the composites was analyzed by SEM, the higher contents of magnesium hydroxide whisker, the worse-distributed whisker in ABS matrix.

Abstract: Industrial dust emission is one of the main sources of fine particle especially for PM2.5 in atmosphere. Filter media is the key component for baghouse. In the paper, several normal needle felt filters and membrane filter are studied through experiments. The performances of filter such as resistance, capture efficiency for total particle and number counting efficiency for fine particle are tested.The experimental results show that the resistance of filter increase after aging, the resisitance increasing rate of membrane filter is the smallest; The efficiencies for total particles of normal filter are above 99.9% at clean state, and 99.99% at stable state after aging; Although the filters have high efficiency for total particle, but the number counting efficiency for 10μm particle is 94%-99%, and 52%-92% for 2μm particles. New filters for fine particles are needed.