Advanced Materials Research Vols. 284-286

Abstract: In this paper, the deformation measurements of impacted and non-impacted composite laminates under compressive loading are taken. [0₃/90₃]_S orientated cross-ply laminated plates with impact delamination and without delamination are tested using an anti-buckling testing device in compression experiment. The delamination is induced by low-velocity impact test at the impact energy level of 3.105J. For both impacted and non-impacted specimens, the compressive deformation is measured by a carrier electronic speckle pattern interferometry (CESPI) optical measurement technique. It is found that the deformation behavior of the two specimens presents a mixed deformation mode. However, the delamination has significant effect on the compressive deformation of composite laminates.

Abstract: The friction coefficient of carbon nanotube reinforced the nitrile composites under water lubricated condition was investigated using a ship propeller bearing friction tester at different condition. The mechanical properties of the composites were also tested. The results showed that CNTs could improve the mechanical properties and reduce the friction coefficient of nitrile rubber considerably under water lubricated conditions, due to the effective reinforcing and self-lubricating effects of CNTs on the nitrile matrix. With the increasing pressure, the friction coefficient of the nitrile/CNT nanocomposites decreased under the water lubricated condition, which is because that the surface deformation of the nanocomposites was in favor of the water films forming. However, with the increasing temperature of water, the friction coefficient of the nitrile/CNT nanocomposites increased under water lubricated condition, owing to the thinner operating film and the increasing real contact area.

Abstract: The process of new materials development traditionally employs science and engineering based inquiry in the initial phases. This paper explores how product design can help determine the feasibility of new materials for commercial application earlier and provide benefits of reduced timeframes, cost and risk factors. It discusses a case study of new materials development based on Microwave Modified Timber Technology, set in the context of an Australian Collaborative Research Centre (CRC) for Wood Innovations. The study supports benefits in early integration of product design research into new materials development processes.

Abstract: The SiC/Cu electronic packaging composites with excellent performance were successfully prepared by the chemical plating copper on the surface of SiC powders and high-speed flame spraying technology. The results showed that the homogeneous dense coated layers can be obtained on the surface of SiC powder by optimizing process parameters. The volume fraction of SiC powders in the composites could significantly increase and figure was beyond 55vol% after spraying Copper. The SiC and Cu were the main phases in the spraying SiC/Cu electronic packaging composite, at the same time Cu₂O can be tested as the trace phase. The interface combination properties of SiC/Cu in the hot-pressed samples can obviously improve. The thermal expansion coefficient and thermal conductivity of SiC/Cu electronic packaging composite basic can satisfy the requirements for electronic packaging materials.

Abstract: Waterborne polyurethanes(WPUs) based on isophorone diisocyanate(IPDI), Polybutylene adipate (PBA) and dimethylolproprionic acid(DMPA) were synthesized by prepolymer mixing process. Effect of NCO/OH ratio on the properties of the dispersions was studied. The structure of the WPUs was studied by FT-IR. Besides the mechanical properties and water swelling of the films, the number average diameters of the dispersions and the viscosity of WPUs were characterized, results showed that all WPUs had higher solid content (over 45%). With higher NCO/OH ratio, WPUs had bigger dispersion size and lower dispersion viscosity; the casting film had higher water swelling, lower tensile strength, and more water-soluble substance.

Abstract: In this study, mechanical behavior and failure pattern of composite concrete deck were investigated. A unique dimension of steel concrete deck was fabricated and tested in four-point bending. Two series of decking were also designated with bolts at a spacing of 15 cm and 30 cm, used to compare with those without bolt. Totally, 9 composite concrete decks were tested in a close-loop servo-hydraulic testing system (MTS) using displacement control. Load versus displacement curves as well as failure patterns of the specimens were studied to figure out the mechanical behavior of this type of composite structure.

Abstract: The arrangement and caving order of the mouths after the shield are the key technological problems of lateral caving in flexible shield support face of steep inclined coal seam,and restrict the production.Based on the geological and production conditions of Muchengjian Mining 5113 flexible shield support face in Beijing mining area,lateral caving was simulated by using PFC2D.Single mouth caving and double mouth caving in different orders were researched.It showd that double mouth caving discharged more coal than the single one.When opening two mouths,caving from the upper to the lower had discharged the most coal.Open the third mouth between the two mouths could discharge more coal.The best technology of caving was caving from the upper mouth to the lower one.It increased the rate of recovery and decreased the workload.

Abstract: MgO-Al₂O₃-TiO2 composite refractories were prepared by using magnesium aluminate spinel (MgAl₂O₄) and titanium dioxide as main starting materials and being sintered at high temperature. The influences of titanium dioxide additions on the room temperature physical properties, phase composition and microstructure were investigated. The phase composition and microstructure were tested by means of XRD and SEM. The results revealed that with increasing TiO₂ content, the densification of the composites first increased sand then decreased and maximized at 4% TiO₂ loading. This showed appropriate amount of TiO₂ could contribute to the sintering of the composites due to the solid solution of TiO₂ in magnesium aluminate spinel.

Abstract: Nanosized CoFe₂O₄ powders of 12nm particle size were directly prepared by solution SHS method at room temperature. The overall process involves three steps: formation of homogeneous sol; formatiom of dried gel; and combustion of the dried gel. Experiments revealed that CoFe₂O₄ dried gel derived from citrate and nitrate sol exhibited self-propagation combustion(SHS) at room temperature once it was ignited in air. After self-propagating combustion, the gel directly transforms into nanosized CoFe₂O₄ particles. The self-propagating combustion was considered as a heat-induced exothermic oxidation-reduction reaction between nitrate ions and carboxyl group. Differential thermal analysis-thermogravimetry (DTA-TG) was used to study the decomposition of the precursor. The structure of the nanosized CoFe₂O₄ powders was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM).

Abstract: 17 amino acids were used to examine their effects on production of bacterial cellulose (BC) by Acetobacter xylinum. It found that these amino acids can be classified into three groups based on BC production: the efficient group (His/Glu/Asp/Thr/Leu/Ala/Cys), the less efficient one (Met/Ser/ Arg/Phe/Val/Pro/Try/Cystine/Tyr) and the non-efficient one (Lys). Among the efficient group, effects of amino acids on BC were insignificant except His through a L₈ (2⁷) factorial design, so it concluded that His was the best amino acid for BC produced by A. xylinum in defined medium. Even so, His was not the best nitrogen source, compared to ammonium sulphate. When His and ammonium sulphate co-existed in the medium, they were both comsumed by A. xylinum independently, but their synergic effect on BC production was not significant.