Applied Mechanics and Materials Vols. 217-219

Abstract: A reliability based analysis method for composite panels with tophat stiffened topology was presented in this paper. An energy based grillage method was developed for the buckling problems of the stiffened panels subject to bi-directional in-plane loads. The variables that have large impact on structural safety were identified using a sensitivity analysis procedure. The coupling effects of the plate dimension ratio and in-plane loading ratio on the critical buckling loads were investigated.

Abstract: In this paper, a new dopant of P₃N₅ (phosphorus nitride) was doped into the diamond growth cell to grow diamond crystals by temperature gradient growth method (TGM) under high pressure and high temperature (HPHT). The experiments were performed at a fixed pressure of about 6.0 GPa and temperatures of 1600-1650 K. The gained diamond crystals were characterized by infrared (IR) absorption spectroscopy, micro-Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), respectively. IR measurements demonstrated that, nitrogen atom was indeed doped into diamond crystals, and the diamond crystals with perfect shape containing nitrogen concentration ranging from 461 atomic parts per million (ppm) to 2186 atomic ppm were successfully synthesized. Nitrogen atoms present in diamond crystal were predominantly in isolated form accompanied by a small amount of nitrogen pairs. Micro-Raman spectra implied that crystalline quality deteriorated with nitrogen concentration gradually increased in diamond-growing environment. The XPS spectra revealed that only a few of phosphorus impurities about tens of ppm level were incorporated into a diamond crystal which was heavily doped with P₃N₅. This study will promote the application of doping diamonds in micro-electronics field and other fields.

Abstract: In this Paper, electroless nickel-phosphorus composite of Al₂O₃ deposit is prepared by chemical plating on 45 steel. Surface topography, microstructure and major elements are analyzed by SEM, EDS and XRD. The results show that the deposit is compact and the binding of the coating interface is very good. It is found that the microstructure of deposit is amorphous and after heat treatment is crystalline. Corrosion test showed that the coating's corrosion resistance is related to heat treatment temperature. It exhibits better corrosion resistance at annealing temperature of 250°C.

Abstract: A new mixed method is adopted to make the powders mixed into bond particles, which is prepared for the PM iron-based sintered composites. The influences of phosphorus content on the physical properties and the frictional and wear properties of composites were analyzed in this paper. The morphology of frictional surface was confirmed by scanning electron microscopy. The results show the phosphorus addition may increase the matrix hardness and the anti-adhesion and anti-scratch behaviours significantly, and improve the anti-friction property and load carrying capacity of iron-based P/M composites. The composites containing 0.3 wt% of phosphorus has the optimal wear and frictional properties, and the self-lubricating performance is also improved obviously.

Abstract: The hypereutectic HCCI/plain carbon steel bimetal composite hammer which has metallurgical combination layer were prepared by bimetal liquid casting method and the influence of the pouring temperatures on the microstructure of the hypereutectic HCCI and the combination layer were studied. The results show that lower pouring temperature was not benefit for refinement of primary carbide and formation of metallurgical combination layer. A bad metallurgical combination layer between two metals which were mixed along the interface exhibited at higher pouring temperature.

Abstract: Al2O3，Al3Ti and Al3Zr particles reinforced 7055 aluminium matrix composites were fabricated via melt reaction method. The volume fraction is controlled at about 4-5%. After extrusion and solution-aging heat treatment the sample was prepared for deep cryogenic treatment, The microstructure and evolution of mechanical properties of (Al3Ti+Al3Zr)p/7055 composites were analyzed using optical microscopy(OM),scanning electronic microscopy(SEM) and X-ray diffraction(XRD). Some θ(Al2Cu) phases with nanometer size precipitate in the inner grain. As some grains preferred orient the intensity of some main diffraction peaks increase. Compared with those of as-cast and squeezed states the micro hardness has increased by 16.8% and 10.0% separately.

Abstract: Glass ceramics of the CaO-MgO-Al₂O₃-SiO₂ system were fabricated by adopting the melting-casting procedure. Steel slag and fly ash were used as the major starting materials. The influence of CaO/SiO₂ Ratio variations on the microstructure and mechanical properties were investigated using X-ray diffraction, scanning electron microscopy and property measurements. Augite is identified as the main crystalline phase of the as studied glass ceramics. The average size of augite grains in form of spherical particles is found within the range of 100-250nm. The bending strength of the glass-ceramics could reach as high as 170.74MPa. Increasing CaO/SiO₂ show a beneficial influence on the crystallization of glass ceramics, and its effectiveness is inferior compared with that of increasing addition of nucleating agent, TiO₂.

Abstract: GLARE laminates with outstanding impact resistance, high fatigue resistance and a number of excellent performances are combined by ductile aluminum layers and high strength FRP layers. An experimental program was conducted to estimate the influence of geometric parameters, ply orientation and tightening torque on the performances of GLARE bolted joint. The study showed that the parameters of GLARE bolted joint have intrinsic properties of metal bolted joint and composite bolted joint. The design threshold values including of geometric parameters, ply orientation and tightening torque were given.

Abstract: A conductive silicone rubber (SR) composite, filled with both carbon nanotubes (CNT) and carbon black (CB) is prepared by a simple ball milling method. Because of the good dispersion and synergistic effects of CNT and CB, the SR composite shows improvement in mechanical properties. As well, due to the assembly of conductive pathways generated by the CNT and CB, the nanocomposite becomes highly conductive at a comparatively low concentration, with very high sensitivity for tensile and compressive stress. These outstanding properties show that the SR composite has potential applications in tensile and pressure sensors.

Abstract: Thermally conductive silicon carbide (SiC) filled linear low density polyethylene (LLDPE) plastics were prepared by using powder-mix method. Effects of coupling agent treatment on the thermal conductivity, mechanical properties, morphology and electric properties were also investigated. The results indicate that the coupling agent treatment for SiC particles improves the thermal conductivity of the plastics when using 1 wt.% to 3 wt.% coupling agent. The coupling agent treatment for SiC particles enhances interfacial adhesion between filler and matrix, giving the material higher mechanical properties. The coupling agent treatment for SiC particles also lowers the dielectric constant and dielectric loss of the material, performing better dielectric properties.