Abstract: A novel rapid chemical vapor infiltration (CVI) processing defined by multi-physics fields CVI was used to fabricate carbon/carbon (C/C) composites. Liquid petrol gas is used as carbon source and the parameters were experimental tested and optimized. Because of the influence of multi-physics fields, a new surface morpha is grown under control parameters. It is called “Dot Structure”. The structure of pyrocarbon is analyzed and characterized by XRD, SEM with EDS, and Raman spectrum. At the end, a simple model of point discharge for growth of pyrocarbon is proposed. The deposited pyrocarbon based on multi-physics fields chemical vapor infiltration is expected to provide an improve performance in rapid C/C composites fabrication.
Abstract: The bonding properties of post-installed bar in concrete are fundamental to evaluate the results of reinforced concrete. Including 102 specimen of post-installed bar and 18 specimen of embedded bar, 120 specimens were tested by pull-out test altogether. Comparative analysis considering diameter of steel bar, tensile strength of concrete, anchoring depth of steel bar, anchorage aperture are conducted. Based on the experimental results, it is shown that the bonding properties of post-installed bar are significantly influenced by steel bar, concrete tensile strength, installed depth bar and anchorage aperture. The ultimate average pullout forces of steels in specimen of post-installed bar and specimen of embedded bar are nearly equal. Three kinds of failure models are obtained. The experimental results can be useful for analyzing and evaluating bonding behaviors of post-installed bar in concrete.
Abstract: With methyl vinyl silicone (MVQ) as the base rubber, filled with self-synthesized carbon coated aluminum nanoparticles, the high thermal conductive composite was prepared by using the method of mechanical blending. The effect of carbon coated aluminum nanoparticles on thermal conductivity and coefficient of thermal expansion (CTE) of the silicone rubber were investigated, and it was found that thermal conductivity of the composite increased with increasing carbon coated aluminum nanoparticles content during the process of thermal conductive network initially formed to throughout the whole composite, the thermal conductivity began to decrease when the filling content reached 250phr,the optimum filling amount of carbon coated nanoparticles was 250phr.The Y-Agrai model was employed to investigate the thermal conductivity of the thermal conductive composite, results indicated that when the filling content was less than 200phr,theoretical value was coincided with measured value. While the filling content was more than 200phr, theoretical value was gradually less than measured value. While the carbon coated aluminum nanoparticles content increased, the coefficient of thermal expansion (CTE) of composite decreased significantly.
Abstract: As a fair deck pavement material of its kind used in steel bridge, the epoxy asphalt concrete is considered much more superior to ordinary asphalt concrete in terms of road performance, while still greatly subject to the level of design and construction. Starting from a practical case of the epoxy asphalt concrete that has been applied in the deck pavement of Pingsheng Steel Bridge, this paper centers on a comprehensive study and discussion of the epoxy asphalt mixture, specifically in aspects of physical and mechanical performance test of stability under high temperature, performance under low temperature, tortuosity, immersion stability, linear contraction performance, fatigue performance and oil-erosion resistance performance. This will provide positive instruction for future deck pavements on steel bridges.
Abstract: A flame retardant wood was prepared using a series of insoluble stannates through the double bath technique. The flame retardancy of the wood samples was studied with the LOI method. The relationships between the flame-retardant performance and the thermal property of wood were studied by the thermogravimetric analysis (TGA), differential thermogravimetry (DTG), differential thermal analysis (DTA) and scanning electron microscopy (SEM) methods. The results show that the insoluble stannates, which were precipitated into the wood by the double bath technique, can obviously improve the flame retardancy of wood. Na2SnO3 can catalyze the intermolecular dehydration reaction and increase the stability and amount of the char residue, and the metal ions not only catalyze the intermolecular dehydration reaction in the second stage but also changed the degradation reaction of the char residues in the third and fourth stages.
Abstract: In this paper, the producing process of using V2O3 as raw material to obtain vanadium nitride was analyzed through the predominance area diagrams. The analysis shows that VN-phase can be accessed in the conversion process of V2O3 by controlling gas phase composition and temperature of the reaction system and the one-step method preparing for vanadium nitride is feasible. Effect of technical parameters on nitrogen content of products is investigated. The temperature of the reaction system has prominent influence on the nitrogen content of products, and the reaction is very sensitive to temperature. The quantities of nitrogen increase first and decrease later with increasing the reactive temperature, and the result researches the optimum at 1673K. The nitrogen content of the products tended to be constant after soaking over 2 hours at 1673K.Experimental observations shows that additives can increase the nitrogen content of VN. However, the effect of various additives on the nitrogen content is different. Among the additives referred in this paper, the effect of the iron powder, compounds of alkaline earths and NH4Cl are superior.
Abstract: In order to provide technical reference in soft soil foundation treatment for construction of high-grade highway in wetlands soft soil area,by collecting undisturbed soil samples in Qiqihaer-Fuyu section of Jiagedaqi-Beijing highway and using triaxial tests, direct shear test, compressed consolidation testing and other testing methods, a detailed laboratory test and study has been carried out on the soft soil engineering properties and the comparative study on physical and mechanical index, compressed consolidation properties, shearing strength and shearing strength index and so on of wetlands soft soil and other genesis soft soil has been carried out,the results showed that: wetlands soft soil is better than delta soft soil in basic physical and mechanical index; comparing shearing strength parameters of wetlands soft soil and lacustrine soft soil shows that: under smaller consolidation degree and the consolidation pressure, their cohesion decreased with the increase of consolidation degree;with the consolidation degree and the consolidation pressure become bigger, the cohesion of wetlands soft soil is higher than lacustrine soft soil, internal friction angle changed little; Comparing with marine soft soil, the primary consolidation coefficient of wetlands soft soil is bigger and the secondary consolidation coefficient is smaller, that shows the foundation of wetlands soft soil is easy to drainage and consolidation. The research results have guiding significances for treatment of wetland soft soil foundation.
Abstract: Based on the Monte Carlo (MC) simulation, the film growth and magnetic properties of Ni (100) films are investigated. The simulated results indicate that the surface roughness of the Ni films drops with the increase of the substrate temperature and the decrease of the deposition rate. The Curie temperature Tc is greatly influenced by the surface roughness and size of Ni films. Moreover, it is found that the Curie temperatures of the films are related to the mean coordination number Z and the surface roughness r. The simulated results explain the experimental facts well.
Abstract: Spheroidal composite filter material was made with activated clinoptilolite powder as the main stuff. The best condition of the process determined by orthogonal test were ωclinoptilolite: ωbond: ωadditive=55%:35%:10%, activation temperature at 150 ,activation time at 3h. The piled density, compressive stress and apparent porosity of the composite filter materials are 674Kg/m3, 4.32MPa and 59.02%. Compared with ceramsite and natural clinoptilolite, the composite filer materials has larger specific surface area and higher poriness, so it can be well used in BAF.
Abstract: Finite element method and optimization method are two major ones in engineering analysis. The optimization of a wedged-ring joint structure can be performed by using these two methods unitedly. The response surface design method was employed to determine the combination of geometrical parameters to be designed of the wedged-ring joint structure. The stress of the wedged-ring joint structure which has the different geometrical parameters was numerically simulated and analyzed by using engineering software ANSYS. The optimized geometrical parameters of the wedged-ring structure were obtained by using MATLAB multi-objective optimization method. The results show that the maximum stress and the mass of the optimized wedged-ring structure decrease 13.6% and 12.5%, respectively.