Papers by Author: Wei Xu

Abstract: Through the finite element analysis, studies on mechanical performance of prestressed steel-concrete composite beams when it is undered the low reversed cyclic loading, based on constitutive model of elastic-plastic and consider nonlinear property of materials, it indicated good agreement with the experiment. Change concrete strength of composite beams and study hysteresis curve, energy dissipation and so on.Study found that with the improvement of concrete strength, the hysteresis loop of prestressed steel-concrete composite beams become plump, down by the load carrying capacity, energy dissipation ability were improved significantly.when the load upward, the load bearing capacity,energy dissipation have a small rise, but not obvious. Incresae the concrete strength is good for dynamic performance of prestressed steel-concrete composite on the whole.

Abstract: Porous β-TCP scaffold was prepared using three-dimensional gel-lamination technology with foamy slurry. Then the sintered scaffolds were soaked in 1.5SBF solution to achieve scaffolds with bone-like structure. After soaking, a low crystallized bone-like apatite layer containing CO3 -2 was formed on the surface of the scaffold. With presoaking in NaOH solution, the formation of the bone-like apatite layer on the surface of the scaffold in 1.5SBF solution was accelerated. In this way, a bioactive porous β-TCP scaffold with bone-like structure could be prepared.

Abstract: Porous hydroxyapatite (HA) ceramic scaffolds were prepared using three-dimensional (3-D) gel-lamination technology with sodium lauryl sulfate as foaming agent and lauryl as foaming stabilizing agent. With gelling system of sodium alginate and calcium chloride, the foamy HA slurry was gelled layer by layer on the 3-D gel-lamination machine to prepare the porous ceramic scaffolds. The viscosity of the foamy ceramic slurry was examined. After sintering, the porous HA bioceramic was characterized in terms of the porous microstructure and mechanical properties. The experimental results demonstrated that the resultant porous ceramic with appropriate pore size, porosity characters, mechanical properties and bioactivity could be obtained.

Abstract: In the study, the spark plasma sintering (SPS) method was adopted to fabricate Si3N4 ceramics with Y2O3-MgO additives. Specimens with different grain dimensions, grain shapes, α/β phase ratios, densities were obtained by changing the heating rate and dwell time of SPS. The relationship between the microstructure and the thermal conductivity was studied. Results show that the heating rate and the dwell time have great influence on the microstructure and properties of Si3N4 ceramics. Both equiaxed and columnar β- Si3N4 grains are formed during sintering, but the thermal conductivity of Si3N4 ceramics is affected only by columnar grains. The thermal conductivity of the ceramics increases together with the formation and the growth of the β- Si3N4 columnar grains.

Abstract: α-Si3N4 ceramics were sintered at a low temperature of 1773K by using a spark-plasma-sintering (SPS) method with different heating rates, and then they were further heat-treated at different temperatures from 1773K to 2273K, to study the effect of the heating rate of SPS on the microstructure and the thermal conductivity of Si3N4 ceramics after the heat-treatment. Results show that the heating rate of SPS has great influence on the phase transformation and the microstructure of the β-Si3N4, but it has little influence on the thermal conductivity of the ceramics. This proves that the thermal conductivity of the ceramics does not have an obvious relationship with the ratio and the size of the columnar β-Si3N4 grain.