The synthesis of Ti3AlC2/TiB2 composites was studied by in-situ spark plasma sintering with different volume content of TiB2. Results indicated the bulk Ti3AlC2/TiB2 was fabricated by SPS, which soaked for 8 min under...
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The synthesis of Ti3AlC2/TiB2 composites was studied by in-situ spark plasma sintering with different volume content of TiB2. Results indicated the bulk Ti3AlC2/TiB2 was fabricated by SPS, which soaked for 8 min under a pressure of 30 MPa at 1250°C. The properties of composites was great increased with the addition of TiB2;the Vicker's hardness increased with addition of TiB2 content, the maximum value is 10.4 GPa. The maximum flexural strength and fracture toughness reached maximum value, which were 696 MPa and 6.6 MPa·m1/2 when the volume content of TiB2 was 10%.
α-Al2O3 nanopowders were prepared by a novel synthesis process, using the nanosized α-Al2O3 obtained from pyrolyzing ammonium aluminum carbonate hydroxide as seeds and the self-dispersed nanosized AlOOH crystal powd...
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α-Al2O3 nanopowders were prepared by a novel synthesis process, using the nanosized α-Al2O3 obtained from pyrolyzing ammonium aluminum carbonate hydroxide as seeds and the self-dispersed nanosized AlOOH crystal powders as precursors. Based on their good self-dispersion in water, the α-Al2O3 seeds were dispersed evenly into the AlOOH sol by the new homodispersion mixing technique. This process enables the conversion of AlOOH to alumina at 190°C (hydrothermal temperature), in which the alumina is calcined to nanosized alpha-alumina having an average length to diameter ratio of 60nm:15nm at 930°C. In the synthesis reaction for transforming the AlOOH to alumina, the effect of superfine pulverization and self-dispersion of the precursors was studied.
A coupled and uncoupled non-linear thermomechanical finite element analysis using ANSYS have been carried out to analyze the heat transfer and associated thermal stresses during different simulated thermal shock proce...
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A coupled and uncoupled non-linear thermomechanical finite element analysis using ANSYS have been carried out to analyze the heat transfer and associated thermal stresses during different simulated thermal shock processes, and the results of two analyses are discussed. It indicates that piezocaloric effect can be neglect when thermal shock intensity is mild and piezocaloric effect should be taken into account when thermal shock intensity is severe.
In this study, K3Li2-xNb5+xO 15+2x (KLN) thin films were prepared by laser-ablated a sintered ceramic target. For an optimum deposition condition, in-situ post annealing method was employed on as-deposited films. XRD ...
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In this study, K3Li2-xNb5+xO 15+2x (KLN) thin films were prepared by laser-ablated a sintered ceramic target. For an optimum deposition condition, in-situ post annealing method was employed on as-deposited films. XRD measurements showed that KLN films with (310) preferred orientation were obtained on fused quartz substrate. Surface morphology studies indicated mat in-situ post annealing could improve the surface quality of KLN thin films. The average transmittance of as-deposited and annealed films in the visible range was nearly 80% to 90%.
Silver-coated glass microsphere core-shell composite particles were used as electric fillers, nitrile-butadiene rubber electric composite materials were prepared by rubber processingtechnology. The formula for compos...
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Silver-coated glass microsphere core-shell composite particles were used as electric fillers, nitrile-butadiene rubber electric composite materials were prepared by rubber processingtechnology. The formula for composite electric rubber material was studied, and the processing technical parameters of it were optimized. The influences of the quantity of shielding filler on the related properties of electric rubber materials were discussed, including conductive capability, mechanics properties and electromagnetic shielding effectiveness. The results showed that the composite electric rubber is light-weight rubber material and has good durability. With increasing volume fraction of electric fillers, the electric property and electromagnetic shielding effectiveness of the electric rubber material strengthen, its mechanics properties decline. And the volume fraction of the filler reached 40%, the volume resistivity of the rubber materials is 7.41 × 10-3 Ω · cm, it has good mechanics properties and electromagnetic shielding properties.
e effect of sintering temperature on the microstructure, nonlinear electrical behavior, and dielectric properties of the Y2O3-doped WO3 ceramics was studied. The decrease in breakdown voltage directly relates to the g...
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e effect of sintering temperature on the microstructure, nonlinear electrical behavior, and dielectric properties of the Y2O3-doped WO3 ceramics was studied. The decrease in breakdown voltage directly relates to the grain growth of WO3 grains when increasing the sintering temperatures from 1050 to 1200 'C. The capacitor-varistor of WO3- 0.8 mol％ Y2O3 composite sintered at 1150 °C exhibits the maximal nonlinear coefficient of 3.5 and the highest dielectric constant of 1.13 x 104. However, higher sintering temperature than 1150 °C is not favorable for the nonlinear electrical behavior of the WO3 ceramics. The best nonlinear properties of the samples sintered at 1150 'C can be explained by the most efficient boundary barrier layer with can be formed sintered at the proper temperature.
Using the development tool C++ Builder and adopting object oriented programming method, the ceramic/metal gradient thermal barrier coating design software (CCDS) is developed according to software engineering criterio...
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Using the development tool C++ Builder and adopting object oriented programming method, the ceramic/metal gradient thermal barrier coating design software (CCDS) is developed according to software engineering criterion. The CCDS, which has user-friendly interface, is composed of three functional modules: preprocess module, analysis module and post process module. In addition, this software is attached with an optimal design module and an expert module. The calculation and design of the ceramic/metal gradient thermal barrier coating can be carried out by the CCDS, and the numerical results show good agreement with the analytical results.
Buffer material plays an important role in the hypervelocity launching experiments. By using numerical calculations, the influence of TPX buffer material's thickness on high impedance tantalum flier plate's ve...
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Buffer material plays an important role in the hypervelocity launching experiments. By using numerical calculations, the influence of TPX buffer material's thickness on high impedance tantalum flier plate's velocity is analyzed, and the optimal thickness of buffer material is also evaluated. For thickness of 0.3 mm and 0.5 mm tantalum flier plate, the relative error of tantalum flier plate's center velocity is about 5%-6% at different thicknesses of the TPX buffer materials. In order to compare the influence of different buffer materials on tantalum flier plate's velocity, the two-dimensional results of tantalum flier plate's center velocity and pressure histories are calculated at the same thickness of TPX and Lexan buffer.
The high intensity of thermal stress was generated during fabrication of 6063 aluminum/60SiC‐35Al‐5Si double‐layer material. In order to decrease the thermal stress, graded materials of Al/60SiC‐35Al‐5Si was fabr...
The high intensity of thermal stress was generated during fabrication of 6063 aluminum/60SiC‐35Al‐5Si double‐layer material. In order to decrease the thermal stress, graded materials of Al/60SiC‐35Al‐5Si was fabricated by spark plasma sintering. The CTE in the graded layer was controlled by SiC fraction and particle sizes. The calculation results indicate that the net stress of more than 800 MPa was generated in the double‐layer materials, but it decreased to 170 MPa or less in the graded materials. So the stability can be guaranteed in the graded composites. The graded layers also have the potential for high thermal conductivity, more than 180W/Mk for every layer, which satisfies the application.
The 5-axis milling processes were conducted with several uncoated WC-Co tools, which are with taper ball end mills with four flutes. There is a severe problem of high rate of tool failure, which has led to the high co...
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The 5-axis milling processes were conducted with several uncoated WC-Co tools, which are with taper ball end mills with four flutes. There is a severe problem of high rate of tool failure, which has led to the high cost and low productivity of the milling process. In order to find out the real reason, some former work, which included the tool geometry analysis, tool path and tool posture analysis, as well as the cutting force calculating, had been done. It has been found that most of the tool failures are resulted from cutting edge chipping or the workpiece material of titanium alloys attached to the tool, Meanwhile, a suddenly applied load or an abrupt unloading of the tool at the end of a cut is another important factor. Moreover, the tool materials had been analyzed, which included the element composition analysis with XRD, the microstructure analysis with SEM. XRD results indicate the cobalt at the tip of tool is less than at the shank of tool. SEM results indicate there are micro-cracks concentrated in the cutting edge area. The tool material failure mechanism will be set up based on the tool material analysis in this study.
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