The spark plasma sintering (SPS) was applied to prepare α-Si3 N4 ceramics of different densities with magnesia, silicon dioxide, alumina as the sintering aids. The mechanism of liquid phase sintering (LPS) wus d...
详细信息
The spark plasma sintering (SPS) was applied to prepare α-Si3 N4 ceramics of different densities with magnesia, silicon dioxide, alumina as the sintering aids. The mechanism of liquid phase sintering (LPS) wus discussed and the factors influencing the density of the prepared samples were analyzed. The dielectric constant of sintered samples was tested. The experimental results show that the density can be controlled from 2.48 g/ cm^3 to 3.09 g/ cm^3 while the content of the sintering aids and the sintering temperature alter and the dielectric constant is closely dependent on the density of obtained samples.
A new niobate Ba6Mg0.67Nb9.33O30 was ssnthesized in the BaO-MgO-Nb2O5 system by solid state reaction at 1350 ℃ for 48 b. The strncture and dielectric properties of Ba6Mg0.67Nb9.33O30 were determined by X-ray pouder d...
详细信息
A new niobate Ba6Mg0.67Nb9.33O30 was ssnthesized in the BaO-MgO-Nb2O5 system by solid state reaction at 1350 ℃ for 48 b. The strncture and dielectric properties of Ba6Mg0.67Nb9.33O30 were determined by X-ray pouder diffraction, straining electron microscopy and dielectric measurements. The results show that Ba6Mg0.67Nb9.33O30 belongs to ferroelectric phase of filled tetragonal tungsten bronze structure at room temperature with unit cell parameters : a = 1. 26052(4) nm , c = 0.40045(2) nm, space group P4bm , calculated density 5 . 707g. cm ^-3 . Ba6Mg0.67Nb9.33O30 belongs to relaxor ,ferroetectrics undergoing diffusive phase transition, and the transition temperature ( Tc ) is 30 ℃ observed at 10 kHz. At room temperature, Ba6Mg0.67Nb9.33O30 eeramic has a high dielectric constant 850 at 1 MHz and a low dielectric loss of 0. 0052.
In order to improve the bioavailab.lity, Radix salvia miltiorrhiza raw powder mixed with distilled water (5.5wt%) was ultrafinely ground to nanosize particles using HSCS pulverizer, and the dissolving-out quantity o...
详细信息
In order to improve the bioavailab.lity, Radix salvia miltiorrhiza raw powder mixed with distilled water (5.5wt%) was ultrafinely ground to nanosize particles using HSCS pulverizer, and the dissolving-out quantity of tanshinone IIA in the filtrate that obtained from nanoparticles suspension and raw powder marinated in water for different time was determined by HPLC. The experimental results show that raw powder can be ultrafinely ground to 133.5 nm at 1500 r/min for 50 min and the molecular structure of active ingredients doesnot change, and the dissolving-out quantity of tanshinone IIA obtained from the filtrate is increased greatly from 12.77 μg/g to 54.55 μg/g.
A facile modification strategy is developed to promote the proliferation and osteogenic differentiation of rat bone marrow stromal cells(rBMSCs)through deposition of a bioactive calcium silicate(CS)coating on the poro...
详细信息
A facile modification strategy is developed to promote the proliferation and osteogenic differentiation of rat bone marrow stromal cells(rBMSCs)through deposition of a bioactive calcium silicate(CS)coating on the porous surface of poly(ether-ether-ketone)(PEEK)with the assistance of poly(dopamine)(PDA).The porous structures are etched on the surface of PEEK after sulfonation treatment.A poly(dopamine)layer is coated on the porous surface of the sulfonated PEEK(SPEEK),which provides anchoring groups for the subsequent deposition of the CS *** show that the CS coating on the porous surface of SPEEK significantly improve the hydrophilicity and biomineralization formation of *** with PEEK,SPEEK-PDA-CS displays higher bioactivity to promote the proliferation and osteogenic differentiation of rBMSCs,including the increase of ALP activity and formation of calcium nodules,the expression of osteogenic differentiation-related *** results are beneficial to extending clinical applications of PEEK-based implants for bone tissue repair and orthopedic surgery.
The three dimensional profile for valence electron structure across the triple pocket junction in SrTiO3 ceramic has been quantitatively determined by analysis of spatially resolved low loss electron energy-loss spect...
详细信息
Ordered iron fiber arrays were electrodeposited on the surface of zinc foils using "FeSO4 solution-sodium caprylate-Decanol" 3-component reverse hexagonal liquid crystal as soft templates. The structure of the soft ...
详细信息
Ordered iron fiber arrays were electrodeposited on the surface of zinc foils using "FeSO4 solution-sodium caprylate-Decanol" 3-component reverse hexagonal liquid crystal as soft templates. The structure of the soft templates and the synthesized iron ,fibers were characterized by polarizing microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis etc. The experimental results shou that the synthesized iron fibers with a crystal phase grew up in the form of fiber clusters of about 200 nm along the direction perpendicular to the cathode surface. Each cluster was composed of several tens of fibers. The fibers had almost the same length of more than 10μm with a diameter of about 50 nm.
By using such flier-plate material,quasi-isentropic compression can be *** on it,hypervelocity launching is further *** a result,an extremely high dynamic pressure can be obtained in lab.ratory,offering a practical me...
详细信息
By using such flier-plate material,quasi-isentropic compression can be *** on it,hypervelocity launching is further *** a result,an extremely high dynamic pressure can be obtained in lab.ratory,offering a practical method for the comprehensive determination of materials behavior,response,equation-of-state and properties in dynamic loading process.
0.5 wt%Nb_(2)O_(5)doped 0.12BiAlO_(3)-0.88BaTiO_(3)(12BA5N)multilayer ceramic capacitor(MLCC-1)was prepared,which satisfied EIA X7R specification(where X is the minimum temperature,R is the percentage of capacitance v...
详细信息
0.5 wt%Nb_(2)O_(5)doped 0.12BiAlO_(3)-0.88BaTiO_(3)(12BA5N)multilayer ceramic capacitor(MLCC-1)was prepared,which satisfied EIA X7R specification(where X is the minimum temperature,R is the percentage of capacitance variation limit)at 1 *** distribution of internal electric field under breakdown voltage was simulated by finite element method(FEM),indicating that the electric field strength increased significantly at the terminal of internal *** areas may become the headstream of breakdown for MLCC-1 due to the shape *** order to improve the breakdown performance of MLCC-1,it was optimized by 12BA5N+2G green sheets(prepared by 12BA5N ceramic powder with 2 wt%B-Al-Si glass additive),then MLCC-2 was obtained which satisfied EIA X8R *** BDS rose from 20 to29.4 kV·mm^(-1),and the electric field distribution of dielectric layer was also analyzed by ***,it was also found that the grain size and the dielectric constants of"core"and"shell"parts for the 12BA5N+2G dielectric layer both contributed to the enhanced BDS of MLCC-2according to the simulation results from FEM.
High quality nano-sized zirconium carbide (ZrC) powders were successfully fabricated via a developed chemical active dilution self-propagating high-temperature synthesis (SHS) method assisted by ball milling pretr...
详细信息
High quality nano-sized zirconium carbide (ZrC) powders were successfully fabricated via a developed chemical active dilution self-propagating high-temperature synthesis (SHS) method assisted by ball milling pretreatment process using traditional cheap zirconium dioxide powder (ZrO2), magnesium powder (Mg) and sucrose (C12H22Oll) as raw materials. FSEM, TEM, HRTEM, SAED, XRD, FTIR and Raman, ICP- AES, laser particle size analyzer, oxygen and nitrogen analyzer, carbon/sulfur determinator and TG-DSC were employed for the characterization of the morphology, structure, chemical composition and thermal stability of the as-synthesized ZrC samples. The as-synthesized samples demonstrated high purity, low oxygen content and evenly distributed ZrC nano-powders with an average particle size of 50nm. In addition, the effects of endothermic rate and the possible chemical reaction mechanism were also discussed.
An improved multi-step sintering process was used to in-situ prepare TiB2-TiB-Ti FGMs. According to the sintering temperatures, the functionally graded materials (FGMs) were divided into three sections. After sinter...
详细信息
An improved multi-step sintering process was used to in-situ prepare TiB2-TiB-Ti FGMs. According to the sintering temperatures, the functionally graded materials (FGMs) were divided into three sections. After sintering at a proper temperature, the three sections were sintered together in turn. The experimental results showed that there were no obvious pores and cracks in the whole TiB2-TiB-Ti FGMs, and no delamination was found in the impacting test with good performance features, which indicated that there were no interface effects in FGMs during penetration, so that the TiB2-TiB-Ti FGMs were an ideal FGM.
暂无评论