The crude drug of Liuwei Dihuang was pulverized to nano particles to improve its bioavailability. The appropriate technique parameters were studied. Paeonol, typical marker of Liuwei Dihuang , was extracted with organ...
详细信息
The crude drug of Liuwei Dihuang was pulverized to nano particles to improve its bioavailability. The appropriate technique parameters were studied. Paeonol, typical marker of Liuwei Dihuang , was extracted with organic solveat in ultrasonic and its content was determined by HPLC. The appropriate techrdques parameters are as follows ： rotating speed control 1200 r/ min , grinding time control 50min and mass percent concentration control 3.8% . The experimental results show that the average particle diameter is 161.9 nm and the great majority of the plant cell wall is broken into pieces after nano pulverization. The extraction efficiency of paeonol is increased by 23.5% .
The superthin PEM (&le 30μm in thickness) can be used in CCMs(Catalyst coated membranes) and helpful to lower the cost of fuel cells. In this paper, the CCM based on Nafion NRE® 211 membrane (thickness ∼2...
详细信息
Combustion synthesis method with reductive process was used to synthesize TiB2 powder from TiO2 - B2O3 - Mg system. Main impurity phase can be cleaned out by acid washing treatment. The influences of acid washing cond...
详细信息
Combustion synthesis method with reductive process was used to synthesize TiB2 powder from TiO2 - B2O3 - Mg system. Main impurity phase can be cleaned out by acid washing treatment. The influences of acid washing conditions (acid concentration, treatment time, treatment temperature and so on) on the purity of TiB2 powder were studied. Results showed that acid treatment temperature and amount of excessive acid were the main factors that effected purity of TiB2 powder. With increase of acid treatment temperature and amount of excessive acid, purity of TiB2 powder increased continuously. The analysis of thermodynamics and kinetics showed that the increase of acid treatment temperature could increase chemistry reaction speed constant (K), and accelerate acid washing processing. Diffusion mechanism controlled mainly acid treatment reaction.
The microstructure and microwave dielectric properties of the CuO-doping CaTiO3-Ca(Zn1/3Nb2/3)O3 ceramics prepared by the conventional solid-method were investigated. XRD results indicate the ceramics with orthorhombi...
详细信息
Mesocarbon microbeads （MCMB） and super fine mesophase powder （SFMP） were prepared firstly from a coal tar pitch and then hot-condensed into high-density isotropic carbon （HDIC） bulks under 160 MPa and finally si...
详细信息
Mesocarbon microbeads （MCMB） and super fine mesophase powder （SFMP） were prepared firstly from a coal tar pitch and then hot-condensed into high-density isotropic carbon （HDIC） bulks under 160 MPa and finally sintered at 1 000 ℃. By analyzing the thermogravimetric behavior of the MCMB and SFMP powders, their volume shrinkage and weight loss during sintering and the bulk density and flexural strengths of their sintered bulks, it was found that the smaller sizes and the richer β-resin contents of SFMP ha）re facilitated formation of sintered bulks with more compact isotropic structure and higher flexural strengths than MCMB. Because of the filling and bonding effects of SFMP on MCMB bulks, addition of SFMP, albeit a little, can greatly increase the flexural strengths of sintered bulks of MCMB. However, adding MCMB, even a slight amount, into SFMP can severely impair the flexural strength of sintered bulks. This might be attributed to both the crack initiation along the boundaries between MCMB and SFMP and the formation of layered texture of MCMB sphere.
Aluminum nitride-boron nitride (AlN/BN) composite ceramics were prepared by spark plasma sintering (SPS). The sintering behaviors of AlN/BN composites with 5-15% volume fraction of BN were studied. The influences of B...
详细信息
Aluminum nitride-boron nitride (AlN/BN) composite ceramics were prepared by spark plasma sintering (SPS). The sintering behaviors of AlN/BN composites with 5-15% volume fraction of BN were studied. The influences of BN content, as well as the sintering temperature on the density, microstructure, mechanical strength, thermal conductivity and machinability of the composites were also investigated. The results showed that the full densification of AlN/BN composite ceramics could be realized by SPS technique at the temperature no higher than 1800°C for 3 minutes. The thermal conductivity of AlN/BN composites is in the range of 66-79W/mK, and AlN/BN composites can be cut or drilled by carbides or even steel tools when BN content is 15% volume fraction. The mechanical strength of AlN/BN composites is about 330MPa and is not remarkably affected by the addition of BN. The improvement of mechanical properties of AlN/BN composite ceramics is due to the fine and homogenous microstructure developed in the SPS process.
In this paper, the effect of imperfect inner interface on the stress fields in the coated inclusion composite is investigated, the spring-layer of vanishing thickness model is introduced to simulate the imperfect inte...
详细信息
In this paper, the effect of imperfect inner interface on the stress fields in the coated inclusion composite is investigated, the spring-layer of vanishing thickness model is introduced to simulate the imperfect interface, assuming that across the interface between the inclusion and the coating the interfacial traction is continuous while displacement discontinuities are permitted through interfacial traction-displacement jump relations. Numerical examples corresponding to the composites containing single coated spherical and fibrous inclusion, respectively, under shear loading at infinity, are calculated, which indicate that the imperfect inner interfaces have significant effect on stress fields of the composites.
C/BN laminated composites were obtained by hot-pressing, and the micro-structure and property of the sintered bodies were investigated. The results indicated that the relative density of the samples was 99%. SEM indic...
详细信息
C/BN laminated composites were obtained by hot-pressing, and the micro-structure and property of the sintered bodies were investigated. The results indicated that the relative density of the samples was 99%. SEM indicated that the combined interface between graphite and BN was good, and the transition of graphite and BN was gradual. The sintered bodies between the graphite and BN were destroyed at 1200°C after thermal shocks for 30 times. The tensile strength of materials reached 8.9 MPa.
C/BN laminated composites were obtained by spark plasma sintering. The relationship between sintering conditions, microstructure and properties were studied. The analysis of micro structure indicated that with increas...
详细信息
C/BN laminated composites were obtained by spark plasma sintering. The relationship between sintering conditions, microstructure and properties were studied. The analysis of micro structure indicated that with increasing the temperature and time of heat preservation the coalescent between graphite and BN was increased gradually. The bonding strength transformed from molecular gravitation to the union of molecular gravitation and mechanical strength. The circulation times of materials reached 40 times at sintering temperature of 1750°C for 5 min. The test of mechanical properties of the materials indicated that the largest tensile strength reached 18.2 MPa.
暂无评论