Fu Zhengyi

Study of temperature field in spark plasma sintering

The paper presents a brief derivation of the temperature distribution in the sample and the die in spark plasma sintering. It aims to point out that temperature difference is inevitable in the samples of SPS system. Under certain conditions, the difference may reach a few hundreds of degrees of centigrade. Experiments also proved the existence of such a difference, which is larger than the one under steady-state temperature distribution.

Space-confined growth of Ag3PO4 nanoparticles within WS2 sheets: Ag3PO4/WS2 composites as visible-light-driven photocatalysts for decomposing dyes

A highly efficient Ag3PO4/WS2 composite photocatalyst was synthesized by controlling the growth of Ag3PO4 nanoparticles within WS2 sheets. The process can tune the microstructure, stability and visible-light photocatalytic performance of Ag3PO4. The WS2 sheets, possessing uncoordinated sulfur atoms on exposed surfaces and edges, play an important role in the formation of Ag3PO4/WS2 composite. With 0.05 mol of AgAc added, the Ag3PO4/WS2 composite shows the highest photocatalytic activity. The matched energy level between Ag3PO4 and WS2 inhibits the recombination of the photogenerated electrons and holes. The enhanced photocatalytic activity is also attributed to the multi-interface heterojunction structure assembled by two-dimensional sheets and nanoparticles, driven by chemical binding. The addition of WS2 sheets can also reduce the rate at which Ag+ dissolves from Ag3PO4 into the water, improving the stability of Ag3PO4. This work could provide new insights into fabricating highly efficient and stable Ag3PO4-transition-metal dichalcogenide composite photocatalysts for dye degradation.

Chemistry reaction processes during combustion synthesis of B2O3–TiO2–Mg system

Abstract In this paper, combustion synthesis method was used to synthesize TiB2 ceramic powder from various oxides. Thermal analysis methods were employed to reveal the chemical reaction processes, a high-speed image recorder was used to monitor and analyze the features of combustion processes. Study results indicated that in B2O3–TiO2–Mg system, B2O3 was reduced to elemental B and MgB2 in one step and TiO2 was reduced to element Ti through following steps: TiO2→Ti3O5→Ti2O→Ti, and then, TiB2 was formed by reaction Ti+2B→TiB2 and Ti+MgB2→TiB2+Mg. In synthesis processing, Mg plays a important role in controlling the mineral phase component of synthesized production and combustion processing. The propagating combustion wave model was found to become unstable with increasing diluent additive amount in raw mixture.

Progress of (Sr, Ba) TiO3 ferroelectric thin film and tunability

The fabrication method, technology route and structure performances of (Sr, Ba) TiO3 (SBT) ferroelectric thin film have been summarized in this paper. The tunability of dielectric constant, dielectric loss and leakage current are the basic parameters of tunable microwave devices. The thin films of SBT with high properties could be fabricated by means of RF magnetron sputtering and sol- gel processing. The electrical performances of thin film material can be improved largely by dopants. Some problems are put forward to pay attention to this material research process.

The nano pulverization of traditional Chinese medicine Liuwei Dihuang

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 solvent in ultrasonic and its content was determined by HPLC. The appropriate techniques parameters are as follows: rotating speed control 1200 r/min, grinding time control 50 min 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%.

Breaking and characteristics of Ganoderma lucidum spores by high speed entrifugal shearing pulverizer

The spores of Ganoderma lucidum were ground and broken to ultrafine particles by high speed centrifugal shearing(HSCS) pulverizer. The characteristics of Ganoderma lucidum spores were analyzed by scanning electron microscope (SEM), Fourier transform infrared spectrophotometry (FTIR). Ultraviolet-visible pectrophotometer was used to determine the extraction ratio of aqueous solubility polysaccharide between the raw and broken spores. The immunological function on the mice before and after the breaking of spores was investigated. The experimental results show that after being ground, the sporoderm-broken ratio reachs 100%, the original active ingredients of ganoderma lucidum spores do not change, and the extraction ratio of aqueous solubility polysaccharide is greatly increased by 40.08%. The broken spores show much higher immunological activity comparing with original spores of Ganoderma lucidum.

Equivalent Resistance in Pulse Electric Current Sintering

The sintering resistance for conductive TiB2 and non-conductive Al2O3 as well as empty die during pulse current sintering were investigated in this paper. Equivalent resistances were measured by current and valtage during sintering the conductive and non-conductive materials in the same conditions. It is found that the current paths for conductive are different from those for non-conductive materials. For non-conductive materials, sintering resistances are influenced by powder sizes and heating rates, which indicates that pulse current has some interaction with non-conductive powders. For conductive TiB2, sintering resistances are influenced by heating rates and ball-milling time, which indicates the effect of powders activated by spark.

Study on the surface free energy of ground CaO by IGC

CaO formed by decomposing CaCO3 at 1450°C was ground in a vibrational mill, then the long-time ground sample was reheated at different temperatures. Inverse Gas Chromatography (IGC) was used to measure the variation of the samples surface free energy under grinding and reheoting. It is concluded that the total surface free energy and the London dispersive component of the surface free energy increases with grinding, while the polar component, first increases with grinding, and then decreases, and finally disappears. When the long-time ground sample was reheated, its total surface free energy decreases, among which the London component decreases, but the polar component appears again.

Study on adsorption of submicrometer gold on kaolinite by quantum chemistry calculations

Abstract The electronic structure and energies of Au atoms adsorbed on an atomic cluster of kaolinite were calculated using the self-consistent-field Discrete Variational (DV) method. A hexagonal ring of SiO4 tetrahedra and three AlO2(OH)4 octahedra, comprising 38 atoms, was used to model the kaolinite crystal flake. An Au atom was used to model the submicrometer Au. Calculations were performed with Au atoms adsorbed at different sites. The systems with lower total energy are those with Au adsorbed on the edge surfaces. The adsorption of Au atoms on the edges is more stable than Au atoms adsorbed on the basal plane. Bond order calculations suggest that significant shifting of atomic charge and overlap of electron clouds between Au and the surface atoms of kaolinite takes place in the systems with Au adsorbed on the edges, especially at sites near Al octahedra.

In-situ synthesis and characteristics of TiC−Fe cermet graded composite coating on a steel substrate

By means of an inherent elevated-temperature of poured liquid steel, a Ti-C-30 wt% Fe preform, which was pre-placed in a mould cavity, was directly ignited and a combustion synthesis reaction took place. As a result, a TiC−Fe cermet coating with a thickness of about 10 mm was simutaneously synthesized on the solidified steel matrix. The synthesized coating exhibits a feature of graded composite structure, in which both the amount and size of TiC particles decrease gradually with an increasing distance from the furface of the coating. Moreover, by a proper casting technique, the pores formed during the combustion synthesis of the preform could be centrally distributed in 2–3 mm in outer layer of the coating. When this outer porous layer was worn off, the rest coating with a thickness of about 8 mm possesses a dense structure and a high abrasive wear resistance.