磁性纳米颗粒膜微波物性研究

采用磁控溅射工艺和复合靶技术制备FeCoB-SiO2磁性纳米颗粒膜;利用X射线衍射仪、扫描探针显微镜分析这类薄膜的微结构和形貌特征;采用振动样品磁强计、四探针法、微波矢量分析仪及谐振腔法测量薄膜试样的磁电性能和微波复磁导率;重点对SiO2介质相含量、薄膜微结构对电磁性能产生重要影响的机理做了分析和探讨.结果表明,这类FeCoB-SiO2磁性纳米颗粒膜具有良好的软磁性能和高频电磁性能,2GHz时,磁导率μ＞50,可以应用于高频微磁器件中.

Fe_(95)Nd_5合金微波物性研究

采用高频熔炼、快淬甩带和高能球磨的方式制备了Fe95Nd5合金,并通过控制球磨时间来调控合金粉末的微波物性。结果表明:长时间球磨可以减少合金中α-Fe的晶粒尺寸,使其自然共振频率向低频偏移,从而能够提高其低频的磁损耗μ",采用这种后处理工艺可以获得低频高损耗微波吸收材料。

缺铁BaZn_xCo_(2-x)Fe_(155)O_(27)W型铁氧体微波物性研究

采用缺铁配方BaZn_xCo_(2-x)Fe_(15.5)O_(27)制备W型六角铁氧体材料,并深入研究了Zn含量以及铁氧体复合物浓度对材料的微波介电特性和磁特性的影响。结果表明,通过控制Zn含量和浓度可以有效调控铁氧体介电常数的大小以及共振频率的高低,为铁氧体材料的微波应用提供了研究基础。

Carburization of ferrochromium metals in chromium ore fines containing coal during voluminal reduction by microwave heating

Chromium ore fines containing coal (COFCC) can be rapidly heated by microwave to conduct the voluminal reduction, which lays a foundation of getting sponge ferrochromium powders with a lower content of C. Under the conditions of COFCC with n(O)-n(C) (molar ratio) as 1.00-0.84 and n(SiO2)-n(CaO) as 1.00-0.39, the samples were heated by 10 kW microwave power to reach the given temperatures and held for different times respectively. The results show that the low-C-Cr ferrochromium metal phase in the reduced materials forms before the high-C-Cr ferrochromium metal phase does. With increasing temperature the C content of ferrochromium metals is in a positive correlation with the content of Cr. The C content of ferrochromium metal in reduced materials is 0-10.07% with an average value of 4.68%. With the increase of holding time the Cr content in ferrochromium metals is in a negative correlation with the content of C, while the content of Fe changes in the contrary way. In the microwave field the kinetic conditions of carburization are closely related with the temperature of microwave heating, holding time and carbon fitting ratio.

Understanding the influence of microwave on the relative volatility used in the pyrolysis of Indonesia oil sands

In this paper, pyrolysis of Indonesian oil sands （lOS） was investigated by two different heating methods to develop a better understanding of the microwave-assisted pyrolysis. Thermogravimetric analysis was conducted to study the thermal decomposition behaviors of lOS, showing that 550 ℃ might be the pyrolysis final temperature. A explanation of the heat-mass transfer process was presented to demonstrate the influence of mi- crowave-assisted pyrolysis on the liquid product distribution. The heat-mass transfer model was also useful to explain the increase of liquid product yield and heavy component content at the same heating rate by two differ- ent heating methods. Experiments were carried out using a fixed bed reactor with and without the microwave irradiation. The results showed that liquid product yield was increased during microwave induced pyrolysis, while the formation of gas and solid residue was reduced in comparison with the conventional pyrolysis. Moreover, the liquid product characterization by elemental analysis and GC-MS indicated the significant effect on the liquid chemical composition by microwave irradiation. High polarity substances （ε 〉 10 at 25 ℃）, such as oxy- organics were increased, while relatively low polarity substances （ε 〈 2 at 25℃）, such as aliphatic hydrocarbons were decreased, suggesting that microwave enhanced the relative volatility of high polarity substances. The yield improvement and compositional variations in the liquid product promoted by the microwave-assisted pyrolysis deserve the further exploitation in the future,

Synthesis, characterization and bioactivity evaluation of diallyl disulfide

Diallyl disulfide was synthesized by phase transfer catalyst （PTC） during microwave irradiation. The effects of different factors, such as the power of microwave irradiation, the time of microwave irradiation, PTC reagents amount and the mole ratio of reactants, on the yield of product were investigated. The structure of diallyl disulfide was characterized by infrared spectra, mass spectra and ^1 H nuclear magnetic resonance. The bioactivity of diallyl disulfide was evaluated by cell viability assay on HepG2 hepatoma cells. The results show that the optimal reaction conditions are as follows： tetrabutylammonium bromide（TBAB） selected as a PTC, the mass ratio of TBAB to sodium disulfide of 0.021 ： 1, the power of irradiation of 195 W, the reaction time of 12 rain, and the mole ratio of sodium disulfide to allyl chloride of 0.65 ： 1. The yield of diallyl disulfide is 82.2%. The synthetical diallyl disulfide appears to be cytotoxic to HepG2 heoatoma cells in a dose-dependent manner.

Impact of ultrasonic power on liquid fraction,microstructure and physical characteristics of A356 alloy molded through cooling slope

This study involves A356 alloy molded through ultrasonically vibrated cooling slope.The slope alongside ultrasonic power enables indispensable shear for engendering slurry from which the semisolid cast/heat treated billets got produced.An examination demonstrates ultrasonically vibrated cooling slope influencing the liquid fraction/microstructure/physical characteristics of stated billets.The investigation encompasses five diverse ultrasonic powers(0,75,150,200,250 W).The ultrasonic power of 150 W delivers finest/rounded microstructure with enhanced physical characteristics.Microstructural modifications reason physical transformations because of grain refinement and grain boundary/Hall-Petch strengthening.A smaller grain size reasons a higher strength/shape factor and an increased homogeneity reasons a higher ductility.Microstructural characteristics get improved by reheating.It is owing to coalescence throughout temperature homogenization.The physical characteristics is improved by reheating because of a reduced porosity and enhanced dissolution besides augmented homogeneity.A direct comparison remains impossible owing to unavailability of researches on ultrasonically vibrated cooling slope.

Microwave absorbing properties of high titanium slag

Microwave absorbing properties of high titanium slag were investigated by using microwave cavity perturbation technique. High titanium slag containing more than 90% TiO2 was prepared by carbothermal reduction of ilmenite. The temperature rise curve of high titanium slag in microwave heating process was obtained. Crystalline compounds of high titanium slag before and after microwave irradiation were obtained and characterized by X-ray diffractometry （XRD）. Effects of particle size of high titanium slag anal mixtures of high titanium slag with different mass fractions of V2o5 on microwave absorbing properties were investigated systematically. The results show that high titanium slag has good microwave absorption property; untreated high titanium slag mainly consists of crystalline compounds of anatase and iron titanium oxide, while the microwave-irradiation treated one is mainly composed of crystalline compounds of rutile and irgn titanium oxide. Synthetic anatase is transformed completely into rutile at about 1 050 ℃ for 20 min under microwave irradiation. High frequency shift and low amplitude of voltage make high titanium slag an ideal microwave absorbent. 180 μm of particle size and 10% mass fraction of V2O5 are found to be the optimum conditions for microwave absorption.

Effect of Microwave Radiation on Dielectric Behavior of Two Vegetable Oils

The effect of microwave （MW） heating on the dielectric properties and oxidation processes of virgin olive oil and refined sunflower oil were determined by dielectric and UV- spectroscopy. Samples were heated in the microwave oven （850 W, 2.450 MHz） for 0 to 14 minutes. The results show degradation of dielectric characteristics, conductivity and oxidative stability of investigated oils, increasing with the exposure time. UV spectrum shows only one defined peak at 206 nm for olive oil confirming the dominant presence of monounsaturated fats and four peaks for sunflower oil （203 nm, 230 nm, 269 nm and 278 nm） dependent on polyunsaturated acid fats contents. Increasing of absorbance at all peak wave lengths indicates production of lipid oxidation, due to formation of conjugated monoenes and dienes and in small amounts due to trienes and secondary products like ketoaldehydes. Dielectric constant for olive oil is stable and almost unchangeable with MW radiation while sunflower oil＇s c＇ oscillates around the origin value in greater rate. Dielectric loss e＂ decreases with increasing time of MW radiation and its maximum shifts towards higher frequencies for sunflower oil indicating shortening of the relaxation times, while for olive oil it is unchanged. Cole-Cole analysis show the presence of only one relaxation process in the oils. Conductivity of oils is increasing in similar way with increasing frequency following the Jonscher＇s power law and is not changed with MW exposure time. Olive oil has conductivity higher for four orders of magnitude than sunflower oil, which is connected to the high content of monounsaturated fats. The differences between sunflower and olive oil characteristics are discussed.

Complex Research of Using Microwave in Processing Grains and Plants Materials for Agriculture

It is observed contamination and subsequent growth of various types of mycotoxins in the production and processing of grain and non-grain crops. The contamination of grain and non-grain cereals crops harvest was analyzed. The aim of this research is using of microwave energy to disinfect grains of harvest and giving new properties to the grains and plants materials. The author has presented researches of the grains disinfection, during seedbed preparation and post processing. Rational parameters of heating rates of different biological objects were identified, revealed their dependence and impact on infection pathogens, through using of microwave energy technology. The author found a reduction of the number of pathogenic microbes and organisms at the various stages of processing agricultural products during using of microwave energy, and found new qualitative indicators of the products properties.

Fe4N粉体的制备与微波特性研究

在400-550℃采用渗氮工艺氮化羰基铁粉制备出纯相微米级Fe4N粉末,并研究它的静磁和微波特性。结果显示,Fe4N饱和磁化强度达到193emu/g,85%质量浓度的Fe4N复合物的磁导率实部和虚部均略高于羰基铁粉,而介电性能和羰基铁粉基本相当,由此导致在2-18GHz频段内Fe4N的吸收峰处于比羰基铁复合物更低的频率。对羰基铁粉和Fe4N粉末在350℃进行磁场退火半小时,退火后Fe4N吸波性明显优于羰基铁粉,说明Fe4N有更好的温度稳定性。

Fe4N粉体的制备与微波特性研究

在400—550℃采用渗氮工艺氮化羰基铁粉制备出纯相微米级Fe4N粉末，并研究它的静磁和微波特性。结果显示，Fe4N饱和磁化强度达到193emu／g，85％质量浓度的Fe4N复合物的磁导率实部和虚部均略高于羰基铁粉，而介电性能和羰基铁粉基本相当，由此导致在2—18GHz频段内Fe4N的吸收峰处于比羰基铁复合物更低的频率。对羰基铁粉和Fe4N粉末在350％进行磁场退火半小时，退火后Fe4N吸波性明显优于羰基铁粉，说明Fe4N有更好的温度稳定性。

Preparation and bioactive surface modification of the microwave sintered porous Ti-15Mo alloys for biomedical application

Biomedical porous Ti-15 Mo alloys were prepared by microwave sintering using ammonium hydrogen carbonate（NH4HCO3） as the space holder agent to adjust the porosity and mechanical properties. The porous Ti-15 Mo alloys are dominated by β-Ti phase with a little α-Ti phase, and the proportion of α and β phase has no significant difference as the NH4HCO3 content increases. The porosities and the average pore sizes of the porous Ti-15 Mo alloys increase with increase of the contents of NH4HCO3, while all of the compressive strength, elastic modulus and bending strength decrease. However, the compressive strength, bending strength and the elastic modulus are higher or close to those of natural bone. The surface of the porous Ti-15 Mo alloy was further modified by hydrothermal treatment, after which Na2Ti6O13 layers with needle and flake-like clusters were formed on the outer and inner surface of the porous Ti-15 Mo alloy. The hydrothermally treated porous Ti-15 Mo alloy is completely covered by the Ca-deficient apatite layers after immersed in SBF solution for 14 d, indicating that it possesses high apatiteforming ability and bioactivity. These results demonstrate that the hydrothermally treated microwave sintered porous Ti-15 Mo alloys could be a promising candidate as the bone implant.

The measurement and model construction of complex permittivity of vegetation

The complex permittivity of targeted objects is an important factor that influences its microwave radiation and scattering characteristics.In the quantitative research of microwave remote sensing,the study of the dielectric properties of the vegetation to establish the relationship between its specific physical parameters and complex permittivity is fundamental.In this study,six categories of vegetation samples were collected at the city of Zhangye,a key research area of the Heihe watershed allied telemetry experimental research.The vector network analyzer E8362B was used to measure the complex permittivity of these samples from 0.2 to 20 GHz by the coaxial probe technique.The research focused mainly on the corn leaves,and an empirical model was established between the gravimetric moisture and the real/imaginary parts of complex permittivity at the main frequency points of microwave sensors.Furthermore,the empirical model and the classical Debye-Cole model were compared and verified by the measured data collected from the Huailai County of Hebei Province.The results show that the newly- established empirical model is more accurate and more practical as compared to the traditional Debye-Cole model.