bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Mineral Composition and Main Mineral Morphology of Bauxite from ZhongXiang, HuBei Province
Authors: Li Yan , Huang Zhao Hui , Liu Yan Gai
Published: June 2012

In this paper, the mineral composition and main mineral morphology of bauxite were studied from ZhongXiang deposit, HuBei province. Through Electron Microscope Identification, there are two main rock types, oolitic, bean-like and aphanitic or fine crystalline structure of bauxite. The main mineral morphology is micro-crystalline or flake, crumby forms. The mineral and chemical compositions of samples were investigated by XRD, EPMA analysis tests. The EPMA results showed that Al2O3 content is 47.95% ~ 75.04%, in association with other isomorphous impurities, such as Si, Fe, Ti and Mg in varying proportions. The mineral compositions of bauxite ore are mainly aluminum, iron, silicon minerals, which totally account for from 83.01% to 86.40%. The XRD revealed that diaspore, hematite and kaolinite are the major mineral components in the bauxite ores. The bauxite from ZhongXiang deposits is a type of high diaspore bauxite, partly with clay minerals. Furthermore, the function of bauxite as a good fire-resistant material was discussed.
Synthesize Ti3SiC2 from TiH2 by Pressureless Sintering
Authors: Li Liang , Zhou Ai Guo , Wang Li Bo , Hu Fei Xiang
Published: June 2012

In this paper, titanium silicon carbide (Ti3SiC2) powders were synthesized from TiH2 as Ti source by pressureless sintering in flowing argon atmosphere without preliminary dehydrogenation. Starting materials are powder mixtures with the mole ratio of 3TiH2/Si/2C or 3TiH2/SiC/C. Both kinds of starting materials were sintered in a tube furnace at the temperature range from 1300°C to 1500°C for 10~180min in flowing argon atmosphere. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the phase compositions and morphology of the products after different treatments. It was showed that almost single phase Ti3SiC2 powder (94.7 wt.%) can be synthesized by pressureless sintering from 3TiH2/Si/2C powders at 1400~1425°C for about 180min or from 3TiH2/SiC/C powders at 1425~1500°C for about 180min. From SEM micrographs, as-synthesized samples were porous. Most plate-like grains were about 5~10 μm in diameter and 1~2 μm in thickness. The speed of temperature increasing is an important factor to affect the purity of as-synthesized Ti3SiC2.
Theoretical Calculation of Crystal Cohesive Energy of (ZrTi)B2 Solid-Solutions
Authors: Li Jin Ping , Meng Song He , Liu Shi Qiang , Zhang Yu Min
Published: June 2012

The two kinds of the Ti-rich (Ti0.8Zr0.2)B2 and Zr-rich (Zr0.8Ti0.2)B2 permutation solid solutions were formed when hot pressed ZrB2 and TiB2 ceramics. On the base of the empirical electron theory (EET) of solids and molecules, the crystal bond energy of the two solid-solutions was calculated by use of Average Atom Model, Average Cell Model and Real Cell Model. In Real Cell Model, the crystal cell parameters were assumed to be unchanged and changed. The calculation results were compared among the three models. The results showed that the general trend about the deviation electrons of B element is consistent except Real Cell Model when the lattice constant is unchanged. Namely, the number of the deviation electrons in TiB2 is more than that in ZrB2.The maximum error of crystal bond energy calculated by the three models is 38KJ/mol and the relative error is less than 2%.The general trend of the crystal bond energy calculated by the three models is monotonically increased similar to the trend of melting point of these materials. Relatively speaking, the calculation of crystal bond energy calculated by Average Atom Cell Model is simpler and more reasonable.
Ablation Property of ZrB2-SiC Composite Sharp Leading Edges with Varying Radiuses of Curvature under Oxy-Acetylene Torch
Authors: He Ru Jie , Zhang Xing Hong , Hu Ping
Published: June 2012

Ablation behavior of ZrB2-SiC sharp leading edges with five different curvature radiuses was investigated using an oxy-acetylene torch. During the test, the curvature radiuses were 0.15 mm, 0.5 mm, 1.0 mm, 1.5 mm, and 2.0 mm, respectively. Under the same ablation condition, the smaller was the radius, the severer ablation underwent. The sharp leading edge with a curvature radius of 0.15 mm had the highest surface temperature and maximum surface temperature rising rate, exceeded 2100°C in less than 30 s. However, the surface of sharp leading edge with a curvature radius of 2.0 mm achieved only 1900°C in more than 60 s. After 5 min ablation, the mass and linear ablation rates were measured. All the five sharp leading edges evolved to nearly a same radius after ablation. The microstructure of the oxidation layers was also investigated. A ZrO2-SiO2 layer generated from oxidation of ZrB2-SiC acts as a thermal barrier and reduces the diffusion of oxygen.
Influence of the Content of B4C on Microstructure and Oxidation Resistance of Carbon/Carbon Composites Modified by a Sol-Gel/Solvothermal Process
Authors: Zhu Jia , Huang Jian Feng , Cao Li Yun , Wu Jian Peng
Published: June 2012

In order to improve the oxidation resistance property of carbon/carbon composites, the C/C matrix was modified with a borate sol precursor and B4C micro-powders by a sol-gel integrating with a solvothermal process. The phase compositions, surface and cross-section microstructures of the C/C matrix modified by different B4C content were particularly investigated. Results show that the surface of the modified composites is covered by a coating composed of B2O3 and B4C, meanwhile, the internal micro-holes of the C/C composites are occupied by B2O3 and B4C. After oxidation in air at 973 K, the B2O3 glassy phase, due to the oxidation of B4C, seals the cracks and holes and effectively prevents C/C composites from oxidation. The weight loss of the modified C/C composites is only 2.21 % after oxidation in air at 973 K for 20 h.
Fabrication of High Strength α-SiAlON/BN Composition Ceramics by Hot Pressing
Authors: Shan Ying Chun , Wang Guang , Ye Hui , Han Xiao Guang , Xu Jiu Jun , Li Jiang Tao
Published: June 2012

Dense Y3+-dopted α-SiAlON/BN composition ceramics was fabricated by hot pressing at 1900 °C for 60 min, and flextural strength at room and 1000 °C was investigated through three-point bending test. The results show that h-BN contribute to the densification of powder body, but h-BN have little affect on the key temperature region of sintering densification of α-SiAlON ceramics. When content of BN is lower, which didn’t affect on the phase transformation of α-SiAlON, but when content of BN is higher, besides of major phase α-SiAlON, a little of β-SiAlON was also formed. For the α-SiAlON/BN composite ceramics content of 20 wt.% h-BN, the higer flexural strength( room-temperature and 1000 °C) were abtained, the formation of β-SiAlON should be an important resonon for the higher strentgh, more important is , whose flexural strength at 1000 °C is higher 50 MPa than at room temperature, the differnce of thermal properties between SiAlON and BN should contribute to the improve of high-temperature flextural strength.
Synthesis and Characterization of Magnetite Particles by Co-Precipitation Method
Authors: Li Ming Ya , Sui Xu Dong
Published: June 2012

The Fe3O4nanoparticles with different diameters were prepared by co-precipitation method in this paper. Magnetite particles with different diameters were fabricated by changing the concentration of the reactants and the reaction temperature. The influences of process parameters on the microstructure and properties of magnetic nanopariticles were studied. The obtained samples were characterized by X-ray powder diffraction and scanning electronic microscopy. Besides, vibrating sample magnetmeter was used to characterize the magnetic properties. The results show that all the as-synthesized magnetite nanoparticles are well crystallized and can be indexed into spinel structure. The appearance and magnetism of the particles with different diameter are different from each other. When the ratio of Fe3+and Fe2+is 2:1 or 4:3, the product was pure and good crystalline. Furthermore, higher saturation magnetization was obtained in a higher bath temperature.
First-Principles Investigation of Electronic Structural and Optical Properties of Rare Earth Doped β-Si3N4 Crystals
Authors: Qiu Dong , Lu Xue Feng , Li Bai Hai , Wang Hong Jie
Published: June 2012

Based on the density functional theory within the generalized gradient approximation (GGA) method, the geometric structure, electronic and dielectric properties of rare earth (La and Y) doped β-Si3N4 were studied and the origin of the differences and similarities among the rare earths (La and Y) characterized in this work were discussed. The fully relaxed structural parameters of β-SiN4 crystal are found to be in good agreement with experimental data. The formation energy calculations indicate that both La and Y atoms are preferentially doped on the Si sites, which is in agreement with previous experimental observations. Furthermore, the calculated band gap of the doped structures decreases significantly, specifically, the larger La atom results in narrower band gap than that of Y doped β-Si3N4. The reason was extensively analyzed by the density of states (DOS). Subsequently, the dielectric function, absorption coefficient of the polycrystalline were compared with these values for plane polarized at [100] and [001] directions. The calculations show that the optical dielectric constant in the rare earth (especially La) doped structures increase remarkably, compared with the undoped β-Si4N4.
High Performance Porous Wave-Transmitting Silicon Nitride Ceramics by Gel-Casting Technique
Authors: Zhang Jian , Chen Ji Wei , Wang Hong Jie
Published: June 2012

Porous wave transmitting Si3N4 ceramics have been of great interest and technological importance in aerospace area. In this paper, the high performance wave transmitting porous Si3N4 ceramics was prepared by gel-casting method, without any pore-former. The porosity was controlled by the solid content of the slurry and the sintering temperature. The flexural strength and dielectric properties of the material were determined by three bending method and a resonant cavity method. The relationship of the dielectric constant versus the sintering temperature was discussed, and the effect of porosity on dielectric properties was investigated also. As a result, the flexural strength of the porous Si3N4 is 40-200MPa with porosity of 67-45%, dielectric constant of 2.2-3.4 in the frequency of 8GHz at room temperature. With the increase of porosity, both the dielectric constant and dielectric loss decreased. This technique is considered to be a potentially useful method to fabricate the porous ceramics with complex shape.
Thermal Expansion of Anti-Perovskite Mn3Zn1-xSnxN Compounds
Authors: Yan Xue Hua , Liu Jia Qi , Hua Zhu Yuan , Li Bing Yun , Cheng Xiao Nong
Published: June 2012

The anti-perovskite structured Mn3XN(X=Cu,Al,Ag,Zn,Ga,Sn,In) have wide perspective and practicability with unique advantages compared with other materials as a new negative thermal expansion (NTE) material. Because of its simple preparation and unique properties of NTE, this kind of compounds aroused scientists’ attention. The metallic nitrides Mn3Zn1-xSnxN (x=0.1, 0.2, 0.3, 0.4, 0.5) were prepared by solid-state sintering. The anti-perovskite compound Mn3Zn1-xSnxN has a cubic crystal structure with space group Pm3m. It shows that Zn element is partial replaced by Sn element. The Sn doping in Mn3Zn1-xSnxN compound can cause the thermal expansion behavior of the compound to change between positive and negative by analyzing the curve of thermal expansivity with the temperature. Mn3Zn0.7Sn0.3N shows a very strong NTE. Its negative thermal expansion coefficients were -4.39×10-4/K from 345.4 °C to 476.2 °C. In addition, the variation of the thermal expansion curve for Mn3Zn0.8Sn0.2N is almost negligible with the increasing of temperature to 600 °C, exhibiting nearly zero thermal expansion behavior. Therefore, the thermal expansion of Mn3Zn1-xSnxN could be tuned via different contents of Sn in Mn3ZnN.
Synthesis of Polyceriborosilazane via Substitution and Polymerization and Pyrolysis to SiBCN(Ce) Ceramics
Authors: Wang Si Hui , Wang He Yun , Meng Fan Xing , Li Ya Li
Published: June 2012

Abstract: The introduction of metal atoms into SiBCN network allows the development of novel high temperature ceramics and functional ceramics. In this work, cerium (Ce) containing polyborosilazane (PBSZ) is synthesized through substitution and polymerization reactions. Ce atoms are incorporated into PBSZ through the lithium replacement of H in PBSZ followed by Ce replacement of lithium. The chemical structure of the PBSZ and as-synthesized Li containing PBSZ are analyzed by Fourier transform infrared (FTIR) shows that the bands at 598 and 1183 cm-1 which can be assigned to Li-N and Si-N-Li stretching. It is suggested that lithium is incorporated into PBSZ. PBSZCe is transformed into SiBCNCe ceramic by pyrolysed in argon. Scanning electron microscope shows that the SiBCNCe ceramics are porous on the surface and corallike in the section. The chemical bondings of SiBCNCe ceramics are BN, the BN, SiC and Si3N4 characterized by X-ray photoelectron spectroscopy.
High Frequency Dielectric Properties and Thermal Conductivity of AlN-BN Composites by Spark Plasma Sintering
Authors: Qu Zhi Xue , Qun Wang , Cui Chang Chun , Zhang Yao Hui
Published: June 2012

AlN-BN composite is considered to be a promising material for microwave transparent applications. In this paper, a series of AlN-BN composites with various content of BN (0 wt%, 5 wt%, 15 wt% and 30 wt%) were prepared by spark plasma sintering with multiple components sintering additives at a low temperature (1650 °C), and the effect of sintering conditions and composition on the thermal conductivity and high frequency dielectric properties within frequency range from 10 MHz to 1.5 GHz was investigated. The results show that the spark plasma sintering process and the multiple components of the sintering additives promote the densification of the samples. The thermal conductivity and dielectric constant of samples decrease with increasing BN content, while the variation of the dielectric loss depends on the content of residual carbon and other impurities which may result in the relaxation loss of electronic polarization and conductive loss.
Fabrication and Properties of Al2O3-SiC/Sialon Composite Refractories
Authors: Ye Ding Yun , Liu Yan Gai , Huang Zhao Hui , Fang Ming Hao , Liu Yang Yang
Published: June 2012

Sialon powder was synthesized using low grade bauxite as raw materials by carbothermal reduction-nitridation reaction. The influence of synthesizing temperatures (1300°C, 1350°C, 1400°C, 1450°C, 1500°C and 1550°C) on the phases of the final products was studied by XRD technique. β-Sialon (Z=3) formed at 1350°C and decreased when the temperature was higher than 1450°C. The optimizing reaction temperature for preparing Sialon was 1450°C. The Al2O3-SiC/Sialon composite refractories were prepared at 200°C, 400°C and 600°C for 24h with white corundum, brown corundum, SiC, Sialon powders prepared at 1450°C and calcium aluminate cement. The bulk density, apparent porosity, water absorption and bending strength of the Al2O3-SiC/Sialon composite refractories at room temperature were studied. The results show that the bulk density decreased and then increased with the enhancing of the temperature and reached the highest value of 2.43g/cm3 at 200°C. The apparent porosity and water absorption reached the lowest values of 26.68% and 10.99% at 200°C respectively. The bending strength decreased as the temperature increased, reached the highest value of 0.73MPa at 200°C.
Ultrafine WC-Ni-SiCw Cemented Carbides Fabricated by Spark Plasma Sintering
Authors: Rong Hui Yong , Peng Zhi Jian , Ren Xiao Yong , Peng Ying , Wang Cheng Biao , Fu Zhi Qiang , Qi Long Hao , Miao He Zhuo
Published: June 2012

Ultrafine WC-Ni cemented carbides with addition of SiC whisker (SiCw) were fabricated by spark plasma sintering. The microstructure and mechanical properties of the fabricated cemented carbides were investigated. It was found that the addition of SiC whisker had no obvious influence on the phase compositions of the cemented carbides, but the mean grain size of the cemented carbides decreased as the addition fraction of SiC whisker increased. The fabricated WC-Ni cemented carbides presented the highest hardness when 0.75 wt% SiC whisker was added. However, the addition of SiC whisker was detrimental to the flexural strength of the cemented carbides because of the formation of inhomogeneous microstructure in the WC-Ni cemented carbides.
Preparation of Calcium Hexaluminate Using Al2O3 and White Beach Sand from Western Australia
Authors: Zeng Chun Yan , Huang Zhao Hui , Huang Jun Tong , Li Yan , Xu You Guo , Yi Shuai , Fang Ming Hao , Liu Yan Gai
Published: June 2012

Calcium hexaluminate (CA6) because of its high stability, high melting point and low thermal conductivity properties make it as a new high-temperature insulation materials are valued. In this paper, chemical analysis and XRD were used to investigate the composition of the white beach sand mineral from Perth coast of Western Australia. The main composition of it was carbonate. White beach sand as calcium source respectively, and industrial alumina as aluminum source synthesized CA6 at 1550°C-1650°C for 3h. The results showed that: synthetic CA6 shapes in platelet crystalline. Influence of different amounts of alumina and sintering temperature on synthesis of calcium hexaluminate are studied.The main phase of the samples with different amounts of alumina which decrease or increase 5%, 10% and 15% alumina around theory are CA6. The porosity of the samples obtained is about 53%. The bending strength of Sample S-0 of theoretical ratio values up to 7.73Mpa. Sintering temperature from 1500°C to 1650°C is not conductive to the improvement of apparent porosity of CA6 materials.
Hydrothermal Synthesis of Yttrium Hydroxide Nanotubes
Authors: Ren Hui Jun , Tan Guo Qiang , Song Li Hua , Zhang Wei , Xia Ao
Published: June 2012

Yttrium hydroxide nanotubes were synthesized by hydrothermal method using Y(NO)3•6H2O as raw materials. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the crystal phase and morphology of the as-prepared yttrium hydroxide nanotubes. In this paper, the hydrothermal temperature and the concentration of the mineralization agent were studied to have the effects on the formation of yttrium hydroxide nanotubes and their forming mechanism. The results indicate that the yttrium hydroxide nanotubes are prepared by hydrothermal method with the following optimal conditions: water as a solvent, NaOH concentration is 0.6 mol/L, the reaction temperature is 200°C, and the reaction time is 8h. In the growth process of yttrium hydroxide nanotubes, the hexagonal crystal nucleus of yttrium hydroxide is obtained first because the hexagonal crystal nucleus has the crystallization habit of growing along c axis orientationally. The yttrium hydroxide nanorods are obtained. The surface activating energy of the nanorods is stronger than that in its center. The yttrium hydroxide nanotubes are got finally.
The Effect of SiC Surface Treatment on the Interface Bonding Behavior of SiC/Cu Composite Particles
Authors: Fan Bing Bing , Guo Huan Huan , Li Jian , Wang Hai Long , Bao Ke , Zhang Rui
Published: June 2012

The SiC/Cu composite is one of the "structural-functional" materials. It shows good mechanical properties and very high thermal, high electrical conductivity etc. But the co-dispersion, wetting and bonding between SiC and Cu interface are of practical importance in the preparation of SiC/Cu composites. In this work, surface treatment techniques such as high-temperature oxidation, acid dipping and alkaline wash were adopted separately on silicon carbide particles, in order to improve the wettability and physical and chemical compatibility between silicon carbide and copper, then we used the replacement reaction method and decomposition-reduction reaction method to generate Cu coating on the surface of silicon carbide. The results shown that, the surface of silicon carbide particle which treated by alkaline wash was cleaner and more rough than that only treated by high-temperture oxidation, moreover, the specific surface of the particle was increased, which resulted in a compact layer of Cu coating. for the same silicon carbide particles, the effect of the Cu coating prepared by decomposition reaction method was better than that by reduction reaction method.
Anisotropic Mechanical and Thermal Properties of Nd2SrAl2O7
Authors: Feng J. , Huang Z.C. , Zhou R. , Pan W.
Published: June 2012

For a long time since the anisotropy basically confined to a single crystal, used as a polycrystalline ceramic materials generally considered to be isotropic. In this paper, the anisotropic mechanical, thermal expansion coefficient and thermal conductivity of a double perovskite slab-rocksalt layer Nd2SrAl2O7 was studied by first principles as an example. The method is using density functional theory (DFT) and crystal parameters, which has been used to calculate the modulus of elasticity of anisotropic in a three-dimensional space. While combined with traditional thermal conductivity theory, we have obtained the tensor of thermal diffusion, thermal conductivity in 3D space for the first time in the world within no. The results are in good agreement with the experiment. The advantage of method is avoiding the difficulty of experimental measurement, reducing the time and obtaining relatively accurate results.
Thermophysical and Mechanical Properties of Carbonated Hydroxyapatite
Authors: Zhu Qing Xia , Jiang Wei Hui , Shao Chuan , Bao Yi
Published: June 2012

The carbonated hydroxyapatite (CHA) was synthesized by precipitation-calcination method. The influences of carbonate subsitution on high-temperature sintering, thermal expansion coefficient (CET) and flexural strength were investigated by the high-temperature dilatometer, scanning electron microscopy (SEM) and universal testing machine. The results showed that the sintering temperatures of CHA were related to the initial carbonate contents. The sintering temperature decreased with increasing initial carbonate contents. The CET of CHAs decreased with the increase of carbonate content, due to the stoma caused by the partially decompostion of CHAs. The CHA ceramics tested were as strong in flexure strength when compared to non-carbonated hydroxyapatite.
Preparation of Light-Weight Forsterite Insulation Materials Through Extrusion Processing
Authors: Yang Li , Li Yuan Bing , Ma Ming Jun , Zhao Lei , Jiang Mei , Li Ya Wei , Li Shu Jing
Published: June 2012

Light-weight insulation materials were prepared by extrusion processing using forsterite raw tailings, light-burned magnesia and fused magnesia as main raw materials with addition of rice hull powder as a pore-forming agent. The results show that the plasticity of green compact and the cold compressive strength of bricks are improved with the addition of 2-3 wt% dextrin as plasticizer. Light weight insulation materials, which meet different application requirements, were prepared by controlling the addition amount of rice hull powder by firing at 1550 °C with volume weight of obtained materials varies from 1.4-1.8 g/cm3, thermal conductivity at 600 °C is less than 0.48 W/(m•K), cold compressive strength varies from 8-24MPa and reheating linear change rate is less than 1% (1400°C × 6h).
Structure and Electrochemical Performance of Modificated LiMn2O4 by S-Co Codoping and Nano SiO2 Surface Coating
Authors: Fan Xue Feng , Zhao Shi Xi , Li Long , Nan Ce Wen
Published: June 2012

In this paper, to improve the elevated temperature performance of spinel LiMn2O4 as cathode materials, the cation/anion co-doping and surface modification together were adopted. The SiO2 coated Li1.02Co0.1Mn1.9O4−xSx spinels were synthesized by the solid-state reaction method and Sol-gel coating process. The samples are characterized by XRD, SEM, galvanostatic charge-discharge. The results show that the Li1.02Co0.1Mn1.9O3.98S0.02 exhibits the best initial discharge capacity of 122mAh/g, and capacity retention rate gets to 92% after 100 cycles at room temperature (25 °C). The substitution of Co and S for Mn and O in LiMn2O4 can enhance the crystal structure stability and overcomes the Jahn-Teller distortion, but cannot resolve the elevated temperature cycling issue of the spinel cathode materials. The capacity loss of Li1.02Co0.1Mn1.9O3.98S0.02 without SiO2 coating gets to 38% after 50 cycles, whereas the 2.0wt.% SiO2-coated Li1.02Co0.1Mn1.9O3.98S0.02 cathode material has only 5.0% capacity loss after 50 cycles at elevated temperature (55°C). It indicates that nano SiO2 coating could suppress Mn dissolution in the electrolyte during cycles. So combining cation/anion co-doping and surface modification is best way to improve the elevated temperature cycling performance of spinel LiMn2O4 as cathode materials.
LiFePO4/Porous Carbon Nanocomposite Cathode Material for Lithium Ion Batteries
Authors: Liu Jin Kun , Fan Li Zhen
Published: June 2012

A LiFePO4/porous carbon nanocomposite was synthesized by using spontaneous precipitation combined with solid-state reaction. The microstructure, morphology and electrochemical properties of as-prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), differential thermal analysis (TGA) and charge-discharge cycling tests. The results reveal that LiFePO4 particles are well-dispersed into porous carbon framework. The initial discharge of nanocomposite is 143 mAh g-1 at 0.1 C and 114 mAh g-1 at 1 C with satisfactory capacity retention. The superior electrochemical performance of the composites can be attributed to the nano-confined effect of conducting porous carbon and the nano-size of LiFePO4 particles in LiFePO4/porous carbon nanocomposite.
Effect of Nanocomposite Additives on Corrosion Inhibition of Zn Anode in Neutral Solution
Authors: Li Hong Fei , Li Bao Hua , Xu Cheng Jun , Wei Chun Guang , Kang Fei Yu
Published: June 2012

Effects of hexadecyl trimethyl ammonium bromide (CTAB), polyethylene glycol nanowire (NPEG) and their nanocomposite additives on corrosion inhibition of Zn in 1 mol/L ZnSO4 solution were investigated by weight-loss measurements, electrochemical tests，scanning electron microscopy and battery discharge tests. The results show that the inhibition efficiency of nanocomposite additives is 70%, which is much higher than individual inhibitors of CTAB or NPEG alone, because of the notable synergistic effect between CTAB and NPEG. While CTAB can cause a negative shift of corrosion potential of zinc, NPEG can form a very thick hydrophobic layer on the surface of zinc electrode by adsorption. Furthermore, NPEG can render part of CTAB cations to form large micelle particles along the NPEG macromolecular chains and cross-link with NPEG, and thus greatly enhance the blocking effect of the hydrophobic layer. Therefore，the corrosion inhibition efficiency of the composite additives is much higher. The battery containing 0.05% CTAB and 0.05% NPEG performs better than the batteries with individual additives, especially at high discharge current rate.
Ordered Macroporous Carbon/Polyaniline Nanocomposites as Electrode Materials for Supercapacitors
Authors: Qiao Su Yan , Fan Li Zhen
Published: June 2012

Polyaniline (PANI) and ordered macroporous carbon (C80) composites were prepared via a simple and speedy polymerization of aniline in the presence of C80. The effect of PANI content on the electrochemical properties was studied in detail. The morphologies were manifested through field emission scanning electron microscopy (FE-SEM), and the electrochemical properties were investigated by cyclic voltammetry (CV), galvanostatic charge-discharge and impedance in 1 mol/L H2SO4. The results indicate that the polymerization of aniline occurred in the pores of carbon, and as the aniline content increased, more polyaniline was synthesized in the pores. When the PANI content was 43 wt%, the specific capacitance of the composite was as high as 368.7 F/g at a current density of 0.06 A/g, which was 2.6 times higher than that of the host C80 (140 F/g).
Effects of Zinc Content on the Magnetic Properties of Ni-Zn Ferrite/Epoxy Composites
Authors: Wu Yan Min , Zhu Peng Li , Sun Rong
Published: June 2012

Magnetic composites, especially ferrite composites, are of great interest for embedded inductor applications. In this paper, the Ni-Zn ferrite particles (Ni1-xZnxFe2O4, x=0.2～0.8) with different zinc contents were synthesized via chemical coprecipitation method followed by modification with γ-glycidoxypropyl trimethoxysilane (KH-560). The particles were investigated by X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The results show that the prepared Ni1-xZnxFe2O4(x=0.2～0.7) have good spinel structures, higher saturation magnetization (35.18～77.69 emu/g) and smaller hysteresis hoops, while Ni0.2Zn0.8Fe2O4 grains exhibit some paramagnetic behaviors, such as almost zero hysteresis and non-saturated magnetization. Next Ni1-xZnxFe2O4 magnetic/epoxy composites with different volume fraction of ferrite were prepared and their magnetic performances at high frequencies were characterized by an Agilent E4991A impedance analyzer (USA). It is found that with zinc content in Ni1-xZnxFe2O4 increasing from 0.2 to 0.7, the real part of the complex permeability (μ′) of these composites increase first and then decrease with the frequency increasing gradually from 10 MHz to 1 GHz. Of all, the epoxy composites with filler of Ni0.6Zn0.4Fe2O4 or Ni0.5Zn0.5Fe2O4 ferrite show good frequency stability, and the composites including Ni0.4Zn0.6Fe2O4 ferrite have the highest permeability, and the maximal value at the frequency of 100 MHz is 5.55 when the volume faction is 42.75%. The imaginary part of the complex permeability (μ′′) of all magnetic composites is low For the Ni0.2Zn0.8Fe2O4/epoxy composites, they have very low real permeability (μ′～1) and imaginary permeability (μ″≤0.2).
Research on Chemical Transformation of Diamond with Fe Catalysis Based on Thermal Analysis
Authors: Zou Lai , Dong Guo Jun , Zhou Ming
Published: June 2012

It is known that diamond is not suitable for cutting of ferrous metals, ascribed to serious tool wear occurred in machining process. For the sake of studying the tool wear mechanism further, this paper presents thermal analysis method to discuss the chemical transformation of diamond with Fe catalysis. Raman scattering experiment was performed to identify the transformation of crystal structure of the diamond specimens. The surface wear morphology of workpiece was detected by scanning electron microscopy, and energy dispersive X-ray analysis was used to study the change of chemical composition. Experimental results revealed the law of graphitization and diffusion of single crystal diamond at elevated temperature in different gas environment.
Research on the Method of Error Prediction in Milling Thin-Walled Impeller Blade
Authors: Liu Zhi Gang , Qi Hou Jun , Cai Yu Jun
Published: June 2012

The thin-walled blade of aero engine has low stiffness, during machining, it easily generates deflection due to the milling force, but because high accuracy of such component is required, the prediction of the deflection exactly becomes extremely important. Therefore, this paper analyzes the milling process, and simplifies it reasonably. The deformation of the blade is predicted based on ABAQUS using FEM, and then the machining deflection curves of the blade is got. The result is analyzed soon afterwards, and deflection law is summarized. Finally, an experiment has been designed. The reliability of the method of predicting deflection is proved by comparing the measurement results and the simulation ones.
Determination of Constitutive Equation Parameters for Face Milling 3-D Simulation via Pressure Bar and Orthogonal Cutting Tests
Authors: Liu Sha , Zhang Jian Fu , Feng Ping Fa , Yu Ding Wen , Wu Zhi Jun
Published: June 2012

Material constitutive equation plays an important role in Finite Element Analysis (FEA) of metal cutting process. This paper proposes a method to obtain parameters for Power Law model of a Japanese type of alloy steel (SCM440H) for 3-D FEA of face milling process, involving pressure bar experiments and orthogonal metal cutting experiments. Since pressure bar test cannot reach the high strain rate occurred in cutting process, orthogonal cutting experiment was combined to obtain parameters for material model. By this method, the ideal parameters for FEA of the face milling process were finally determined. Face milling experiments were performed to verify the accuracy of the model built.
Tool Path Planning of 5-Axis Finishing Milling Machining for Closed Blisk
Authors: Huang Jiu Chao , Liu Xian Li , Yue Cai Xu , Cheng Yao Nan , Zhang Hui
Published: June 2012

To solve the difficult problem of NC machining of closed blisk, the paper combines with the structure characteristics of processing surface and the characteristics of Channel processing, and at the same time to study the technology of processing impeller channel tool path planning. By planning different processing methods of tool axis control for different processing parts, take outer arc processing as an example, tool path planning method is analyzed. By the method to generate the ruled envelope surfaces in view of blade offset surfaces, to put forward new methods of dividing plunging region. The method of surface offset was applied to determine the safety space of tool axis movement. To determine the range of tool axis angle by the relationship between the boundary curves and division the processing area by the tangent method. Finally, The results of tool path planning were verified by using five-axis processing, which proved the reasonability and feasibility of the scheme.
Investigation into Roughness of Surface Polished by Abrasive Waterjet with Taguchi Method and Dimensional Analysis
Authors: Chen Tian Xiang , Wang Cheng Yong
Published: June 2012

Abrasive water jet was utilized to polish the 40CrMnMo7 mold steel and BK7 glass in this experiment designed by Taguchi method. The influence of polishing parameters on the polishing quality, their significance order, and the optimum polishing parameters were analyzed and reported. With the experimental data, the mathematic molds of surface roughness of polished workpieces were created by dimensional analysis, and then they were validated by the test experiment.
The Optimization of Cutting Parameters for Surface Roughness in High Speed Milling Based on Taguchi Method
Authors: Li Peng Nan , Chen Ming , Kang Xiao Jian , Zhang Li Na , Zhou Ming
Published: June 2012

In this study AISI 1045 steel of different hardness are used in high speed milling. According to Taguchi method, cutting parameters (milling speed, milling depth, feed per tooth) and workpiece hardness for the influence of high speed milling of the surface roughness are optimized. Through this study, not only the optimal cutting parameters of the minimum surface roughness is obtained, but also the main cutting parameters that effect performance in high speed milling is analysed. Researching results can be provided to guide establishment of the high speed milling process.
Influence of Milling Parameters on Surface Residual Stresses of 7050-T7451 Aluminum Alloy
Authors: Wan Yi , Li Chen , Liu Zhan Qiang , Sun Shu Feng
Published: June 2012

Residual stresses generated in milling process affect the performance of machined components. Milling residual stresses correlate closely with the cutting parameters. In this paper, the generation and distribution of surface residual stresses in milling of aluminum alloy 7050-T7451 was investigated. The cutting speed changes from 300m/min to 3000m/min. In the experiments, the residual stresses on the surface of specimen are detected by X-ray diffraction technique. The result shows that compressive residual stresses are generated when cutting speed is under 500 m/min. In feed and its orthogonal direction, the effect of cutting speed and feed rate on residual stresses is similar. The formation of the residual stresses can be explained by thermo-mechanical coupling effects.
Effect of (Ni,Mo) and (W,Ti)C on the Microstructure and Mechanical Properties of TiB2 Ceramic Tool Materials
Authors: Yang Tong Chun , Huang Chuan Zhen , Liu Han Lian , Zou Bin , Zhu Hong Tao , Wang Jun
Published: June 2012

TiB2-(W,Ti)C composites with (Ni,Mo) as sintering additive have been fabricated by hot-pressing technique, and the microstructure and mechanical properties of the composites have been investigated. (Ni,Mo) promotes grain growth of the composites. In the case of 7vol.% (Ni,Mo), the grain size decreases consistently with an increase in the content of (W,Ti)C. When the proper content of (W,Ti)C is added to TiB2 composites, the growth of matrix grains is inhibited and the mechanical properties of the composites are improved. The best mechanical properties of the composites are 1084.13MPa for three-point flexural strength, 7.80MPa•m 1/2 for fracture toughness and 17.92GPa for Vickers hardness.
A Computer-Based Intelligent System for Automatic Tool Selection
Authors: Ren Xiao Ping , Liu Zhan Qiang , Wan Yi
Published: June 2012

Tool selection is one of the most significant process considerations when deciding how a machined product will be manufactured. The tool selection activity is rooted in feature geometry but it also has a direct impact on machinability and machine tool performance. This paper presents a computer-based intelligent system for the automatic selection of cutting processes and tools. The main objective of the research work was to develop a procedure for the selection of cutting tools and cutting parameters. This will help the designers and manufacturing planners to select an optimal set of cutting tools and cutting conditions for different material properties and to give users alternatives on how to reduce cost and time.
Preliminary Study on Carbon Fibre Composites Cutting Technology and Cutting Tools
Authors: Shi Run Ping , Wang Cheng Yong , Wang Xi
Published: June 2012

Carbon fiber reinforced plastics (CFRP)/Ti super hybrid laminates are newly developed structural materials with excellent properties. But they are restricted in aircraft manufacturing because of their poor machining quality and short tool life. The machining quality and tool life are determined by machining ways, tool materials, drill point forms and drilling sequence. Spiral milling, drilling from Ti side, using the PCD tools and carbide drills with special point angle can improve the quality of hole and prolong tool life.
Development of Al2O3/TiC/CaF2 Graded Self-Lubricating Ceramic Cutting Tool Materials
Authors: Wu Guang Yong , Xu Chong Hai , Zhang Yong Lian , Yi Ming Dong
Published: June 2012

The design concept of functionally graded materials was first introduced into the development of self-lubricating ceramic cutting tool materials. An Al2O3/TiC/CaF2graded self-lubricating ceramic cutting tool material was designed and fabricated. Mechanical properties were evaluated by comparing with those of Al2O3/TiC/CaF2homogeneous self-lubricating ceramic cutting tool material. The results showed that the Al2O3/TiC/CaF2graded self-lubricating ceramic cutting tool material had superior performance to the counterpart. Graded self-lubricating ceramic cutting tool materials are bound to have promising prospect in the field of high speed dry machining.
Research on NC System of Flame Cutting Machine Based on Trio Motion Control Card
Authors: Zhang Sheng Fang , Wang Yi , Mao Jun Feng , Wang Wei Guo , Sha Zhi Hua
Published: June 2012

An open architecture NC system of flame cutting machine applied in auto white-body welding line manufacturing is developed in this paper. The general planning and the composition of the NC system is presented based on IPC and Trio MC206 motion card, the hardware and software of the control system are designed detailedly. IPC management software developed by using C# language in Visual Studio 2008 and rock-bottom control program of Trio control card developed in Motion Perfect2 are realized. The application results show that the NC system of flame cutting machine is reliable and stable which can meet the requirements of auto white-body manufacturing perfectly.
Research on the Effect of Low Temperature on the Performance of Drilling Carbon Fibre Reinforced Polymer and Ti Stack Materials
Authors: Wang Xi , Wang Cheng Yong , Shi Run Ping , Song Yue Xian , Hu Ying Ning
Published: June 2012

The thermal conductivity of carbon fiber reinforced polymer(CFRP) and titanium alloy is lower which caused the increasing of drilling temperature and larger tool wear resistance. The low temperature air is aided for the drilling of laminated stack board of CFRP/Ti with double apex angles carbide drill at different feed rate. The drilling force and the quality of hole are analyzed. The results showed that the low temperature air can reduce the tool wear and the thrust force effectively.
Experimental Investigations of Size Effect on Cutting Force, Specific Cutting Energy, and Surface Integrity during Micro Cutting
Authors: Zhang Tao , Liu Zhan Qiang , Xu Chong Hai , He Ning , Li Liang
Published: June 2012

Micro cutting is a promising technology to manufacture the micro parts. The shear mechanism of micro cutting is different from the conventional cutting due to the round cutting edge. The ratio of uncut chip thickness to cutting edge radius plays an important role on the micro cutting process. This paper investigates the size effect phenomena of micro cutting. Firstly, the cutting force and size effect of specific cutting energy depending on the ratio of uncut chip thickness to cutting edge radius are analyzed according to the experimental results. Then, the size effect of surface roughness due to the size effect of specific cutting energy is explored. Lastly, the size effect of the exit burr height is depicted and the potential reason is analyzed. The paper supplies a good understanding of how to get the best surface integrity and minimize the exit burr height for micro cutting.
Experimental Study on Cutting Force of High-Speed Micro-Drilling Flexible Printed Circuit Board
Authors: Zhang Xin , Wang Cheng Yong , Zheng Li Juan , Wang Lin Fang , Song Yue Xian
Published: June 2012

Cutting force is one of the most important parameters in the drilling process of FPC (Flexible printed circuit board). It has a directly affect on the micro-drills’ life and the micro-holes quality. It causes the FPC delamination, pulling of the plastic, the burr of exit hole and other processing defects. In this paper, some experimental investigations of cutting force of high speed micro-drilling are carried out to improve the drilling quality of FPC. The results indicate that the drilling parameters(spindle speed, feed speed and drill-bit diameter) have significant influence on micro-drilling thrust force. The thrust force of drill copper foil is larger than the thrust force of drill adhesiver layer and the thrust force of drill PI layer is the smallest. The larger the thrust force is, the bigger the exit burr is.
Analytical Modeling to Predict Adiabatic Shear Critical Condition for Orthogonal Cutting
Authors: Yang Qi Biao , Liu Zhan Qiang , Shi Zhen Yu
Published: June 2012

As the deformation of chip increases with cutting speed, the morphology of chip changes from continuous to serrated type. It is supposed that serrated chips generate due to adiabatic shear instability in the primary deformation zone. A new analytical model for predicting adiabatic shear critical condition in orthogonal cutting is proposed by considering cutting conditions and properties of workpiece material. It is found that the influence of shear strain on the onset of adiabatic shear could be neglected. The shear strain rate and temperature, however, play a leading role on the onset of adiabatic shear. At lower cutting speed the shear strain rate plays a dominant role while at higher cutting speed the situation is just the reverse. With the increase of cutting speed, the yield stress, material characteristic constant and uncut chip thickness will facilitate adiabatic shear instability, while the coefficient of strain rate hardening, coefficient of strain hardening, coefficient of thermal softening, thermal diffusivity and tool rake angle have negative effect on adiabatic shear instability.
Load Distribution Balance Principle of Petroleum Buttress Casing Thread and its NC Machining Method
Authors: Wang Xiao Wei , Guo Pei Quan , Zhao Lian Yi , Zhang Pu
Published: June 2012

The force of each API standard buttress casing thread teeth under axial tension is uneven, so the bearing capacity of this kind of thread is seriously restricted. On the basis of structural characteristics, mechanical model of the casing thread under axial tension is established and the loading and deforming features of thread teeth are analyzed. Based on this, to improve force distribution of casing thread, the designing method of multi-segment variable pitch thread is put forward and NC machining method of variable pitch thread with equal tooth thickness is presented.
Experimental Study on Water-Jet Guided Laser Machining Magnesium Alloy
Authors: Li Chun Qi , Yang Li Jun , Wang Yang
Published: June 2012

Drilling and cutting experiments in magnesium alloy sheet were conducted using water-jet guided laser. Morphology characteristics in processing areas were analyzed and compared with that of the conventional laser processing. The results show the processing areas are clean, with almost no molten residues attached and negligible heat damage in water-jet guided laser processing. The hole walls and cut surfaces are smooth and have some degree of slope, and are completely covered with dense protruding particles at microcosmic scale. However, with conventional laser, the processed areas are attached with a large number of residues, and obvious secondary solidified layers.
Study on Drilling Force of Carbide Drill with Different Edge Preparation
Authors: Liu Gang , Mao Zhe Xi
Published: June 2012

The carbide drills with different edge preparation were used for drilling of 40Cr. The influence of drilling speed and amount of feed on drilling forces has been studied by the single factor experiment. The conclusions indicated: when the feed went bigger, the drilling forces of the polished drills were lesser than unpolished drills for un-coating drills; but for coating drills, the drilling forces of the polished drills were greater than unpolished drills. With the increase of cutting speed, drilling forces of un-coating drills mounted up first but went down afterward; and the drilling forces of coating drills increased monotonously.
Experimental Analysis on Spherical Chips in High-Speed Machining of Hardened AerMet100
Authors: Su Guo Sheng , Liu Zhan Qiang
Published: June 2012

Spherical chip appears frequently in high speed grinding of metals. It is attributed to the melt or oxidation of the small chips in grinding. Spherical chip in machining of steels is observed when the cutting speed is high enough. To clarify the formation mechanism of spherical chip in metal cutting, high speed machining of AerMet100 at cutting speeds from 40 m/min to 3000m/min was investigated. Spherical chip of AerMet100 was obtained at cutting speed range 2000-3000m/min. Optical and SEM (Scanning Electron Microscope) observations of the spherical chip was carried out. The chemical composition of the spherical ship was analyzed through X-ray energy dispersive spectroscopy (XEDS) analysis. The formation mechanism of the spherical chip was proposed. The results showed that the spherical shape of chip is due to the intense reaction between Fe of workpiece and O2 in the air accompanying which large mount of heat is released to melt the oxide into small spheres. The formation of the spherical chip is highly influenced by cutting speed and the size of the chip (surface-volume ratio).