bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Al and Si Additions on the Synthesis of Spark Plasma Sintered Zr2Al4C5 Creamic
Authors: Guo Q.L. , Pei Jun Jun , Gan Ji Zhong , Li Jun Guo , Zhang Lian Meng
Published: July 2016

The Zr2Al4C5 ceramic was successfully fabricated by the spark plasma sintering at 1800 °C for 10 min under uniaxial 20 MPa pressure in vacuum using a mixed raw materials of Zr, Al, Si and graphite powders. The X-ray diffraction analysis results showed that the unexpected Zr2Al3C5 phase rather than target compound Zr2Al4C5 formed in the sintered samples. An initial Zr:Al:C molar ratio of 2:4.2:4.8 for raw powders, and even 55 mol.% excess Al, did not lead to a phase transformation from Zr2Al3C5 to Zr2Al4C5. When 4 wt.% Si was induced in the starting powders, the major phase became Zr2Al4C5 and no obvious Zr2Al3C5 was detected in the sintered samples with an initial Zr:Al:C molar ratio of 2:6.2:4.8 (55 mol.% excess Al). The introduction of Si could suppress and even remove additional ZrC, and Si atoms would exclusively occupy the site of Al to make Zr2Al4C5 become a stable solid solution. The scanning electron microscopy observation showed that the as-synthesized Zr2Al4C5 grains had elongated, rod-like and/or plate-like shapes. The mechanical properties of the sintered Zr2Al4C5 ceramic were also investigated, and it showed a hardness of 11.06±0.34 GPa and a fracture toughness of 4.6 ± 0.4 MPa×m1/2.
Preparation and Properties of TiB2-SiC-Si Composites Fabricated by Reaction Bonding
Authors: Zhang Cui Ping , Ru Hong Qiang , He Ru Peng , Sun Wei Kang , Zhu Jing Hui , Wang Wei , Yue Xin Yan
Published: July 2016

TiB2-SiC-Si composite was fabricated by reaction bonding. The influence of carbon content on the phase compositions, microstructure, density and mechanical properties was studied. The results showed that the composite consists of TiB2, SiC and Si phases. The vol% of SiC increased with the increase of C contents, while that of TiB2 and free silicon reduced respectively. The mechanical properties of TiB2-SiC-Si composites are improved initially and then deteriorated with the increase in C contents of which the optimal amount is 8 %. The optimum open porosity, volume density, Vikers-hardness, flexural strength and fracture toughness of the obtained TiB2-SiC-Si composite are 0.12 %, 3.73 g/cm3, 17 GPa, 290 MPa and 5.9 MPa·m1/2, respectively.
Wetting and Interfacial Behaviors of Molten Ag, Cu and Ag-28Cu on WC-8Co Cemented Carbide
Authors: Fu Hao , Zhang Xiang Zhao , Liu Gui Wu , Xu Zi Wei , Pan Tie Zheng , Qiao Guan Jun
Published: July 2016

The wetting and spreading of molten Cu, Ag and Ag-28Cu (wt.%) on the WC-Co cemented carbide were investigated by the sessile drop technique at different temperatures, and the interfacial behaviors of the metal/WC-Co couples were analyzed by scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). The experimental results showed that the testing temperature and the composition of drop can play a key role in the wetting and spreading, and the good wettability with contact angle of less than 40o can be obtained. Moreover, the strongest interactions can be produced between the molten Cu and the WC-Co substrate at the higher temperature of 1100 oC due to the strong interdiffusion and solid solution between Cu and Co, resulting in the lowest equilibrium contact angle of ~0o. In addition, smooth and clean interfaces, without formation of visible interfacial reaction layer, were observed in all the three wetting systems. This work may also provide guidance to brazing of the cemented carbide.
Preparation of Glass-Ceramics by Reactive Crystallization with Waste Glass and Mullite
Authors: Si Wei , Wang Zhi Yang , Zhang Wei Yi , Pan Wei
Published: July 2016

Diopside glass-ceramics were prepared by reactive crystallization with mixed powder of waste glass and mullite. The effects of mullite content and sintering temperature and holding time on the crystal phase and morphology of diopside glass-ceramics were investigated. The reactive crystallizing behavior between waste glass powder and mullite was studied using energy dispersive spectrdmeter during the sintering and holding process. The result show that the optimum preparation conditions were as follows: the addition of 30 wt% mullite used as crystallization promoting agent, sintering temperature of 900 °C and holding time of 2h. The main difference between reactive crystallization method and the traditional method of preparing diopside glass-ceramics was the reactive crystallization mechanism. The diopside and corundum crystals were formed via an interaction between glass powder and mullite instead of direct precipitation from the parent glass during the calcining and holding process. With the increasing of sintering temperature and holding time, the Ca and Mg element concents of the glass were increased, on the contrary, that Si element concent was decreased in the mullite. It shows that the Si element diffused from mullite to glass and precipitated diopside crystals.
Preparation of TiB2 Ultrafine Powders by Carbothermal Reduction
Authors: Yu Jin Cheng , Ma Li , Zhang Yu Jun , Gong Hong Yu , Zhou Li Wei
Published: July 2016

TiO2, B2O3, H3BO3, B4C and carbon black were used as the raw materials to prepare TiB2 powders by carbothermal reduction method. The influence of different content of carbon black (13.6~14.8 wt%) on products was discussed. The effects of different boron sources and holding time (10~50 min) on the microstructure of TiB2 powders were also investigated. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to study the phase composition and structural evolution of the powder. The final results showed that hexagonal TiB2 crystal grain could be successfully synthesized without impurities when heated at 1700°C for 30 min in Ar atmosphere with the addition of 14.1 wt% carbon black. Submicrometric TiB2 powders range from 0.5 to 1.0 μm could be obtained when B4C was used as the boron source. The increase in holding time contributed to the grain growth and completion of chemical reactions, but could also result in oversintering.
Effect of Spinel Content on the Reaction of Porous Periclase-Spinel Ceramics and Cement Clinker
Authors: Lin Xiao Li , Yan Wen , Chen Qing Jie , Li Nan , Ma San Bao , Zhou Wen Ying
Published: July 2016

Corrosion of five porous ceramics with near apparent porosities (26%~29%) and different spinel contents by cement clinker was conducted, and the effect of the spinel content on the reaction between porous periclase-spinel ceramics and cement clinker was investigated by SEM, EDS, and FactSage® thermo-chemical software, etc. It can be found that : (1) The dissolution rate of periclase into cement clinker is slow whereas that of spinel into cement clinker is fast; (2) The more the spinel content in the porous ceramics, the higher the dissolution rate of porous ceramics into cement clinker, then the higher corrosion index; the dissolution of spinel into cement clinker changes the composition of the penetrated slag and made the viscosity increases; (3) For the specimens with similar pore size and low viscosity of penetrated liquid phase, the more the liquid content, the higher the penetration degree of liquid to specimens; the further penetration will be stopped with an increase of liquid viscosity, then the contact area between refractory and cement clinker decreases, in the result, the corrosion index decreases. When spinel contents is 0~10mol%, porous periclase-spinel ceramics possess higher penetration resistance and corrosion resistance.
Effect of Sintering Temperature on the Physical Properties and Microstructure of In Situ Nitrides Bonded MgAl2O4-C Refractories
Authors: Wang Shao Hua , Deng Cheng Ji , Zhu Hong Xi , Yuan Wen Jie
Published: July 2016

The in situ nitrides bonded MgAl2O4-C refractories were prepared by using high quality fused spinel (MgAl2O4≥ 97%), natural flake graphite (C ≥ 96%) and silicon powder (Si ≥ 98%) as raw materials and the liquid calcium lignosulfonate with a concentration of 1.25 g/ml was used as binder (4 wt%). The effect of sintering temperatures on physical properties and phase compositions were investigated. The results show that β-sialon and α-Si3N4were formed in the samples sintered at 1400°C, 1450°C and 1500°C, and AlON and AlN were formed in the samples sintered at 1550°C. The sample that sintered at 1450°C exhibits the best bulk density and apparent porosity of 2.84 g/cm3 and 14.73%, respectively, and the highest compressive strength
Effect of Particle Size Distribution of Raw Materials on Properties of Magnesia-Alumina Refractory
Authors: Chai Zhin An , Deng Cheng Ji , Zhu Hong Xi , Zhang Xiao Jun , Zhou Liang Yi
Published: July 2016

Starting from different sizes of magnesia and bauxitewith sodium hexametaphosphate as anchoring agent, specimens obtained by suppression were sintered at 1500°C and 1550°C and heat preservation for 3h in the electric hearth furnace, respectively. The effect of particle size distribution of magnesia and bauxite on the properties of magnesia-alumina refractory materials was investigated. The composition of magnesia-alumina refractory which consists of various particle size distributions was determined, according to Andreasen packing model, with distribution coefficient (q) of 0.15, 0.20, 0.25, 0.30, 0.35, 0.40 and 0.50. The fractographs of the specimen were observed by scanning electron microscopy. The linear rate of change, apparent porosity, bulk density and crushing strength of these specimens were studied. The results showed: a crushing strength of 52.39 MPa, an apparent porosity value of 15.55% and a bulk density value of 2.91 g/cm3 were obtained via a particle size distribution coefficient of 0.30 at 1550°C. Simultaneously, the refractory materials had small linear rate of change.
Effects of Short PAN Fiber Contents on Mechanical Properties of Metakaolin-Blast Furnace Slag Based Geopolymers
Authors: Luo Xin Chun , Wang Chang An
Published: July 2016

This paper investigated mechanical properties and microstructure of metakaolin/slag based geopolymers reinforced by short polyacrylonitrile (PAN) fibers. The results showed that addition of short PAN fibers had no effect on the phase composition of the geopolymer but could strengthen and toughen the geopolymers remarkably. When the content of short PAN fibres was 0.8wt%, the geopolymers showed the highest compressive strength (99.84MPa) and flexural strength (13.76MPa). The addition of PAN fibers enlarged the work of fracture of the geopolymers and changed the fractural behavior from brittle to non-brittle fractural mode through fiber bridging and pull-out effects.
Mechanical Properties and Microstructure of 2.5D Cf/ZrO2 Composites Prepared by Precursor Infiltration and Pyrolysis
Authors: Ai Jian Ping , Luo Shan Shan , Li Wen Kui , Wang Shi Wei , Zhou Guo Hong
Published: July 2016

The 2.5D Cf/ZrO2 composites were fabricated by precursor infiltration and pyrolysis (PIP) with ZrO2 precursor slurry as an impregnation liquid and 2.5D carbon preform as a framework. The effect of cycles of infiltration-pyrolysis on mechanical properties and microstructure of composites was investigated. The results showed that with the increase of cycles of infiltration-pyrolysis the flexural strength and relative density of as-prepared 2.5D Cf/ZrO2 composites increased. After 15 cycles of infiltration-pyrolysis, the density and flexural strength of as-prepared composites were 2.53±0.04g/cm3 and 73.2±2.2MPa respectively. In addition, the specimens with higher densification can transfer load efficiently between ZrO2 and carbon fiber, result in good mechanical properties of composites.
The Oxidation Resistance of ZrB2-SiC Composites Fabricated by High Pressure and High Temperature Sintering
Authors: Zhao Xiao Tong , Wang Hai Long , Zhang Rui
Published: July 2016

Dense ZrB2-SiC composites were fabricated by high pressure and high temperature sintering(HPHT) at 1500 oC for 3 min under a pressure of 5 GPa. The vickers’ hardness of ZrB2-SiC composite is 25 GPa. The flexural strength of the ZrB2-SiC composite is 300 MPa with the amount of SiC increased to 30wt.%, which increased after the composites oxidized at high temperature. The generated glass phase like SiO2 sealed pores and cracks on the surface of the ZrB2-SiC composite to increase the mechanical properties of the ZrB2-SiC composite. After oxdized at 1500oC for 45 mins, the dense oxidized film formed on the surface of ZrB2-SiC composites to improve the resistance oxi dation of ZrB2 ceramics.
Improvement of SrAl2O4:Eu2+, Dy3+ Phosphor via AlN Incorporation
Authors: Quan Chao , Zhou You Fu , Huang De Cai , Xu Wen Tao
Published: July 2016

SrAl2O4:Eu2+,Dy3+ long-lasting phosphors were incorporated AlN successfully by a conventional solid-state reaction in the reductive atmosphere. When a certain amount of AlN was doped, the specimen SrAl2O4-3xN2x: Eu2+, 0.01Dy3+ (x = 0.0-0.2) maintained the phase purity. Under the excitation at 398nm, an intense broadband emission centered at 514 nm, originating from the 4f65d1→4f7 transition of Eu2+, was observed. It is noteworthy that partial nitridation leads to an enhancement in the emission intensity up to 240%. The study of thermal stability shows that the intensity of SrAl2O3.55N0.3:Eu2+,0.01Dy3+ phosphor still remains 72% at 150 °C comparing with the initial, while only 62% for the un-doped phosphor. Taking enhanced photoluminescence (PL) property and good thermal stability into account, SrAl2O4-3xN2x:Eu2+, 0.01Dy3+ is a promising candidate for the phosphors used in alternating current (AC) LEDs.
Synthesis of V6O13 Flowers-Like with Control pH for Li-Ion Battery Cathodes
Authors: Zou Zheng Guang , Chen Hong Xu , Yuan Qi , Hou Zhong Liang
Published: July 2016

To improve electrochemical performance of Li ion battery , we synthesis flower-like V6O13 in oxalic acid solvent with HCl. The composition and morphology of the V6O13 were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements, respectively. The synthesized flowers-like V6O13 are less than 600nm in the width of the ribbon and have purity phase of the V6O13.The electrochemical performance of the flowers-like V6O13 were characterized by charge and discharge performance, EIS and CV. The flowers-like V6O13 exhibited high electrochemical performance.
Effects of Annealing Temperature and Coating Layers on Properties of ZnO Thin Films Prepared by Sol-Gel Immerse Technique
Authors: Du Chao , Zou Yu Chun , Chen Zhi Qing , Li Wen Kui , Luo Shan Shan
Published: July 2016

ZnO thin films is a kind of very potential semiconductor materials, due to their excellent chemical, electrical and optical properties. The effects of annealing temperature and coating layers on properties of ZnO thin films prepared by sol-gel immerse technique is studied in this work. The structure properties and optical properties were investigated by XRD, SEM and UV-Vis spectrophotometry respectively. It is found that the thin films were composed of better hexagonal wurtzite crystals with the c-axis preferred orientation by thermal annealing 550°C. With coating layers increasing from 2 layers to 8 layers, the intensity for all diffraction peaks were increased gradually, and the crystallite size of ZnO thin films is slightly increased. The transmittance of prepared thin films is over 80% in the visible-near IR region from 460 nm - 800 nm.
A Single-Phase Full-Color Ca4Si2O7F2:Ce3+, Tb3+, Sm3+ Micron Belt Mat for White-Light Emitting Diode Application
Authors: Cui Bo , Zhang Qing Hong , Wang Hong Zhi , Li Yao Gang
Published: July 2016

A new kind of Ca4Si2O7F2:Ce3+, Tb3+, Sm3+ oxyfluoride phosphor micron belt mat was obatained by simply electrospinning process and subsequent heat treatment. XRD result shows that a pure Ca4Si2O7F2 phase can be obtained at low temperature of around 900 °C. The micron belt precursor has a smooth surface and uniform morphology, and the width and thickness of the belt is about 2 μm and 200 nm. The morphology of micron belt is well retained after heat treatment, forming a plat phosphor mat consisting of uniform micron belt network. Ca4Si2O7F2:Ce3+, Ca4Si2O7F2:Tb3+, and Ca4Si2O7F2:Sm3+ exhibit the characteristic emissions of Ce3+ (4f7→4f65d1, blue), Tb3+ (4f8→4f75d, green), and Sm3+ (4f6→4f65d, red) under the excitation of near-UV light, respectively. By adjusting the doping concentration of Ce3+, Tb3+, Sm3+ ions a white emission in a single phase was obtained under the excitation of 360 nm. We have demonstrated that Ca4Si2O7F2:Ce3+, Tb3+, Sm3+ phosphor mat can be a promising candidate for a color-tunable phosphor mat applied in a near-UV White light emitting diodes.
A Metastable Ion (III) Oxide Phase (ε-Fe2O3): Preparation and Gas Sensing Properties
Authors: Wang Ming Jing , Ji Hui Ming , Chen Ya Lu , Jia Qian Qian
Published: July 2016

ε-Fe2O3 is a rare and metastable iron (III) oxide phase. ε-Fe2O3/SiO2 composites were prepared by combining the reverse-micelle and sol-gel methods. An appropriate amount of Ba2+ was needed in this system to promote the formation of ε-Fe2O3 nanorods in SiO2. The size of nanorods varied with different Ba2+ addition amount and sintering procedure. Then pure ε-Fe2O3 nanorods were obtained after stripping SiO2 by etching due to NaOH aqueous solution. The as-synthesized ε-Fe2O3 nanorods were discussed using X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). Interestingly, metastable ε-Fe2O3 nanorods showed a promising performance for the response for ethanol, compared with the stable phases of α-Fe2O3 and γ-Fe2O3. It indicates that nanostructure ε-Fe2O3 (including ε-Fe2O3 nanorods) could be a valuable material for the fabrication of advanced sensing devices.
Photocatalytic Behaviors Observed in Microstructured PbS under Visible Light
Authors: Qiao Li Na , Wang Huan Chun , Shen Yang , Lin Yuan Hua , Nan Ce Wen
Published: July 2016

Micro-dendrite structure lead sulfide was synthesized by a simple hydrothermal method at 180°C using lead acetate and thiourea as raw materials. The obtained powder sample was characterized by XRD, TEM and ED. Photocatalytic performance of the sample was investigated by the degradation of Congo red under visible light. The sample shows high photocatalytic activity and the charge-carrier of the hole plays an important role in the photodegradation process.
Research Progress of Adsorption on Heavy Metals from Aqueous Solutions by Modified Diatomite
Authors: Li Hao , Xie Qing Lin , Chen Nan Chun , Xu Hui , Ma Li Li
Published: July 2016

Pollution of heavy metals has become a serious environmental problem and it needs to be solved as soon as possible. Diatomite is a kind of biogenic rock and it is siliceous and sedimentary. There is abundant diatomite resource in China. Diatomite has distinctive structure of diatom monoblock. It has strong adsorbability, its specific area is large and it has high porosity. Its surface adheres a lot of active groups and negative charge. Diatomite with proper modification would show outstanding absorption effect of heavy metal ions. This paper reviewed the absorption efficiency of heavy metal ions on diatomite modified by metallic oxide, acids and bases, acticarbon, calcium carbonate and organics, the results would offer references for related researches. At last, this paper takes the outlook for the modified methods and application prospects of diatomite in wastewater treatment of heavy metals.
Formation Mechanisms of the Point Defects from the 4H-SiC (0001) Surface to the Interior Layers: First Principle Calculation
Authors: Shao Zhen Wei , Xu Zi Wei , Zhang Xiu Yun , Liu Gui Wu , Li Hao Hua , Qiao Guan Jun
Published: July 2016

With the extended applications of hexagonal silicon carbide (h-SiC) in the various fields, particularly in the application of the electronic devices, more and more attentions have been focused on the micro structures as well as their physical properties of h-SiC surface. In this study, we have performed the first principal calculations to compare the formation energies of four typical defects (Vc, Vsi, CI and SiI) on the 4H-SiC (0001) surface as well as in the interior layers. Due to the surface reconstruction and the reduced lattice constrain, the optimized structures of the defects on/near the 4H-SiC (0001) surface are quite different from the ones in the deeper layers. The distinguished formation energies as function of chemical potential indicate that we may control the defects concentrations in different layers by tuning the environmental conditions. This theoretical work provides a significant understanding to the formation mechanism of the point defects on the 4H-SiC surface, and paves a way to the modification of the SiC surface via electron irradiation or ion implantation with micro-defects introduced.
Effect of Bias Voltage on Microstructure and Mechanical Properties of CrN Coatings Prepared by Single Target Magnetron Sputtering
Authors: Luo Chen Gang , Zhang Hao , Shang Jin , Duo Shu Wang
Published: July 2016

CrN coatings were deposited by reactive magnetron sputtering at different substrate bias voltages. The effects of bias voltage on micro-structure and mechanical properties of CrN coatings were studied by scanning electron microscopy, X-ray diffraction, micro-hardness tester and a multi-functional tester for material surface properties, respectively. The results showed that bias voltage had a great influence on morphologies of CrN coatings and CrN coatings presented obvious preferred orientation with the increase of bias voltage. In addition, bias voltages in a certain range can also improve hardness and adhesion of CrN coatings, but higher voltages were not good. In this paper, the adhesion and hardness of CrN coatings presented the trend that a rise first followed by a decline with the ever-increasing bias voltages at the same time, but CrN coating had the superior mechanical properties when the bias voltage was-100 V.
Dual-Functional Phase Change Nanocapsules Based on n-Octadecane Core and Polypyrrole Shell
Authors: Yang Yan Yang , Wang Hao , Song Guo Lin , Tang Guo Yi
Published: July 2016

Phase change method is one of the efficient approach in resolving energy problem for solar energy storage. However, phase change materials seriously affect the heat storage system with low heat releasing and absorbing rate for poor thermal conductivity performance, which result in an inefficient thermal energy storage technology and uncertain economic perspective. In this paper, we prepared dual-functional phase change nanocapsules based on n-octadecane core and polypyrrole shell. Polypyrrole was employed to enhance the electric conductivity and thermal conductivity. The nanocapsules was characterized using Fourier transformed infrared spectrophotometer (FTIR), field emission scanning electron microscope (FESEM), differential scanning calorimeter (DSC), thermal gravimetric analyzer (TGA) and infrared thermal imaging. The results shows a good thermal behavior and high latent heat of 81.99J/g. The dual-fuctional phase change nanocapsules can be expected with a prospect of future profits in energy storage technology.
Principle Design of Graphite Components for HTTR and R&D on Nuclear Graphite for HTGR in JAEA
Authors: Sumita Junya , Shibata Taiju , Iyoku Tatsuo , Ishihara Masahiro , Nishihara Tetsuo
Published: July 2016

Nuclear energy is one of the most promising energy sources to satisfy energy security, environmental protection, and efficient supply. The High Temperature Gas-cooled Reactor (HTGR) has attractive inherent safety features and it can be used as many kinds of heat applications such as hydrogen production, electricity generation, process heat supply, district heating and desalination. Many countries, especially developing countries, show their interests in HTGR. Graphite materials are used for the core components of the HTGR. IG-110 graphite, fine-grained isotropic graphite, with high strength and high oxidation resistance is used in the High temperature Engineering Test Reactor (HTTR) of Japan Atomic Energy Agency (JAEA) and High Temperature Reactor-Pebble-bed Modules (HTR-PM) in China. IG-110 graphite is a major candidate for the core graphite components of the Very High Temperature Reactor (VHTR) which is one of HTGRs and one of the most promising candidates as the Generation-IV nuclear reactor systems. This paper describes design of core components of HTTR and R&D on nuclear graphite for HTGR. JAEA established the graphite structural design code and inspection standard of graphite to construct the HTTR. JAEA developed an in-service inspection method and a draft graphite structural design code for future HTGR on the basis of the HTTR technologies. Moreover, JAEA are now developing the design data base of IG-110 graphite and IG-430 graphite including irradiation data for HTGR.
Preparation and Characterization of Lithium Orthosilicate Ceramic Pebbles by Melt Spraying Method
Authors: Zhai You Wen , Hu Jin , Zhu Xiao Qin , Wang Kai Jun , Zhang Wei Jun
Published: July 2016

This paper studied the experimental procedures,, test equipment and test methodology of the melt spraying method. Meanwhile, according to performance index of lithium orthosilicate (Li4SiO4) ceramic pebbles to optimize the melt spraying method. Test analysis of the diameter of orthosilicate pebbles, degree of spheroid of orthosilicate pebbles, surface topography of orthosilicate pebbles, metallographic structure of orthosilicate pebbles, section morphology, crushing strength and phase composition. Results in this work indicate that the lithium orthosilicate (Li4SiO4) ceramic pebbles with a flat or even surface，porous internals, diameter of orthosilicate pebbles between 0.9~1.1mm,density of orthosilicate pebbles more than 90%T.D., the mean crushing strength is 25N, the degree of roundness is 1.027 can be obtained by the optimized melt spraying method. The optimization process provides a basis for obtaining the low cost and high performance of the lithium orthosilicate (Li4SiO4) ceramic pebbles.
Preparation of Silicon Carbide Coating Layer by Fluidized Bed Chemical Vapor Deposition Using a Halogen-Free Precursor
Authors: Liu Ma Lin , Liu Rong Zheng , Chang Jia Xing , Shao You Lin
Published: July 2016

Tristructural-isotropic (TRISO) particle, with spherical ceramic fuel particle kernels followed by three layers of pyrolytic carbon and one layer of silicon carbide (SiC), has been successful now in high temperature gas cooled reactor (HTGR). The silicon carbide (SiC) layer used in TRISO coated fuel particles is normally produced at high temperatures (~1600°C) via fluidized bed chemical vapor deposition from methyltrichlorosilane (MTS) in a hydrogen environment. The precursor is strong corrosive and the process is not environmentally friendly. In this work, hexamethyldisilane (HMDS) was used instead of MTS and the deposition behavior was investigated via fluidized bed chemical vapor deposition method. Different experimental parameters were tested, such as deposition temperature (800~1450°C) and gas flow ratio of Ar: H2. The deposition rates were obtained and compared. It was found that the optimization parameters of highest deposition rate is 1000°C with the ratio of Ar: H2 of 1:1. The microstructures of the products were further investigated by SEM, XRD and Raman scattering. From the X-ray diffraction pattern it could be inferred that the β-SiC phase was obtained, and free carbon was also found in deposition products. Different types of SiC layer, including dense and porous layer can be prepared. The experimental results validated that HMDS was an alternative precursor for preparing the SiC layer in producing the TRISO particle and other SiC-coated materials in lower temperatures
High-Temperature Sulfidation of SUS316L, TiN, and CrN Thin Films in (N2/3.1%H2O/2.42%H2S)-Mixed Gas
Authors: Kim Min Jung , Chung Seok Woo , Lee Dong Bok
Published: July 2016

SUS316L, TiN and CrN films were corroded at 500 °C for up to 30 h in 1 atm of (N2/3.1%H2O/2.42%H2S)-mixed gas. SUS316L displayed poor corrosion resistance due to the formation of FeS. It corroded to (Fe, Ni)-mixed sulfides and FeS, forming highly fragile, porous, and nonadherent scales. TiN and CrN films suppressed the sulfidation of SUS316L.
Compressive Behavior of Concrete Confined by Hemp Fiber Composite Jackets
Authors: Sangthongtong Arissaman , Hussain Qudeer , Pimanmas Amorn
Published: July 2016

This paper presents an experimental study on the strengthening of small scaled concrete columns externally confined with hemp fiber composite jackets. The major benefit of using hemp fiber is that their low price, high toughness, and hemp is natural fiber product which that can be found locally. In this study, two different types of columns i.e. circular and square were casted and tested under axial compression. The hemp fiber composite jacket of different thicknesses i.e. 2 and 4 layers were applied using epoxy resin. The test result show that hemp fiber composite jackets are very effective to enhance compressive strength and deformability of the confined concrete. There is found increase in ultimate load carrying capacity with an increase in the jacket thickness. The efficiency of hemp fiber composite jackets is found higher for circular columns then square columns.
The Analysis of the Mechanics Performance about GFRP Tube Confined Concrete Short Column under the Axial Compression
Authors: Song Zhi Gang , Fan Cheng
Published: July 2016

In order to study the axial compression performance of GFRP tube composite columns filled with concrete and better applied to engineering, the influence of different winding angle of GFRP tube, thickness of GFRP tube, concrete strength and the containing rate of steel are simulated by using finite element analysis software ABAQUS when the column under the axial compression ,The results show that: the numerical results are in good agreement with the experimental results; reduced GFRP tube winding angle, increasing the GFRP tube thickness, improve the core concrete strength and an increase in steel containing rate could increase the bearing capacity of columns.
Silver Doped Nano-Sized Bioglass Ceramics: Synthesis, Characterization and Biocompatibility Studies
Authors: Mariappan Chinnasamy Ramaraj , Ranga Narender
Published: July 2016

We report on the structural and biocompatibility properties of nanosized calcium phosphosilicate bioglass ceramics doped with 0, 2, 4 and 6 mol% Ag2O. Silver doped bioceramics were synthesized by sol-gel method. The prepared samples were characterized by means of powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-visible and high resolution transmission electron microscopy. The XRD reveals the glass-ceramic nature of the samples. The FT-IR spectra show the possible stretching and bending vibrations of silicate and phosphate groups. Absorptions in UV-visible spectra reveal the silver embedment as Ag+/Ago form into the glass matrix. nanosize of the glass ceramics is confirmed by HR-TEM analysis. The bioactivity of silver doped bioceramics was investigated by in-vitro method with Dulbecco’s Modified Eagel’s Medium. It confirms the formation of bone-like hydroxylapatite layer formation on the surface of bioceramics.
Impedance Analysis and Modulus Spectroscopy of Fe (III) Containing Strontium Stannate Nanoparticles
Authors: Kumar Ashok , Kumar Astakala Anil , Quamara Jitender Kumar
Published: July 2016

We report the sol-gel synthesis of pristine and Fe containing perovskite structured strontium stannate nanoparticles, stabilized by cetyl trimethyl ammonium bromide (CTAB). The X-ray diffraction data of pristine and Fe doped strontium stannate nanoparticles reveals the formation of orthorhombic phase with Pbnm space symmetry. Raman spectra of pristine and Fe doped SrSnO3 nanoparticles depicts peaks at 220, 256 and 561 corresponding to Sn-O-Sn, O-Sn-O and Sn-O band stretching, respectively. The dc resistivity of pristine and Fe doped SrSnO3 is found to decrease with increase in Fe content. The variation of impedance (Zʹ and Z′′) and electric modulus (Mʹ and M′′) of pristine and Fe doped strontium stannate nanoparticles as a function of frequency (20 Hz to 2 MHz) at different temperatures (310-410 K) has been studied.
Plasmon-Enhanced Performance of an Array of Core-Shell Silver Nanoparticles Photodeposited onto a Titanium Dioxide Layer
Authors: Yuan-Fong Chou Chau
Published: July 2016

A plasmonic photocatalytic reactor which composed of a periodic array of core-shell silver nanoparticles (CSSNPs) photodeposited onto a Titanium Dioxide (TiO2) thin film in a multilayer rotating-disk system was numerically investigated by using three-dimensional finite element method. Results show that the proposed structure can exhibit much higher photocalytic activity in a broad range of incident angle of light that are not observed for the same counterpart without the CSSNPs on the SiO2 surface. The enhanced electric field distribution and intensity could be expanded as the inner diameter of CSSNPs and incident angle of light increased.
Anatase Type Titanium Dioxide Prepared by Oxidation of Titanium Carbide
Authors: Matsushita Junichi , Tsuchiyama Tomoyuki , Hamaguchi Kazuya , Iwamoto Naoya , Wang Xiao Ling , Yang Jian Feng , Sekino Tohru , Wu Xiao Yong , Yin Shu , Sato Tsugio
Published: July 2016

Titanium carbide has been attractive for years an engineering ceramics due to its high hardness, high melting point, and good chemical stability. Similarly, titanium dioxide has excellent anti-microbial ceramic material by photon energy. In this study, the anatase type titanium dioxide layer prepared by oxidation of the titanium carbide powder by high temperature oxidation in air atmosphere was investigated in order to determine the possibility of its photocatalyst materials by radiant energy. TiC powder samples of different grain size were gained by ball mill. These samples were oxidized at room temperature to high temperature. The samples exhibited a steady mass gain with increasing oxidation temperature. Based on the results of the X-ray diffraction analysis, anatase type TiO2 was detected on the titanium carbide samples. It is considered, the titanium carbide showed convension anatase type titanium dioxide layer produced by oxidation.
Study on Slurry of Chemical Mechanical Polishing 304 Stainless Steel Based on Ferric Chloride and Oxalic Acid
Authors: Su Jian Xiu , Chen Jia Peng , Li Qing , Qin Hong Quan
Published: July 2016

Stainless steel will become one of the substrate materials used in flexible display. In this paper, the influence of the ferric chloride and the oxalic acid on the material removal rate (MRR) and surface roughness had been studied in the chemical mechanical polishing (CMP) 304 stainless steel. By analysis and research, the slurry ingredients based on the type of ferric chloride and oxalic acid had been obtained. The experimental results show that, the material removal rate reached more than 200nm/min. By the qualitative analysis on the phases of the surface material of 304 stainless steel using X-ray diffraction (XRD) after CMP, it is proved that the ferric chloride based slurry did not change the original phases and did not affect the performance of 304 stainless steel. The research results of this paper can provide the reference for the study the CMP slurry of 304 stainless steel.
An Experimental Study of the Effects of Electrode Shapes on Micro-EDM Performances
Authors: Wang Kan , Zhang Qin He , Liu Qing Yu , Zhang Min , Zhang Jian Hua , Liu Yong
Published: July 2016

In this paper, experiments were conducted to investigate the effects of cylindrical electrode and helical electrode on the micro electrical discharge machining (EDM) performances during micro-hole machining of titanium alloy. The results show that the material removal rate (MRR) and the tool wear rate (TWR) increase with open circuit voltage, regardless of electrode shapes. Compared to the cylindrical electrode, helical electrode can result in higher MRR and lower relative tool wear ratio (RTWR). It can be concluded that the helical electrode is more suitable than cylindrical electrode for machining micro parts.
Microstructures, Mechanical and Creep Properties of Rapidly Solidification/Powder Metallurgy Mg-6wt.%Zn Alloys with 5wt.%Ce and 1.5wt.%Ca Additions
Authors: Zhou Tao , Song Deng Hui , Chen Zhen Hua
Published: July 2016

Rapidly solidification/powder metallurgy (RS/PM) Mg-6Zn, Mg-6Zn-5Ce and Mg-6Zn-5Ce-1.5Ca (wt.%) alloys were produced via hot extrusion with RS powders, produced by atomization-twin roll quenching. Microstructures, mechanical and creep properties of the alloys were investigated. The results showed that for the Mg-6Zn alloys with 5wt.%Ce and 1.5wt.%Ca additions, the microstructures of the alloys were gradually refined, which caused the strength of the alloy at room temperature to increase remarkably, especially for the RS/PM Mg-6Zn-5Ce-1.5Ca alloy, exhibited a high compressive strength of 394MPa at room temperature. At elevated temperatures, due to the fine and stable intermetallic compounds i.e. MgxZnyCez and MgxZnyCez-(Ca) phases were formed for the Mg-6Zn-5Ce alloy and Mg-6Zn-5Ce-1.5Ca alloys, respectively, and the thermal stability of the ternary phase was a little lower than that of the quaternary phase because of the dissolving of Ca into the MgxZnyCez phase, the mechanical and creep properties at elevated temperatures increased remarkably with Ce and Ca additions, especially for the RS/PM Mg-6Zn-5Ce-1.5Ca alloy, which exhibited a high compressive strength of 258MPa at 200°C, and the minimum creep rate was decreased about 2 times, compared with that of the Mg-6Zn-5Ce alloy.
Sandwich Wound Closure Reduces the Risk of Cerebrospinal Fluid Leaks in Posterior Fossa Surgery
Authors: Heymanns Verena , Oseni Abidemi W. , Alyeldien Ameer , Maslehaty Homajoun , Parvin Richard , Scholz Martin , Petridis Athanasios K.
Published: July 2016

Posterior fossa surgery is demanding and hides a significant number of obstacles starting from the approach to the wound closure. The risk of cerebrospinal fluid (CSF) leakage in posterior fossa surgery given in the literature is around 8%. The present study aims to introduce a sandwich closure of the dura in posterior fossa surgery, which reduces significantly the number of CSF leaks (3.8%) in the patients treated in our department. Three hundred and ten patients treated in our hospital in the years 2009-2013 for posterior fossa pathologies were retrospectively evaluated. The dura closure method was as following: lyophilized dura put under the dura and sealed with fibrin glue and sutures, dura adapting stitches, TachoSil® (Takeda Pharma A/S, Roskilde, Denmark), Gelfoam® (Pfizer Inc., New York, NY, USA) and polymethylmethacrylate (osteoclastic craniotomy). The incidence of postsurgical complications associated with the dural closure like CSF leakage, infections, bleeding is evaluated. Only 3.8% of patients developed CSF leakage and only 0.5% needed a second surgery for CSF leakage closure. Two percent had a cerebellar bleeding with no need for re-operation and 3% had a wound infection treated with antibiotics. The sandwich wound closure we are applying for posterior fossa surgery in our patients correlates with a significant reduction of CSF leaks compared to the literature.
Role of matrix metalloproteinase in the aneurismatic aortic disease
Authors: Troisi Nicola , Mazza Alfredo , Mazza Felice , Iannelli Gabriele
Published: July 2016

The aorta is involved in a large variety of diseases and the atherosclerotic aneurysms represent the most common type of these. Recent reports have attempted to clarify the mechanisms, that cause the formation and the progression of the atherosclerotic aneurysms, caused not only by the atherosclerosis. One of the features of this disease is the extensive proteolytic destruction of structural matrix proteins in the aortic wall realized by the matrix metalloproteinases. The atherosclerotic aneurysm can be considered a disease caused by an imbalance between connective tissue destruction and its repair. Knowledge of the role played by matrix metalloproteinases in the formation process of the aneurysms has made the inhibition of these proteins a logical therapeutic strategy. Once completed the aneurysm treatment, surgical or endovascular, the endothelial damage must disappear; the persistence of this damage, after endovascular procedure, is the cause of the formation of the endoleaks. The preoperative matrix metalloproteinases plasmatic levels are related to the aneurysm diameter and after endovascular treatment these values come back normal, except in the case of presence of an endoleak, that don’t make possible the reduction of these values. In spite of that, obscure points still remain, above all about the dosage of these proteins and their inhibition through drugs with clear metalloproteinases- inhibiting properties. The aim of this study is to clarify further on the mechanisms of the formation of the aneurysms with particular care to the matrix metalloproteinases, their dosage and their drug inhibition.
Documento di consenso La strategia di intervento nel paziente ad alto rischio cardiovascolare
Authors: Pede Sergio , Urbinati Stefano , Mureddu Gianfrancesco , Vigorito Carlo
Published: July 2016

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Non-HDL cholesterol predicts coronary heart disease in primary prevention: findings from an Italian a 40-69 year-old cohort in general practice
Authors: Ciardullo Anna V. , Azzolini Luigi , Bevini Massimo , Cadioli Tiziano , Malavasi Paolo , Morellini Alberto , Daghio Monica M. , Guidetti Patrizia , Lorenzetti Manuela , Carapezzi Carlo
Published: July 2016

Scopo. La frazione lipoproteica denominata “colesterolo non-HDL” viene raccomandata come un indice di rischio coronarico (RC) associata alla dislipidemia combinata ed è stata trovata un utile fattore predittivo del rischio coronarico nei pazienti diabetici. Abbiamo studiato l’associazione tra i fattori di RC noti, incluso la colesterolo non-HDL ed una “condizione di RC elevato”, cioè un “RC a 5-anni >15%” in medicina generale. Metodi. Abbiamo studiato 4085 individui di età 40-69 anni, 489 diabetici e 3596 non-diabetici, appartenenti ad una coorte opportunistica. Sono state utilizzate le statistiche descrittive, e la regressione logistica multivariata aggiustata per età e sesso per i confronti tra i 2 gruppi. Risultati. Circa il 12% dei participanti era diabetico. I confronti aggiustati per età e sesso hanno mostrato che tutte le variabili erano significativamente peggiori nei diabetici rispetto ai non-diabetici (eccetto fumo, colesterolo totale e rapporto colesterolo totale/HDL). I diabetici avevano un “RC medio a 5-anni” più alto dei non-diabetici (18.8±11.9% vs 7.5±6.9%, P15%” (55.4% vs 11.1%, P<0.01). Nei diabetici, le variabili associate ad una “condizione di RC elevato” sono: fumo, pressione arteriosa sistolica (PAS) e colesterolemia non-HDL; nei non-diabetici: fumo, PAS, colesterolemia non-HDL e HDL (inversamente). Conclusioni. Il colesterolo non-HDL – oltre a fumo e PAS – è un forte predittore di una “condizione di RC elevato” sia negli individui diabetici che non-diabetici.
The diastolic function: an echocardiographic study and its clinical meaning
Authors: Serafini Oscar , Misuraca Gianfranco
Published: July 2016

Many patients with manifestations and/or symptoms of heart failure show a normal or only slight depressed systolic function of the left ventricle. The origin of these symptoms is attributed to anomalies of the diastolic function and the echocardiography has became an important technique for a non-invasive investigation of such anomalies. The valuation of the diastolic function, mainly in patients with a left ventricle dysfunction, is usually performed by means of the analysis of the transmitral flow with pulsed Doppler, integrating as necessary the basal information with actions of preload variations. However, in many cases it is necessary to use other procedures of study to better characterise the diastolic function in each patient by means of the analysis of venous pulmonary flow, the valuation of propagation velocity of mitral flow with Color M-Mode, or the valuation of diastolic velocities of myocardium with Doppler tissue imaging. The integrated analysis of these various methods of exam, moreover, allows to enhance the diagnostic accuracy in the evaluation of the filling pressure, which is a fundamental parameter to stratify the risk of short/medium term events, being equal the left ventricle dysfunction.
Heart failure: preventing rehospitalizations by disease management programs
Authors: Verdiani Valerio , Nozzoli Carlo
Published: July 2016

Chronic heart failure is a growing public health problem for prevalence, morbidity and costs. The major proportion of costs is attributable to rehospitalizations and many of these readmissions may be preventable. Since 1990, some investigators have tested a variety of disease management programs designed to improve quality of life, functional status and decrease rehospitalizations rates. We identified these studies by a computerized search of the MEDLINE database. The programs described reflected a wide variety of methods and we categorized these programs recognizing the prevalent disease management approach. We reported the results of these trials about rehospitalizations and analysed a number of limitations that must be considered when determining their adoption into clinical practice.
Nursing Role in Cardiac Prevention
Authors: Riccio Carmine , Sommaruga Marinella , Vaghi Paola , Cassella Alfonso , Celardo Silvana , Cocco Emilia , De Chiro Vincenzo , Marzaioli Maria , Ruotolo Enza , Zanni Ornella , Iacomino Maria , Chieffo Carmelo
Published: July 2016

The lack of a multidisciplinary approach is certainly among the causes of the ineffectiveness of intervention in the field of cardiovascular secondary prevention. By multidisciplinary approach is meant involving cardiologists, nurses, rehabilitation therapists, dieticians as well as psychologists in the framing of interventions tailor made to patients needs. In particular, people working in the nursing area can play a very important role which can be summed up into three different levels: a technical level, aiming at the cooperation with cardiologists to carry out diagnostic examinations and give a portrait of patients in terms of risks; a second level consists in giving information, and helping to face the disease, as well as stepping in during its evolution, almost a health counsellor for the patients; finally the nurse can act as a psychological support both to the patient and his/her family during acute illnesses and reassure him/her that he/she is being treated properly and that successively will resume a good quality of life. Hospital represent an ideal place for secondary prevention, at least in the first phases of the intervention. The results collected during hospitalization would be rapidly lost if they were not followed and sustained in the medium- long term by structured follow-up programmes. The development of ambulatories might represent a link between hospitals and the territory, i.e. the specialist and one’s personal physician. The staff of ambulatories should comprise a cardiologist and a trained professional nurse, this being specialized, specifically, in cardiology and cardiovascular prevention. Staff of the type described could work independently, co-ordinating ambulatories on the territory within the framework of standardized recognized protocols and relating information concerning patients, general practitioners and other surgeries. In this way, an essential link of the continuity in medical care would be guaranteed.
Gruppo Italiano di Cardiologia Riabilitativa e Preventiva: attività del biennio 2002-2004
Authors: Fattirolli Francesco
Published: July 2016

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