bluuebunny/crossref_metadata_2025 huggingface dataset:
Fire Performance of Flax Laminates and their Hybrids
Authors: Rao S. , Bhardwaj A. , Beehag Andrew , Bhattacharyya Debes
Published: December 2011

In the current age of growing environmental awareness, natural fibre composites have gained wide acceptance in various facets of engineering. However, in industries, such as aerospace and mining, their acceptance is primarily dependent on them meeting the stringent fire test requirements. In this paper, symmetric laminates consisting of only glass, glass/flax hybrid and only flax as reinforcements in thermoset matrices were tested for their time to ignition, heat release rate and smoke constituents as per standard ASTM E 1354 in a cone calorimeter. Four fire retardant versions of resin systems, were used in this study. The laminates were manufactured using wet hand-layup technique that was vacuum bagged and cured between hot platens of a hydraulic press. A constant fibre volume fraction of 0.5 for all the laminates was obtained by maintaining a constant laminate thickness of 4mm. The results from the cone calorimeter tests were compared to examine the influence of natural fibres on the fire properties of the laminates. It was observed that the degree of fire retardance in the polyester based composites decreased with the increase in the flax fibre content; however, in the modified urethane composites, flax fibre composites performed better by exhibiting higher ignition time compared to the hybrid and glass fibre composites. Another important observation was that the carbon monoxide emissions during testing decreased with the increase in flax content in the composites, no matter what resin system was used. These preliminary tests suggest that, by judiciously incorporating natural fibres in a synthetic system, a hybrid system could be designed to sustain loads in environments with high fire risks.
Europium Complex with Functionalized Carbon Nanotubes: A New Lanthanide Photoluminescence Nanomaterial
Authors: Li Xiao Feng , An Yan , Lau Kin Tak , Li Wen Ge , Yin Yan Sheng
Published: December 2011

N-(2-Amino-phenyl)-2-{2-[(2-amino-phenylcarbamoyl)-methoxy]-phenoxy}-acetamide (B) was firstly immobilized on the single-walled carbon nanotubes and characterized by 1H NMR, IR spectra and TEM images. The longer 5D0 fluorescence lifetime was observed in the europium (III) complex of this functionalized carbon nanotube than in the Eu (III) complex of free B.
Effect of MWCNT on Mechanical Properties of γ-Irradiated UHMWPE during Shelf Ageing Process
Authors: Sreekanth P.S. , Kumar N.Naresh , Kanagaraj S.
Published: December 2011

Crosslinking of UHMWPE by gamma irradiation has been the prime choice to improve the wear resistance of the polymer. However, it is always associated with few setbacks like degradation of material properties during the shelf ageing period. In the present work, nanocomposites were prepared using ball milling process and then compression moulding process where UHMWPE was reinforced by MWCNTs with 0.20 and 0.40 wt. %. The samples were gamma irradiated using60Co at 25 and 50 kGy sterilizing doses in air without any post irradiative treatments and then shelf aged for 240 days. The mechanical properties of the composites were studied using small punch technique according to ASTM F2183 standards. Both toughness and hardness of the composites were found to be improved with an increase of irradiation dosage and MWCNT concentration. It is observed that the percentage reduction in Young’s modulus, yield stress and % strain at fracture of 0.4% composite at 50 kGy dose are 6.4%, 8.8% and 12.7%, respectively compared to that of virgin UHMWPE irradiated at same dosage. It is concluded that presence of MWCNTs in UHMWPE prevents the degradation of material properties during the shelf ageing period after irradiation.
Potential Composite Structures for NASA Future Launch Vehicles and Crew Spacecraft
Authors: Gyekenyesi John P.
Published: December 2011

Because of their well known specific strength, stiffness and excellent durability properties, advanced composites are being considered for primary structures in launch vehicles, crew modules and various components for increased performance and cost reduction. Therefore, it is prudent and beneficial to review the engineering practices and lessons learned in connection with their use in related aeronautic and energy applications, where they are already replacing formerly used metallic materials. Examples of composite components will be shown for the reusable space shuttle orbiter where a number of different composite systems performed very satisfactorily. In addition, very large potential polymer composite designs for future launch vehicles will be discussed. Among them are payload shrouds, interstage structures and the typical intertank shell, wherein thrust booster rockets are often attached between the core stage propellant and oxidizer tanks. In addition, cryogenic propellant composite vessels of different sizes and shapes were fabricated with mostly excellent results, although some spectacular failures were also observed. High pressure composite overwrapped vessels, with and without metallic liners, will be described. Compared to widely used metallic materials, some special features of composites are listed. Relevant design allowables, depending on mission requirements, will be summarized and currently used design practice for aircraft and spacecraft in the US will be reviewed. The well-known “building - block” approach, which is often used to design military as well as civilian aircraft, will be summarized. Some of the most popular micromechanics and macromechanics computer programs used to analyze composite structures, especially with finite elements, will be listed. Although very high temperature composites like carbon/carbon, carbon/ceramic and ceramic/ceramic fiber/matrix systems are also selectively used, the focus in our discussion will be on advanced polymer matrix, carbon/glass fiber systems.
Characterization of Precipitated Calcium Carbonate from Eggshell Powder
Authors: Sutapun Wimonlak , Ruksakulpiwat Yupaporn , Suppakarn Nitinat , Jeencham Rachasit , Aontee Ajcharaporn
Published: December 2011

In this work, PCC was prepared from chicken eggshell powder (ESP) by dissolving 100 g ESP in 1 M hydrochloric acid at room temperature. Under vigorous stirring, PCC was precipitated from the ESP-dissolved solution using 1 M sodium carbonate solution. The dried PESP (precipitated eggshell powder) was then characterized by particle size analyzer, X-ray diffractometer, Brunauer-Emmett-Teller surface analyzer and thermogravimetric analyzer. The particle shape of the PESP was revealed using scanning electron microscope. It was found that PESP was a binary mixer of calcite and vaterite. The particles were in cubic and spherical shape. In addition, PESP had a volume average diameter of 8.16 μm, D[V, 0.5] of 7.22 μm, D[V,0.9] of 16.57 μm, and the specific surface area of 4.38 m2/g. The average particle size was lower than and the specific surface area was higher than that of ESP. The decomposition process of PESP occured in a single step between 610 and 770 °C, with 44.43% weight loss.
Plant Fiber Reinforced Composites and their Applications
Authors: Li Yan
Published: December 2011

Plant fibers are promising reinforcements for use in composite materials due to the low cost, high specific strength and modulus, easy availability, especially the renewability and environmental friendly characteristics. Natural fiber reinforced composites (NFRCs) have raised great attentions and interests from both the academic and industry in recent years.
Aging Behaviors of Al 6061 and Al 6061/SiCp Composite
Authors: Ourang S.M.R. , Ekrami A. , Reihani S.M. Seyed , Abarghouie S.M.R.Mousavi
Published: December 2011

In the present research the aging behavior of Al6061 alloy and Al6061/SiCp composite fabricated by powder metallurgy method was investigated. The solution treatment of the samples were carried out at 527°C for 2, 3and 4 h followed by aging at 180°C for different aging times between 1 and 10 h. The existence of SiC particles led to increasing the peak hardness of the composite. The peak hardness of the composite took place at shorter times than that of the 6061 alloy for the samples solution treated for 3and 4 h, but took place at longer times for the samples solution treated for 2 h. The optimum solution treating time was about 3 h for both the composite and the 6061 alloy that led to the fastest aging kinetics and the maximum hardness. At the solution treating time shorter than 3h due to incomplete dissolution of precipitates, the aging kinetics decelerated and the hardness values decreased. For the composites solution treated more than 3 h, hardness values decreased due to the grain growth of matrix while changing in the aging kinetics was not significant. EDS and SEM studies indicated the presence of bight enrichment zones including Mg and Si elements in the composite in solution treatment conditions.
Modeling the Flexural Properties of SLG Reinforced Phenol Formaldehyde Composites Using Langrage’s Method
Authors: Ku Harry , Zhou Hong , Wong Peter , Su Gang , Vadher Jayant
Published: December 2011

The flexural properties of SLG filled phenolic composites have been determined in previous study. It is time consuming to prepare the samples for the tests. In addition, it is even more time consuming to carry out the tests and analyze the results. It is therefore necessary to develop a mathematical model that will predict the flexural properties of particulate filled phenolic composites. Mathematical models for tensile strength, Young’s modulus are available but not for impact strength, flexural strength and fracture toughness. There is no sign that it can be built up from simple mathematical model; polynomial interpolation using Lagrange’s method was therefore employed to generate the flexural properties model using the data obtained from experiments. From experiments, it was found that the trend of the flexural properties of the samples post-cured conventionally was similar to that post-cured in microwaves; it is therefore possible to predict the flexural properties of the samples post-cured in microwaves from the mathematical model generated for flexural properties of samples post-cured in a conventional oven. The workload is therefore halved as the process of generating the mathematical was much faster and simpler.
Compressive Strength Characterization of Polyester Based Fillers
Authors: Sirimanna Chamila Sampath , Lokuge Weena , Islam Md Mainul , Aravinthan Thiru
Published: December 2011

This paper investigates the compressive properties of polyester based fillers with different proportions of resin, sand and fly ash. The research program aims at developing a polymer based filler for a glass fibre reinforced polymer (GFRP) tube to be used as a structural rehabilitation system. It has been initiated to improve fundamental understanding of this material and to provide the knowledge required for its broad utilization. In this development, sample trial mixes were considered based on several weight percentages of polyester resin, fly ash and sand. These weight percentages were selected after analyzing volumetric properties of sand. The effect of resin (binder), sand and fly ash contents on the compressive strength of polyester based fillers with respect to age is reported. It has been found that at the age of 7 days all the batches reached about 90% of the compressive modulus. The experimental compressive stress-strain curves reported here were compared with established analytical models for normal strength concrete.
Numerical Simulations for Hail Impact on Lightweight Sandwich Structures
Authors: Han B. , Xin Feng Xian , Jin Feng , Lu T.J.
Published: December 2011

Hail impact has been a long lasting threat for aircraft structures such as leading edges and forward sections. To mimic the physical process of hail impact on aircraft structures, a FEM model is established for all-metal sandwich structures having four different kinds of cores: corrugated core, pyramidal lattice core, metal foam core, and corrugation-foam hybrid core. Smoothed particle hydrodynamic (SPH) method is employed to predict the failure behavior of the hail, whilst the sandwich structures are described by a Lagrangian reference configuration. It is demonstrated that the sandwich structures with hybrid core outperforms the other three types for withstanding hail penetration as well as absorbing impact energy.
UV Weathering Effect on Antibacterial Performance in Silicone Rubber Compounds
Authors: Taptim Kulnida , Sombatsompop Narongrit
Published: December 2011

Silicone rubber compounded with three different types of antibacterial agents: namely; nanoAg colloids, Silver substituted Zeolite compound (SSZ) and 2-Hydroxypropyl-3-Piperazinyl-Quinoline Carboxylic Acid Methacrylate (HPQM) were prepared and changes in antibacterial performance were assessed before and after exposure to UV light at different aging times. Drop plate and halo tests were performed to study the antibacterial performance of silicone rubber compounds. The results indicated that antibacterial activity of silicone compound changed when the UV aging time was increased. The antibacterial activity of the rubber added with HPQM extremely decreased considered by the inhibition zone and %reductions of Staphylococcus aureus and Escherichia coli bacteria for any given contact times. On the other hand, the UV light did not affect the antibacterial activity of silicone rubber compounds added with nanoAg colloids and SSZ agents.
The Preparation of Poly(lactic acid) via Chain Linked Hydroxy-Terminated Lactic Acid Prepolymer
Authors: Songprateepkul Suek , Rakmae Suriyan , Deeprasertkul C. , Suppakarn Nitinat , Chumsamrong Pranee
Published: December 2011

In this work, hydroxyl-terminated lactic acid prepolymer was firstly prepared by adding diethylene glycol in the condensation of lactic acid. Molecular weight, acid value and structure of prepolymer were characterized. The results showed that the prepolymer was hydroxyl-terminated with weight average molecular weight (MW) of 10,000 g/mol. After that, the chain linking polymerization of the prepolymer was carried out in a glass tube at 160 °C for 1 h employing 1,6-hexamethylene diisocyanate (HMDI) as a chain extender. By varying the hydroxyl/isocyanate ratio, it was found that the OH/NCO ratio of 1:2 seemed to be the most suitable ratio which gave PLA with the maximum MW of 93,000 g/mol.
Molding of C-FRP Plate with Using Induction Heating
Authors: Nakanishi Eitoku , Maki Seijiro , Matsumoto Satonori
Published: December 2011

Recently, the market for composite materials is dominated by small and medium series production and prototyping [1]. And the VaRTM (Vacuum assisted Resin Transfer Moldings) process is thought to be low cost composite fabrication technique [2]. The preforms in VaRTM are placed on one–side mold and they are sealed by a flexible vacuum bag [3]. The resin is infused into dry fabric formed on a mold near product shape under vacuum pressure and cured in an oven. In general, part defects often arise during the mold filling stage of the process, where a resin is drawn into performs through the use of vacuum. Uniform fill of resin and complete fiber saturation are required for fabricating high quality products [5]. So the resin flow control is extremely required. To solve these problems and short time fabrication, this article investigates the new molding process of C-FRP plate with using the combination of induction heating for quick heating and vacuuming method. To control of the volume fraction easily and to achieve homogeneous impregnation, thermoplastic resin sheet was chosen instead of liquid type. And the C-FRP in a size of 120mm*120mm and the thickness is 6.6mm was able to fabricate by this method.
Development and Characterisation of Lightweight Sandwich Panel for Table Tennis Table
Authors: Penneru Anjaneya Prasad , Lin Richard , Antcliff Paul , Choi Hansol
Published: December 2011

Lightweight sandwich panels (LWSP) have been used in various sectors of construction and transportation industries. However, due to the cost and complexity of the manufacturing process, their usage in high level sport equipment has been somewhat neglected. This study investigates the feasibility of using a wood veneer sandwich panel to construct the playing surface of a table tennis table. The effects of material parameters, such as the face sheet thickness, core configuration, core thickness and surface coating, on the dynamic friction coefficient and coefficient of restitution, which ultimately dictate the speed, bounce and spin of the ball, will be examined. All results from characterisation of the LWSP table using the International Table Tennis Federation (ITTF) standards will be compared with those from commercially available tables. The material parameters identified to yield the most consistent and favourable characteristics for a table tennis game will be applied for construction of a full size demonstration table.
Effects of PPV-g-PSFu Graft Copolymer on Morphology and Power Conversion Efficiency of Bulk Heterojunction Solar Cell Base on P3HT/C60 Blends
Authors: Seeponkai Narumon , Woothikanokkhan Jatuphorn , Thanachayanont Chanchana
Published: December 2011

This research work concerns a study on the effect of donor-acceptor graft copolymer, namely poly-p-phenylene vinylene grafted with polystyrene fullerene (PPV-g-PSFu), on morphology and power conversion efficiency of bulk heterojunction solar cells (BHJ) based on P3HT/C60. The aim of this work is to investigate the effect of the graft copolymers content (10, 20 and 40 pph) on morphology and efficiency of the solar cells. The copolymer was mixed with P3HT and C60, by using a solution blending technique. The blend film was fabricated by using a spin coating technique. Power conversion efficiency of the cells was determined by using current density-voltage (J-V) measurements. From the results, it was found that power conversion efficiency (PCE) of various BHJ cells increased from 0.07 x10-4 % to 1.45 x10-4 % after the copolymer (20 pph) was added. The above change was discussed in the light of some changes in morphology of the P3HT/C60 blend. Atomic force micrographs (AFM) the various blends showed that, by adding the graft copolymer, the domain size decreased and finer dispersed particle morphology was obtained.
Fabrication of the Nanoparticles of the Cu (II), Zn (II) Complexes with Pyrithione Derivative and their Marine Biological Activities
Authors: Li Wen Ge , An Yan , Li Xiao Feng , Yin Yan Sheng , Wen Yong Hong , Zhang Yu Liang , Wang Guo Qing
Published: December 2011

In this work, pyrithione was modified chemically and resulted in a new molecule of bis (2-(pyridine-N-oxide--2-ylthio) ethyl) amine (abbreviated as BEPA). The suspension of the nanoparticles of the zinc (II) and copper (II) complexes with BEPA were fabricated.
Composite Materials Based on Natural Rubber Modified Epoxy Resin and Sisal Fiber
Authors: Srisuwan Sawitri , Prasoetsopha N. , Suppakarn Nitinat , Chumsamrong Pranee
Published: December 2011

In the present work, bisphenol-A based epoxy resin was blended with methyl methacrylate (MMA)/glycidyl methacrylate (GMA) grafted depolymerized natural rubber (GDNR). GDNR/epoxy resin blend was composite with woven sisal fiber. GDNR was prepared by solution grafting MMA/GMA (90/10 w/w%) onto depolymerized natural rubber (DNR). The occurrence of GDNR was confirmed by proton nuclear magnetic resonance spectroscopy (1H-NMR). Amount of GDNR in the blend was 1 part per hundred resins. Impact strength of epoxy resin was increased by 62% when GDNR was added. Composites of GDNR/epoxy resin and woven sisal fiber were prepared by hand-lay up process. Amounts of woven sisal fiber in the composite were 3, 5 and 7% by weight (wt%). The flexural modulus of the composites was higher than that of neat epoxy resin and increased with increasing amount of woven sisal fiber. Nevertheless, flexural strength of all composites was lower than those of neat epoxy resin and the blend. Compared to neat epoxy resin, the impact strength of the composite containing 7 wt% woven sisal fiber was further increased to 114%.
Modulation of Behaviours of Cultured Cells on Polycaprolactone/Chitosan Blended Biomaterials
Authors: Young Tai Horng
Published: December 2011

Our previous study has illustrated that chitosan could enhance human anterior cruciate ligament cells to exhibit a dramatic effect on increasing the gene expression of transforming growth factor β1, which is a specific gene for wound healing and collagen synthesis. However, most of cells could not adhere and proliferate well on chitosan. In order to overcome this drawback, we introduced polycaprolactone (PCL) into chitosan by the method of blending in this study. It was found that the morphology, viability and gene expression of specific cells on the chitosan/PCL blended materials could be effectively regulated. Therefore, it is possible to combine the advantages of chitosan and PCL to create a new blended material, which could control cellular morphologies specifically, and further to regulate the gene expression and protein production of cells for specific applications.
Preparation and Characteristics of Pr1.2Sr0.8NiO4-Sm0.2Ce0.8O1.9 Composite Powders for Solid Oxide Fuel Cell Cathode Applications
Authors: Yang Jun Fang , Cheng Ji Gui , Jiang Qiu Mei , Gao Jian Feng
Published: December 2011

Pr1.2Sr0.8NiO4 (PSNO) and Sm0.2Ce0.8O1.9 (SCO) powders were synthesized by a glycine-nitrate process and a gel-casting process, respectively. Pr1.2Sr0.8NiO4-x Sm0.2Ce0.8O1.9 (x=0, 25, 50) composite cathode materials were prepared by mechanically mixing the two powders. The particle size of the synthesized PSNO and SCO powders is about 100nm and 50nm, respectively. PSNO and SCO have a good chemical compatibility. Area specific resistance value for the Pr1.2Sr0.8NiO4-x Sm0.2Ce0.8O1.9 (x=25, 50) composite cathode on SCO electrolyte is 0.087 and 0.076Ωcm2 at 750°C, which indicates Pr1.2Sr0.8NiO4-Sm0.2Ce0.8O1.9 composite materials may be a promising cathode material for intermediate temperature solid oxide fuel cell (IT-SOFC).
Preparation of SiO2 Encapsulated ZnO Nanopowders by Sol-Gel Method
Authors: Wang Yan Xiang , Sun Jian , Li Xiao Yan
Published: December 2011

The shell-core structures of SiO2/ZnO nanopowders were obtained by simple two-step technique based on low-temperature crystallization from liquid phase. The influence of molar ratio of SiO2/ZnO in the reaction mixture on the morphology of obtained SiO2/ZnO nanopowders was studied. Crystalline structure of SiO2/ZnO nanocrystals obtained was proofed by the X-ray diffraction data. The average diameter of SiO2/ZnO nanocrystals was about 80~100nm according to FSEM and TEM data. It is shown that SiO2 components on the surface prevent the thermal interfusion of ZnO particles. Morphology and diameter of raw ZnO, SiO2/ZnO nanopowders prepared with molar ratio of SiO2/ZnO 0.1, 0.2, and 0.5 were almost same. When molar ratio of SiO2/ZnO was 0.5, ZnO core was coated with SiO2, and the thickness of shell was about 10nm. At the same time, SiO2 nanocrystals also formed the islands structure.
Characterization of Ultrafine Glassy Powder for Al-Si-Ca-P-O-F Polynary System by Sol-Gel Method
Authors: Yuan G.C. , Zhu Z.H. , Ni X.M. , Ling Z.Y.
Published: December 2011

The ultrafine bio-glass powder of Si-Al-Ca-P-F-polynary system was prepared by sol-gel method with organic and inorganic compounds such as Si (OC2H5)4, (C2H5)3PO4, Ca (NO3)2·4H2O, Al (NO3)3·9H2O and NH4F. The powder was heat-treated at the different temperature in the range from 200 to 900°C and its crystallized transition was ascertained. The morphology, composition, structure state and crystallized behavior of the glassy powder were characterized by means of TEM, XRD, EDS, DSC-TG, FT-IR etc methods and compared with the glassy powder of the same system by melting-quenching and liquid precipitation. The results show that the powder containing elements Si, Al, Ca, P, F and O belongs to typical amorphous state, and is composed of the near spherical particles with the size from 100 to 400nm; The transition temperature of glass was about 580°C, and the crystallized phase CaF2precipitate firstly above 600°C; A series of crystallized phases Ca5(PO4)3F and Ca5(PO4)2SiO4were separated sequentially with increasing temperature; The network structure of glass is similar to that of melt-quenching or liquid precipitation glass.
Technological Conditions and Magnetic Properties of Y-Type Hexaferrite Prepared by Chemical Co-Precipitation Method
Authors: Chen Wen Guo , Dai Jian Qing , Xia Jing Bing , Ding Yao Min , Hu Zhi Gang
Published: December 2011

The Y-type hexaferrite precursors was synthesized by co-precipitation, and the pivotal technological conditions, including pH value, temperature (T), rotate speed (R) and the flow velocity of salt solution (V) were discussed. The particles of precursors were studied by Laser particle size analyzer (LPS). The precursor calcined at 900°C was characterized via X-ray Diffraction (XRD), the vibrating sample magnetometer (VSM) and HP4291A impedance analyzer were used to investigated magnetic properties. The results showed that the particle sizes were around 3µm (D50) and the distribution range was from 2.28μm to 4.47μm, in the optimized technological conditions: pH = 10.50, T = 50°C, R = 300 rpm, V = 0.35 ml/min, SDBS = 0.3 g/L, the specific saturation magnetization, coercive force, residual magnetization, initial permeability and factor of quality of the sample were σs≈ 29.72A·m2·kg-1, Hc≈ 4.11/kA·m-1, σr≈ 7.74 A·m2·kg-1, μi≈ 9 and Q ≈ 18 respectively.
Preparation and Surface Modification of Fe3O4 Nano-Magnetic Powders
Authors: Zhang Zhi Li , Shi Dan , Li De Cai , Qi Han , Shangguan Ya Fei
Published: December 2011

Because of aggregation and low chemical stability of nanomagnetic particles, we use Sol-Gel method as surface modification in this paper to improve the disperse ability and the chemical stability of Fe3O4particles. At first, Fe3O4were prepared by chemical-precipitation method. Then, the Sol-Gel method was used to modify the surface of the particles. Core-shell structural Fe3O4@ S iO2composite magnetic particles were prepared by hydrolysis and condensation of tetraethyl orthosilicate using Fe3O4nanomagnetic particles as seeds. XRD,VSM were applied to characterize the composite magnetic particles. The effects of rotational speed and the quantity of TEOS on the performance of Fe3O4@ S iO2composite magnetic particles were investigated.
Synthesis, Characterization and the Growth Formation of Spindle-Like CdS Nanostructures
Authors: Liu Shu Ling , Shi Qiang Qiang , Tong Jian Bo , Li Shu , Li Miao Miao
Published: December 2011

Spindle-like CdS structures were successfully synthesized via a simple one-step solvothermal process. The as-prepared products were characterization by X-ray powder diffractometer (XRD), scanning electron microscopy (SEM), and UV-vis absorption spectroscopy (UV-vis). By discussing the captive indimediates, the formation process of the spindle-like CdS structure was proposed as the splitting and the Oswald growth mechanism. The optical property of the as-prepared CdS showed obvious blue shift relative to the bulk CdS materials.
Experimental Study on Transition Heat Adjustment of CaCl2·6H2O
Authors: Zhu Xiao Qin , Liu Jun Ming , Hu Jin , Chi Wen , Li Ning , Gu Hai Ming , Yi Xu Xiao
Published: December 2011

Transition heat adjustment of CaCl2·6H2O added small quantity of stable additives (Ba (OH)2 and SrCl2·6H2O) was investigated by means of adding excess water. The experimental investigation results showed that, the transition heat adjustment of CaCl2·6H2O could be realized by adding excess water. With regard to CaCl2·6H2O, the suitable adjustment range of transition heat was 170kJ/kg-191.2kJ/kg as the proportion of adding excess water was 0-12.5% by weight; during the suitable adjustment range of transition heat, the phase change material with a random transition heat could be prepared by adding suitable excess water according to the actual requirement, and the transition heat of CaCl2·6H2O with different proportion of excess water could be forecasted. It is very beneficial for temperature and heat control in greenhouse.
Preparation of Highly Permeable Al2O3 Hollow Fiber Membrane via Phase Inversion Method with Ethanol as External Coagulant
Authors: Zhang Xiao Zhen , Zhou Jian Er , Jiang Yu Hua , Zhang Jing
Published: December 2011

Highly permeable porous alumina (Al2O3) hollow fiber membranes have been developed by a combined phase inversion and sintering technique. Ethanol substituting for water was used as the external coagulant in order to prepare Al2O3 hollow fiber membranes with low trans-membrane resistance. The prepared Al2O3 membranes show a special asymmetric structure with an outer skin layer, highly porous inner surface and sub-layer composed of long and large finger-like pores. The influences of sintering temperature on the average pore size, N2 permeability and bending strength were investigated. Results show that Al2O3 hollow fiber membranes with higher permeability can be prepared using ethanol as the external coagulant. The prepared Al2O3 hollow fiber membranes show a N2 permeability of 871.5 m3·m-2·h-1·bar-1 and a bending strength of 91.4 MPa when sintered at 1550°C for 5h.
Preparation and Characterization of Porous Alumina Insulation Materials by Gel-Foaming
Authors: Zhang Lin , Du Jing Hong , Gan Guo You , Yan Ji Kang , Yi Jian Hong
Published: December 2011

Porous alumina insulation materials were prepared by the combination method of gelcasting and foaming. The effects of the amount of blowing agent, the solid volume, and the sintering temperature on porosity of aluminum oxide ceramic were studied. The result showed that, when the amount of blowing agent is 1wt %, the solid volume is 45vol % and the sintering temperature is 1500°C, the porous alumina ceramics with high porosity, small pore diameters, evenly distributed, high bending strength and low heat conductance can prepared.
Preparation of ZnO Nanopowders by One-Step Hydrothermal Synthesis
Authors: Wang Yan Xiang , Sun Jian , Li Xiao Yan
Published: December 2011

In the paper, ZnO nanopowders were synthesized by using zinc acetate and sodium hydroxide as raw materials. The influences of different soft templates and synthesis temperature on the properties of ZnO nanopowders were investigated. The results showed that: when using the polyethylene glycol (PEG (400)) or polyvinyl alcohol (PVA) as soft template, the ZnO nanoparticles with the diameter about 100nm were obtained, whereas the ZnO nanorods which the length and diameter were 300nm and 150nm respectively were obtained without soft template. When the synthesis temperature was 220°C and 70°C, the ZnO nanorods were obtained. When the temperature was 100°C, the ZnO nanosheets were produced, and the length, width and thickness of ZnO nanosheets were about 800 nm, 500nm and 80nm, respectively. When the temperature was 90°C, the ZnO nanosheets composed with nanorods were prepared.
Synthesis and Photoelectrocatalytic Property of Two-Nonmetal-Codoped TiO2 Nanotube Arrays with High Aspect Ratio
Authors: Liao Hai Da , Zhang Wei Ping , Sun Xiao Ming , Shi Liang , Qin Ming Feng
Published: December 2011

Electrolyte containing F–was employed to conduct two-step anodic oxidation. Through adjustment of the composition of electrolyte, TiO2nanotube array with high aspect ratio was grown in situ on Ti matrix, and meanwhile the binary doping with non-metallic elements, namely, F and S, was achieved. Using FSEM, XRD and EDS, the characterization on the topography, structure and doped elements of TiO2nanotubes were performed. Taking methyl orange as the target degradation substance and using xenon lamp to simulate natural lighting, the comparison between the doped non-high-aspect-ratio nanotube and the doped high-aspect-ratio nanotube was made to investigate the related photoelectrocatalytic property. The results showed that the photoelectrocatalytic property of doped nanotube with high aspect ratio was significantly superior to that with non-high aspect ratio. The mixed crystal ratio of anatase and rutile obtained after calcination for 2h at 500°C enabled higher photoelectrocatalytic activity of TiO2nanotube array.
Effect of Modification Powders on Low Alloy Cast Steel
Authors: Zhang Cheng , Chen Yi , Wang Zhao Hui
Published: December 2011

Effects of V-Ti-Zr-Re containing modification powders on the mechanical properties and microstructure of low alloy steel castings by conventional normalizing, hardening and tempering processes and normalizing-free heat treatment were investigated. The results showed that for the as-modified casting, martensite and carbides were the main phases after direct quenching and low-temperature tempering but skipping normalizing. The mechanical properties were almost the same or even higher in impact toughness than the same material but bearing also normalizing treatment. Both samples modified by alloy powders, whether normalizing treated or not, possessed superior mechanical properties to those castings without being modified. The modification technique can be applied in low alloy steel production to eliminate the time and energy consuming normalization process, so that the cheap, energy saving and environment friendly materials are thus expected.
Preparation of Ultrafine Tungsten-Based Alloy Powders by GNP-Reduction Method
Authors: Wan Lei , Cheng Ji Gui , Jiang Qiu Mei , Wang Yong Hong
Published: December 2011

A novel glycine-nitrate process (GNP)-reduction method has been developed to fabricate ultrafine tungsten heavy alloy powders, with ammonium metatungstate (AMT), iron nitrate nonahydrate (Fe (NO3)3·9H2O), nickel nitrate hexahydrate (Ni (NO3)2·6H2O) as raw materials and gylcine as a complexant and incendiary agent. Precursor powders were obtained by self-propagation reaction in a suspension containing above materials. The precursor powders were then hydrogen-reduced to obtain composite powders with 90W-7Ni-3Fe composition (wt.%). Phase constitution and morphology of the precursor powders and the reduced powders were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Chemical composition of resultant powders was analyzed by energy dispersive spectrometer (EDS) analysis. It was shown that the GNP-reduction method produces ultrafine 90W-7Ni-3Fe powders with particle size of about 200 nm and highly dispersion of the composition.
A Calcination Technology for Ultrafine La3NbO7 Powder Prepared by Sol-Gel Process
Authors: Li Ying , Xu Qiang , Dai Ling
Published: December 2011

In order to prepare ultrafine La3NbO7 powder, a potential material for thermal barrier coatings, the calcination process of La3NbO7 was studied in this paper.The precursor of La3NbO7 was synthesized by using a citric acid complex method. A calcination process had been systematically investigated. The reaction temperature was determined by differential scanning calorimetry (DSC). The phase composition of powders was characterized by X-ray diffraction (XRD), and the morphology was obtained by scanning electron microscope (SEM). The results revealed that the single-phase La3NbO7 powder could be successfully prepared while the calcination temperature exceeded 800°C and a better morphology could be maintained at 800°C for 4 hours. Considering all above, an optimum calcination scheme was adopted at 800°C for 4 hours. The as-prepared La3NbO7 powders had a grain size of about 50nm and an average particle size of about 300nm.
Structure and Piezoelectric Properties of (K,Na)NbO3 Ceramics Fabricated from Microwave Hydrothermal Synthesized Powders
Authors: Li Yue Ming , Shen Zong Yang , Liu Hu , Wang Zhu Mei , Hong Yan
Published: December 2011

First, (K,Na)NbO3 (abbreviated as KNN) powders were synthesized by microwave hydrothermal method using Nb2O5, NaOH and KOH as raw materials. The effects of NaOH/KOH mole ratio and reaction temperature on the structure of KNN powders were studied systematically. Near spherical KNN powders of about 800 nm in diameter can be obtained at the optimized processing parameters as follows: NaOH/KOH mole ratio was 1.40/4.60, reaction temperature was 200 °C. Second, the ceramics were successfully prepared from the microwave hydrothermal synthesized KNN powders under 1090 °C for 2 h. This ceramic sample showed the enhanced piezoelectric properties such as piezoelectric constant d33=142 pC/N and planar electromechanical coupling coefficient kp=38%, in addition to other good properties as relative dielectric constant εr=426, Curie temperature Tc=410 °C, remnant polarization Pr=17.45μC/cm2 and coercive field Ec=1.41 kV/mm, indicating that microwave hydrothermal method can improve the properties of KNN ceramics high efficiently.
Electrical Characteristics and Microstructures of Ce2O3-Doped Bi4Ti3O12 Ceramics
Authors: Chen Min , Mei X.A. , Cai A.H. , Liu J. , Huang Chong Qing
Published: December 2011

The electrical properties of Ce-doped bismuth titanate, Bi4-xCexTi3O12(BCT) ceramics prepared by a conventional electroceramic technique were investigated. XRD analyses revealed Bi-layered perovskite structure in all samples. SEM micrographs showed randomly oriented and plate-like morphology. For the samples with x=0.4 and 1.0 the current-voltage characteristics exhibited negative differential resistance behaviors and their P-E hysteresis loops were characterized by large leakage current, whereas for the samples with x=0.6 and 0.8 the current-voltage characteristics showed simple ohmic behaviors and their P-E hysteresis loops were the saturated and undistorted hysteresis loops. The remanent polarization ( Pr) and coercive field (Ec) of the BCT ceramic with x=0.8 were above 20μC/cm2and 60KV/cm , respectively.
Electrical Characteristics and Microstructures of Gd-Doped Bi4Ti3O12 Ceramics
Authors: Liu J. , Chen Min , Mei X.A. , Sun Y.H. , Huang Chong Qing
Published: December 2011

The electrical properties of Gd-doped bismuth titanates Bi4-xGdxTi3O12) prepared by a conventional ceramic technique have been investigated. At applied d.c. field below 200V/mm, the current-voltage curve of Gd-doped sample exhibits a negative differential resistance behavior. The conducting filamentary model has been used to explain the negative differential resistance phenomenon in Gd-doped bismuth titanates. The impedance spectrum of Gd sample indicates that both consist of semiconducting grain and moderately insulating grain boundary regions. XRD, SEM and EPMA analyses reveal crystalline phase characterized by a Bi-layered perovskite structure of Bi4Ti3O12and the distribution of every element is uniform. Gd-doped sample exhibites randomly oriented and plate-like morphology.
Electrical Characterization and Microstructures of La-Doped Bi4Ti3O12 Thin Films
Authors: Mei X.A. , Chen Min , Liu R.F. , Sun Y.H. , Liu J.
Published: December 2011

La-doped bismuth titanate (Bi4-xLaxTi3O12: BLT) and pure Bi4Ti3O12 (BIT) thin films with random orientation were fabricated on Pt/Ti/SiO2/Si substrates by rf magnetron sputtering technique. These samples had polycrystalline Bi-layered perovskite structure without preferred orientation, and consisted of well developed rod-like grains with random orientation. La-doping into BIT caused a large shift of the Curie temperature ( TC ) from 675°C to lower temperature and a improvement in dielectric property. The experimental results indicated that La doping into BIT also result in a remarkable improvement in ferroelectric property. The Pr and the Ec values of the BLT film with x=0.75 were 20 μC/cm2 and 82kV/cm, respectively.
Fabrication of Al3Bc3-Based Porous Ceramics by Pressureless Sintering
Authors: Che Qing Lun , Ma Qin , Lu Jin Jun
Published: December 2011

Al3BC3-based porous ceramics are prepared by pressureless sintering using Al, B4C, and graphite powders as the starting materials. The influences of molar ratio of starting materials on the purity, open porosity and pore size of the porous ceramics are investigated. Graphite is the main impurity of the Al3BC3-based porous ceramics and can be eliminated by adjusting the molar ratio of starting material. With the molar ratio of Al:B4C:C = 3.2:0.25:2.30, high pure Al3BC3porous ceramic is successfully fabricated by pressureless sintering in vacuum at 1800 °C for 2 h. The open porosity of the Al3BC3-based porous ceramics ranges from 36% to 47%. The pores are uniformly distributed.
Influence of Clay Materials on Acicular Mullite Porous Ceramic
Authors: Zhou Jian Er , Zhang Xiao Zhen , Zhang Jing , Wang Yong Qing , Zhao Shi Kai , Cai Xi E
Published: December 2011

Porous acicular mullite ceramic was prepared by in-situ reaction sintering, using clay materials and Al (OH)3) as the raw materials. The influences of different clay materials on the phase composition, formation of acicular grains and microstructure of prepared porous ceramics were investigated. Results show that the metal oxide impurities were beneficial for the synthesis of acicular mullite. The prepared porous ceramic from Longyan kaolin with high impurity content has the highest mullite content of 93.5%, and composed of interlaced acicular grains with high slenderness ratio of 26.4 and large average diameter of about 0.7μm when sintered 1400°C for 2h. The TEM analysis indicates that the growth direction of acicular grains is along the [001] direction (c axis) of orthorhombic mullite crystals.
Preparation of High Thermal Expansion Coefficient Glass-Ceramics in Li2O-ZnO-SiO2 System
Authors: Xiao Zhuo Hao , Zhu Li Gang , Wang Sheng Long
Published: December 2011

Lithium carbonate, zinc oxide and silica as the main raw materials, potassium oxide and sodium as flux, phosphorus pentoxide as nucleating agent, the glass in Li2O-ZnO-SiO2 was synthesized by conventional melt cooling method and then converted to glass-ceramics. The crystallization behavior, microstructure and thermal expansion coefficient of the resulting glass-ceramics were investigated by XRD, SEM and thermal performance test. The results show that the Tg of the matrix glass is about 508°C, initial crystallization temperature is about 620°C. When the crystallization temperature ranges from 650°C to 750°C, the main crystal phase is Li2ZnSiO4. Increasing crystallization temperature to 850°C, much cristobalite crystals is formed. Owing to the high TEC of the cristobalite, the glass-ceramics with TEC of 12.27×10-6°C-1 were obtained, which is matched with the TEC of stainless steel SAE 1010.
Spectral Transmittance of Six All-Ceramic Core Materials after Veneering Ceramic
Authors: Liu Yi Han , Liu Hong Chen , Deng Bin , Shao Long Quan , Yi Yuan Fu , Wen Ning
Published: December 2011

The spectral transmittance of six kinds of Vita In-Ceram and Cercon all-ceramic core materials after veneering ceramic was determined. Based on the production method recommended by the manufacturer, specimens of the same thickness are made. PERKIN ELMER Spectrophotometer is adopted to measure the spectral transmittance of In-Ceram AL2 slip-casting glass/alumina composite, AL2 electroformed alumina, Z21 slip-casting glass/zirconia composite, Z21 electroformed zirconia, Cercon base color zirconia and Cercon base zirconia all-ceramic core materials, after veneering ceramic. The results show that, after veneering ceramic, Cercon base Zirconia has the highest spectral transmittance, followed by AL2 Electroformed Alumina and Z21 Electroformed Zirconia, whereas the transmittance of Z21 slip-casting Glass/Zirconia composite has the lowest. Statistical data show that, among the groups, In-Ceram slip-casting Glass/Alumina composite (AL2), Electroformed Alumina (AL2), Cercon base color Zirconia and Cercon base Zirconia have significant differences between every group. On the other hand, there is no significant difference between In-Ceram slip-casting Glass/Zirconia composite (Z21) and Electroformed Zirconia (Z21). Therefore, we should choose all-ceramic restoration materials based on the spectral transmittance of all-ceramic core materials after veneering ceramic and transparency of the remaining natural teeth of patients.
Effect of Background Color on In-Ceram and Cercon All-Ceramic Core Material
Authors: Liu Yi Han , Liu Hong Chen , Deng Bin , Shao Long Quan , Yi Yuan Fu , Wen Ning
Published: December 2011

The present paper probes into the effect of background color of different post-core materials on the core materials of In-Ceram AL2 Electroformed Alumina, Z21 Electroformed Zirconia, Cercon base color Zirconia, and Cercon base Zirconia. The spectrocolorimeter was used to measure colorimetric values of all groups of samples against the background of noble metal, nickel-chromium alloy, silver amalgam and resin, and to calculate the color difference among the groups. The result showed that the color difference of Cercon base color Zirconia viewed against different backgrounds was identifiable by human eyes (ΔE > 1.5). In contrast, the color differences of In-Ceram AL2 Electroformed Alumina, Z21 Electroformed Zirconia and Cercon base Zirconia viewed against different backgrounds were unidentifiable by human eyes (ΔE < 1.5). Based on this, it can be stated that Cercon base color Zirconia is significantly affected by background color. Thus, proper method to shelter the background color should be adopted. In addition, AL2 Electroformed Alumina, Z21 Electroformed Zirconia, and Cercon base color Zirconia are less influenced by the background color, thus it is not necessary to cover the background color.
Structure Analysis of Type-A Zeolites Molecular Sieve Prepared from Stellerite
Authors: Chen Nan Chun , Tang Quan , Zhang Xiao Hu , Wang Wei , Li Meng Ying
Published: December 2011

Type-A zeolites molecular sieve is prepared after crystallization of the type-A zeolites molecular sieve precursor, which is prepared from Stellerite, at temperature of 90 ~ 100°C for 6 hours. It has a complete structure, with crystallinity of 98%, volume average particle size of 3.72µm and particle size distribution which is less than 10µm over 90%. Multi-member rings structure in the type-A zeolites molecular sieve cover each other, forming the cage (β-cage, α-cage, octahedral cage) structure. Nuclei and nanometer particles are formed after the further congregation reaction, and then gather and grow, result in the formation of nanometer crystal particles and transformation to micrometer particles.
The Compatibility of Magnesium Hydroxide Whiskers in Organic Phase
Authors: Li Yan Bo , Jiang Yu Zhi , He Jin Gui , Wang Yu Lian
Published: December 2011

The magnesium hydroxide (MH) whiskers were modified in micro-emulsion by introducing monomer that can polymerize. The SEM and FT-IR were used to analyze the structure after polymeration in whiskers surface. The results shows that there was flexible layer forming in the surface of whisker and the compatibility of whiskers in organic phase was improved. Get the MH/PE (polyethylene) composites by melt extrusion, study the compatibility of MH whiskers in organic phase. The results shows that MH whiskers after modification play a signification toughening effect in composites.
Solvothermal Synthesis and Photocatalysis of SnO2 Nanocrystal Microspheres
Authors: Liu Hui , Dong Xiao Nan , Li Guang Jun , Wang Xiao Feng , Zhu Zhen Feng
Published: December 2011

Quasi-monodispersed SnO2nanocrystal microspheres were successfully fabricated by a solvothermal route with the assistance of poly (ethylene glycol) (PEG, Mn=6000) template. The as-prepared SnO2microspheres were well characterized by XRD, SEM, TEM, and FT-IR. The photocatalytic activity for Rh B on the SnO2microspheres was also investigated under UV irradiation. The experimental results show that the quasi-monodispersed SnO2microspheres with diameter about 1.3µm are self-assembled by large quantity of crystallites less than 10 nm. The SnO2microspheres have a good photocatalytic property, as evidenced by the result that over 95% of the Rh B decomposed over the SnO2nanocrystal microspheres within 180 min. The high degradation rate of rhodamine B (Rh B) on the as-synthesized SnO2nanocrystal microspheres can be attributed to the small size of crystals.