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Sample records for ceramic fibers prepared

  1. Engineering of silicon-based ceramic fibers: Novel SiTaC(O) ceramic fibers prepared from polytantalosilane

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Z., E-mail: xiezhengfang@163.com [State Key Laboratory of Advanced Ceramic Fibers and Composites, National University of Defense Technology, Changsha 410073 (China); Cao, S.; Wang, J. [State Key Laboratory of Advanced Ceramic Fibers and Composites, National University of Defense Technology, Changsha 410073 (China); Yan, X. [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Bernard, S., E-mail: Samuel.Bernard@univ-lyon1.fr [Laboratoire des Multimateriaux et Interfaces (UMR CNRS 5615), Universite de Lyon, Universite Lyon1, 43 bd du 11 Novembre 1918, 69622 Villeurbanne Cedex (France); Miele, P. [Laboratoire des Multimateriaux et Interfaces (UMR CNRS 5615), Universite de Lyon, Universite Lyon1, 43 bd du 11 Novembre 1918, 69622 Villeurbanne Cedex (France)

    2010-10-15

    Research highlights: {yields} This paper reports the preparation and characterization of a novel variety of silicon-based ceramic fibers. {yields} In the present paper, we provide a detailed picture of the preparation process of SiTaC(O) ceramic fibers from a polytantalosilane. {yields} We have fully characterized the polymer by FT-IR, NMR, chemical composition, GPC and TGA as well as the chemical composition, the structure, the texture, and the mechanical properties of the ceramic fibers by XPS, SEM, X-ray diffraction (XRD), and mechanical tests. - Abstract: A novel variety of silicon-based ceramic fibers has been prepared from a preceramic organosilicon polymers called polytantalocarbosilane (PTaCS). This melt-spinnable polymer has been synthesized by thermally induced reactions between tantalum (V) tetraethoxyacetylacetonate (Ta(Acac)(OEt){sub 4}) and polysilacarbosilane (PSCS). The polymer in which [-Si-C-]{sub n} chains are crosslinked via Ta-containing bridges as identified by infrared spectroscopy, XPS and NMR, is decomposed in high ceramic yield (76%) and can be spun in the molten state into fibers to be cured in air then pyrolyzed in flowing nitrogen at 1200 deg. C into amorphous SiTaC(O) fibers. Complete characterization of this new generation of silicon-based ceramic fibers was made based on mechanical tests, XRD and SEM. These fibers exhibit relatively good mechanical properties and excellent high-temperature stability with good oxidation resistance.

  2. Heat treatment of piezoelectric Pb(ZrTi)O3 ceramic fibers prepared with continuous spinning

    Science.gov (United States)

    Xiong, Z. X.; Pan, J.; Xue, H.; Mai, M. F.; Qiu, H.; Chen, L. F.

    2009-07-01

    Ceramic of Pb(ZrTi)O3 is one kind of typical smart materials, with excellent ferroelectric and piezoelectric properties. In this paper, a novel heat treatment was applied for the ceramic fibers prepared via sol-gel route with continuous spinning. Aided with microwave energy, dense ceramic fibers are obtained after treated at around 900°C for 1h, in which the diameters of the fibers are between 5μm and 30μm. The samples were also characterized with thermal analysis, FTIR spectroscopy and X-ray diffraction. By using of a scanning electron microscope, SEM, it was observed that a dense microstructure of the fiber was reached.

  3. Mullite Continuous Ceramic Fiber Prepared by Sol—Gel Method

    Institute of Scientific and Technical Information of China (English)

    LIQuan; LIJing-hua; 等

    1995-01-01

    As oxide materials,continuous mullite fiber has superior properties in high temperature resis-tance when exposed in air,Present work shows the production of oxide solutio and the spinning of the nullite fiber,The stable spinning lasted over 10 hours,The strength of the mullite-based fiber is 1900 MPa with a diameter of 10μm after about 1000℃ treatment,When the treatment temperature exceeds 1300℃ the grains of fiber become column crystals and results in reduction of fiber strength.

  4. Continuous Fiber Ceramic Composites

    Energy Technology Data Exchange (ETDEWEB)

    None

    2002-09-01

    Fiber-reinforced ceramic composites demonstrate the high-temperature stability of ceramics--with an increased fracture toughness resulting from the fiber reinforcement of the composite. The material optimization performed under the continuous fiber ceramic composites (CFCC) included a series of systematic optimizations. The overall goals were to define the processing window, to increase the robustinous of the process, to increase process yield while reducing costs, and to define the complexity of parts that could be fabricated.

  5. Preparation of CeO(2)-ZrO(2) ceramic fibers by electrospinning.

    Science.gov (United States)

    Zhang, Yanfei; Li, Jiayan; Li, Qin; Zhu, Ling; Liu, Xiangdong; Zhong, Xinghua; Meng, Jian; Cao, Xueqiang

    2007-03-15

    Electrospinning was employed to fabricate polymer-ceramic composite fibers from solutions containing poly(vinyl pyrrolidone) (PVP), Ce(NO(3))(3) x 6H(2)O and ZrOCl(2) x 8H(2)O. Upon firing the composite fibers at 1000 degrees C, Ce(0.67)Zr(0.33)O(2) fibers with diameters ranging from 0.4 to 2 microm were synthesized. These fibers exhibit strong resistance to sintering. They still have specific surface area around 11.8 m(2)/g after being heated at 1000 degrees C for 6 h.

  6. Active Optical Fibers Doped with Ceramic Nanocrystals

    Directory of Open Access Journals (Sweden)

    Jan Mrazek

    2014-01-01

    Full Text Available Erbium-doped active optical fiber was successfully prepared by incorporation of ceramic nanocrystals inside a core of optical fiber. Modified chemical vapor deposition was combined with solution-doping approach to preparing preform. Instead of inorganic salts erbium-doped yttrium-aluminium garnet nanocrystals were used in the solution-doping process. Prepared preform was drawn into single-mode optical fiber with a numerical aperture 0.167. Optical and luminescence properties of the fiber were analyzed. Lasing ability of prepared fiber was proofed in a fiber-ring set-up. Optimal laser properties were achieved for a fiber length of 20~m. The slope efficiency of the fiber-laser was about 15%. Presented method can be simply extended to the deposition of other ceramic nanomaterials.

  7. Ceramic fiber filter technology

    Energy Technology Data Exchange (ETDEWEB)

    Holmes, B.L.; Janney, M.A.

    1996-06-01

    Fibrous filters have been used for centuries to protect individuals from dust, disease, smoke, and other gases or particulates. In the 1970s and 1980s ceramic filters were developed for filtration of hot exhaust gases from diesel engines. Tubular, or candle, filters have been made to remove particles from gases in pressurized fluidized-bed combustion and gasification-combined-cycle power plants. Very efficient filtration is necessary in power plants to protect the turbine blades. The limited lifespan of ceramic candle filters has been a major obstacle in their development. The present work is focused on forming fibrous ceramic filters using a papermaking technique. These filters are highly porous and therefore very lightweight. The papermaking process consists of filtering a slurry of ceramic fibers through a steel screen to form paper. Papermaking and the selection of materials will be discussed, as well as preliminary results describing the geometry of papers and relative strengths.

  8. Preparation of continuous Si-Fe-C-O functional ceramic fibers

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new polymer named polyferrocarbosilane(PFCS) was prepared from polydimethylsilane and ferrocene. The spinnability of this polymer can be tailored by controlling the content of ferrocene in the polymer. The prepared polymer was spun into a continuous polymer fiber that was subsequently cured in air and heat-treated finally in N2 up to 1 350 ℃ for conversion into Si-Fe-C-O fibers. The resulted Si-Fe-C-O fibers display low specific resistance and magnetic property due to the existence of Fe,which also reduces the specific resistance significantly to 10-2 Ω·cm at room temperature when the amount of ferrocene in feed is as low as 3.0% (mass fraction). The resulted Si-Fe-C-O fibers, with C/Si molar ratio of about 1.3 and the maximum Fe content of about 2.0% (mole fraction), are composed of β-SiC and small amount of Fe3Si-like crystalline and have an average tensile strength of about 2.0 GPa.

  9. Preparation and characterization of lead zirconate titanate ceramic fibers with alkoxide-based sol-gel route

    Energy Technology Data Exchange (ETDEWEB)

    Mai Manfang; Lin Cheng; Xiong Zhaoxian; Xue Hao; Chen Lifu [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China)], E-mail: zxxiong@xmu.edu.cn

    2009-03-01

    Lead zirconate titanate (PZT) fibers with diameters from 10{mu}m to 40{mu}m were prepared via a sol-gel route. Several kinds of chemicals were used, including lead acetate trihydrate, zirconium n-butoxide and titanium n-butoxide, in addition to butanol as a solvent. As a water source for hydrolysis reaction, Pb(CH{sub 3}COO){sub 2}{center_dot}3H{sub 2}O was directly used without further adding of water or catalyst conventionally. Acetylacetonate and acetate were added as stabilization agents to obtain stable sols for fiber drawing. The gel-to-ceramic conversion was characterized with thermal analysis, infrared spectroscopy and X-ray diffraction. A pure perovskite phase was obtained after heat treatment at 650 deg. C for 1h. By using scanning electron microscope (SEM), it was observed that a lower rate of heat treatment resulted in a denser microstructure of the fibers. The relative permittivity and the P-E hysteresis loop of the crystalline PZT fibers were also measured and discussed in the paper.

  10. Preparation and characterization of lead zirconate titanate ceramic fibers with alkoxide-based sol-gel route

    Science.gov (United States)

    Mai, Manfang; Lin, Cheng; Xiong, Zhaoxian; Xue, Hao; Chen, Lifu

    2009-03-01

    Lead zirconate titanate (PZT) fibers with diameters from 10μm to 40μm were prepared via a sol-gel route. Several kinds of chemicals were used, including lead acetate trihydrate, zirconium n-butoxide and titanium n-butoxide, in addition to butanol as a solvent. As a water source for hydrolysis reaction, Pb(CH3COO)2·3H2O was directly used without further adding of water or catalyst conventionally. Acetylacetonate and acetate were added as stabilization agents to obtain stable sols for fiber drawing. The gel-to-ceramic conversion was characterized with thermal analysis, infrared spectroscopy and X-ray diffraction. A pure perovskite phase was obtained after heat treatment at 650°C for 1h. By using scanning electron microscope (SEM), it was observed that a lower rate of heat treatment resulted in a denser microstructure of the fibers. The relative permittivity and the P-E hysteresis loop of the crystalline PZT fibers were also measured and discussed in the paper.

  11. PZT压电纤维的制备及性能研究%Study on the Preparation and Properties of PZT Ceramic Fibers

    Institute of Scientific and Technical Information of China (English)

    杨杰; 刘兴钊

    2009-01-01

    以溶胶-凝胶(Sol-Gel)工艺制备的PZT陶瓷粉为原料,采用氧化物粉末装管法制备PZT压电陶瓷纤维.SEM分析显示,该陶瓷纤维呈圆柱型形貌,直径约为250 μm.分析了不同烧结温度下PZT陶瓷纤维的断面微结构及Pb含量变化,得出PZT陶瓷纤维的最佳烧结温度为1 000 ℃.XRD分析表明,此温度下烧结的陶瓷纤维呈单一的钙钛矿结构.实验结果表明,采用氧化物粉末装管法制备的陶瓷纤维大小均匀,结构致密,具有高长径比,克服了传统工艺不能制备结构致密的长纤维的缺陷.%Using the PZT ceramic powder prepared by Sol-Gel method as the raw material, the PZT piezoelectric ceramic fibers have been prepaared by using the Oxide Powder in Tube(OPTT)procedure.The SEM morphology showed that the PZT ceramic fibers had a cylindrical morphology with a diameter of about 250 μm.The sectional micro-structure and the content of Pb of the PZT ceramic fiber were analyzed at different sintering temperature. The result showed that the optimal sintering termperature of the PZT ceramic fiber was 1 000 ℃.The X-ray diffraction patterns showed that the ceramic fibers were pure perovskite structure.Compared with conventional fabrication process,PZT ceramic fibers prepared by the OPIT method have the advantage of dense ,uniform and high height-to-width ratio.

  12. Fiber-reinforced ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Belcheva, D. [Technological University `Prof. A. Zlatarov`, Bourgas (Bulgaria); Lubchev, L.; Jelezkov, G.; Georgiev, W.

    1995-03-01

    The possibilities for preparation of reinforced composite materials were studied. Test specimens based on different types of alumina matrices, plasticized with formaldehyde oligomer and polyvinyl alcohol, and reinforced with carbon and mullite fibers were prepared and investigated. The results confirmed that reinforced composite materials with valuable properties such as high thermal shock resistance, chemical resistance and mechanical strength can be produced. The density of technical alumina materials is lower, compared with that of pure alumina. The density can also be influenced by the type and quantity of the plasticizers used. By increasing the fiber content, the density of the material decreases. The shrinkage is influcenced by the type and the quantity of the reinforcing material. (orig.)

  13. 新型中空纤维陶瓷膜的制备方法%PREPARATION METHODS OF HOLLOW FIBER CERAMIC MEMBRANES

    Institute of Scientific and Technical Information of China (English)

    张小珍; 周健儿; 江瑜华

    2011-01-01

    Ceramic hollow fiber membranes have recently attracted considerable attention, due to the high active area/volume ratio provided by its high packing density, thin wall, high permeability and less material consumption. With the application of ceramic membranes in hollow fiber configuration, the separation equipment can be miniaturized. Ceramic hollow fiber membranes have potential applications in various fields, such as porous and dense ceramic membranes for separation, solid oxide fuel cells, microchannel-reactor, and supports of catalysts. This paper summarized the characteristics and progress in preparation methods of hollow fiber ceramic membranes. The emphasis was put on the comparison of different preparation methods. The phase inversion method was cost-effective, since the derived ceramic hollow fiber membranes with selfsupported asymmetric structure and thus high permeability can be obtained in one step. The application of phase inversion method could simplify the fabrication process of ceramic membranes and greatly reduce the production cost.%新型中空纤维陶瓷膜由于具有装填密度大、单位体积膜有效分离面积大、膜壁薄、渗透通量高和节省原料、易于实现分离设备小型化等独特优点而受到广泛关注,在用于多孔和致密陶瓷分离膜、固体氧化物燃料电池、微通道反应器、催化剂载体等方面都有着潜在的应用前景.本文在概括中空纤维陶瓷膜特点的基础上,综述了中空纤维陶瓷膜的制备方法及研究进展,着重分析比较了不同制备方法的优缺点.将相转化法应用于中空纤维陶瓷膜的制备,可实现通过一步成型制造具有自支撑非对称结构的复合陶瓷膜,有利于提高膜的渗透通量,简化膜制备工艺和显著降低制造成本.

  14. Polymer-Derived Ceramic Fibers

    Science.gov (United States)

    Ichikawa, Hiroshi

    2016-07-01

    SiC-based ceramic fibers are derived from polycarbosilane or polymetallocarbosilane precursors and are classified into three groups according to their chemical composition, oxygen content, and C/Si atomic ratio. The first-generation fibers are Si-C-O (Nicalon) fibers and Si-Ti-C-O (Tyranno Lox M) fibers. Both fibers contain more than 10-wt% oxygen owing to oxidation during curing and lead to degradation in strength at temperatures exceeding 1,300°C. The maximum use temperature is 1,100°C. The second-generation fibers are SiC (Hi-Nicalon) fibers and Si-Zr-C-O (Tyranno ZMI) fibers. The oxygen content of these fibers is reduced to less than 1 wt% by electron beam irradiation curing in He. The thermal stability of these fibers is improved (they are stable up to 1,500°C), but their creep resistance is limited to a maximum of 1,150°C because their C/Si atomic ratio results in excess carbon. The third-generation fibers are stoichiometric SiC fibers, i.e., Hi-Nicalon Type S (hereafter Type S), Tyranno SA, and Sylramic™ fibers. They exhibit improved thermal stability and creep resistance up to 1,400°C. Stoichiometric SiC fibers meet many of the requirements for the use of ceramic matrix composites for high-temperature structural application. SiBN3C fibers derived from polyborosilazane also show promise for structural applications, remain in the amorphous state up to 1,800°C, and have good high-temperature creep resistance.

  15. Preparation and performance of ZnO nanowires modified carbon fibers reinforced NiFe{sub 2}O{sub 4} ceramic matrix composite

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lei, E-mail: jwlzl77@163.com; Jiao, Wanli

    2013-12-25

    Highlights: •Unlike existing chemical modification, the liquid growth remains fiber’s strength. •ZnO nanowires array are grown on carbon fibers with controllable morphology. •ZnO nanowires array modified carbon fibers can reinforce the strength of ceramic matrix composite. •This research will provide a means to produce multifunctional composites. -- Abstract: The surface of carbon fibers was modified by ZnO nanowires using the liquid growth method. NiFe{sub 2}O{sub 4} ceramic matrix composites reinforced by the modified carbon fibers were prepared by a high-temperature solid-state reaction method at 1300 °C for 5 h in N{sub 2} atmosphere. The influences of modified carbon fibers on the mechanical performances of NiFe{sub 2}O{sub 4} composites were investigated. The crystal structure of modified carbon fibers and the morphology of modified carbon fibers surface and the NiFe{sub 2}O{sub 4} composites fracture cross-section were observed by meaning of X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The results showed that hexagonal wurtzite ZnO nanowires array grew from the surface of carbon fibers vertically, with nanowires diameters ranging from 170 nm to 380 nm and lengths up to 2.8 μm. Unlike existing chemical modification and high temperature oxidation method, the liquid growth allowed morphology control and maintained the single fiber tensile strength substantially unchanged under certain growth procedures. Compared to pure NiFe{sub 2}O{sub 4} ceramic and bare carbon fibers reinforced NiFe{sub 2}O{sub 4} composite, the bending strength of NiFe{sub 2}O{sub 4} composite reinforced with ZnO nanowires surface modified carbon fibers was shown to increase by up to 70% and 45%, respectively. The development of an interphase offering control over the morphology will provide a means to produce multifunctional composites.

  16. Ceramic fibers from Si-B-C polymer precursors

    Science.gov (United States)

    Riccitiello, S. R.; Hsu, M. S.; Chen, T. S.

    1993-01-01

    Non-oxide ceramics such as silicon carbide (SiC), silicon nitride (Si3N4), and silicon borides (SiB4, SiB6) have thermal stability, oxidation resistance, hardness, and varied electrical properties. All these materials can be prepared in a fiber form from a suitable polymer precursor. The above mentioned fibers, when tested over a temperature range from 25 to 1400 C, experience degradation at elevated temperatures. Past work in ceramic materials has shown that the strength of ceramics containing both carbides and borides is sustained at elevated temperatures, with minimum oxidation. The work presented here describes the formation of ceramic fibers containing both elements, boron and silicon, prepared via the polymer precursor route previously reported by the authors, and discusses the fiber mechanical properties that are retained over the temperature range studied.

  17. Properties of textile grade ceramic fibers

    Science.gov (United States)

    Pudnos, Eric

    1992-01-01

    The availability of textile grade ceramic fibers has sparked great interest for applications in composite reinforcement and high temperature insulation. This paper summarizes the properties of various small diameter textile grade ceramic fibers currently available. Room temperature mechanical and electrical properties of the fibers are discussed for three cases: ambient conditions, after heat aging in argon, and after heat aging in wet air. Dow Corning (R) HPZ Ceramic Fiber, a silicon nitride type fiber, is shown to have improved retention of mechanical and electrical properties above 1200 C.

  18. Preparation and catalytic performance of La0.8Sr0.2CoO3 supported on the mullite fiber ceramic

    Institute of Scientific and Technical Information of China (English)

    ZENG Lingke; LIU Yanchun; DUAN Bilin; LIU Ping'an; WANG Hui; SHUI Anze

    2007-01-01

    The perovskite-type La0.8Sr0.2CoO3 supported on the mullite fiber porous ceramics was prepared by means of the impregnating method,and was then characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD);thus we can come to the conclusion that the perovskite-type composite oxidant can disperse on the surface of mullite fiber ceramics.The catalytic activity of the La0.8Sr0.2CoO3 for NO and CO was evaluated.The effect of the doped 0.1 wt-% PdCl2 on the catalytic activity of the perovskite-type La0.8Sr0.2CoO3 was also discussed.The results show that the conversion rates of NO and CO respectively reaches 74.5% and 99% at 601℃ without doped Pd,and both reach 100% at 350℃ with a little doped Pd.

  19. Preparation of Bauxite Ceramic Microsphere

    Institute of Scientific and Technical Information of China (English)

    CHENG Xiaosu; LIU Pingan; LI Xiuyan; SHUI Anze; ZENG Lingke

    2007-01-01

    Ceramic microspheres were prepared by using Chinese bauxite as raw materials through the centrifugal spray drying method. The control technology of microsphere size, degree of sphericity was researched. The ceramic microspheres were sintered by a double sintering process. The microstructure and composition of ceramic microsphere were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray energy spectroscopy. The results show that the degree of sphericity of the ceramic microsphere was good and the particle size was 10-100 μm. The XRD analysis reveals that the main crystalline phase of the ceramic microsphere was α- Al2O3 and mullite (3Al2O3·2SiO2). The product can be used as reinforced material for composite material, especially for antiskid and hard wearing aluminum alloy coating.

  20. Preparation and characteristics of porous ceramics

    Institute of Scientific and Technical Information of China (English)

    Dongmei SHAO; Peiping ZHANG; Liyan MA; Juanjuan LIU

    2007-01-01

    Pyrophyllite is always used for making porous ceramics. In order to design the preparation technics of porous ceramics with pyrophyllite reasonably we must know the classifications, characteristics, properties and applications of porous ceramics. The classification and characteristics of porous ceramics are reviewed in this article; and several common preparations with their advantages and disadvantages are also introduced. The authors discussed the problems existing in researching and developing process for porous ceramics, and forecasted the development prospect of porous ceramics.

  1. Ceramic veneers with minimum preparation.

    Science.gov (United States)

    da Cunha, Leonardo Fernandes; Reis, Rachelle; Santana, Lino; Romanini, Jose Carlos; Carvalho, Ricardo Marins; Furuse, Adilson Yoshio

    2013-10-01

    The aim of this article is to describe the possibility of improving dental esthetics with low-thickness glass ceramics without major tooth preparation for patients with small to moderate anterior dental wear and little discoloration. For this purpose, a carefully defined treatment planning and a good communication between the clinician and the dental technician helped to maximize enamel preservation, and offered a good treatment option. Moreover, besides restoring esthetics, the restorative treatment also improved the function of the anterior guidance. It can be concluded that the conservative use of minimum thickness ceramic laminate veneers may provide satisfactory esthetic outcomes while preserving the dental structure.

  2. Simple Creep Test For Ceramic Fibers

    Science.gov (United States)

    Dicarlo, James A.; Morscher, Gregory N.

    1994-01-01

    Simple bend-stress-relaxation test yields information on creep-related properties of polycrystalline ceramic fibers. Determination of these properties important part of efforts to develop ceramic composite materials that retain mechanical strength and resistance to creep at high temperatures. Present test measures effects of time, temperature, and applied strain on creep-related relaxation of bend stress in ceramic fiber of almost any diameter in almost any environment, without need for contact sensors. Degree of relaxation of bend stress determined from radii of curvature.

  3. 新型陶瓷纤维的制备及性能研究现状及发展趋势∗%Research Status and Development Trend of Preparation and Properties of New Ceramic Fiber

    Institute of Scientific and Technical Information of China (English)

    高伟超; 康永

    2016-01-01

    Ceramic fiber is a set of traditional insulation materials,refractory fibrous excellent perform-ance in one light-weight refractories,ceramic fiber,light weight,high temperature,thermal stability,low ther-mal conductivity,heat re-sistance of small and advantages such as mechanical vibrations,which involves all areas of its products,development pros-pects.This paper points out the present situation of the preparation and properties of the new ceramic fiber,and points out the development direction of the ceramic fiber technology in the future.%陶瓷纤维是一种集传统绝热材料、耐火材料优良性能于一体的纤维状轻质耐火材料。它具有质量轻、耐高温、热稳定性好、导热率低、比热小及耐机械震动等优点,因而其产品涉及众多领域,发展前景十分看好。笔者叙述了新型陶瓷纤维的制备、性能研究现状及未来陶瓷纤维技术发展方向。

  4. Ceramic veneers with minimum preparation

    OpenAIRE

    da Cunha, Leonardo Fernandes; Reis, Rachelle; Santana, Lino; Romanini, Jose Carlos; de CARVALHO, Ricardo Marins; Furuse, Adilson Yoshio

    2013-01-01

    The aim of this article is to describe the possibility of improving dental esthetics with low-thickness glass ceramics without major tooth preparation for patients with small to moderate anterior dental wear and little discoloration. For this purpose, a carefully defined treatment planning and a good communication between the clinician and the dental technician helped to maximize enamel preservation, and offered a good treatment option. Moreover, besides restoring esthetics, the restorative t...

  5. Preparation of Glass Ceramic Based on Granulated Slag and Cullet

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The glass-ceramic was prepared on the basis of materials of granulated slag containing high-calcium oxide and cullet.The content of granulated slag ranges from 50%-60%wt in the glass compositions. The samples were analyzed by DTA, SEM and XRD.The results show that the main crystal phase of the glass-ceramic is β-CaSiO3,Which is in scattering fiber or column form.The applying properties have also been measured.

  6. Preparation of mullite fiber

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L.; Wang, B.; Liu, S.; Yan, Y. [Xiamen Univ. (China). Dept. of Chemistry

    1996-06-01

    Transparent mullite fibers have been prepared using aluminum carboxylates (ACs) and tetraethyl orthosilicate (TEOS) as starting materials. The ACs are derived from the catalyzed dissolution of elemental aluminum in a mixture of formic acid and acetic acid. The solubility of aluminum in the acids is influenced by the concentrations of the acids, water, and additives and the preparation temperature. A 1:4:3:24 molar ratio of aluminum, formic acid, acetic acid, and water dissolves the aluminum completely to give a colorless, clear solution suitable for fiber synthesis. The mixture of the ACs and TEOS, in the presence of ethyl alcohol as a mutual solvent at 50--60 C, is concentrated to give a spinnable dope, from which mullite precursor fibers can be drawn. Heat treatment of the precursor at 1,250 C yields crystallized and transparent mullite fibers.

  7. Making Ceramic Fibers By Chemical Vapor

    Science.gov (United States)

    Revankar, Vithal V. S.; Hlavacek, Vladimir

    1994-01-01

    Research and development of fabrication techniques for chemical vapor deposition (CVD) of ceramic fibers presented in two reports. Fibers of SiC, TiB2, TiC, B4C, and CrB2 intended for use as reinforcements in metal-matrix composite materials. CVD offers important advantages over other processes: fibers purer and stronger and processed at temperatures below melting points of constituent materials.

  8. Electron microscopy study of refractory ceramic fibers.

    Science.gov (United States)

    MacKinnon, P A; Lentz, T J; Rice, C H; Lockey, J E; Lemasters, G K; Gartside, P S

    2001-10-01

    In epidemiological studies designed to identify potential health risks of exposures to synthetic vitreous fibers, the characterization of airborne fiber dimensions may be essential for assessing mechanisms of fiber toxicity. Toward this end, air sampling was conducted as part of an industry-wide study of workers potentially exposed to airborne fibrous dusts during the manufacture of refractory ceramic fibers (RCF) and RCF products. Analyses of a subset of samples obtained on the sample filter as well as on the conductive sampling cowl were performed using both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to characterize dimensions of airborne fibers. Comparison was made of bivariate fiber size distributions (length and diameter) from air samples analyzed by SEM and by TEM techniques. Results of the analyses indicate that RCF size distributions include fibers small enough in diameter ( 60 microm) may go undetected by TEM, as evidenced by the proportion of fibers in this category for TEM and SEM analyses (1% and 5%, respectively). Limitations of the microscopic techniques and differences in fiber-sizing rules for each method are believed to have contributed to the variation among fiber-sizing results. It was concluded from these data that further attempts to characterize RCF exposure in manufacturing and related operations should include analysis by TEM and SEM, since the smallest diameter fibers are not resolved with SEM and the fibers of longer length are not sized by TEM.

  9. Mn and Sm doped lead titanate ceramic fibers and fiber/epoxy 13 composites

    Science.gov (United States)

    Li, Kun; Pang, Geoffrey; Wa Chan, Helen Lai; Choy, Chung Loong; Li, Jin-hua

    2004-05-01

    Manganese and samarium doped lead titanate [Pb0.85Sm0.10(Ti0.98Mn0.02)O3, PSmT] fibers were prepared by sol-gel method. The micrographs obtained using scanning electron microscope show that PSmT ceramic fibers are round and dense. The diameter of the fibers was in the range of 30-35 μm. The crystalline grains size is ˜2.5 μm. The micrographs obtained using transmission electron microscope also unveiled the layer-by-layer 90° domains in the grains. X-ray diffraction patterns of the fibers show that PSmT ceramics have a pure perovskite structure. The c/a ratio of the unit cell was 1.04. The PSmT fiber/epoxy 1-3 composites were fabricated by filling the ceramic fiber bundle with epoxy. The dielectric permittivity ɛ, electromechanical coefficient kt, and the piezoelectric constant d33 of PSmT fiber/epoxy 1-3 composites with 68% fiber loading were 118, 0.51, and 48 pC/N, respectively. The hysteresis loop of the composites was measured by the Sawyer-Tower method. It was also found that the composites could withstand an electric field of 15 kV/mm at room temperature.

  10. Ceramic silicon-boron-carbon fibers from organic silicon-boron-polymers

    Science.gov (United States)

    Riccitiello, Salvatore R. (Inventor); Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

    1993-01-01

    Novel high strength ceramic fibers derived from boron, silicon, and carbon organic precursor polymers are discussed. The ceramic fibers are thermally stable up to and beyond 1200 C in air. The method of preparation of the boron-silicon-carbon fibers from a low oxygen content organosilicon boron precursor polymer of the general formula Si(R2)BR(sup 1) includes melt-spinning, crosslinking, and pyrolysis. Specifically, the crosslinked (or cured) precursor organic polymer fibers do not melt or deform during pyrolysis to form the silicon-boron-carbon ceramic fiber. These novel silicon-boron-carbon ceramic fibers are useful in high temperature applications because they retain tensile and other properties up to 1200 C, from 1200 to 1300 C, and in some cases higher than 1300 C.

  11. 溶剂对溶胶-凝胶法制备钛酸铅陶瓷纤维的影响%Effects of Solvent on PbTiO3 Ceramic Fibers prepared by sol-gel process

    Institute of Scientific and Technical Information of China (English)

    胡亚伟; 李琰; 张彦; 焦其帅; 孙娜; 谢英

    2013-01-01

    Lead titanate ceramic fibers are excellent piezoelectric and pyroelectric materials,In order to synthesize the ceramic fibers with high-performance,the preparation of the stable sol is very imporant step.The effects of different solvents of the tetrabutyl titanate-lead acetate trihydrate-solvent-catalyst systems on the stability of sol,the annealing temperature and the morphology of ceramic fibers have been investigated by the measurement of TGA-DTA、XRD、SEM method.Comprehensive consideration,The most suitable solvent for the optimized systems is selected out.%钛酸铅陶瓷纤维是一种非常优异的电子陶瓷材料,合成透明稳定的溶胶是制备性能优良的钛酸铅陶瓷纤维非常重要的一步.本文采用溶胶-凝胶法制备钛酸铅陶瓷纤维,并通过TGA-DTA、XRD、SEM方法研究了钛酸四丁酯-醋酸铅-催化剂-溶剂体系中,溶剂的种类对溶胶的稳定性、产品的结晶温度及纤维形貌的影响,综合考虑选择出了最适合所选体系的溶剂.

  12. Preparation of Crack-free 3Y-TZP/Al2O3 Composite Ceramic Fiber by Electrolysis-sol-gel Method

    Institute of Scientific and Technical Information of China (English)

    LI Jian-jun; JIAO Xiu-ling; CHEN Dai-rong

    2007-01-01

    Polycrystalline 3Y-TZP/Al2O3 tetragonal zirconia fiber was obtained by the pyrolysis of gel fibers using zirconium oxychloride octahydrate(ZOC) as the raw material. The spinnable zirconia sol was prepared by electrolyzing the zirconium oxychloride octahydrate (ZOC) solution in the presence of acetic acid and sugar( sucrose, glucrose or fructose),in which the molar ratios of CH3COOH/ZOC and sugar/ZOC were 1.0-4.0 and 0.2-0.4, respectively. The prepared tetragonal zirconia fibers sintered at different temperatures showed smooth and crack-free surfaces with diameters of 5-10 μm. The addition of Al2O3 enhanced the sintering process and prevented the crystals from growing.Thermogravimetric analysis(TG), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope(SEM) techniques were used to characterize the prepared fibers.

  13. Piezoelectric ceramic fibers for active fiber composites: a comparative study

    Science.gov (United States)

    Kornmann, Xavier; Huber, Christian; Elsener, Hans-Rudolf

    2003-08-01

    The morphology and the free strain performances of three different piezoelectric ceramic fibers used for the manufacture of active fiber composites (AFCs) have been investigated. The morphology of the fibers has a direct influence on the manufacture of the AFCs. Fibers with non-uniform diameters are more difficult to contact with the interdigitated electrodes and can be the cause of irreparable damages in AFCs. An indirect method requiring the use of a simple analytical model is proposed to evaluate the free strain of active fiber composites. This indirect method presents a relatively good agreement with direct free strain measurements performed with strain gages glued on both sides of an AFC. The results show a systematic difference of ca. 20 % between the indirect and the direct methods. However, the indirect method did not permit to see differences of piezoelectric performance between the types of fibers.

  14. Properties of Ceramic Fiber and Ceramic Shot in Wet-laid Processes

    Institute of Scientific and Technical Information of China (English)

    CHENG Long-di

    2002-01-01

    The paper deals with the different sinking properties of ceramic fiber and the ceramic shot in wetlaid nonwoven processes. The difference between the sinking properties of the fiber and the shot is very great according to theory analysis and the test. From results of calculating and practical testing, the method of removing ceramic shots during manufacturing is put forward.

  15. Ni(2+) doped glass ceramic fiber fabricated by melt-in-tube method and successive heat treatment.

    Science.gov (United States)

    Fang, Zaijin; Zheng, Shupei; Peng, Wencai; Zhang, Hang; Ma, Zhijun; Dong, Guoping; Zhou, Shifeng; Chen, Danping; Qiu, Jianrong

    2015-11-02

    Glass ceramic fibers containing Ni(2+) doped LiGa(5)O(8) nanocrystals were fabricated by a melt-in-tube method and successive heat treatment. Fiber precursors were prepared by drawing at high temperature where fiber core glass was melted while fiber clad glass was softened. After heat treatment, LiGa(5)O(8) nanocrystals were precipitated in the fiber core. Excited by 980 nm laser, efficient broadband near-infrared emission was observed in the glass ceramic fiber compared to that of precursor fiber. The melt-in-tube method can realize controllable crystallization and is suitable for fabrication of novel glass ceramic fibers. The Ni(2+)-doped glass ceramic fiber is promising for broadband optical amplification.

  16. Interphase for ceramic matrix composites reinforced by non-oxide ceramic fibers

    Science.gov (United States)

    DiCarlo, James A. (Inventor); Bhatt, Ramakrishna (Inventor); Morscher, Gregory N. (Inventor); Yun, Hee-Mann (Inventor)

    2008-01-01

    A ceramic matrix composite material is disclosed having non-oxide ceramic fibers, which are formed in a complex fiber architecture by conventional textile processes; a thin mechanically weak interphase material, which is coated on the fibers; and a non-oxide or oxide ceramic matrix, which is formed within the interstices of the interphase-coated fiber architecture. During composite fabrication or post treatment, the interphase is allowed to debond from the matrix while still adhering to the fibers, thereby providing enhanced oxidative durability and damage tolerance to the fibers and the composite material.

  17. Guanidine Soaps As Vehicles For Coating Ceramic Fibers

    Science.gov (United States)

    Philipp, Warren H.; Veitch, Lisa C.; Jaskowiak, Martha H.

    1994-01-01

    Soaps made from strong organic base guanidine and organic fatty acids serve as vehicles and binders for coating ceramic fibers, various smooth substrates, and other problematic surfaces with thin precious-metal or metal-oxide films. Films needed to serve as barriers to diffusion in fiber/matrix ceramic composite materials. Guanidine soaps entirely organic and burn off, leaving no residues.

  18. Clearance of inhaled ceramic fibers from rat lungs.

    Science.gov (United States)

    Yamato, H; Tanaka, I; Higashi, T; Kido, M

    1994-10-01

    Deposition, clearance, retention, and durability of inhaled particles in lung are important factors for induction of pulmonary fibrosis or lung cancer. To study the deposition and clearance of aluminium silicate ceramic fibers from the lung, male Wistar rats were exposed to ceramic fibers, with a mass median aerodynamic diameter (MMAD) of 3.7 microns, for 6 hr/day, 5 days/week for 2 weeks. The average exposure concentration was 27.2 mg/m3 (SD 9.0). The rats were killed at 1 day, 1 month, 3 months, and 6 months after the end of exposure, and the fiber numbers and dimensions were measured with a scanning electron microscope. No significant difference in length of residual ceramic fibers in the lungs was found among the groups. The geometric mean diameter and number of ceramic fibers, however, decreased according to the clearance period. These findings suggest that the fibers were dissolved at their surface.

  19. Preparation and properties of dental zirconia ceramics

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Y2O3-stabilized tetragonal zireonia polyerystalline (Y-TZP) ceramics with high-performance were prepared for dental application by use of the micro-emulsion and two-step sintering method.The crystal phase,morphology,and microstructure of the reaction products were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM),and transmission electron microscopy (TEM).XRD results show that the ceramics mainly consist of tetragonal zirconia.Physical and mechanical properties test results show that the bending strength,fracture toughness,and the density of full sintered Y-TZP ceramics are llS0 MPa,5.53 crown machined with this material by CAD/CAM system exhibits a verisimilitude configuration and the material's expansion coefficient well matches that of the glaze.These results further indicate that the product can be used as a promising new ceramic material

  20. 含硅聚硼氮烷裂解转化制备氮化硼陶瓷纤维%Preparation of Boron Nitride Ceramic Fibers by Pyrolysis of Silicon-containing Polyborazine

    Institute of Scientific and Technical Information of China (English)

    李文华; 王军; 谢征芳; 王浩; 唐云

    2012-01-01

    以低活性含硅聚硼氮烷为先驱体,经熔融纺丝,BCl3脱硅不熔化处理以及在氨气气氛中高温裂解制备的氮化硼纤维仍含有硅元素,这主要是含硅聚硼氮烷结构中的B-N(SiMe3)2和B-N(SiMe3)-B由于位阻与BCl3反应脱除SiMe3不完全所致.而采用HCl首先与含硅聚硼氮烷反应减少其位阻,再通过BCl3进一步脱硅不熔化处理制备的氮化硼陶瓷纤维经FT-IR、X射线衍射(XRD)分析表明纤维基本不含硅元素,并且扫描电子显微镜(SEM)表明得到的氮化硼陶瓷纤维直径约为11μm,断面致密无孔,室温下抗拉强度为0.45 GPa.%ilicon still exists in boron nitride(BN) ceramic fibers which were prepared by melt-spinning,curing with BCl3 and pyrolysis under NH3 of a preceramic silicon-containing polyborazine.That is because B-N(SiMe3)2 and B-N(SiMe3)-B could not react with BCl3 completely for the steric hindrance.So HCl was used to react with silicon-containing polyborazine first to reduce its steric hindrance.Then,BCl3 reacted with silicon-containing polyborazine to remove the residual SiMe3.After pyrolysis under NH3,BN ceramic fibers without silicon were obtained which was proved by FT-IR and X-ray diffraction.The obtained BN ceramic fibers with diameter of about 11 μm were dense which was demonstrated by scanning electron mi-croscopy(SEM) and the fibers showed room temperature mechanical property with average tensile strength of 0.45 GPa.

  1. Refractory ceramic fibers activate alveolar macrophage eicosanoid and cytokine release.

    Science.gov (United States)

    Leikauf, G D; Fink, S P; Miller, M L; Lockey, J E; Driscoll, K E

    1995-01-01

    Refractory ceramic fiber has been developed for industrial processes requiring materials with high thermal and mechanical stability. To evaluate the biological activity of this fiber, rat alveolar macrophages were exposed for < or = 24 h to 0-1,000 micrograms/ml of refractory ceramic fiber, crocidolite asbestos, silica (fibrogenic particles), or titanium dioxide (a nonfibrogenic particle), and eicosanoid, tumor necrosis factor-alpha (TNF), and lactate dehydrogenase release were measured. Particle dimensions were determined by electron microscopy. Radioactivity coeluting with leukotriene B4 (LTB4) and immunoreactive LTB4 and TNF release increased after refractory ceramic fiber and were similar in magnitude after asbestos but less than after silica. For example, the total [3H]eicosanoid release increased 3.9-fold after refractory ceramic fiber, 4.6-fold after asbestos, and 8.7-fold after silica. Refractory ceramic fiber and asbestos also have similar particle dimensions (diameter, length, and surface area). Inasmuch as macrophage-derived LTB4 and TNF are potent mediators in inflammatory events, including migration and activation of neutrophils, these findings suggest that refractory ceramic fiber can activate macrophages in vitro to release mediators relevant to in vivo findings of inflammation and fibrotic lung disease in laboratory animals.

  2. Core–Shell Electrospun Hollow Aluminum Oxide Ceramic Fibers

    OpenAIRE

    2015-01-01

    In this work, core–shell electrospinning was employed as a simple method for the fabrication of composite coaxial polymer fibers that became hollow ceramic tubes when calcined at high temperature. The shell polymer solution consisted of polyvinyl pyrollidone (PVP) in ethanol mixed with an aluminum acetate solution to act as a ceramic precursor. The core polymer was recycled polystyrene to act as a sacrificial polymer that burned off during calcination. The resulting fibers were analyzed wit...

  3. Thermomechanical Property Data Base Developed for Ceramic Fibers

    Science.gov (United States)

    1996-01-01

    A key to the successful application of metal and ceramic composite materials in advanced propulsion and power systems is the judicious selection of continuous-length fiber reinforcement. Appropriate fibers can provide these composites with the required thermomechanical performance. To aid in this selection, researchers at the NASA Lewis Research Center, using in-house state-of-the-art test facilities, developed an extensive data base of the deformation and fracture properties of commercial and developmental ceramic fibers at elevated temperatures. Lewis' experimental focus was primarily on fiber compositions based on silicon carbide or alumina because of their oxidation resistance, low density, and high modulus. Test approaches typically included tensile and flexural measurements on single fibers or on multifilament tow fibers in controlled environments of air or argon at temperatures from 800 to 1400 C. Some fiber specimens were pretreated at composite fabrication temperatures to simulate in situ composite conditions, whereas others were precoated with potential interphase and matrix materials.

  4. Lower energy costs in the ceramics industry - via ceramic fibers

    Energy Technology Data Exchange (ETDEWEB)

    Zander, H.P.

    1983-04-01

    Ceramic fibres, due to their high thermal and chemical resistance, receive increasing attention as insulating material for industrial purposes. After a short characterisation, examples of furnace wall lining are given, and a tunnel-kiln car for baking of sanitation ceramics is investigated with a view to possibilities of supplementary insulation.

  5. Preparation and Characterization of Yb - doped YAG Ceramics

    OpenAIRE

    2011-01-01

    Rare-earth doped yttrium aluminum garnet (YAG) ceramics are among the most widely produced transparent ceramics for laser applications. Yb:YAG ceramics are an interesting IR laser material [1], which allows significantly higher doping compared to the generally more used Nd:YAG [2,3]. This work presents the preparation of polycrystalline Yb:YAG ceramics with dopant concentration from 0 up to 20 at.% via solid state reactive sintering. Samples were prepared via cold isostatic pressing of spray ...

  6. A Novel Seeding Method of Interfacial Polymerization-Assisted Dip Coating for the Preparation of Zeolite NaA Membranes on Ceramic Hollow Fiber Supports.

    Science.gov (United States)

    Cao, Yue; Wang, Ming; Xu, Zhen-Liang; Ma, Xiao-Hua; Xue, Shuang-Mei

    2016-09-28

    A novel seeding method combining interfacial polymerization (IP) technique with dip-coating operation was designed for directly coating nanosized NaA seed crystals (150 nm) onto the micrometer-sized α-Al2O3 hollow fiber support, in which the polyamide (PA) produced by IP acted as an effective medium to freeze and fix seed crystals at the proper position so that the controlled seed layer could be accomplished. While a coating suspension with only 0.5 wt % seed content was used, a very thin seed layer with high quality and good adhesion was achieved through dip coating twice without drying between, and the whole seeding process was operated at ambient conditions. The resulting zeolite NaA membranes not only exhibited high pervaporation (PV) performance with an average separation factor above 10000 and flux nearly 9.0 kg/m(2)·h in dehydration of 90 wt % ethanol aqueous solution at 348 K but also demonstrated great reproducibility by testing more than eight batches of zeolite membranes. In addition, this seeding strategy could be readily extended to the preparation of other supported zeolite membranes for a wide range of separation applications.

  7. Development of ceramic fibers for high-energy laser applications

    Science.gov (United States)

    Fair, Geoff E.; Kim, Hyun Jun; Lee, HeeDong; Parthasarathy, Triplicane A.; Keller, Kristin A.; Miller, Zachary D.

    2011-06-01

    Polycrystalline ceramics offer a number of advantages relative to single crystal materials such as lower processing temperatures, improved mechanical properties, and higher doping levels with more uniform distribution of dopants for improved laser performance. Ceramic YAG (Y3Al5O12) and rare earth sesquioxide (RE2O3) fibers promise to enable a number of high power laser devices via high thermal conductivity and higher allowable dopant concentration; however, these materials are not currently available as fine diameter optical-quality fibers. Powder processing approaches for laser quality polycrystalline ceramic fibers are in development at AFRL. Current processing techniques will be reviewed. The effects of a number of processing variables on the resulting fibers as well as preliminary optical characterization will also be presented.

  8. Ceramic Fiber as a New Material%新型纤维材料——陶瓷纤维

    Institute of Scientific and Technical Information of China (English)

    王小雅; 曹云峰

    2012-01-01

    陶瓷纤维以其质轻,耐火,耐腐蚀等性能,目前已经在机械、冶金、石油和化工等行业得到了广泛的应用,随着各种其他技术的应用,各种陶瓷纤维基复合材料得到了快速的发展。根据使用功能,陶瓷纤维可以分为高温陶瓷纤维和功能陶瓷纤维,用作绝热材料,过滤材料,高温超导材料等,此外陶瓷纤维还被用于生产耐高温陶瓷纤维纸和箱板纸。文章简述了陶瓷纤维的发展,列举了陶瓷纤维的种类、制备方法、应用及发展趋势。%Ceramic fiber as a new material was widely used in all fields,because of its light weight and fire-resistant,now ceramic fiber was widely used in machinery,metallurgy,petroleum,chemical industry.With a variety of other technology,all kinds of ceramic fiber composite has been developed rapidly.According to the function,ceramic fibers can be divided into high-temperature ceramic fibers and functional ceramic fibers.It can be used as insulation materials,filter materials,high-temperature superconducting materials,etc.In addition,ceramic fiber was also used in the production of high-temperature paper and cardboard paper.This paper is a brief overview of the development of ceramic fiber,the types of ceramic fiber,the preparation methods,applications and its developing trends.

  9. Faceted ceramic fibers, tapes or ribbons and epitaxial devices therefrom

    Science.gov (United States)

    Goyal, Amit

    2013-07-09

    A crystalline article includes a single-crystal ceramic fiber, tape or ribbon. The fiber, tape or ribbon has at least one crystallographic facet along its length, which is generally at least one meter long. In the case of sapphire, the facets are R-plane, M-plane, C-plane or A-plane facets. Epitaxial articles, including superconducting articles, can be formed on the fiber, tape or ribbon.

  10. Faceted ceramic fibers, tapes or ribbons and epitaxial devices therefrom

    Energy Technology Data Exchange (ETDEWEB)

    Goyal, Amit (Knoxville, TN)

    2012-07-24

    A crystalline article includes a single-crystal ceramic fiber, tape or ribbon. The fiber, tape or ribbon has at least one crystallographic facet along its length, which is generally at least one meter long. In the case of sapphire, the facets are R-plane, M-plane, C-plane or A-plane facets. Epitaxial articles, including superconducting articles, can be formed on the fiber, tape or ribbon.

  11. A simple test for thermomechanical evaluation of ceramic fibers

    Science.gov (United States)

    Morscher, Gregory N.; Dicarlo, James A.

    1992-01-01

    A simple bend stress relaxation (BSR) test was developed to measure the creep related properties of ceramic fibers and whiskers. The test was applied to a variety of commercial and developmental Si based fibers to demonstrate capabilities and to evaluate the relative creep resistance of the fibers at 1200 to 1400 C. The implications of these results and the advantages of the BSR test over typical tensile creep tests are discussed.

  12. Piezoelectric polymer and ceramic ultrafine fibers for piezocomposite films

    OpenAIRE

    Yördem, Sinan Onur; Yordem, Sinan Onur; Papila, Melih; Menceloğlu, Yusuf Z.; Menceloglu, Yusuf Z.; Öğüt, Erdem; Ogut, Erdem; Gülleroğlu, Mert; Gulleroglu, Mert

    2006-01-01

    This paper describes the process development and characterization of Poly(vinylidene fluoride) (PVDF) films and fiber mats and Zinc Oxide (ZnO) fibers as ingredients of a future piezo-composite film. The polymer system PVDF is electroactive and processed here by solution casting and annealing to form active films. Electrospinning of PVDF and Poly(vinyl alcohol)-Zincacetate precursor solutions were also under investigation to produce randomly oriented polymer and ceramic fiber mats, respective...

  13. Creep and stress relaxation modeling of polycrystalline ceramic fibers

    Science.gov (United States)

    Dicarlo, James A.; Morscher, Gregory N.

    1994-01-01

    A variety of high performance polycrystalline ceramic fibers are currently being considered as reinforcement for high temperature ceramic matrix composites. However, under mechanical loading about 800 C, these fibers display creep related instabilities which can result in detrimental changes in composite dimensions, strength, and internal stress distributions. As a first step toward understanding these effects, this study examines the validity of a mechanism-based empirical model which describes primary stage tensile creep and stress relaxation of polycrystalline ceramic fibers as independent functions of time, temperature, and applied stress or strain. To verify these functional dependencies, a simple bend test is used to measure stress relaxation for four types of commercial ceramic fibers for which direct tensile creep data are available. These fibers include both nonoxide (SCS-6, Nicalon) and oxide (PRD-166, FP) compositions. The results of the Bend Stress Relaxation (BSR) test not only confirm the stress, time, and temperature dependencies predicted by the model, but also allow measurement of model empirical parameters for the four fiber types. In addition, comparison of model tensile creep predictions based on the BSR test results with the literature data show good agreement, supporting both the predictive capability of the model and the use of the BSR text as a simple method for parameter determination for other fibers.

  14. Preparation of thin ceramic monofilaments for TEM observation with novel embedding processes.

    Science.gov (United States)

    Li, Siwei; Feng, Zude; Zhang, Litong; Wang, Yanyan; Chen, Lifu

    2011-01-01

    An applicable method to prepare transmission electron microscopy specimens from ceramic fibers for longitudinal and cross-sectional observations is investigated. The method includes novel embedding processes to fix fibers, a polishing process using a self-manufactured device to get uniformly low thickness (40 μm for L-fiber, 60 μm for C-fiber), a one-side dimpling process to grind the specimen to near electron transparency (about 5 μm in thickness for both L-fiber and C-fiber) and an efficient ion milling process using calculated parameters. These techniques are reliable to accomplish the preparation with high quality in a relatively short time. Many factors related to the preparation processes are discussed.

  15. Conductive ceramic composition and method of preparation

    Science.gov (United States)

    Smith, J.L.; Kucera, E.H.

    1991-04-16

    A ceramic anode composition is formed of a multivalent metal oxide or oxygenate such as an alkali metal, transition metal oxygenate. The anode is prepared as a non-stoichiometric crystalline structure by reaction and conditioning in a hydrogen gas cover containing minor proportions of carbon dioxide and water vapor. The structure exhibits a single phase and substantially enhanced electrical conductivity over that of the corresponding stoichiometric structure. Unexpectedly, such oxides and oxygenates are found to be stable in the reducing anode fuel gas of a molten carbonate fuel cell. 4 figures.

  16. The effect of ceramic fibers on the immune system.

    Science.gov (United States)

    Tulinská, Jana; Kuricová, Miroslava; Lisková, Aurelia; Kováciková, Zuzana; Tatrai, Elizabeth

    2005-12-01

    Male Sprague-Dawley rats were treated by intratracheal instillation with 1 mg/animal of refractory ceramic fibers. Intratracheal exposure to ceramic fibers led to significant changes of immune response. Results of proliferative activity of spleen lymphocytes showed significantly decreased proliferative activity of T-cells in response to mitogens phytohemagglutinin and concanavalin A in animals given ceramic fibers in comparison with control rats. Similarly, T-dependent B-cell response to pokeweed mitogen was significantly suppressed. Spontaneous proliferative activity of lymphocytes in non-stimulated spleen cell cultures did not differ in exposed and control rats. No significant changes were found among groups in percentage of phagocytic blood polymorphonuclear leukocytes and percentage of cells with respiratory burst.

  17. Clearance of inhaled ceramic fibers from rat lungs.

    OpenAIRE

    1994-01-01

    Deposition, clearance, retention, and durability of inhaled particles in lung are important factors for induction of pulmonary fibrosis or lung cancer. To study the deposition and clearance of aluminium silicate ceramic fibers from the lung, male Wistar rats were exposed to ceramic fibers, with a mass median aerodynamic diameter (MMAD) of 3.7 microns, for 6 hr/day, 5 days/week for 2 weeks. The average exposure concentration was 27.2 mg/m3 (SD 9.0). The rats were killed at 1 day, 1 month, 3 mo...

  18. Electrospun ceramic fibers: Composition, structure and the fate of precursors

    Energy Technology Data Exchange (ETDEWEB)

    Tuttle, R.W.; Chowdury, A. [Department of Physics, Ayer Hall, 302 Buchtel Common, University of Akron, Akron, OH 44325-4001 (United States); Bender, E.T. [Department of Chemistry, Knight Chemical Laboratory, 302 Buchtel Common, University of Akron, Akron, OH 44325-3601 (United States); Ramsier, R.D. [Department of Physics, Ayer Hall, 302 Buchtel Common, University of Akron, Akron, OH 44325-4001 (United States); Department of Chemistry, Knight Chemical Laboratory, 302 Buchtel Common, University of Akron, Akron, OH 44325-3601 (United States); Institute for Teaching and Learning, Leigh Hall, 302 Buchtel Common, University of Akron, Akron, OH 44325-6236 (United States)], E-mail: rex@uakron.edu; Rapp, J.L.; Espe, M.P. [Department of Chemistry, Knight Chemical Laboratory, 302 Buchtel Common, University of Akron, Akron, OH 44325-3601 (United States)

    2008-06-15

    Fibers are electrospun from aluminum acetate/polymer mixtures and characterized by an array of techniques before and after annealing at 1200 deg.C. We demonstrate that sodium and boron present in the initial starting materials as adducts and stabilizers remain incorporated into the resulting fibers after annealing and pyrolysis of the host polymer. The influence of these minor constituents on the surfaces of the fibers is suggested by infrared and X-ray photoelectron spectroscopic data. The presence of these species may impact potential chemical applications of small diameter ceramic fibers, such as their use as catalytic supports or for chemical decomposition.

  19. Refractory ceramic fibers (RCFs) induce germline aneuploidy in Drosophila oocytes.

    Science.gov (United States)

    Osgood, C J

    1994-06-01

    Mineral fibers are ubiquitous in the natural environment and are widely used in industry in such applications as insulators. We have previously shown that asbestos fibers induce aneuploidy in oocytes of Drosophila melanogaster; here we extend those studies by testing refractory ceramic fibers (RCFs) for their mutagenicity to germ cells. The results establish that the tested RCFs are inducers of aneuploidy following feeding of adult females. A subset of the RCFs were also effective following larval feeding. Our results suggest that RCFs, like certain asbestos fibers, may pose a hazard to germ cells.

  20. Electrospun ceramic fibers: Composition, structure and the fate of precursors

    Science.gov (United States)

    Tuttle, R. W.; Chowdury, A.; Bender, E. T.; Ramsier, R. D.; Rapp, J. L.; Espe, M. P.

    2008-06-01

    Fibers are electrospun from aluminum acetate/polymer mixtures and characterized by an array of techniques before and after annealing at 1200 °C. We demonstrate that sodium and boron present in the initial starting materials as adducts and stabilizers remain incorporated into the resulting fibers after annealing and pyrolysis of the host polymer. The influence of these minor constituents on the surfaces of the fibers is suggested by infrared and X-ray photoelectron spectroscopic data. The presence of these species may impact potential chemical applications of small diameter ceramic fibers, such as their use as catalytic supports or for chemical decomposition.

  1. Retention modeling of refractory ceramic fibers (RCF) in humans.

    Science.gov (United States)

    Yu, C P; Ding, Y J; Zhang, L; Oberdörster, G; Mast, R W; Maxim, L D; Utell, M J

    1997-02-01

    A mathematical retention model has been developed to predict the lung burden and size distribution of kaolin refractory ceramic fibers (RCF) in the pulmonary region of the human lung during exposure. Fiber dissolution, breakage, and differential clearance are considered in this model; rates for these processes are obtained by extrapolation from available data on laboratory rats. The lung burden predicted by this model is in general agreement with fiber counts from three factory workers. An important prediction from this study is that clearance of RCF is not significantly impaired at a fiber concentration beneath 10 f/cm3 during occupational exposure.

  2. Core–Shell Electrospun Hollow Aluminum Oxide Ceramic Fibers

    Directory of Open Access Journals (Sweden)

    Jonathan W. Rajala

    2015-10-01

    Full Text Available In this work, core–shell electrospinning was employed as a simple method for the fabrication of composite coaxial polymer fibers that became hollow ceramic tubes when calcined at high temperature. The shell polymer solution consisted of polyvinyl pyrollidone (PVP in ethanol mixed with an aluminum acetate solution to act as a ceramic precursor. The core polymer was recycled polystyrene to act as a sacrificial polymer that burned off during calcination. The resulting fibers were analyzed with X-ray diffraction (XRD and energy dispersive spectroscopy (EDS to confirm the presence of gamma-phase aluminum oxide when heated at temperatures above 700 °C. The fiber diameter decreased from 987 ± 19 nm to 382 ± 152 nm after the calcination process due to the polymer material being burned off. The wall thickness of these fibers is estimated to be 100 nm.

  3. Overview of NASA Studies on High-Temperature Ceramic Fibers

    Science.gov (United States)

    DiCarlo, James A.; Yun, Hee Mann

    2001-01-01

    NASA, DOD (Department of Defense), and DOE (Department of Energy) are currently looking to the NASA UEET (Ultra-Efficient Engine Technology) Program to develop ceramic matrix composites (CMC) for hot-section components in advanced power and propulsion systems. Success will greatly depend on developing ceramic fibers with a variety of key thermostructural properties, in particular, high as-produced tensile strength and retention of a large fraction of this strength for long times under the anticipated CMC service conditions. Current UEET approaches center on selecting the optimum fiber type from commercially available fibers since the costs for development of advanced fibers are high and the markets for high-temperature CMC have yet to be established.

  4. Mechanical behavior of high strength ceramic fibers at high temperatures

    Science.gov (United States)

    Tressler, R. E.; Pysher, D. J.

    1991-01-01

    The mechanical behavior of commercially available and developmental ceramic fibers, both oxide and nonoxide, has been experimentally studied at expected use temperatures. In addition, these properties have been compared to results from the literature. Tensile strengths were measured for three SiC-based and three oxide ceramic fibers for temperatures from 25 C to 1400 C. The SiC-based fibers were stronger but less stiff than the oxide fibers at room temperature and retained more of both strength and stiffness to high temperatures. Extensive creep and creep-rupture experiments have been performed on those fibers from this group which had the best strengths above 1200 C in both single filament tests and tests of fiber bundles. The creep rates for the oxides are on the order of two orders of magnitude faster than the polymer derived nonoxide fibers. The most creep resistant filaments available are single crystal c-axis sapphire filaments. Large diameter CVD fabricated SiC fibers are the most creep and rupture resistant nonoxide polycrystalline fibers tested to date.

  5. Preparation of thin ceramic monofilaments for TEM observation with novel embedding processes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Siwei [College of Materials, Key Laboratory of High Performance Ceramic Fibers (Xiamen University), Ministry of Education, Xiamen 361005 (China); National Key Laboratory of Thermostructure Composite Materials, Northwestern Polytechnical University, Xi' an 710072 (China); Feng, Zude, E-mail: zdfeng@xmu.edu.cn [College of Materials, Key Laboratory of High Performance Ceramic Fibers (Xiamen University), Ministry of Education, Xiamen 361005 (China); Zhang, Litong [National Key Laboratory of Thermostructure Composite Materials, Northwestern Polytechnical University, Xi' an 710072 (China); Wang, Yanyan; Chen, Lifu [College of Materials, Key Laboratory of High Performance Ceramic Fibers (Xiamen University), Ministry of Education, Xiamen 361005 (China)

    2011-01-15

    An applicable method to prepare transmission electron microscopy specimens from ceramic fibers for longitudinal and cross-sectional observations is investigated. The method includes novel embedding processes to fix fibers, a polishing process using a self-manufactured device to get uniformly low thickness (40 {mu}m for L-fiber, 60 {mu}m for C-fiber), a one-side dimpling process to grind the specimen to near electron transparency (about 5 {mu}m in thickness for both L-fiber and C-fiber) and an efficient ion milling process using calculated parameters. These techniques are reliable to accomplish the preparation with high quality in a relatively short time. Many factors related to the preparation processes are discussed. -- Research Highlights: {yields}We develop an applicable method to prepare TEM specimens from thin ceramic fibers. {yields}We develop novel embedding processes to enhance the polishing efficiency. {yields}A self-manufactured device is used to get uniformly low thickness. {yields}One-side dimpling method and calculated ion milling process are introduced. {yields}Samples with large thin area for longitudinal and cross-sectional view are obtained.

  6. Parametric Study Of A Ceramic-Fiber/Metal-Matrix Composite

    Science.gov (United States)

    Murthy, P. L. N.; Hopkins, D. A.; Chamis, C. C.

    1992-01-01

    Report describes computer-model parametric study of effects of degradation of constituent materials upon mechanical properties of ceramic-fiber/metal-matrix composite material. Contributes to understanding of weakening effects of large changes in temperature and mechanical stresses in fabrication and use. Concerned mainly with influences of in situ fiber and matrix properties upon behavior of composite. Particular attention given to influence of in situ matrix strength and influence of interphase degradation.

  7. Preparation and characteristic of NASICON ceramics

    Institute of Scientific and Technical Information of China (English)

    ZHU Dongmei; LUO Fa; XIE Zhanglong; ZHOU Wancheng

    2006-01-01

    Hot-pressed sintering was employed to prepare the sodium super ionic conductor (Na1+xZr2SixP3-xO12,1.8≤x≤2.2)ceramics and compare with the sample obtained from normal-press sintering. The phase formation, density, and conductivity of the hot-press sintered and the normal-press sintered samples were investigated in detail. Results show that the density of NASICON ceramics and the degree of crystallization can be improved by hot-press process efficiently. The density of the sample sintered by normal sintering is obviously lower than that sintered by hot press. XRD analysis indicates all the hot press sintered samples contain mainly monoclinic NASICON and no ZrO2 phase was found. The ionic conductivity of normal-press sintered sample is much lower than that of hot-press sintered sample. When the composition is close to Na3Zr2Si2PO12 , the dc conductivities of the hot press sintered samples were in the order of 10-3 S·cm-1.The variation of the ac conductivity with frequency in the high frequency region agrees with the power law feature of σ(ω) ∝ωn(0<n<1).

  8. Continuous Fiber Ceramic Composite (CFCC) Program: Gaseous Nitridation

    Energy Technology Data Exchange (ETDEWEB)

    R. Suplinskas G. DiBona; W. Grant

    2001-10-29

    Textron has developed a mature process for the fabrication of continuous fiber ceramic composite (CFCC) tubes for application in the aluminum processing and casting industry. The major milestones in this project are System Composition; Matrix Formulation; Preform Fabrication; Nitridation; Material Characterization; Component Evaluation

  9. Preparation of (Sc{sub 2}O{sub 3}){sub 0.1}(CeO{sub 2}){sub 0.01}(ZrO{sub 2}){sub 0.89} ceramic hollow fiber for micro tubular solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, N.T.; Meng, X.X.; Tan, X. [Shandong Univ. of Technology, Zibo (China). School of Chemical Engineering

    2010-07-01

    Due to their high volumetric power density, good mechanical properties, good thermocycling behaviour, and quick start-up and shut-down operations, micro tubular (MT) solid oxide fuel cells (SOFCs) have attracted significant interest. They may be applied in a variety of situations such as power sources for portable devices, uninterruptible power supplies and dynamical power sources for automobiles. Some effort has been placed on the research of anode and cathode supported tubular cells since a thin dense electrolyte membrane can be easily prepared on them, and a relative high power density can be obtained. However, electrolyte supported SOFCs have shown very good durability and reliability and high mechanical performances. When they are prepared into micro tubular or hollow fiber structure, their wall thicknesses will go down to 0.1 mm. If a unique electrolyte material is utilized to prepare a ceramic hollow fiber instead of traditional yttrium stabilized zirconium oxide (YSZ) material, better cell performance with an electrolyte supported structure can be achieved. This paper presented a study that synthesized the electrolyte powder of 1Ce{sub 10}ScZr with uniform size and a parasite structure using the EDTA-citric acid method. The paper described the experiment with particular reference to the preparation of material through a phase inversion/sintering technique. The morphology of the powder and the hollow fiber ceramics was determined by scanning electron microscopy. The performances of the powder were characterized by thermogravimetric/differential thermal analyzer, and X-ray diffraction. 5 refs.

  10. Oxidation-resistant interfacial coatings for continuous fiber ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Stinton, D.P.; Besmann, T.M.; Bleier, A. [Oak Ridge National Lab., TN (United States); Shanmugham, S.; Liaw, P.K. [Univ. of Tennessee, Knoxville, TN (United States)

    1995-08-01

    Continuous fiber ceramic composites mechanical behavior are influenced by the bonding characteristics between the fiber and the matrix. Finite modeling studies suggest that a low-modulus interfacial coating material will be effective in reducing the residual thermal stresses that are generated upon cooling from processing temperatures. Nicalon{trademark}/SiC composites with carbon, alumina and mullite interfacial coatings were fabricated with the SiC matrix deposited using a forced-flow, thermal gradient chemical vapor infiltration process. Composites with mullite interfacial coatings exhibited considerable fiber pull-out even after oxidation and have potential as a composite system.

  11. High-Hot-Strength Ceramic Fibers

    Science.gov (United States)

    Sayir, Ali; Matson, Lawrence E.

    1994-01-01

    Continuous fibers consisting of laminae of alumina and yttrium aluminum garnet offer exceptionally high strength, resistance to creep, and chemical stability at high temperatures. These fibers exceed tensile strength of sapphire fibers. Leading candidates for reinforcement of intermetallic-matrix composites in exhaust nozzles of developmental high-speed civil transport aircraft engines. Other applications are in aerospace, automotive, chemical-process, and power-generation industries.

  12. Enhanced upconversion emission in crystallization-controllable glass-ceramic fiber containing Yb3+-Er3+ codoped CaF2 nanocrystals

    Science.gov (United States)

    Peng, Wencai; Fang, Zaijin; Ma, Zhijun; Qiu, Jianrong

    2016-10-01

    Functional nanocrystal-containing materials have been a hot topic in recent years. However, few researches have focused on functional nanocrystals contained in optical glass fibers. In this research, transparent CaF2 glass-ceramic was prepared by a melt-quenching method. Greatly enhanced upconversion luminescence was observed after heat treatment. By applying a novel method called melt-in-tube, precursor fiber free of crystals was fabricated at the drawing temperature where the clad was softened while the core was melted. Glass-ceramic fiber with fiber core containing Yb3+-Er3+ codoped CaF2 nanocrystals was obtained after heat treatment at a relatively low temperature. Electron probe micro-analyzer measurement shows no obvious element diffusion between the core and clad. Greatly enhanced upconversion emission was detected in the glass-ceramic fiber excited by a 980 nm laser, suggesting the developed glass-ceramic fiber is a promising material for upconversion laser.

  13. Enhanced upconversion emission in crystallization-controllable glass-ceramic fiber containing Yb(3+)-Er(3+) codoped CaF2 nanocrystals.

    Science.gov (United States)

    Peng, Wencai; Fang, Zaijin; Ma, Zhijun; Qiu, Jianrong

    2016-10-07

    Functional nanocrystal-containing materials have been a hot topic in recent years. However, few researches have focused on functional nanocrystals contained in optical glass fibers. In this research, transparent CaF2 glass-ceramic was prepared by a melt-quenching method. Greatly enhanced upconversion luminescence was observed after heat treatment. By applying a novel method called melt-in-tube, precursor fiber free of crystals was fabricated at the drawing temperature where the clad was softened while the core was melted. Glass-ceramic fiber with fiber core containing Yb(3+)-Er(3+) codoped CaF2 nanocrystals was obtained after heat treatment at a relatively low temperature. Electron probe micro-analyzer measurement shows no obvious element diffusion between the core and clad. Greatly enhanced upconversion emission was detected in the glass-ceramic fiber excited by a 980 nm laser, suggesting the developed glass-ceramic fiber is a promising material for upconversion laser.

  14. Modeling oxidation damage of continuous fiber reinforced ceramic matrix composites

    Institute of Scientific and Technical Information of China (English)

    Cheng-Peng Yang; Gui-Qiong Jiao; Bo Wang

    2011-01-01

    For fiber reinforced ceramic matrix composites (CMCs), oxidation of the constituents is a very important damage type for high temperature applications. During the oxidizing process, the pyrolytic carbon interphase gradually recesses from the crack site in the axial direction of the fiber into the interior of the material. Carbon fiber usually presents notch-like or local neck-shrink oxidation phenomenon, causing strength degradation. But, the reason for SiC fiber degradation is the flaw growth mechanism on its surface. A micromechanical model based on the above mechanisms was established to simulate the mechanical properties of CMCs after high temperature oxidation. The statistic and shearlag theory were applied and the calculation expressions for retained tensile modulus and strength were deduced, respectively. Meanwhile, the interphase recession and fiber strength degradation were considered. And then, the model was validated by application to a C/SiC composite.

  15. Analysis of chromosomal alterations induced by asbestos and ceramic fibers.

    Science.gov (United States)

    Dopp, E; Schiffmann, D

    1998-08-01

    Asbestos and other mineral fibers have long been known as carcinogenic agents. However, the primary mechanisms of fiber-induced carcinogenesis still remain unclear. We have investigated mitotic disturbances caused by amosite, crocidolite, and chrysotile in Syrian hamster embryo (SHE) fibroblasts. We also analyzed micronucleus formation as a result of mitotic disturbances, and carried out a characterization of the induced micronucleus population by kinetochore staining. In addition, the spindle fiber morphology was examined. Supravital UV-microscopy was used to analyze changes in chromatin structure, impaired chromatid separation and blocked cytokinesis. All three fiber types induced micronuclei in SHE cells with a high frequency (up to 200 MN/2000 cells; dose range: 0.1-5.0 microg/cm2) in a dose-dependent manner with a maximum between 48 and 66 h. Kinetochore staining revealed that 48% of fiber-induced micronuclei reacted positively. Furthermore, spindle deformation was observed in cells with disturbed meta- and anaphases while the spindle fiber morphology appeared unchanged. Our results show that asbestos fibers may cause both loss as well as breakage of chromosomes in the absence of direct interaction with spindle fibers. In addition, we analyzed the induction of micronuclei, hyperdiploidy and chromosome breakage in human amniotic fluid cells (AFC) in vitro by amosite, chrysotile and crocidolite asbestos and ceramic fibers. The response of human (AFC) and rodent (SHE) cells to fiber treatment was compared using the micronucleus assay. AFC were much less susceptible than SHE cells to the induction of micronuclei by mineral fibers. The application of fluorescence in situ hybridization (FISH) with tandem DNA probes yielded more detailed informations about specific structural chromosome aberrations in the 1(cen-q12) and 9(cen-q12) regions and about abnormal numbers of chromosomes in interphase AFC. Using this FISH approach we found a statistically significant

  16. Catalytic property of fiber media supported palladium containing alloy nanoparticles and electrospun ceramic fibers biodurability study

    Science.gov (United States)

    Shin, Hyeon Ung

    The nanoscale of the supporting fibers may provide enhancements such as restricting the migration of metal catalyst particles. In this work, palladium nanoparticle doped alumina fibers were electrospun into template submicron fibers. These fibers were calcined at temperatures between 650°C and 1150°C to vary the crystal structures of the calcined fibers with the Pd particle size. Higher calcination temperatures led to higher reaction temperatures from 250 to about 450°C for total conversion, indicating the effective reactivity of the fiber-supported catalysts decreased with increase in calcination temperature. Pd-Au alloy nanoparticle doped titania fibers were also fabricated using an electrospinning method and assembled into a fibrous porous medium structure by a vacuum molding process. In reactor tests, the fiber media with Pd-Au alloy nanoparticle catalyst had greater reactivity in conversion of NO and CO gases than that of fiber media with Pd monometallic catalyst alone, attributed to a lower activation energy of the Pd-Au catalyst particles. In carbon monoxide oxidation reaction tests, the results showed that the performance was optimal for a catalyst of composition Pd2Au1 molar ratio that was active at 125°C, which had higher dispersion of active components and better catalytic performance compared to monometallic particle Au/TiO 2 and Pd/TiO2 fiber media. Moreover, the improved reaction activity of Pd2Au1/TiO2 fiber medium was attributed to a decreased in the activation energy. Further experiments were conducted using the electrospun ceramic fibers biodurability study. The properties of nano-sized fiber structures have attracted the attention of recent research on ceramic nanostructures as nonwoven media for applications in hazardous chemical and high temperature environments. However, health and safety concerns of micro and nano scale ceramic materials have not been fully investigated. Little is known about the physicochemical effects of the properties

  17. Poly(borosiloxanes as precursors for carbon fiber ceramic matrix composites

    Directory of Open Access Journals (Sweden)

    Renato Luiz Siqueira

    2007-06-01

    Full Text Available Ceramic matrix composites (CMCs, constituted of a silicon boron oxycarbide (SiBCO matrix and unidirectional carbon fiber rods as a reinforcement phase, were prepared by pyrolysis of carbon fiber rods wrapped in polysiloxane (PS or poly(borosiloxane (PBS matrices. The preparation of the polymeric precursors involved hydrolysis/condensation reactions of alkoxysilanes in the presence and absence of boric acid, with B/Si atomic ratios of 0.2 and 0.5. Infrared spectra of PBS showed evidence of Si-O-B bonds at 880 cm-1, due to the incorporation of the crosslinker trigonal units of BO3 in the polymeric network. X ray diffraction analyses exhibited an amorphous character of the resulting polymer-derived ceramics obtained by pyrolysis up to 1000 °C under inert atmosphere. The C/SiBCO composites showed better thermal stability than the C/SiOC materials. In addition, good adhesion between the carbon fiber and the ceramic phase was observed by SEM microscopy

  18. Preparation and Chiral Selectivity of BSA-Modified Ceramic Membrane

    Institute of Scientific and Technical Information of China (English)

    Cai Lian SU; Rong Ji DAI; Bin TONG; Yu Lin DENG

    2006-01-01

    An affinity-transport system, containing porous ceramic membranes bound with bovine serum albumin (BSA) was used for chiral separation of racemic tryptophan. The preparation of BSA modified ceramic membrane included three steps. Firstly, the membrane was modified with amino group using silanization with an amino silane. Secondly, the amino group modified membrane was bound with aldehyde group using gluteraldehyde. Finally, BSA was covalently bound on the surface of the ceramic membrane. Efficient separation of racemic tryptophan was carried out by performing permeation cell experiments, with BSA modified, porous ceramic membranes.

  19. Preparation of nanocrystalline BaTiO3 ceramics

    Institute of Scientific and Technical Information of China (English)

    DENG XiangYun; LI DeJun; LI JianBao; WANG XiaoHui; LI LongTu

    2009-01-01

    The high-dense nanocrystalline BaTiO3 (BT) ceramics with grain size smaller than 100 nm have been successfully prepared by the two step sintering and the spark plasma sintering (SPS) process. The successive transitions in nanograin BT ceramics from rhombohedrel to orthorhombic, tetragonal and cubic transitions, similar to those in coarse BT ceramics, were revealed by in-situ temperature dependent Raman spectrum. The multiphase coexistence and the diffused phase transition character were demonstrated in the 8 nm nanocrystalline BT ceramics.

  20. Preparation of nanocrystalline BaTiO3 ceramics

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The high-dense nanocrystalline BaTiO3(BT)ceramics with grain size smaller than 100nm have been successfully prepared by the two step sintering and the spark plasma sintering(SPS)process.The successive transitions in nanograin BT ceramics from rhombohedral to orthorhombic,tetragonal and cubic transitions,similar to those in coarse BT ceramics,were revealed by in-situ temperature dependent Raman spectrum.The multiphase coexistence and the diffused phase transition character were demonstrated in the 8nm nanocrystalline BT ceramics.

  1. Chemical vapor deposition of ceramic coatings on metals and ceramic fibers

    Science.gov (United States)

    Nable, Jun Co

    2005-07-01

    The research presented in this study consists of two major parts. The first part is about the development of ceramic coatings on metals by chemical vapor deposition (CVD) and metal-organic chemical vapor deposition (MOCVD). Ceramics such as Al2O3 and Cr2O3, are used as protective coatings for materials used at elevated temperatures (>700°C). These metal oxides either exhibit oxidation resistance or have been used as environmental bond coats. Conventional methods of coating by chemical vapor deposition requires deposition temperatures of >950°C which could damage the substrate material during the coating process. Lower deposition temperatures (400 to 600°C) by MOCVD of these metal oxides were successful on Ni metal substrates. Surface modification such as pre-oxidation and etching were also investigated. In addition, a novel approach for the CVD of TiN on metals was developed. This new approach utilizes ambient pressure conditions which lead to deposition temperatures of 800°C or lower compared to conventional CVD of TiN at 1000°C. Titanium nitride can be used as an abrasive and wear coating on cutting and grinding tools. This nitride can also serve as a diffusion coating in metals. The second major part of this research involves the synthesis of interfacial coatings on ceramic reinforcing fibers for ceramic matrix composites. Aluminum and chromium oxides were deposited onto SiC, and Al2O3-SiO 2 fibers by MOCVD. The effects of the interface coatings on the tensile strength of ceramic fibers are also discussed. New duplex interface coatings consisting of BN or TiN together with Al2O3 or ZrO 2 were also successfully deposited and evaluated on SiC fibers.

  2. Fracture characteristics of refractory composites containing metakaolin and ceramic fibers

    Directory of Open Access Journals (Sweden)

    Ondřej Holčapek

    2015-03-01

    Full Text Available The aim of present article is to describe influence of composition of refractory composites on its response to gradual thermal loading. Attention was focused on the impact of ceramic fibers and application of metakaolin as an aluminous cement supplementary material. Studied aluminate binder system in combination with natural basalt fine aggregates ensures sufficient resistance to high-temperature exposure. Influence of composition changes was evaluated by the results of physical and mechanical testing—compressive and flexural strength, bulk density, and fracture energy were determined on the different levels of temperature loading. Application of ceramic fibers brought expected linear increase of ductility in studied composites. Metakaolin replacement showed the optimal dose to be just about 20% of aluminous cement weight.

  3. Ceramic Fiber Structures for Cryogenic Load-Bearing Applications

    Science.gov (United States)

    Jaskowiak, Martha H.; Eckel, Andrew J.

    2009-01-01

    This invention is intended for use as a load-bearing device under cryogenic temperatures and/or abrasive conditions (i.e., during missions to the Moon). The innovation consists of small-diameter, ceramic fibers that are woven or braided into devices like ropes, belts, tracks, or cables. The fibers can be formed from a variety of ceramic materials like silicon carbide, carbon, aluminosilicate, or aluminum oxide. The fiber architecture of the weave or braid is determined by both the fiber properties and the mechanical requirements of the application. A variety of weave or braid architectures is possible for this application. Thickness of load-bearing devices can be achieved by using either a 3D woven structure, or a layered, 2D structure. For the prototype device, a belt approximately 0.10 in. (0.25 cm) thick, and 3.0 in. (7.6 cm) wide was formed by layering and stitching a 2D aluminosilicate fiber weave.

  4. Ceramic bracket debonding with Tm:fiber laser

    Science.gov (United States)

    Demirkan, İrem; Sarp, Ayşe Sena Kabaş; Gülsoy, Murat

    2016-06-01

    Lasers have the potential for reducing the required debonding force and can prevent the mechanical damage given to the enamel surface as a result of conventional debonding procedure. However, excessive thermal effects limit the use of lasers for debonding purposes. The aim of this study was to investigate the optimal parameters of 1940-nm Tm:fiber laser for debonding ceramic brackets. Pulling force and intrapulpal temperature measurements were done during laser irradiation simultaneously. A laser beam was delivered in two different modes: scanning the fiber tip on the bracket surface with a Z shape movement or direct application of the fiber tip at one point in the center of the bracket. Results showed that debonding force could be decreased significantly compared to the control samples, in which brackets were debonded by only mechanical force. Intrapulpal temperature was kept equal or under the 5.5°C threshold value of probable thermal damage to pulp. Scanning was found to have no extra contribution to the process. It was concluded that using 1940-nm Tm:fiber laser would facilitate the debonding of ceramic brackets and can be proposed as a promising debonding tool with all the advantageous aspects of fiber lasers.

  5. Recent advances in the field of ceramic fibers and ceramic matrix composites

    Science.gov (United States)

    Naslain, R.

    2005-03-01

    Progress achieved during the last decade in the field of ceramic fibers and related ceramic matrix composites is reviewed. Both SiC-based and alumina-based fine fibers have been improved in terms of thermal stability and creep resistance with temperature limit of about 1400 and 1200 ° C, respectively. Two concepts for achieving damage-tolerant ceramic matrix composites have been identified : (i) that of non-oxide composites with a dense matrix in which matrix cracks formed under load are deflected and arrested in a weak fiber coating referred to as the interphase and (ii) that of all-oxide composites with a highly porous matrix with no need of any fiber coating. The lifetime under load of non-oxide composites in oxidizing atmospheres, is improved through the use of multilayered self-healing interphases and matrices deposited from gaseous precursors by chemical vapor infiltration (CVI). Lifetime ranging from 1000 to 10,000 hours at 1200 ° C under cyclic loading in air are foreseen. Alumina-based composites although attractive for long term exposures in oxidizing atmospheres up to ≈1200 ° C, are still experimental materials.

  6. [Preparation of porous ceramics based on waste ceramics and its Ni2+ adsorption characteristics].

    Science.gov (United States)

    Zhang, Yong-Li; Wang, Cheng-Zhi; Shi, Ce; Shang, Ling-Ling; Ma, Rui; Dong, Wan-Li

    2013-07-01

    The preparation conditions of porous ceramics were determined by SEM, XRD and FT-IR characterizations as well as the nickel removal ability of porous ceramics to be: the mass fraction w of sesbania powder doped was 4%, and the calcination temperature was 800 degrees C. SEM and pore structure characterization illustrated that calcination caused changes in the structure and morphology of waste ceramics. With the increase of calcination temperature, the specific surface area and pore volume decreased, while the aperture increased. EDS analyses showed that the main elements of both the original waste porcelain powder and the porous ceramics were Si, Al and O. The SEM, XRD and FT-IR characterization of porous ceramics illustrated that the structure of porous ceramics was stable before and after adsorption. The series of experiments of Ni2+ adsorption using these porous ceramics showed that when the dosage of porous ceramics was 10 g x L(-1), the adsorption time was 60 min, the pH value was 6.32, and the concentration of nickel-containing wastewater was below 100 mg x L(-1), the Ni2+ removal of wastewater reached 89.7%. Besides, the porous ceramics showed higher removal efficiency on nickel in the wastewater. The Ni(2+)-containing wastewater was processed by the porous ceramics prepared, and the adsorption dynamics and adsorption isotherms of Ni2+ in wastewater by porous ceramics were investigated. The research results showed that the Ni2+ adsorption process of porous ceramics was in accordance with the quasi second-order kinetic model (R2 = 0.999 9), with Q(e) of 9.09 mg x g(-1). The adsorption process can be described by the Freundlich equation and Langmuir equation, and when the temperature increased from 20 degrees C to 40 degrees C, the maximum adsorption capacity Q(m) increased from 14.49 mg x g(-1) to 15.38 mg x g(-1).

  7. Support Services for Ceramic Fiber-Ceramic Matrix Composites

    Energy Technology Data Exchange (ETDEWEB)

    Hurley, J.P.

    2000-06-06

    built to simulate the Kellogg entrained-bed gasifier in use at the Southern Company Services Wilsonville facility, but at 1/10 of the firing rate. At the exit of the unit is a large candle filter vessel typically operated at approximately 1000 F (540 C) in which coupons of materials can be inserted to test their resistance to gasifier ash and gas corrosion. The system also has ports for testing of hydrogen separation membranes that are suitably contained in a pressure housing. In addition, NETL is operating the combustion and environmental research facility (CERF). In recent years, the 0.5 MMBtu/hr (0.5 x 10{sup 6} kJ/hr) CERF has served as a host for exposure of over 60 ceramic and alloy samples at ambient pressure as well as at 200 psig (for tubes). Samples have been inserted in five locations covering 1700-2600 F (930-1430 C), with exposures exceeding 1000 hours. In the present program, the higher priority metals are to be tested at 1500-1600 F (820-870 C) in one CERF location and near 1800-2000 F (980-1090 C) at other locations to compare results with those from the EERC tests.

  8. Removing Pathogens Using Nano-Ceramic-Fiber Filters

    Science.gov (United States)

    Tepper, Frederick; Kaledin, Leonid

    2005-01-01

    A nano-aluminum-oxide fiber of only 2 nanometers in diameter was used to develop a ceramic-fiber filter. The fibers are electropositive and, when formulated into a filter material (NanoCeram(TradeMark)), would attract electro-negative particles such as bacteria and viruses. The ability to detect and then remove viruses as well as bacteria is of concern in space cabins since they may be carried onboard by space crews. Moreover, an improved filter was desired that would polish the effluent from condensed moisture and wastewater, producing potable drinking water. A laboratory- size filter was developed that was capable of removing greater than 99.9999 percent of bacteria and virus. Such a removal was achieved at flow rates hundreds of times greater than those through ultraporous membranes that remove particles by sieving. Because the pore size of the new filter was rather large as compared to ultraporous membranes, it was found to be more resistant to clogging. Additionally, a full-size cartridge is being developed that is capable of serving a full space crew. During this ongoing effort, research demonstrated that the filter media was a very efficient adsorbent for DNA (deoxyribonucleic acid), RNA (ribonucleic acid), and endotoxins. Since the adsorption is based on the charge of the macromolecules, there is also a potential for separating proteins and other particulates on the basis of their charge differences. The separation of specific proteins is a major new thrust of biotechnology. The principal application of NanoCeram filters is based on their ability to remove viruses from water. The removal of more than 99.9999 percent of viruses was achieved by a NanoCeram polishing filter added to the effluent of an existing filtration device. NanoCeram is commercially available in laboratory-size filter discs and in the form of a syringe filter. The unique characteristic of the filter can be demonstrated by its ability to remove particulate dyes such as Metanyl yellow. Its

  9. Method for the preparation of carbon fiber from polyolefin fiber precursor, and carbon fibers made thereby

    Energy Technology Data Exchange (ETDEWEB)

    Naskar, Amit Kumar; Hunt, Marcus Andrew; Saito, Tomonori

    2015-08-04

    Methods for the preparation of carbon fiber from polyolefin fiber precursor, wherein the polyolefin fiber precursor is partially sulfonated and then carbonized to produce carbon fiber. Methods for producing hollow carbon fibers, wherein the hollow core is circular- or complex-shaped, are also described. Methods for producing carbon fibers possessing a circular- or complex-shaped outer surface, which may be solid or hollow, are also described.

  10. Towards high-quality optical ceramic YAG fibers for high-energy laser (HEL) applications

    Science.gov (United States)

    Lee, HeeDong; Keller, Kristin; Sirn, Brian

    2012-06-01

    There is a critical demand for high quality, transparent ceramic YAG fibers for high powered fiber lasers. The production of laser quality ceramic fibers hinges on advanced ceramic processing technology, along with the availability of highly sinterable powder with high phase and chemical purity. These two fundamental technologies have been successfully developed at UES. Nd (1.1 a/o) and Yb (1.0 a/o)-doped yttrium aluminum garnet (YAG) fibers with high optical quality were produced by combining UES's tailored powders with advanced consolidation processes including fiber extrusion and vacuum sintering. The as-sintered and as-annealed fibers, approximately 30 microns in diameter, appeared transparent and successfully transmitted laser beams; further development will allow for the production of doped ceramic YAG fiber lasers for advanced high power and high energy fiber laser systems.

  11. Continuous fiber ceramic composites for energy related applications. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-04-07

    The US Department of Energy has established the Continuous Fiber Ceramic Composites (CFCC) program to develop technology for the manufacture of CFCC`s for use in industrial applications where a reduction in energy usage or emissions could be realized. As part of this program, the Dow Chemical Company explored the manufacture of a fiber reinforced/self reinforced silicon nitride for use in industrial chemical processing. In Dow`s program, CFCC manufacturing technology was developed around traditional, cost effective, tape casting routes. Formulations were developed and coupled with unique processing procedures which enabled the manufacture of tubular green laminates of the dimension needed for the application. An evaluation of the effect of various fibers and fiber coatings on the properties of a fiber reinforced composites was also conducted. Results indicated that fiber coatings could provide composites exhibiting non-catastrophic failure and substantially improved toughness. However, an evaluation of these materials in industrial process environments showed that the material system chosen by Dow did not provide the required performance improvements to make replacement of current metallic components with CFCC components economically viable.

  12. Preparation and Structure of Rainbow Piezoelectric Ceramics

    Institute of Scientific and Technical Information of China (English)

    SHEN Xing

    2003-01-01

    Rainbow piezoelectric ceramics are a new type of stress-biased, oxide-reduced composite ferroelectric ceramics, which have a special dome structure. The have shown excellent properties such as ultra-high displacement under an applied electric field and enhanced load-bearing capability. In this article, their manufacture,structures and properties were discussed in detail by combining experiments and theory analysis. The resuts show that the optimal conditions for producing Rainbow samples from PLZT ceramics were determined to be 900℃ for 1 to 1.5 hours. A number of different phases have been found in the reduced layer of Rainbow ceramics by XRD analyses . The phases found include metallic lead and other oxide phases , such cs PbO , ZrO2 and TiO2 . The original PLZT phase was not observed. The reduced layer was transgranularly fractured while the unreduced ceramic was intergranularly fractured. Two kinds of fracture types can be seen at the interface , which denotes the different degrees of reduction. It is shown that the Pb grains ( about 0.2 μm ) constitute a continuous phase in the reduced layer, which accounts for the good electrical condnctivity.

  13. Preparation of zeolite covered cellulose fibers

    Energy Technology Data Exchange (ETDEWEB)

    Mintova, S.; Valtchev, V. [Institute of Applied Mineralogy, Sofia (Bulgaria)

    1995-12-01

    Membrane separation has proved to be an important technology in chemical industry. That is why the design of different type of zeolite containing membranes has received much attention during the last decade. Zeolite containing filters and membranes were prepared by embedding zeolite crystals with adhesive substances in the cellulose matrix. This communication discussed the preparation of zeolite containing cellulose materials by in situ crystallization. Discussed axe: (1) the effect of the vegetal fiber structure and chemical composition (2) the effect of the type of the zeolite coating; (3) the effect of the mechanical and chemical treatment of the fibers on the process of the fiber zeolite coating.

  14. A multiyear workplace-monitoring program for refractory ceramic fibers.

    Science.gov (United States)

    Maxim, L D; Kelly, W P; Walters, T; Waugh, R

    1994-12-01

    This paper summarizes interim results of a 5-year workplace monitoring program conducted by firms belonging to the Refractory Ceramic Fibers Coalition (RCFC) pursuant to a Consent Agreement with the U.S. EPA. The exposure monitoring program is part of a model Product Stewardship Program (PSP) developed by RCFC. This paper reviews the refractory ceramic fiber (RCF) industry, findings of animal bioassay and epidemiological investigations, and the regulatory approach used by EPA. The scope, protocols, sample collection budgets, and experimental design of the monitoring program are summarized. In brief, the program will gather 720 time-weighted average (TWA) workplace concentration measurements annually, partitioned among 8 functional job classifications, both from plants that manufacture and from those that process or use RCF. Statistical analyses reveal that: workplace airborne RCF concentration data are approximately log-normally distributed, 93% of workplace TWAs are beneath the industry's recommended exposure guideline of 1 fiber per cubic centimeter (f/cc), there are significant differences in average workplace RCF concentrations among job types, and PSP activities are effective in lowering workplace exposure. Results of this effort provide an interesting illustration of a successful cooperative effort between a responsible industry and regulatory agencies.

  15. A novel method for preparing microplastic fibers

    Science.gov (United States)

    Cole, Matthew

    2016-10-01

    Microscopic plastic (microplastic, 0.1 µm–5 mm) is a widespread pollutant impacting upon aquatic ecosystems across the globe. Environmental sampling has revealed synthetic fibers are prevalent in seawater, sediments and biota. However, microplastic fibers are rarely used in laboratory studies as they are unavailable for purchase and existing preparation techniques have limited application. To facilitate the incorporation of environmentally relevant microplastic fibers into future studies, new methods are required. Here, a novel cryotome protocol has been developed. Nylon, polyethylene terephthalate and polypropylene fibers (10–28 μm diameter) were aligned, embedded in water-soluble freezing agent, and sectioned (40–100 μm length) using a cryogenic microtome. Microplastic fibers were prepared to specified lengths (P microplastics, with widths similar to those observed in the natural environment, which could ultimately lead to a better understanding of the biological and ecological effects of microplastic debris in the environment.

  16. A novel method for preparing microplastic fibers

    Science.gov (United States)

    Cole, Matthew

    2016-01-01

    Microscopic plastic (microplastic, 0.1 µm–5 mm) is a widespread pollutant impacting upon aquatic ecosystems across the globe. Environmental sampling has revealed synthetic fibers are prevalent in seawater, sediments and biota. However, microplastic fibers are rarely used in laboratory studies as they are unavailable for purchase and existing preparation techniques have limited application. To facilitate the incorporation of environmentally relevant microplastic fibers into future studies, new methods are required. Here, a novel cryotome protocol has been developed. Nylon, polyethylene terephthalate and polypropylene fibers (10–28 μm diameter) were aligned, embedded in water-soluble freezing agent, and sectioned (40–100 μm length) using a cryogenic microtome. Microplastic fibers were prepared to specified lengths (P microplastics, with widths similar to those observed in the natural environment, which could ultimately lead to a better understanding of the biological and ecological effects of microplastic debris in the environment. PMID:27694820

  17. Processing and Material Characterization of Continuous Basalt Fiber Reinforced Ceramic Matrix Composites Using Polymer Derived Ceramics.

    Science.gov (United States)

    Cox, Sarah B.

    2014-01-01

    The need for high performance vehicles in the aerospace industry requires materials which can withstand high loads and high temperatures. New developments in launch pads and infrastructure must also be made to handle this intense environment with lightweight, reusable, structural materials. By using more functional materials, better performance can be seen in the launch environment, and launch vehicle designs which have not been previously used can be considered. The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Polymer matrix composites can be used for temperatures up to 260C. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed and cured and then to be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in the composites. In this study, continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. The oxyacetylene torch testing and three point bend testing have been performed on test panels and the test results are presented.

  18. Development of Ceramic Fibers for Reinforcement in Composite Materials

    Science.gov (United States)

    Gates, L. E.; Lent, W. E.; Teague, W. T.

    1961-01-01

    the. testing apparatus for single fiber tensile strength increased the precision. of tests conducted on nine fibers. The highest mean tensile strength, a value of 295,000 pounds per square inch, was obtained with R-141 fibers. Treatment of R-74 fibers with anhydrous Linde A-1100 silane finish improved its mean fiber tensile strength by 25 percent. The lapse of time after fiber formation had no measurable effect on tensile strength. A static heating test conducted with various high melting fibers indicated that Fiberfrax and R-108 underwent no significant changes in bulk volume or resiliency on exposure to 2750 degrees Fahrenheit (1510 degrees Centigrade) in an oxidizing atmosphere. For fiber-resin composition fabrication, ten fiber materials were selected on the bases of high fiber yield, fusion temperature, and type of composition. Fiberfrax, a commercial ceramic fiber, was included for comparison. A new, more effective method of removing pellets from blown fibers was developed. The de-pelletized fibers were treated with a silane finish and felted into ten-inch diameter felts prior to resin impregnation. Composites containing 30 percent by weight of CTL 91-LD phenolic resin were molded under high pressure from the impregnated felts and post-cured to achieve optimum properties. Flexural strength, flexural modules of elasticity, and punch shear strength tests were conducted on the composite specimens. The highest average flexural strength obtained was 19,958 pounds per square inch with the R-74-fiber-resin composite. This compares very favorably with the military specification of 13,000 pounds per square inch flexural strength for randomly oriented fiber reinforced composites. The highest punch shear strength (11,509 pounds per square inch) was obtained with the R-89 fiber-resin composite. The effects of anhydrous fiber finishes on composite strength were not clearly indicated. Plasma arc tests at a heat flux of 550 British Thermal Units per square foot per second on

  19. Mechanical behavior of Fiber Reinforced SiC/RBSN Ceramic Matrix Composites: Theory and Experiment

    Science.gov (United States)

    1991-01-01

    AD-A235 926 NASA AVSCOM Technical Memorandum 103688 Technical Report 91-C-004 Mechanical Behavior of Fiber Reinforced SiC/RBSN Ceramic Matrix Composites : Theory... CERAMIC MATRIX COMPOSITES : THEORY AND EXPERIMENT Abhisak Chulya* Department of Civil Engineering Cleveland State University Cleveland, Ohio 44115...tough and sufficiently stable continuous fiber- reinforced ceramic matrix composites (CMC) which can survive in oxidizing environ- ments at temperatures

  20. Recrystallization behaviour of CaO-MgO-SiO{sub 2} system ceramic fibers

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xitang; Zhang Baoguo [Hubei Province Key Lab. of Ceramics and Refractories, Wuhan Univ. of Science and Technology, Wuhan (China)

    2007-07-01

    Various kinds of ceramic fibers are used in industries for thermal insulation. Traditional Al{sub 2}O{sub 3}-SiO{sub 2} refractory ceramic fibers have potential health hazard when they come into the lung of human beings. The bio-soluble ceramic fibers in CaO-MgO-SiO{sub 2} system, as a new group of synthetic glass fibers, have been developed recently for high-temperature insulation applications. The fibers were specially designed to have high solubility and hence low bio-durability in human body lung solution. Various calcium magnesium silicate bio-soluble glass fibers are produced at present to replace aluminium silicate ceramic fibers. In practical applications such as fiber lining of various kinds of high temperature furnace or kiln, devitrification of the fibers take place and consequently fiber surface become rougher. Formation and growth of crystal phases could cause the destruction and pulverization of the fibers after a long exposure at high temperature. For traditional Al{sub 2}O{sub 3}-SiO{sub 2} refractory ceramic fibers the recrystallization temperature of the fibers starts at 980 C with the formation of mullite and cristobalite phases. Comparing with Al{sub 2}O{sub 3}-SiO{sub 2} ceramic fibers, the relatively lower application temperature of CaO-MgO-SiO{sub 2} system bio-soluble fibers is considered. In this paper, the studies were focused on recrystallization behaviour of CaO-MgO-SiO{sub 2} system soluble ceramic fibers. (orig.)

  1. Preparation, Characterization and Performance of Conch Ceramics Added With Shell

    Directory of Open Access Journals (Sweden)

    Wang Qingyu

    2016-01-01

    Full Text Available The conch ceramics bodies with different ratios were prepared by compression moulding technology using shell, kaolin, and calcium oxide etc. as the raw materials, and then calcined at the high temperature to obtain the conch ceramics. The effects of raw material ratios and calcination temperatures on the performance of conch ceramics were investigated by rotational viscometer, vernier caliper, digital display whiteness meter, thermal analyzer, and Fourier transform infrared spectrometer(FT-IR. The results indicated that the viscosity, line shrinkage rate, and whiteness of the conch ceramics were 1.29 Pa·s, 17.9%, and 54.1%, respectively, when the content of the shell powder was 20 wt% and kaolin was 65 wt%. The density of the conch ceramics was the largest (3.8 g/cm3 when calcination temperature was 1200 °C. The results of FT-IR spectrum showed that the addition of the shell powders changed the structure of the ceramic body, which improved the performance of the conch ceramics.

  2. Preparation of Porous Silica Ceramics with Low Dielectric Constant

    Institute of Scientific and Technical Information of China (English)

    MAO Xiao-jian; WANG Shi-wei; SHIMAI Shun-zo

    2006-01-01

    Porous silica ceramics has been prepared with the starch consolidation casting method. Slurries with various fractions of starch added in were prepared by ball-milling. The evaluation of the microstructures was done through two techniques: Hg porosimetry and SEM investigation. The bending strength of the sintered samples varied within the range of 10 MPa-20 MPa and the low dielectric constant within the range of 2.0-2.4 correspondent with the porosity of 42%-56%. The ceramics holds a brilliant promise of being a kind of core material used in sandwich-like electromagnetic windows.

  3. Preparation of basalt-based glass ceramics

    Directory of Open Access Journals (Sweden)

    MIHOVIL LOGAR

    2003-06-01

    Full Text Available Local and conventional raw materials–massive basalt from the Vrelo locality on Kopaonik mountain–have been used as starting materials to test their suitability for the production of glass-ceramics. Crystallization phenomena of glasses of the fused basalt rocks were studied by X-ray phase analysis, optical microscopy and other techniques. Various heat treatments were used, and their influences, on controlling the microstructures and properties of the products were studied with the aim of developing high strength glass-ceramic materials. Diopside CaMg(SiO32 and hypersthene ((Mg,FeSiO3 were identifies as the crystalline phases. The final products contained considerable amounts of a glassy phase. The crystalline size was in range of 8–480 mm with plate or needle shape. Microhardness, crashing strength and wears resistence of the glass-ceramics ranged from 6.5–7.5, from 2000–6300 kg/cm2 and from 0.1–0.2 g/cm, respectively.

  4. Fire resistance properties of ceramic wool fiber reinforced intumescent coatings

    Energy Technology Data Exchange (ETDEWEB)

    Amir, N., E-mail: norlailiamir@petronas.com.my; Othman, W. M. S. W., E-mail: wamosa@gmail.com; Ahmad, F., E-mail: faizahmad@petronas.com.my [Mechanical Engineering Department, Universiti Teknologi PETRONAS Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

    2015-07-22

    This research studied the effects of varied weight percentage and length of ceramic wool fiber (CWF) reinforcement to fire retardant performance of epoxy-based intumescent coating. Ten formulations were developed using ammonium polyphosphate (APP), expandable graphite (EG), melamine (MEL) and boric acid (BA). The mixing was conducted in two stages; powdered materials were grinded in Rocklabs mortar grinder and epoxy-mixed using Caframo mixer at low speed mixing. The samples were applied on mild steel substrate and exposed to 500°C heat inside Carbolite electric furnace. The char expansion and its physical properties were observed. Scanning electron microscopy (SEM) analyses were conducted to inspect the fiber dispersion, fiber condition and the cell structure of both coatings and chars produced. Thermogravimetric analyses (TGA) were conducted to study the thermal properties of the coating such as degradation temperature and residual weight. Fire retardant performance was determined by measuring backside temperature of substrate in 1-hour, 1000°C Bunsen burner test according to UL 1709 fire regime. The results showed that intumescent coating reinforced with CWF produced better fire resistance performance. When compared to unreinforced coating, formulation S6-15 significantly reduced steel temperature at approximately 34.7% to around 175°C. However, higher fiber weight percentage had slightly decreased fire retardant performance of the coating.

  5. Matrix cracking of fiber-reinforced ceramic composites in shear

    Science.gov (United States)

    Rajan, Varun P.; Zok, Frank W.

    2014-12-01

    The mechanics of cracking in fiber-reinforced ceramic matrix composites (CMCs) under general loadings remains incomplete. The present paper addresses one outstanding aspect of this problem: the development of matrix cracks in unidirectional plies under shear loading. To this end, we develop a model based on potential energy differences upstream and downstream of a fully bridged steady-state matrix crack. Through a combination of analytical solutions and finite element simulations of the constituent stresses before and after cracking, we identify the dominant stress components that drive crack growth. We show that, when the axial slip lengths are much larger than the fiber diameter and when interfacial slip precedes cracking, the shear stresses in the constituents are largely unaffected by the presence of the crack; the changes that do occur are confined to a 'core' region within a distance of about one fiber diameter from the crack plane. Instead, the driving force for crack growth derives mainly from the axial stresses-tensile in the fibers and compressive in the matrix-that arise upon cracking. These stresses are well-approximated by solutions based on shear-lag analysis. Combining these solutions with the governing equation for crack growth yields an analytical estimate of the critical shear stress for matrix cracking. An analogous approach is used in deriving the critical stresses needed for matrix cracking under arbitrary in-plane loadings. The applicability of these results to cross-ply CMC laminates is briefly discussed.

  6. Refractory ceramic fiber (RCF) toxicity and epidemiology: a review.

    Science.gov (United States)

    Utell, Mark J; Maxim, L Daniel

    2010-05-01

    This paper provides a review of the relevant literature on refractory ceramic fibers (RCFs), summarizing relevant data and information on the manufacture, processing, applications, potential occupational exposure, toxicology, epidemiology, risk analysis, and risk management. RCFs are amorphous fibers used for high-temperature insulation applications. RCFs are less durable/biopersistent than amphibole asbestos, but more durable/biopersistent than many other synthetic vitreous fibers (SVFs). Moreover, as produced/used, some RCFs are respirable. Toxicology studies with rodents using various exposure methods have shown that RCFs can cause fibrosis, lung cancer, and mesothelioma. Interpretation of these animal studies is difficult for various reasons (e.g., overload in chronic inhalation bioassays). Epidemiological studies of occupationally exposed cohorts in Europe and the United States have demonstrated measurable effects (e.g., mild respiratory symptoms and pleural plaques) but no disease (i.e., no interstitial fibrosis, no excess lung cancer, and no mesothelioma) to date. The RCF industry, working cooperatively with various government agencies in the United States, has developed a comprehensive product stewardship program (PSP) to identify and control risks associated with occupational exposure. One provision of the PSP is the adoption of a voluntary recommended exposure guideline (REG) of 0.5 fibers/milliliter (f/ml). Selected on the basis of prudence and demonstrated feasibility, compliance with the REG should reduce risks to levels between 0.073/1000 and 1.2/1000, based on extrapolations from chronic animal inhalation studies.

  7. Implementation Challenges for Sintered Silicon Carbide Fiber Bonded Ceramic Materials for High Temperature Applications

    Science.gov (United States)

    Singh, M.

    2011-01-01

    During the last decades, a number of fiber reinforced ceramic composites have been developed and tested for various aerospace and ground based applications. However, a number of challenges still remain slowing the wide scale implementation of these materials. In addition to continuous fiber reinforced composites, other innovative materials have been developed including the fibrous monoliths and sintered fiber bonded ceramics. The sintered silicon carbide fiber bonded ceramics have been fabricated by the hot pressing and sintering of silicon carbide fibers. However, in this system reliable property database as well as various issues related to thermomechanical performance, integration, and fabrication of large and complex shape components has yet to be addressed. In this presentation, thermomechanical properties of sintered silicon carbide fiber bonded ceramics (as fabricated and joined) will be presented. In addition, critical need for manufacturing and integration technologies in successful implementation of these materials will be discussed.

  8. Electrospinning preparation and characterization of polyoxometalate fibers

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Poly(vinyl alcohol)/K7[SiW11O39Co(H3P2- O7)] hybrid fine fiber mats (PVA/SiW11Co-P2O7) were prepared through electrospinning technique. After calcinations of PVA/SiW11Co-P2O7 at 500℃ for 8 h, pure SiW11Co-P2O7 fine fibers were obtained with the Keggin structure keeping unchanged. The fiber mats were characterized by IR, ESR, PXRD and scanning electron microscopy (SEM) methods. The average diameter of the fibers is about 250 nm. The SiW11Co- P2O7 fibers showed color change when absorbing and desorbing moisture.

  9. A dose-response model for refractory ceramic fibers.

    Science.gov (United States)

    Turim, J; Brown, R C

    2003-09-15

    Refractory ceramic fibers (RCFs) are man-made vitreous fibers commonly used in insulation applications above 1000 degrees C. Although they have been subjected to considerable toxicologic evaluation, only the pooled results from two rat inhalation studies provide data that may be suitable for performing a numerical risk assessment. Even in these inhalation studies, good evidence exists that the maximum tolerated dose (MTD) was exceeded and that pulmonary overload occurred, a condition that will cause tumors whatever the dust responsible. Indeed, a significant yield of tumors was only obtained at the highest dose tested. If these results are omitted, there is no statistically significant evidence of carcinogenicity within the RCF results. Although there is little evidence that overload-related tumors are relevant to human risk, we adopted a conservative approach to obtain the estimates of risk regardless of overload, using a biologically based model, the two-stage clonal expansion model, as well as various statistical models, including the benchmark dose model. We argue that the data favor the use of a biologically based model, which gives the best fit when the highest dose RCF exposures are omitted. Continuing with this model, we show that available data from the RCF experiment, less outliers, coupled with results from other experiments with man-made mineral fibers (MMVFs), demonstrate that all MMVFs are potentially carcinogenic, with any risk mediated by the fibers' biopersistence. Application of this "all MMVF data set" model yields a maximum likely estimate for RCF excess unit risk of 4.6 x 10(-5) (95% upper confidence limit = 9.2 x 10(-5) per fiber/ml). This implies that the risk from occupational exposure to RCFs at 1 fiber/ml for a typical working lifetime would not exceed 10(-4).

  10. Modeling and simulation of continuous fiber-reinforced ceramic composites

    Science.gov (United States)

    Bheemreddy, Venkata

    Finite element modeling framework based on cohesive damage modeling, constitutive material behavior using user-material subroutines, and extended finite element method (XFEM), are developed for studying the failure behavior of continuous fiber-reinforced ceramic matrix composites (CFCCs) by the example of a silicon carbide matrix reinforced with silicon carbide fiber (SiC/SiCf) composite. This work deals with developing comprehensive numerical models for three problems: (1) fiber/matrix interface debonding and fiber pull-out, (2) mechanical behavior of a CFCC using a representative volume element (RVE) approach, and (3) microstructure image-based modeling of a CFCC using object oriented finite element analysis (OOF). Load versus displacement behavior during a fiber pull-out event was investigated using a cohesive damage model and an artificial neural network model. Mechanical behavior of a CFCC was investigated using a statistically equivalent RVE. A three-step procedure was developed for generating a randomized fiber distribution. Elastic properties and damage behavior of a CFCC were analyzed using the developed RVE models. Scattering of strength distribution in CFCCs was taken into account using a Weibull probability law. A multi-scale modeling framework was developed for evaluating the fracture behavior of a CFCC as a function of microstructural attributes. A finite element mesh of the microstructure was generated using an OOF tool. XFEM was used to study crack propagation in the microstructure and the fracture behavior was analyzed. The work performed provides a valuable procedure for developing a multi-scale framework for comprehensive damage study of CFCCs.

  11. Preparation of porous hydroxyapatite ceramics with starch additives

    Institute of Scientific and Technical Information of China (English)

    YANG Lei; NING Xiao-shan; CHEN Ke-xin; XIAO Qun-fang; ZHOU He-ping

    2005-01-01

    Porous ceramics prepared from nano-sized hydroxyapatite powders by adding water soluble starch and insoluble starch were investigated. The results show that small pores of several micrometers or less can be produced by adding water soluble starch as a pore former. Two kinds of starch have different pore forming mechanisms. The permeability of the porous ceramics can be greatly improved by adding the insoluble starch to channel the small pores rather than solely using water soluble starch. The control of permeability can be achieved by adjusting the content ratio of water soluble starch to insoluble starch. Strength tests show the ceramics have rather high strength. Therefore a kind of porous filtering material with small pores, controllable permeability and good strength can be prepared by using starch additives.

  12. Precipitation Coating of Monazite on Woven Ceramic Fibers: 1. Feasibility (Postprint)

    Science.gov (United States)

    2007-02-01

    AFRL-ML-WP-TP-2006-480 PRECIPITATION COATING OF MONAZITE ON WOVEN CERAMIC FIBERS: I. FEASIBILITY (POSTPRINT) Geoff E. Fair, Randall S. Hay...GRANT NUMBER 4. TITLE AND SUBTITLE PRECIPITATION COATING OF MONAZITE ON WOVEN CERAMIC FIBERS: I. FEASIBILITY (POSTPRINT) 5c. PROGRAM ELEMENT...08 Aug 2006. Paper contains color. 14. ABSTRACT Monazite coatings were deposited on woven cloths and tows of NextelTM 610 fibers by heterogeneous

  13. Ablation Property of Ceramics/Carbon Fibers/Resin Novel Super-hybrid Composite

    Institute of Scientific and Technical Information of China (English)

    Jun QIU; Xiaoming CAO; Chong TIAN; Jinsong ZHANG

    2005-01-01

    A novel super-hybrid composite (NSHC) is prepared with three-dimension reticulated SiC ceramic (3DRC), high performance carbon fibers and modified phenolic resin (BPR) in this paper. Ablation performance of super-hybrid composite is studied. The results show that the NSHC has less linear ablation rate compared with pure BPR and CF/BPR composite, for example, its linear ablation rate is 50% of CF/BPR at the same fiber content. Mass ablation rate of the NSHC is slightly lower than that of pure BPR and CF/BPR composite because of their difference in the density. Scanning electron microscopic analysis indicates that 3DRC can increase anti-erosion capacity of materials because its special reticulated structure can control the deformation of materials and strengthen the stability of integral structure.

  14. Preparation and properties of continuous Al-containing silicon carbide fibers

    Institute of Scientific and Technical Information of China (English)

    YU Yu-xi; LI Xiao-dong; CAO Feng; WANG Ying-de; ZOU Zhi-chun; WANG Jun; ZHENG Chun-man; ZHAO Da-fang

    2005-01-01

    Continuous SiC(OAl) fibers, named KD-A fibers, were prepared by the melt-spinning of ceramic precursor polyaluminocarbosilane, air-curing, and pyrolizing at 1 300 ℃. These fibers contained small amount of aluminum and 7%- 9% oxygen. The KD-A fibers were converted into sintered SiC(Al) fibers, named KD-SA, by sintering at 1 800 ℃. The fibers were characterized by chemical analysis, tensile strength test, SEM and XRD. The tensile strength, elastic modulus and diameter of the KD-A fibers are 2.6 GPa, 210 GPa, 12 - 14 μm, respectively. The KD-A fibers have higher thermal stability, more excellent oxidation resistance than the Nicalon fibers. The properties of the KD-A fibers have reached the level of Hi-Nicalon fibers. The tensile strength, elastic modulus and diameter of the KD-A fibers are 2.1 GPa, 405 GPa, 10 - 12 μm, respectively. The KD-SA fibers with nearly stoichiometric component have stable performance at high temperature, and better creep resistance than the Tyranno SA fibers.

  15. Preparation and mechanical properties of silicon oxycarbide fibers from electrospinning/sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaofei [School of Materials Sciences and Engineering, Tianjin University, 300072 Tianjin (China); Gong, Cairong, E-mail: gcr@tju.edu.cn [School of Materials Sciences and Engineering, Tianjin University, 300072 Tianjin (China); Fan, Guoliang [School of Materials Sciences and Engineering, Tianjin University, 300072 Tianjin (China)

    2011-12-15

    Graphical abstract: Ceramic fibers, silicon oxycarbide (SiOC) fibers were demonstrated and showed higher mechanical properties from electrospinning/sol-gel process at 1000 Degree-Sign C. Highlights: Black-Right-Pointing-Pointer SiOC fibers with low cost are promising to substitute the non-oxide fibers. Black-Right-Pointing-Pointer Successful preparation of SiOC fibers by electrospinning/sol-gel process. Black-Right-Pointing-Pointer Confirmation of the designed product using material characterization methods. Black-Right-Pointing-Pointer The SiOC fibers prepared at 1000 Degree-Sign C possess higher strength (967 MPa). -- Abstract: Silicon oxycarbide (SiOC) fibers were produced through the electrospinning of the solution containing vinyltrimethoxysilane and tetraethoxysilane in the course of sol-gel reaction with pyrolysis to ceramic. The effect of the amount of spinning agent Polyvinylpyrrolidone (PVP) on the dope spinnability was investigated. At a mass ratio of PVP/alkoxides = 0.05, the spinning sol exhibited an optimal spinnable time of 50 min and generated a large quantity of fibers. Electrospun fibers were characterized by Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis-differential scanning calorimetry (TGA-DSC), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The SEM results revealed that the SiOC fibers had a smooth surface and dense cross-section, free of residue pores and cracks. The XPS results gave high content of SiC (13.99%) in SiOC fibers. The SiOC fibers prepared at 1000 Degree-Sign C had a high tensile strength of 967 MPa and Young's modulus of 58 GPa.

  16. Transparent ceramics and methods of preparation thereof

    Science.gov (United States)

    Hollingsworth, Joel P.; Kuntz, Joshua D.; Seeley, Zachary M.; Soules, Thomas F.

    2012-12-25

    A method for forming a transparent ceramic preform in one embodiment includes forming a suspension of oxide particles in a solvent, wherein the suspension includes a dispersant, with the proviso that the suspension does not include a gelling agent; and uniformly curing the suspension for forming a preform of gelled suspension. A method according to another embodiment includes creating a mixture of inorganic particles, a solvent and a dispersant, the inorganic particles having a mean diameter of less than about 2000 nm; agitating the mixture; adding the mixture to a mold; and curing the mixture in the mold for gelling the mixture, with the proviso that no gelling agent is added to the mixture.

  17. Preparation and dielectric properties of porous silicon nitride ceramics

    Institute of Scientific and Technical Information of China (English)

    LI Jun-qi; LUO Fa; ZHU Dong-mei; ZHOU Wan-cheng

    2006-01-01

    Porous silicon nitride ceramics with difference volume fractions of porosity from 34.1% to 59.2% were produced by adding different amount of the pore-forming agent into initial silicon nitride powder. The microwave dielectric property of these ceramics at a frequency of 9.36 GHz was studied. The crystalline phases of the samples were determined by X-ray diffraction analysis. The influence of porosity on the dielectric properties was evaluated. The results show that α-Si3N4 crystalline phase exists in all the samples while the main crystalline phase of the samples is β-Si3N4,indicating that the a/b transformation happens during the preparation of samples and the transformation is incomplete. There is a dense matrix containing large pores and cavities with needle-shaped and flaky β-Si3N4 grains distributing. The dielectric constant of the ceramics reduces with the increase of porosity.

  18. Ceramic fiber coatings development and demonstration. Final technical report, 1 July 1989-31 May 1993

    Energy Technology Data Exchange (ETDEWEB)

    Streckert, H.; Hazlebeck, D.; Montgomery, F.; Norton, K.; Schneir, I.

    1993-05-28

    The objective of this program was to develop fiber coating techniques by gas phase and liquid phase processes for interface control in ceramic matrix and metal matrix composites. Thermochemical evaluations of fiber/coating/matrix systems were performed theoretically and experimentally. Liquid phase processes were developed mainly for oxide coatings. Gas phase processes were developed for-carbide, nitride and boride coatings. Coatings were produced on continuous fiber tows and woven fabric. A small scale continuous fabric coater was designed and constructed. Coated fiber tows were infiltrated with silicon nitride matrix by chemical vapor deposition in order to study fiber matrix interactions. Composite coupons were made from Nicalon cloth and infiltrated with silicon nitride. Samples coated with high temperature BN showed flexural strengths up to 350 MPa.... Ceramic Fiber Coating, Chemical Vapor Deposition, Sol-Gel Ceramic Matrix Composites, Metal Matrix Composites.

  19. Structural and impedance characterization of ceramics prepared from NPK fertilizer

    Directory of Open Access Journals (Sweden)

    Diouma Kobor

    2015-06-01

    Full Text Available One of the main objectives of this work was to study the possibilities of valorising the phosphates through the development of a conductive ceramics using NPK fertilizer as a precursor. Phosphorus based powders were synthesized using solid state technique from NPK fertilizer, lithium chloride and iron chloride at different temperatures up to 900 °C and ceramic samples were prepared by the powder pressing and sintering at 1100 °C. XRD spectra of the calcined powders show various sharp peaks indicating a relatively high degree of crystallinity and presence of different crystalline phases, such as: phosphorus based crystalline compounds (AlPO4 and LiFePO4, ferrite (Fe3O4 and DyFeO3, CaSO4 and K3DyCl6. The prepared phosphorus based ceramics showed very interesting electrical and dielectric properties. Thus, in the future the obtained ceramics could find application in electronic or energy storage devices. However, further investigations are necessary to understand the exact chemical composition and structural characteristics of this material, to better understand the origin of the obtained electrical and dielectric behaviour.

  20. Preparation of High Strength Silicon Nitride Ceramic Fibers From Polycarbosilane Fibers byγ-Ray Irradiation and Thermal Cross-Linking%γ辐照联合热交联聚碳硅烷先驱丝热解制备高强度氮化硅陶瓷纤维

    Institute of Scientific and Technical Information of China (English)

    黎阳; 高家诚; 许云书

    2014-01-01

    在空气气氛中采用γ射线辐照处理聚碳硅烷(PCS)先驱丝,辐照先驱丝经 Ar中热交联、NH3中热解氨化、N2中高温氮化处理制备了氮化硅陶瓷纤维。研究了热交联处理对辐照先驱丝化学结构、凝胶含量、氨化陶瓷产率、抗拉强度、微观形貌及氧含量的影响。结果表明:热交联处理生成了 Si—CH2—Si 和 Si—O—Si 桥连结构,桥连结构使PCS先驱丝实现凝胶化;热交联处理不仅大幅提高了辐照 PCS先驱丝的氨化陶瓷产率,还提高了热解所得氮化硅陶瓷纤维的抗拉强度,而且还降低了陶瓷纤维的氧含量;吸收剂量为1.0 MGy的辐照丝经热交联处理后,其热解所得氮化硅陶瓷纤维抗拉强度达2.05 GPa,氧质量分数仅为9.5%。%Polycarbosilane (PCS)precursor fibers were irradiated byγ-ray in air.Silicon nitride ceramic fibers were obtained from the irradiated PCS fibers by process of thermal cross-linking treatment in Ar,ammoniation pyrolysis in NH3 and high temperature nitriding treatment in N2 .The effects of thermal cross-linking treatment on chemical structure,gel content,ammoniation ceramic yield,tensile strength,microstructure and oxygen content were studied.The results show that bridge structures of Si—CH2—Si and Si—O—Si are formed in the PCS fibers by thermal cross-linking treatment and make the PCS fibers become gelling.The ammoniation ceramic yield of the irradiated PCS fibers increases sharply after thermal cross-linking treatment.The tensile strength of the silicon nitride ceramic fibers increases sharply, while the oxygen content decreases. After thermal cross-linking treatment,the tensile strength of the silicon nitride ceramic fibers derived from the PCS fibers with absorbed dose of 1.0 MGy reaches 2.05 GPa and the oxygen mass fraction is 9.5%.

  1. Pulmonary deposition modeling with airborne fiber exposure data: a study of workers manufacturing refractory ceramic fibers.

    Science.gov (United States)

    Lentz, Thomas J; Rice, Carol H; Succop, Paul A; Lockey, James E; Dement, John M; LeMasters, Grace K

    2003-04-01

    Increasing production of refractory ceramic fiber (RCF), a synthetic vitreous material with industrial applications (e.g., kiln insulation), has created interest in potential respiratory effects of exposure to airborne fibers during manufacturing. An ongoing study of RCF manufacturing workers in the United States has indicated an association between cumulative fiber exposure and pleural plaques. Fiber sizing data, obtained from electron microscopy analyses of 118 air samples collected in three independent studies over a 20-year period (1976-1995), were used with a computer deposition model to estimate pulmonary dose of fibers of specified dimensions for 652 former and current RCF production workers. Separate dose correction factors reflecting differences in fiber dimensions in six uniform job title groups were used with data on airborne fiber concentration and employment duration to calculate cumulative dose estimates for each worker. From review of the literature, critical dimensions (diameter <0.4 microm, length <10 microm) were defined for fibers that may translocate to the parietal pleura. Each of three continuous exposure/dose metrics analyzed in separate logistic regression models was significantly related to plaques, even after adjusting for possible past asbestos exposure: cumulative fiber exposure, chi(2) = 15.2 (p < 0.01); cumulative pulmonary dose (all fibers), chi(2) = 14.6 (p < 0.01); cumulative pulmonary dose (critical dimension fibers), chi(2) = 12.4 (p < 0.01). Odds ratios (ORs) were calculated for levels of each metric. Increasing ORs were statistically significant for the two highest dose levels of critical dimension fibers (level three, OR = 11, 95%CI = [1.4, 98]; level four, OR = 25, 95%CI = [3.2, 190]). Similar associations existed for all metrics after adjustment for possible asbestos exposure. It was concluded that development of pleural plaques follows exposure- and dose-response patterns, and that airborne fibers in RCF manufacturing

  2. Low-Cost Innovative Hi-Temp Fiber Coating Process for Advanced Ceramic Matrix Composites Project

    Data.gov (United States)

    National Aeronautics and Space Administration — MATECH GSM (MG) proposes 1) to demonstrate a low-cost innovative Hi-Temp Si-doped in-situ BN fiber coating process for advanced ceramic matrix composites in order to...

  3. Mortality of workers occupationally exposed to refractory ceramic fibers.

    Science.gov (United States)

    LeMasters, Grace Kawas; Lockey, James E; Yiin, James H; Hilbert, Timothy J; Levin, Linda S; Rice, Carol H

    2003-04-01

    This study was prompted by refractory ceramic fibers (RCF) inhalation studies at high dose levels in animals that demonstrated positive effects for lung fibrosis, mesothelioma, and lung cancer. Current and former male workers employed between 1952 and 2000 at two RCF manufacturing facilities were followed to investigate a possible excess in mortality. The mortality analytic methods included: (1) standardized mortality ratios comparing this cohort to the general and state populations, and (2) a proportional hazards model that relates risk of death to the lifetime cumulative fiber-months/cc exposure among the RCF cohort, adjusted for age at hire and for race. There was no excess mortality related to all deaths, all cancers, or malignancies or diseases of the respiratory system including mesothelioma, but there was a statistically significant association with cancers of the urinary organs SMR = 344.8 (95% CL of 111.6, 805.4). The quality of the data for job history, exposure, and smoking history were very high. Although the cohort was relatively small and young with an average age of 51, the mean latency period was over 21 years. Because of these limitations, the preliminary findings warrant the continuation of this mortality registry for future analyses.

  4. Low-Cost Preparation of Boron Nitride Ceramic Powders

    Institute of Scientific and Technical Information of China (English)

    LI Duan; ZHANG Changrui; LI Bin; CAO Feng; WANG Siqing; LIU Kun; FANG Zhenyu

    2012-01-01

    The amorphous boron nitride ceramic powders were prepared at 750-950 ℃ by the lowcost urea route,and the effects of preparation temperatures,molar ratios of the raw materials and oxidation treatment on the composition,structure and surface morphology of the products were investigated through FTIR,XRD and SEM.The results show that the products ceramize and crystallize gradually with the increase of the temperature.When the molar ratio and reaction temperature are 3:2 and 850 ℃,respectively,the products have high purity,compact structure and nice shape.The oxidation treatment at 450 ℃ will not impair the composition and structure of boron nitfide but effectively remove the impurities.

  5. Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor Deposition

    OpenAIRE

    2011-01-01

    International audience; Rare earth (RE) doped silica-based optical fibers with transparent glass ceramic (TGC) core was fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of post-ceramming. The main characteristics of the RE-doped oxyde nanoparticles namely, their density and mean diameter in the fibers are dictated by the concentration of alkaline earth element used as phase separating agent. Magnesium and erbium ...

  6. Polymer-derived ceramic composite fibers with aligned pristine multiwalled carbon nanotubes.

    Science.gov (United States)

    Sarkar, Sourangsu; Zou, Jianhua; Liu, Jianhua; Xu, Chengying; An, Linan; Zhai, Lei

    2010-04-01

    Polymer-derived ceramic fibers with aligned multiwalled carbon nanotubes (MWCNTs) are fabricated through the electrospinning of polyaluminasilazane solutions with well-dispersed MWCNTs followed by pyrolysis. Poly(3-hexylthiophene)-b-poly (poly (ethylene glycol) methyl ether acrylate) (P3HT-b-PPEGA), a conjugated block copolymer compatible with polyaluminasilazane, is used to functionalize MWCNT surfaces with PPEGA, providing a noninvasive approach to disperse carbon nanotubes in polyaluminasilazane chloroform solutions. The electrospinning of the MWCNT/polyaluminasilazane solutions generates polymer fibers with aligned MWCNTs where MWCNTs are oriented along the electrospun jet by a sink flow. The subsequent pyrolysis of the obtained composite fibers produces ceramic fibers with aligned MWCNTs. The study of the effect of polymer and CNT concentration on the fiber structures shows that the fiber size increases with the increment of polymer concentration, whereas higher CNT content in the polymer solutions leads to thinner fibers attributable to the increased conductivity. Both the SEM and TEM characterization of the polymer and ceramic fibers demonstrates the uniform orientation of CNTs along the fibers, suggesting excellent dispersion of CNTs and efficient CNT alignment via the electrospinning. The electrical conductivity of a ceramic fibers with 1.2% aligned MWCNTs is measured to be 1.58 x 10(-6) S/cm, which is more than 500 times higher than that of bulk ceramic (3.43 x 10(-9) S/cm). Such an approach provides a versatile method to disperse CNTs in preceramic polymer solutions and offers a new approach to integrate aligned CNTs in ceramics.

  7. Preparation and Easy-Cleaning Property of Rare Earth Composite Ceramic

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Rare earth and far-infrared mineral composite materials were added to ceramic glazes to prepare easy-cleaning ceramic. The morphology of easy-cleaning ceramic was observed by SEM. The influence of easy-cleaning ceramic on water surface tension and contact angles of water were investigated. Through calculation of ceramic surface free energy and observation of oil drop on ceramic surface in water, the easy-cleaning mechanism of rare earth composite ceramic was studied. It is found that the rare earth composite ceramic can make water surface tension decrease. The surface free energy and the polar component of rare earth composite ceramic are increased. The rare earth composite ceramics have the easy-cleaning property.

  8. An industry-wide pulmonary study of men and women manufacturing refractory ceramic fibers.

    Science.gov (United States)

    Lemasters, G K; Lockey, J E; Levin, L S; McKay, R T; Rice, C H; Horvath, E P; Papes, D M; Lu, J W; Feldman, D J

    1998-11-01

    An industry-wide pulmonary morbidity study was undertaken to evaluate the respiratory health of employees manufacturing refractory ceramic fibers at five US sites between 1987 and 1989. Refractory ceramic fibers are man-made vitreous fibers used for high temperature insulation. Of the 753 eligible current employees, 742 provided occupational histories and also completed the American Thoracic Society respiratory symptom questionnaire; 736 also performed pulmonary function tests. Exposure to refractory ceramic fibers was characterized by classifying workers as production or nonproduction employees and calculating the duration of time spent in production employment. The risk of working in the production of refractory ceramic fibers and having one or more respiratory symptoms was estimated by adjusted odds ratios and found to be 2.9 (95 percent confidence interval 1.4-6.2) for men and 2.4 (95 percent confidence interval 1.1-5.3) for women. The effect of exposure to refractory ceramic fibers on forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), the ratio of the two (FEV1/FVC), and forced expiratory flow (liters/second) between 25 percent and 75 percent of the FVC curve (FEF(25-75)) was evaluated by multiple regression analysis using transformed values adjusted for height, by dividing by the square of each individual's height. For men, there was a significant decline in FVC for current and past smokers of 165.4 ml (p ceramic fibers. For FEV1, the decline was significant (p ceramic fibers. These findings indicate that there may be important sex differences in response to occupational and/or environmental exposure.

  9. [Evaluation of the carcinogenic effect of ceramic fibers in experiments on rats and mice].

    Science.gov (United States)

    Krajnow, A; Lao, I; Stetkiewicz, J

    1997-01-01

    The carcinogenic effect of Kaowoll raw and thermally used ceramic fibres was assessed in experiments on rats and mice. The fibers were applied intraperitoneally in doses by 25 and 5 mg, and the animals were observed over their life-span. It was found that Kaowoll fibers were carcinogenic and that high temperature did not change these properties.

  10. Ceramic fiber technology frontier Quest%陶瓷纤维技术前沿探秘

    Institute of Scientific and Technical Information of China (English)

    刘道春

    2012-01-01

    Ceramic fiber is a set of traditional insulation materials,refractory fibrous excellent performance in one lightweight refractories,ceramic fiber,light weight,high temperature,thermal stability,low thermal conductivity,heat resistance of small and advantages such as mechanical vibrations,which involves all areas of its products,development prospects.This paper describes the types and properties of ceramic fiber characteristics,the nature and structure of ceramic fiber manufacturing methods;ceramic fiber main purpose and scope of application;and ceramic fiber kiln in the application of thermal technology;also pointed out that the development of the ceramic fiber trend%陶瓷纤维是一种集传统绝热材料、耐火材料优良性能于一体的纤维状轻质耐火材料,陶瓷纤维具有重量轻、耐高温、热稳定性好、导热率低、比热小及耐机械震动等优点,因而其产品涉及各领域,发展前景十分看好。本文分别介绍了陶瓷纤维的种类及性能特点,陶瓷纤维的结构性质和制造方法;陶瓷纤维的主要用途和应用范围;以及陶瓷纤维在热工窑炉中的应用技术;同时指出了陶瓷纤维的发展趋势。

  11. Ceramic fibers for matrix composites in high-temperature engine applications

    Science.gov (United States)

    Baldus; Jansen; Sporn

    1999-07-30

    High-temperature engine applications have been limited by the performance of metal alloys and carbide fiber composites at elevated temperatures. Random inorganic networks composed of silicon, boron, nitrogen, and carbon represent a novel class of ceramics with outstanding durability at elevated temperatures. SiBN(3)C was synthesized by pyrolysis of a preceramic N-methylpolyborosilazane made from the single-source precursor Cl(3)Si-NH-BCl(2). The polymer can be processed to a green fiber by melt-spinning, which then undergoes an intermediate curing step and successive pyrolysis. The ceramic fibers, which are presently produced on a semitechnical scale, combine several desired properties relevant for an application in fiber-reinforced ceramic composites: thermal stability, mechanical strength, high-temperature creep resistivity, low density, and stability against oxidation or molten silicon.

  12. Preparation and characterization of porous Si3N4 ceramics prepared by compression molding and slip casting methods

    Indian Academy of Sciences (India)

    Yu Fangli; Wang Huanrui; Bai Yu; Yang Jianfeng

    2010-10-01

    Porous silicon nitride (Si3N4) ceramics were fabricated by compression molding and slip casting methods using petroleum coke as pore forming agent, and Y2O3–Al2O3 as sintering additives. Microstructure, mechanical properties and gas permeability of porous Si3N4 ceramics were investigated. The mechanical properties and microstructure of porous Si3N4 ceramics prepared by compression molding were better than those which were prepared by slip casting method, whereas slip casting method is suitable for the preparation of porous Si3N4 ceramics with higher porosity and excellent gas permeability.

  13. A Family of Prediction Tools for Fine Ceramic Fibers Subcritical Cracking

    OpenAIRE

    Genet, Martin; Ladevèze, Pierre

    2010-01-01

    International audience; Ceramic Matrix Composites reinforced with long fibers are potential candidates for high-temperature structural applications. Their lifetime is mainly controlled by the fibers. The rupture mechanism of fibers under environmental conditions and mechanical stress is the environmentally assisted propagation of their surface defects toward their core.The analysis of cracks subcritical propagation is called static fatigue, because most works use a Paris-like law relating the...

  14. Electrical properties and sensing ability of novel piezoelectric ceramic fibers with Pt core

    Science.gov (United States)

    Du, Jianzhou; Qiu, Jinhao; Zhu, Kongjun; Ji, Hongli; Zhao, Huayun

    2012-04-01

    The traditional sintering method was used to sinter the pure and Fe2O3 doped 0.55Pb(Ni0.33Nb0.67)O3-0.45Pb(Zr0.3Ti0.7)O3 (abbreviate as PNN-PZT and PFNN-PZT, respectively) ceramics. The addition of Fe2O3 significantly improved the microstructure and electrical properties. Compared with pure PNN-PZT ceramics, higher dielectric and piezoelectric properties of d31~-390 pC/N, ɛ r ~6298 were obtained for the PFNN-PZT sample sintered at 1175°C for 2 h. Hence, the PFNN-PZT ceramics sample was selected to fabricate piezoelectric ceramic fibers with Pt core (PFC). Both the green fibers and bulk ceramics were sintered at 1150-1225°C for 2 h in a closed crucible, respectively. The effect of sintering temperature on the microstructure and electrical properties of the PFNN-PZT fibers was investigated. The optimal piezoelectric properties are obtained for the sample sintered at 1175°C for 2 h. The relative dielectric constant and piezoelectric constant show peak values of ɛ r~3683, d31~-197.4 pC/N, respectively. The PFC is a new type piezoelectric device, which can be used for sensors or actuators. The results of sensing experiment show that the piezoelectric ceramic fiber with Pt core has high sensitivity for the Lamb waves.

  15. Alumina ceramics prepared with new pore-forming agents

    Directory of Open Access Journals (Sweden)

    Zuzana Živcová

    2008-06-01

    Full Text Available Porous ceramics have a wide range of applications at all length scales, ranging from fi ltration membranes and catalyst supports to biomaterials (scaffolds for bone ingrowths and thermally or acoustically insulating bulk materials or coating layers. Organic pore-forming agents (PFAs of biological origin can be used to control porosity, pore size and pore shape. This work concerns the characterization and testing of several less common pore-forming agents (lycopodium, coffee, fl our and semolina, poppy seed, which are of potential interest from the viewpoint of size, shape or availability. The performance of these new PFAs is compared to that of starch, which has become a rather popular PFA for ceramics during the last decade. The PFAs investigated in this work are in the size range from 5 μm (rice starch to approximately 1 mm (poppy seed, all with more or less isometric shape. The burnout behavior of PFAs is studied by thermal analysis, i.e. thermogravimetry and differential thermal analysis. For the preparation of porous alumina ceramics from alumina suspensions containing PFAs traditional slip casting (into plaster molds and starch consolidation casting (using metal molds are used in this work. The resulting microstructures are investigated using optical microscopy, combined with image analysis, as well as other methods (Archimedes method of double-weighing in water, mercury intrusion porosimetry.

  16. Effect of aluminum silicate fiber modification on crack-resistance of a ceramic mould

    Directory of Open Access Journals (Sweden)

    Jiang Yehua

    2012-11-01

    Full Text Available To improve the crack-resistance of the mould for silica sol bonded quartz based ceramic mould casting, aluminum silicate fibers with the diameter ranging from 5 µm to 25 µm and the length about 1 mm were dispersed in the ceramic mould. The effect of the aluminum silicate fibers on the tensile strength, shrinkage rate and the cracking trend of the ceramic mould were investigated. In the ceramic slurry, quartz sand was applied as ceramic aggregate, silica sol containing 30% silicon dioxide as bonder, and the weight ratio of quartz sand to silica sol was 2.69; the dispersed fibers changed from 0 to 0.24vol.%. The mould samples were formed after the slurry was poured and gelled at room temperature, and then sintered at different temperatures ranging from 100 to 800 ℃ to measure the tensile strength and shrinkage rate. The results show that, with the aluminum silicate fiber addition increasing from 0 to 0.24vol.%, the tensile strength increases linearly from 0.175 MPa to 0.236 MPa, and the shrinkage rate decreases linearly from 1.75% to 1.68% for the ceramic mould sintered at 400 ℃, from 1.37% to 1.31% for the ceramic mould at room temperature. As the sintering temperature was raised from 100 ℃ to 800 ℃, the tensile strength increases, and the shrinkage rate decreases at all temperatures, compared with those without fiber dispersion, but their variation patterns remain the same. Furthermore, the cracking trend of the mould and its decreasing proportion were defined and analyzed quantitatively considering both effects of the fiber dispersion on the strength and shrinkage. The cracking trend appears to decrease linearly with increasing fiber content and to reach the maximum reduction of 28.8% when 0.24vol.% fiber was dispersed. Therefore, the investigation proposes a new method to improve the crack-resistance of the ceramic mould, i.e., inorganic fiber dispersion into the ceramic mould.

  17. Irradiation conditions for fiber laser bonding of HAp-glass ceramics with bovine cortical bone.

    Science.gov (United States)

    Tadano, Shigeru; Yamada, Satoshi; Kanaoka, Masaru

    2014-01-01

    Orthopedic implants are widely used to repair bones and to replace articulating joint surfaces. It is important to develop an instantaneous technique for the direct bonding of bone and implant materials. The aim of this study was to develop a technique for the laser bonding of bone with an implant material like ceramics. Ceramic specimens (10 mm diameter and 1 mm thickness) were sintered with hydroxyapatite and MgO-Al2O3-SiO2 glass powders mixed in 40:60 wt% proportions. A small hole was bored at the center of a ceramic specimen. The ceramic specimen was positioned onto a bovine bone specimen and a 5 mm diameter area of the ceramic specimen was irradiated using a fiber laser beam (1070-1080 nm wavelength). As a result, the bone and the ceramic specimens bonded strongly under the irradiation conditions of a 400 W laser power and a 1.0 s exposure time. The maximum shear strength was 5.3 ± 2.3 N. A bonding substance that penetrated deeply into the bone specimen was generated around the hole in the ceramic specimen. On using the fiber laser, the ceramic specimen instantaneously bonded to the bone specimen. Further, the irradiation conditions required for the bonding were investigated.

  18. [Exposure to ceramic fibers in the work environment. III. occupational exposure to ceramic fibers in plants which produce and apply insulation materials made of ceramic fibers].

    Science.gov (United States)

    Wojtczak, J; Kieć-Swierczyńska, M; Maciejewska, A

    1997-01-01

    The study was aimed at assessing the exposure to dust in the work environment of plants which produced and apply packing and insulation materials made of ceramic fibres. The study revealed that workers were exposed to dust containing respirable ceramic fibres and in some cases (production of packing cord, insulating tape and paperboard) respirable asbestos fibres. The mean concentration of respirable fibres ranged from 0.05 to 0.62 f/l cm3, and concentrations of total dust fell between 0.6 and 23.2 mg/m3. The mean concentrations of respirable fibres were usually below (0.5 f/l cm3 for respirable ceramic fibres with asbestos mixture; 1 f/cm3 for respirable ceramic fibres), and of total dust much higher (1 mg/m3 and 2 mg/m3, respectively) than MAC values proposed. The initial dermatological examinations (25 workers) allow the conclusion that contact with ceramic fibres induces in some workers acute dermatitis and dermal papilla.

  19. Preparation of long alumina fibers by sol-gel method using tartaric acid

    Science.gov (United States)

    Tan, Hong-Bin

    2011-12-01

    Long alumina fibers were prepared by sol-gel method. The spinning sol was obtained by mixing aluminum nitrate, tartaric acid, and polyvinylpyrrolidone with a mass ratio of 10:3:1.5. Thermogravimetry-differential scanning calorimetry (TG-DSC), Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to characterize the properties of the gel and ceramic fibers. A little of α-Al2O3 phase is observed in the alumina precursor gel fibers sintered at 1273 K. The fibers with a uniform diameter can be obtained when sintered at 1473 K, and its main phase is also indentified as α-Al2O3.

  20. Approach to microstructure-behavior relationships for ceramic matrix composites reinforced by continuous fibers

    Directory of Open Access Journals (Sweden)

    Lamon Jacques

    2015-01-01

    Full Text Available Ceramic matrix composites (CMCs reinforced with continuous fibers exhibit several features that differentiate them from homogeneous unreinforced materials. The microstructure consists of various distinct constituents: fibres, matrix, and fiber/matrix interfaces or interphases. Several entities at micro- and mesoscopic length scales can be defined depending on fiber arrangement. Furthermore, the CMCs contain flaw populations that govern matrix cracking and fiber failures. The paper describes the microstructure-behavior relations for ceramic matrix composites reinforced with continuous fibers. It focuses on matrix damage by multiple cracking, on ultimate fracture, on delayed fracture at high temperatures, and on stochastic features induced by flaw populations. Models of damage and ultimate failure are based on micromechanics and fracture probabilities. They provide a basis for a multiscale approach to composite and component design.

  1. Mechanical behavior and properties of fiber reinforced ceramic matrix composites for high temperature use

    Institute of Scientific and Technical Information of China (English)

    Chongdu Cho; Qiang Pan; Sangkyo Lee

    2007-01-01

    Ceramics can keep their mechanical characteristics up to 2 000℃ or higher.In this paper,A model to predict ultimate strength of continuous fiber-reinforced brittle matrix composites is developed.A statistical theory for the strength of a uni-axially fiber-reinforced brittle matrix composite is presented.Also a semi-empirical frictional heating method for estimating in-situ interfacial shear in fiber-reinforced ceramic matrix composites was improved.Local uneven fiber packing variation as well as uneven micro-damage during fatigue can be expected to have effects on the composites:generation of frictional heating,thermal gradients,and residual stresses around local fiber breaks.This study examined those engineering interests by the finite element method.

  2. Fatigue Life Prediction of Fiber-Reinforced Ceramic-Matrix Composites with Different Fiber Preforms at Room and Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Longbiao Li

    2016-03-01

    Full Text Available In this paper, the fatigue life of fiber-reinforced ceramic-matrix composites (CMCs with different fiber preforms, i.e., unidirectional, cross-ply, 2D (two dimensional, 2.5D and 3D CMCs at room and elevated temperatures in air and oxidative environments, has been predicted using the micromechanics approach. An effective coefficient of the fiber volume fraction along the loading direction (ECFL was introduced to describe the fiber architecture of preforms. The statistical matrix multicracking model and fracture mechanics interface debonding criterion were used to determine the matrix crack spacing and interface debonded length. Under cyclic fatigue loading, the fiber broken fraction was determined by combining the interface wear model and fiber statistical failure model at room temperature, and interface/fiber oxidation model, interface wear model and fiber statistical failure model at elevated temperatures, based on the assumption that the fiber strength is subjected to two-parameter Weibull distribution and the load carried by broken and intact fibers satisfies the Global Load Sharing (GLS criterion. When the broken fiber fraction approaches the critical value, the composites fatigue fracture.

  3. Static tensile and tensile creep testing of four boron nitride coated ceramic fibers at elevated temperatures

    Science.gov (United States)

    Coguill, Scott L.; Adams, Donald F.; Zimmerman, Richard S.

    1989-01-01

    Six types of uncoated ceramic fibers were static tensile and tensile creep tested at various elevated temperatures. Three types of boron nitride coated fibers were also tested. Room temperature static tensile tests were initially performed on all fibers, at gage lengths of 1, 2, and 4 inches, to determine the magnitude of end effects from the gripping system used. Tests at one elevated temperature, at gage lengths of 8 and 10 inches, were also conducted, to determine end effects at elevated temperatures. Fiber cross sectional shapes and areas were determined using scanning electron microscopy. Creep testing was typically performed for 4 hours, in an air atmosphere.

  4. Fiber Optic Cable Thermal Preparation to Ensure Stable Operation

    Science.gov (United States)

    Thoames Jr, William J.; Chuska, Rick F.; LaRocca, Frank V.; Switzer, Robert C.; Macmurphy, Shawn L.; Ott, Melanie N.

    2008-01-01

    Fiber optic cables are widely used in modern systems that must provide stable operation during exposure to changing environmental conditions. For example, a fiber optic cable on a satellite may have to reliably function over a temperature range of -50 C up to 125 C. While the system requirements for a particular application will dictate the exact method by which the fibers should be prepared, this work will examine multiple ruggedized fibers prepared in different fashions and subjected to thermal qualification testing. The data show that if properly conditioned the fiber cables can provide stable operation, but if done incorrectly, they will have large fluctuations in transmission.

  5. Glass-ceramic optical fiber containing Ba2TiSi2O8 nanocrystals for frequency conversion of lasers

    Science.gov (United States)

    Fang, Zaijin; Xiao, Xusheng; Wang, Xin; Ma, Zhijun; Lewis, Elfed; Farrell, Gerald; Wang, Pengfei; Ren, Jing; Guo, Haitao; Qiu, Jianrong

    2017-01-01

    A glass-ceramic optical fiber containing Ba2TiSi2O8 nanocrystals fabricated using a novel combination of the melt-in-tube method and successive heat treatment is reported for the first time. For the melt-in-tube method, fibers act as a precursor at the drawing temperature for which the cladding glass is softened while the core glass is melted. It is demonstrated experimentally that following heat treatment, Ba2TiSi2O8 nanocrystals with diameters below 10 nm are evenly distributed throughout the fiber core. Comparing to the conventional rod-in-tube method, the melt-in-tube method is superior in terms of controllability of crystallization to allow for the fabrication of low loss glass-ceramic fibers. When irradiated using a 1030 nm femtosecond laser, an enhanced green emission at a wavelength of 515 nm is observed in the glass-ceramic fiber, which demonstrates second harmonic generation of a laser action in the fabricated glass-ceramic fibers. Therefore, this new glass-ceramic fiber not only provides a highly promising development for frequency conversion of lasers in all optical fiber based networks, but the melt-in-tube fabrication method also offers excellent opportunities for fabricating a wide range of novel glass-ceramic optical fibers for multiple future applications including fiber telecommunications and lasers. PMID:28358045

  6. [Refractory ceramic fibers, kinds, health effects after exposure, TLVs].

    Science.gov (United States)

    Woźniak, H; Wiecek, E

    1996-01-01

    Ceramic fibres are amorphous or crystalline synthetic mineral fibres which are characterised by refractory properties (i.c. stability in temperature above 1000 degrees C). In general, ceramic fibres are produced from aluminium oxide, silicon oxide and other metal oxides and less frequently from non-oxide materials such as silicon carbide, silicon nitride and boron nitride. In Poland, the production of ceramic fibres was begun in the Refractory Materials Plant, Skawina, during mid-eighties. The production capacity accounts for about 600 tons annually. It is estimated that approximately 3000 persons are exposed to the effect of ceramic fibres in Poland. During the production of ceramic fibres, concentrations of respiral fibres in the air at work places range from 0.07 to 0.27 f/cm3; during the manufacture of ceramic fibre products from 0.23 to 0.71 f/cm3 and during the application of ceramic fibre products from 0.07 to 1.67 f/cm3. As published data depict, fibres longer than 5 microns are most common in the work environment, and the proportion of fibres with diameters below 1 micron accounts for 40-50%. Bearing in mind the present situation in Poland, namely combined exposure to asbestos (during removal of worn out heat-insulating materials) and ceramic fibres (during installation of new insulation), as well as in view of own investigations and literature data which evidence a strong carcinogenic effect of certain fibres, the following MAC values have been adopted: Dusts of refractory ceramic fibres: total dust-2 mg/m3; respirable fibres-1 f/cm3 (L > 5 microns; D fibres mixed with asbestos: total dust-1 mg/m3; respirable fibres-1 f/m3. Dusts of refractory ceramic fibres mixed with other man-made mineral fibres (MMMF): total dust-2 mg/m3; respirable fibres-1 f/m3. According to the IARC, ceramic fibres have been included into group 2B-suspected human carcinogen.

  7. Thermomechanical Performance of Si-Ti-C-O and Sintered SiC Fiber-Bonded Ceramics at High Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Matsunaga, Tadashi [ORNL; Lin, Hua-Tay [ORNL; Singh, Mrityunjay [NASA-Glenn Research Center, Cleveland; Kajii, Shinji [Ube Industries, Ltd.; Matsunaga, Kenji [Ube Industries, Ltd.; Ishikawa, Toshihiro [Ube Industries, Ltd.

    2011-01-01

    The stress-temperature-lifetime response of Si-Ti-C-O fiber-bonded ceramic (Tyrannohex ) and sintered SiC fiber-bonded ceramic (SA-Tyrannohex ) materials were investigated in air from 500 to 1150 C and 500 to 1400 C, respectively. The apparent threshold stress of Si-Ti-C-O fiber-bonded ceramic was about 175 MPa in the 500-1150 C temperature range. When the applied stress of the sintered SiC fiber-bonded ceramic was below an apparent threshold stress (e.g., ~225MPa) for tests conducted 1150 C, no failures were observed for lifetimes up to 1000h. In the case of sintered SiC fiber-bonded ceramic, at the temperature of 1300 C, the apparent threshold stress decreased to 175 MPa. The decrease in strength seemed to be caused by grain growth which was confirmed from the SEM fractography. Both fiber-bonded ceramics exhibited much higher durability than a commercial SiC/SiC composite at temperatures above 500 C. In addition, results suggested that the sintered SiC fiber-bonded ceramic (SA-Tyrannohex) is more stable than a Hi-Nicalon/MI SiC composite with BN/SiC fiber coating at temperatures above 1300 C.

  8. Preparation and Microstructure of Glass-ceramics and Ceramic Composite Materials

    Institute of Scientific and Technical Information of China (English)

    HE Feng; XIE Junlin; HAN Da

    2008-01-01

    The technology and microstructure of glass-ceramics and ceramic composite materials were studied.A suitable ceramic body was chosen on the basis of the sintering temperature of CaO-Al2O3-SiO2 system glass-ceramics.According to the expansion coefficient of the ceramic body,that of CaO-Al2O3-SiO2 system glass-ceramics was adjusted.a-wollastonite was found present as the major crystalline phase in glass-ceramic.The CaO-Al2O3-SiO2 system glass-ceramic layer and ceramic body could be sintered together by adjusting the sintering period.The compositions of glass-ceramic layer and ceramic body diffuse mutually at 1100℃.resulting in an interface between them.To achieve good sintered properties of glass-ceramics and the chosen ceramic body,at least a four-hour sintering time is used.

  9. PREPARATION AND CATALYTIC ACTIVITY OF BIOACTIVE FIBERS

    Institute of Scientific and Technical Information of China (English)

    Yu-yuan Yao; Wen-xing Chen; Bao-yan Zhao; Shen-shui Lü

    2006-01-01

    Two kinds of water-soluble metallophthalocyanines, binuclear cobalt phthalocyanine (Co2Pc2) and binuclear ferric phthalocyanine (Fe2Pc2), were synthesized through phenylanhydride-urea route and characterized by elemental analysis and FT-IR spectra. Binuclear metallophthalocyanine derivatives (Mt2Pc2) were immobilized on silk fibers and modified viscose fibers to construct bioactive fibers of mimic enzyme. Mt2Pc2 was used as the active center ofbioactive fibers, viscose and silk fibers as the microenvironments. The catalytic oxidation ability of bioactive fibers on the malodors of methanthiol and hydrogen sulfide was investigated at room temperature. The experimental results indicated that the catalytic activity of such bioactive fibers was closely correlative to the types ofbioactive fibers and substrates.

  10. [The biological effect of fireproof ceramic fibers--literature review].

    Science.gov (United States)

    Krajnow, A

    1996-01-01

    The work presents reports, selected from the world literature, on the studies of biological effect of refractory ceramic fibres, carried out on experimental animals. The discrepancy between the results of studies performed may originate from differences in the distribution of fibre sizes or the durability of fibres in the organism and their surface properties which, in turn, depend on the chemical composition of fibres. In all studies discussed, ceramic fibres generally activated macrophages and they were characterised by a moderate fibrotic activity. A statistically significant increase in the incidence of tumor (mesothelioma) observed in several very important experimental studies may suggest that some types of refractory ceramic fibres show a similar carcinogenic potential to that of natural asbestos: crocidolite or chrysotile.

  11. Innovative fiber coating systems based on organic modified ceramics

    Science.gov (United States)

    Schuster, Kay; Kobelke, Jens; Rose, Klaus; Helbig, Manfred; Zoheidi, Mohammad; Heinze, Alexander

    2010-02-01

    We describe the application of inorganic organic hybrid materials (ORMOCERs) as optical fiber coatings for use in Fiber Bragg Grating sensors and high power transmission fibers. The materials are UV curable, enable a single layer thickness of about 50 μm and show high a high peak temperature stability >300 °C. Regarding the fiber protection the coatings have been investigated using tensile strength measurements before and after temperature load. Best coatings maintain the high tensile strength of 68 N (125 μm fiber) with a Weibull parameter of 182 after a temperature cycling up to 300 °C. For the first time a low refractive index ORMOCER will be presented showing a numerical aperture of 0.47 at a wavelength of 1000 nm on a pure silica fiber. This corresponds to a refractive index of 1.37. The fiber possesses a fiber loss of 18 dB/km at a wavelength of 1000 nm. The fibers have been coated using a gravity as well as pressure technology. The latter possesses extremely minimized die equipment and is therefore well applicable for small coating amounts. The so called dead volume within the coating die is about 1 ml. The overall dead volume is only influenced by the supply pipe and can be reduced down to 5 ml.

  12. Recent advancements in transparent ceramics and crystal fibers for high power lasers

    Science.gov (United States)

    Kim, W.; Baker, C.; Villalobos, G.; Florea, C.; Gibson, D.; Shaw, L. B.; Bowman, S.; Bayya, S.; Sadowski, B.; Hunt, M.; Askins, C.; Peele, J.; Aggarwal, I. D.; Sanghera, J. S.

    2013-05-01

    In this paper, we present our recent progress in the development of rare-earth (Yb3+ or Ho3+) doped Lu2O3 and Y2O3 sesquioxides for high power solid state lasers. We have fabricated high quality transparent ceramics using nano-powders synthesized by a co-precipitation method. This was accomplished by developments in high purity powder synthesis and low temperature scalable sintering technology developed at NRL. The optical, spectral and morphological properties as well as the lasing performance from our highly transparent ceramics are presented. In the second part of the paper, we discuss our recent research effort in developing cladded-single crystal fibers for high power single frequency fiber lasers has the potential to significantly exceed the capabilities of existing silica fiber based lasers. Single crystal fiber cores with diameters as small as 35μm have been drawn using high purity rare earth doped ceramic or single crystal feed rods by the Laser Heated Pedestal Growth (LHPG) process. Our recent results on the development of suitable claddings on the crystal fiber core are discussed.

  13. Thermal Protection of Carbon Fiber-Reinforced Composites by Ceramic Particles

    Directory of Open Access Journals (Sweden)

    Baljinder Kandola

    2016-06-01

    Full Text Available The thermal barrier efficiency of two types of ceramic particle, glass flakes and aluminum titanate, dispersed on the surface of carbon-fiber epoxy composites, has been evaluated using a cone calorimeter at 35 and 50 kW/m2, in addition to temperature gradients through the samples’ thicknesses, measured by inserting thermocouples on the exposed and back surfaces during the cone tests. Two techniques of dispersing ceramic particles on the surface have been employed, one where particles were dispersed on semi-cured laminate and the other where their dispersion in a phenolic resin was applied on the laminate surface, using the same method as used previously for glass fiber composites. The morphology and durability of the coatings to water absorption, peeling, impact and flexural tension were also studied and compared with those previously reported for glass-fiber epoxy composites. With both methods, uniform coatings could be achieved, which were durable to peeling or water absorption with a minimal adverse effect on the mechanical properties of composites. While all these properties were comparable to those previously observed for glass fiber composites, the ceramic particles have seen to be more effective on this less flammable, carbon fiber composite substrate.

  14. Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor Deposition

    CERN Document Server

    Blanc, Wilfried; Nguyen, Luan; Bhaktha, S N B; Sebbah, Patrick; Pal, Bishnu P; Dussardier, Bernard

    2011-01-01

    Rare earth (RE) doped silica-based optical fibers with transparent glass ceramic (TGC) core was fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of post-ceramming. The main characteristics of the RE-doped oxyde nanoparticles namely, their density and mean diameter in the fibers are dictated by the concentration of alkaline earth element used as phase separating agent. Magnesium and erbium co-doped fibers were fabricated. Optical transmission in term of loss due to scattering as well as some spectroscopic characteristics of the erbium ions was studied. For low Mg content, nano-scale particles could be grown with and relatively low scattering losses were obtained, whereas large Mg-content causes the growth of larger particles resulting in much higher loss. However in the latter case, certain interesting alteration of the spectroscopic properties of the erbium ions were observed. These initial studies should be useful in incorporati...

  15. Specific-heat measurement of single metallic, carbon, and ceramic fibers at very high temperature

    Science.gov (United States)

    Pradère, C.; Goyhénèche, J. M.; Batsale, J. C.; Dilhaire, S.; Pailler, R.

    2005-06-01

    The main objective of this work is to present a method for measuring the specific heat of single metallic, carbon, and ceramic fibers at very high temperature. The difficulty of the measurement is due to the microscale of the fiber (≈10μm) and the important range of temperature (700-2700K). An experimental device, a modelization of the thermal behavior, and an analytic model have been developed. A discussion on the measurement accuracy yields a global uncertainty lower than 10%. The characterization of a tungsten filament with thermal properties identical to those of the bulk allows the validation of the device and the thermal estimation method. Finally, measurements on carbon and ceramic fibers have been done at very high temperature.

  16. Modelling and analysis of CVD processes in porous media for ceramic composite preparation

    NARCIS (Netherlands)

    Lin, Y.S.; Burggraaf, A.J.

    1991-01-01

    A continuum phenomenological model is presented to describe chemical vapour deposition (CVD) of solid product inside porous substrate media for the preparation of reinforced ceramic-matrix composites [by the chemical vapour infiltration (CVI) process] and ceramic membrane composites (by a modified C

  17. Preparation of hybrid scaffold from fibrin and biodegradable polymer fiber.

    Science.gov (United States)

    Hokugo, Akishige; Takamoto, Tomoaki; Tabata, Yasuhiko

    2006-01-01

    A biodegradable hybrid scaffold was prepared from fibrin and poly(glycolic acid) (PGA) fiber. Mixed fibrinogen and thrombin solution homogeneously dispersed in the presence of various amounts (0, 1.5, 3.0, and 6.0mg) of PGA fiber was freeze-dried to obtain fibrin sponges with or without PGA fiber incorporation. By scanning electron microscopy observation, the fibrin sponges had an interconnected pore structure, irrespective of the amount of PGA fiber incorporated. PGA fiber incorporation enabled the fibrin sponges to significantly enhance their compression strength. In vitro cell culture studies revealed that the number of L929 fibroblasts initially attached was significantly larger for any fibrin sponge with PGA fiber incorporation than for the fibrin sponge without PGA fiber. The shrinkage of sponges after cell seeding was suppressed by fiber incorporation. It is possible that the shrinkage suppression of sponges maintains their intraspace, resulting in the superior cell attachment of a sponge with PGA fiber incorporation. After subcutaneous implantation into the backs of mice, the residual volume of a fibrin sponge with PGA fiber incorporation was significant compared with that of a fibrin sponge without PGA fiber. Larger number of cells infiltrated deep inside the fibrin sponges with PGA fiber incorporation implanted subcutaneously. It is concluded that the fibrin sponge reinforced by fiber incorporation is a promising three-dimensional scaffold of cells for tissue engineering.

  18. Processing and properties of textured potassium strontium niobate (KSr2Nb5O15) ceramic fibers--effect of texture on the electrical properties.

    Science.gov (United States)

    Alkoy, Sedat; Dursun, Sinan

    2013-10-01

    Textured ceramic fibers were fabricated from the tungsten-bronze-type piezoelectric (KSr2Nb5O15) . Development of crystallographic texture was evaluated through rocking curve analysis and a texture with Lotgering factor of 0.97 was achieved. 1-3 piezocomposites were prepared from the textured fibers and their electrical properties were evaluated. Highly enhanced properties that are 2 to 3 times higher than the random case were observed with increasing texture fraction with P(r) and d33 reaching 20 μC/cm(2) and 75 pC/N, respectively.

  19. Static tensile and tensile creep testing of five ceramic fibers at elevated temperatures

    Science.gov (United States)

    Zimmerman, Richard S.; Adams, Donald F.

    1989-01-01

    Static tensile and tensile creep testing of five ceramic fibers at elevated temperature was performed. J.P. Stevens, Co., Astroquartz 9288 glass fiber; Nippon Carbon, Ltd., (Dow Corning) nicalon NLM-102 silicon carbide fiber; and 3M Company Nextel 312, 380, and 480 alumina/silica/boria fibers were supplied in unsized tows. Single fibers were separated from the tows and tested in static tension and tensile creep. Elevated test temperatures ranged from 400 C to 1300 C and varied for each fiber. Room temperature static tension was also performed. Computer software was written to reduce all single fiber test data into engineering constants using ASTM Standard Test Method D3379-75 as a reference. A high temperature furnace was designed and built to perform the single fiber elevated temperature testing up to 1300 C. A computerized single fiber creep apparatus was designed and constructed to perform four fiber creep tests simultaneously at temperatures up to 1300 C. Computer software was written to acquire and reduce all creep data.

  20. Modeling of the mechanical behavior of fiber-reinforced ceramic composites using finite element method (FEM

    Directory of Open Access Journals (Sweden)

    Dimitrijević M.M.

    2014-01-01

    Full Text Available Modeling of the mechanical behavior of fiber-reinforced ceramic matrix composites (CMC is presented by the example of Al2O3 fibers in an alumina based matrix. The starting point of the modeling is a substructure (elementary cell which includes on a micromechanical scale the statistical properties of the fiber, matrix and fiber-matrix interface and their interactions. The numerical evaluation of the model is accomplished by means of the finite element method. The numerical results of calculating the elastic modulus of the composite dependance on the quantity of the fibers added and porosity was compared to experimental values of specimens having the same composition. [Projekat Ministarstva nauke Republike Srbije, br. ON174004 i TVH to project III45012

  1. Composites (CFCCs) for low cost energy and cleaner environment. Continuous fiber ceramic composites program

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-01

    For many industrial applications, materials are desired which combine light weight, high temperature strength, and stability in corrosive environments. Among competing materials, ceramics are noteworthy candidates for such applications. The use of ceramics is often constrained, however, by brittleness; i.e., low toughness. Ceramic composites are being developed to overcome this limitation. With recent advances in ceramic fiber technology, it is possible to design a composite material based on continuous ceramic fibers embedded in a ceramic matrix. The use of ceramic composites in industrial applications will result in reduced fuel consumption, but will also prevent airborne pollution (principally NO, SO{sub x}, CO{sub 2}, and particulates), and economically benefit the end user through energy and environmental savings and increased competitiveness. Industry will also benefit through increased productivity and consumers will benefit through lower energy and environmental costs and a cleaner environment. The development and use of CFCCs could become an important factor in the international competitiveness of U.S. industry. CFCCs will be a critical enabling material in the design and engineering of advanced components, systems, and processes. If CFCC technology is developed outside the United States, domestic users of these materials may be forced to rely on foreign suppliers of the products fabricated from CFCCs, as well as the materials themselves. Foreign countries, including Japan and France, have embarked on government-supported CFCC development efforts. With the market for CFCC products expected to be a $10 billion dollar market by 2010, CFCC development will be important for the competitiveness of U.S. industry and for retaining and creating jobs for U.S. citizens. This document summarizes the potential energy, environmental, and economic benefits that CFCCs will have for the U.S. economy and particularly for the industrial sector.

  2. Sonogels in the Preparation of Advanced Glass and Ceramic Materials

    Science.gov (United States)

    1992-10-20

    1 In0 f 7;ra Products) ceramic fibres . -using other yreinforcing phases in the. form of 7’T02 (7YF- 100 ,Zircar Products) and A1203 (MAFTEC) ceramic...usd we -r, made friom ceramic fibres . In both cases t ,- fi bris were I anrgel y continuous and random], oriented in p1lanes parallel Io tahe layers...gives the relative densities for the CT15 ’ A1203 composites . They are designated as CT15Av , where y is the volume fract ion of alt]mina ceramic

  3. Composite polysaccharide fibers prepared by electrospinning and coating

    OpenAIRE

    2013-01-01

    Composite polysaccharide fibers composed two oppositely charged natural polysaccharides, chitosan and hyaluronic acid, were prepared by electrospinning and subsequent coating The fiber size distribution was characterized by scanning electron microscopy. Chitosan/hyaluronic acid composite fibers were stable in water but showed controlled release of hyaluronic acid into phosphate buffered saline, and the presence of 3-wt% hyaluronic acid coating improved the swelling ratio to 30%. The resulting...

  4. The microstructure of erbium-ytterbium co-doped oxyfluoride glass-ceramic optical fibers

    Science.gov (United States)

    Augustyn, Elżbieta; Żelechower, Michał; Stróż, Danuta; Chrapoński, Jacek

    2012-04-01

    Oxyfluoride transparent glass-ceramics combine some features of glasses (easier shaping or lower than single crystals cost of fabrication) and some advantages of rare-earth doped single crystals (narrow absorption/emission lines and longer lifetimes of luminescent levels). Since the material seems to be promising candidate for efficient fiber amplifiers, the manufacturing as well as structural and optical examination of the oxyfluoride glass-ceramic fibers doped with rare-earth ions seems to be a serious challenge. In the first stage oxyfluoride glasses of the following compositions 48SiO2-11Al2O3-7Na2CO3-10CaO-10PbO-11PbF2-3ErF3 and 48SiO2-11Al2O3-7Na2CO3-10CaO-10PbO-10PbF2-3YbF3-1ErF3 (in molar%) were fabricated from high purity commercial chemicals (Sigma-Aldrich). The fabricated glass preforms were drawn into glass fibers using the mini-tower. Finally, the transparent Er3+ doped and Er3+/Yb3+ co-doped oxyfluoride glass-ceramic fibers were obtained by controlled heat treatment of glass fibers. The preceding differential thermal analysis (DTA) studies allowed estimating both the fiber drawing temperature and the controlled crystallization temperature of glass fibers. X-ray diffraction examination (XRD) at each stage of the glass-ceramic fibers fabrication confirmed the undesirable crystallization of preforms and glass fibers has been avoided. The fibers shown their mixed amorphous-crystalline microstructure with nano-crystals of size even below 10 nm distributed in the glassy host. The crystal structure of the grown nano-crystals has been determined by XRD and confirmed by electron diffraction (SAED). Results obtained by both techniques seem to be compatible: Er3FO10Si3 (monoclinic; ICSD 92512), Pb5Al3F19 (triclinic; ICSD 91325) and Er4F2O11Si3 (triclinic; ICSD 51510) against to initially expected PbF2 crystals.

  5. Optimization of dispersing agents for preparing YAG transparent ceramics

    Institute of Scientific and Technical Information of China (English)

    BA Xuewei; LI Jiang; PAN Yubai; LIU Jing; JIANG Benxue; LIU Wenbin; KOU Huamin

    2013-01-01

    The suspensions of the powder mixture of yttria and alumina were prepared by the aqueous tape casting method.Rodia DP270,Dolapix CE64,citric acid and Dammonium 3008 were used as dispersing agents.The morphologies of the powders and the fiacture surface of the green body were observed by scanning electron microscopy (SEM).The zeta potential test was employed to characterize the surface charge states of different suspensions.The dispersion of the suspensions was analyzed by the rheological tests and the sedimentation experiments.The results indicated that the yttria and alumina powder mixtures were well dispersed by the dispersing agents.The rheological curves showed shear thinning behavior.The most efficient dispersing agent was Dammonium 3008.The optimum usage of Dammonium 3008 was 1.0 wt.%.The green body was dense and no interface between the adjacent layers was found.The in-line transmittance of the as-sintered YAG ceramic was higher than 80% between 400 and 1100 nm.

  6. Preparation and characterization of the porous ceramics from fly ash

    Institute of Scientific and Technical Information of China (English)

    REN Xiang-jun; ZHANG Xue-bin; MENG Guang-yao; LIU Xing-qin

    2007-01-01

    Porous ceramics was made from coal fly ash,and the microstructure and other properties were characterized as a function of the amount of the pore-forming agent and firing temperature.The results indicated that the proper sintering temperature for the useful ceramic materials is 1250 ℃.and a liquid-phase was involved in the dansification process.

  7. Composite polysaccharide fibers prepared by electrospinning and coating.

    Science.gov (United States)

    Maeda, N; Miao, J; Simmons, T J; Dordick, J S; Linhardt, R J

    2014-02-15

    Composite polysaccharide fibers composed two oppositely charged natural polysaccharides, chitosan and hyaluronic acid, were prepared by electrospinning and subsequent coating. The fiber size distribution was characterized by scanning electron microscopy. Chitosan/hyaluronic acid composite fibers were stable in water but showed controlled release of hyaluronic acid into phosphate buffered saline, and the presence of 3-wt% hyaluronic acid coating improved the swelling ratio to 30%. The resulting composite polysaccharide fibers have a number of potential biomedical applications in wound healing applications and in drug delivery systems.

  8. A CHEMICAL PROCESS FOR PREPARING CELLULOSIC FIBERS HIERARCHICALLY FROM KENAF BAST FIBERS

    Directory of Open Access Journals (Sweden)

    Jinshu Shi

    2011-02-01

    Full Text Available The objective of this research was to evaluate an all-chemical process to prepare nano-scale to macro-scale cellulosic fibers from kenaf bast fibers, for polymer composite reinforcement. The procedure used in this all-chemical process included alkaline retting to obtain single cellulosic retted fiber, bleaching treatment to obtain delignified bleached fiber, and acidic hydrolysis to obtain both pure-cellulose microfiber and cellulose nanowhisker (CNW. At each step of this chemical process, the resultant fibers were characterized for crystallinity using X-ray diffraction (XRD, for functional groups using the Fourier Transform Infrared spectroscopy (FTIR, and for surface morphology using both the scanning electron microscopy (SEM and transmission electron microscopy (TEM. The chemical components of the different scale fibers were analyzed. Based on the raw kenaf bast fibers, the yields of retted fibers and bleached fibers were 44.6% and 41.4%. The yield of the pure cellulose microfibers was 26.3%. The yield of CNWs was 10.4%, where about 22.6% α-cellulose had been converted into CNWs. The fiber crystallinity increased as the scale of the fiber decreased, from 49.9% (retted single fibers to 83.9% (CNWs. The CNWs had fiber lengths of 100 nm to 1400 nm, diameters of 7 to 84 nm, and aspect ratios of 10 to 50. The incorporation of 9% (wt% CNWs in polyvinyl alcohol (PVA composites increased the tensile strength by 46%.

  9. Facility for continuous CVD coating of ceramic fibers

    Science.gov (United States)

    Moore, Arthur W.

    1992-01-01

    An inductively heated CVD furnace of pilot-plant scale, whose hot zone is 150 mm in diameter x 300 mm in length, has been adapted for continuous coating of ceramic yarns. Coatings at very low pressures are possible in this facility due to the fact that the entire apparatus, including yarn feeding and collecting equipment, is under vacuum. SiC yarn has been coated with 0.1-0.2 microns of BN at yarn speeds of 60 cm/min; a 500-m spool; was coated in about 14 hrs. Coating capacity was tripled by adding pulleys to allow three yarn passes through the furnace.

  10. Characterization on C/SiC Ceramic Matrix Composites with Novel Fiber Coatings

    Science.gov (United States)

    Petko, Jeanne; Kiser, J. Douglas; McCue, Terry; Verrilli, Michael

    2002-01-01

    Ceramic Matrix Composites (CMCs) are attractive candidate materials in the aerospace industry due to their high specific strength, low density and higher temperature capabilities. The National Aeronautics and Space Administration (NASA) is pursuing the use of CMC components in advanced Reusable Launch Vehicle (RLV) propulsion applications. Carbon fiber-reinforced silicon carbide (C/SiC) is the primary material of interest for a variety of RLV propulsion applications. These composites offer high- strength carbon fibers and a high modulus, oxidation-resistant matrix. For comparison, two types of carbon fibers were processed with novel types of interface coatings (multilayer and pseudoporous). For RLV propulsion applications, environmental durability will be critical. The coatings show promise of protecting the carbon fibers from the oxidizing environment. The strengths and microstructures of these composite materials are presented.

  11. Clearance of refractory ceramic fibers (RCF) from the rat lung: development of a model.

    Science.gov (United States)

    Yu, C P; Zhang, L; Oberdörster, G; Mast, R W; Glass, L R; Utell, M J

    1994-05-01

    Chronic exposure and postexposure experiments have been recently performed in rats to evaluate the biological responses of inhaled refractory ceramic fibers (RCF) at different concentration levels. The lung burden data in the accessory lobe of the rat lung were collected during and after different exposure and postexposure periods. The size distribution of retained fibers in the lung at different time points was also measured. We used these data to develop a mathematical model of fiber clearance from the rat lung. It was found that the clearance rate did not depend significantly upon fiber size but there was a clear dependence on lung burden. As lung burden increased, the clearance rate was found to decrease. An empirical equation was derived for the clearance rate as a function of lung burden. At low burdens, rats had a retention half-time of about 126 days for RCF compared to a typical half-time of about 60 days for insoluble nonfibrous particles.

  12. A multiyear workplace-monitoring program for refractory ceramic fibers: findings and conclusions.

    Science.gov (United States)

    Maxim, L D; Allshouse, J N; Kelly, W P; Walters, T; Waugh, R

    1997-10-01

    Results of a monitoring program carried out by members of the Refractory Ceramic Fibers Coalition as part of a Consent Agreement with the U.S. Environmental Protection Agency to measure workplace concentrations of refractory ceramic fiber (RCF) are presented. More than 700 personal monitoring samples were collected and analyzed annually from workers in RCF production and processing plants, as well as from those employed by customers/end users. The data indicate that (i) approximately 90% of time-weighted average (TWA) workplace concentrations are below the industry's recommended exposure guideline of 1 fiber per cubic centimeter TWA; (ii) workplace concentrations vary with functional job category; (iii) concentrations are approximately lognormally distributed; (iv) workplace concentrations are generally decreasing; (v) there are significant differences in workplace concentrations among plants operated by both RCF producers and customers; (vi) equations can be developed to interconvert data analyzed using different measurement techniques and counting rules; (vii) usage of respirators varies with the functional job category of the worker and the average fiber concentration; and (viii) workplace samples differ from those used in animal inhalation experiments in terms of the ratio of respirable particles to fibers.

  13. Sodium sulfate corrosion of silicon carbide fiber-reinforced lithium aluminosilicate glass-ceramic matrix composites

    OpenAIRE

    1993-01-01

    Approved for public release; distribution is unlimited. Sodium sulfate hot corrosion of a SiC fiber-reinforced lithium aluminosilicate (LAS) glass-ceramic matrix composite was studied using Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD). Changes in the microstructural chemical composition of the specimens were investigated. The samples provided by Naval Air Warfare Center (NAWC), Warminster, PA were grouped as follows: (1) as-received, (2) Na2SO4 salt-coated and heat-treate...

  14. Creep performance of oxide ceramic fiber materials at elevated temperature in air and in steam

    Science.gov (United States)

    Armani, Clinton J.

    Structural aerospace components that operate in severe conditions, such as extreme temperatures and detrimental environments, require structural materials that have superior long-term mechanical properties and that are thermochemically stable over a broad range of service temperatures and environments. Ceramic matrix composites (CMCs) capable of excellent mechanical performance in harsh environments are prime candidates for such applications. Oxide ceramic materials have been used as constituents in CMCs. However, recent studies have shown that high-temperature mechanical performance of oxide-oxide CMCs deteriorate in a steam-rich environment. The degradation of strength at elevated temperature in steam has been attributed to the environmentally assisted subcritical crack growth in the oxide fibers. Furthermore, oxide-oxide CMCs have shown significant increases in steady-state creep rates in steam. The present research investigated the effects of steam on the high-temperature creep and monotonic tension performance of several oxide ceramic materials. Experimental facilities were designed and configured, and experimental methods were developed to explore the influence of steam on the mechanical behaviors of ceramic fiber tows and of ceramic bulk materials under temperatures in the 1100--1300°C range. The effects of steam on creep behavior of Nextel(TM)610 and Nextel(TM)720 fiber tows were examined. Creep rates at elevated temperatures in air and in steam were obtained for both types of fibers. Relationships between creep rates and applied stresses were modeled and underlying creep mechanisms were identified. For both types of fiber tows, a creep life prediction analysis was performed using linear elastic fracture mechanics and a power-law crack velocity model. These results have not been previously reported and have critical design implications for CMC components operating in steam or near the recommended design limits. Predictions were assessed and validated via

  15. Creep Behavior and Mechanism for CMCs with Continuous Ceramic Fibers

    Science.gov (United States)

    Chermant, Jean-Louis; Farizy, Gaëlle; Boitier, Guillaume; Darzens, Séverine; Vicens, Jean; Sangleboeuf, Jean-Christophe

    This paper gives an overview on the creep behavior and mechanism of some CMCs, with a SiC ceramic matrix, such as Cf-SiC, SiCf-SiC and SiCf-SiBC. Tensile creep tests were conducted under argon and air in order to have the influence of the environmental conditions on the macroscopical mechanical response. Nevertheless, multi-scale and multi-technique approaches were required to identify and quantify mechanism(s) which is (are) involved in the creep behavior. The initiation and propagation of damages which are occurring under high stress and temperature conditions were investigated at mesoscopic, microscopic and nanoscopic scales using SEM, TEM and HREM, in order to identify the mechanism(s) involved at each scale. Automatic image analysis was used in order to quantify the evolution of some damage morphological parameters. The macroscopical creep behavior has been investigated through a damage mechanics approach which seems to be the most promising route. A good correlation was found between the kinetics of the damage mechanisms and the creep behavior. For such ceramic matrix composites, the governing mechanism is a damage-creep one, with an additional delay effect due to formation of a glass when tests are performed under air.

  16. Comparative investigation of creep behavior of ceramic fiber-reinforced alumina and silica aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaoguang; Wei, Jing [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China); Shi, Duoqi, E-mail: shdq@buaa.edu.cn [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China); Sun, Yantao; Lv, Shuangqi [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China); Feng, Jian; Jiang, Yonggang [National Key Laboratory of Science and Technology on Advanced Ceramic Fibers and Composites, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2014-07-15

    Ambient and high temperature creep experiments at constant stresses of 0.05 MPa and 0.2 MPa were conducted on a ceramic fiber-reinforced alumina aerogel. Experimental results show that at low temperature (below 300 °C), there is no significant creep phenomenon at low stress level (0.05 MPa), but time-dependent creep deformation is found at high stress level (0.2 MPa) for the material. Scanning Electron Microscope (SEM) analysis was also conducted to understand the micro mechanism of the creep behavior. Crack initiation and propagation in matrix are the key factors that change the creep property. Comparative investigation of creep properties was also carried out between ceramic fiber-reinforced alumina and silica aerogel. Finally the application prospect of the two composites was discussed. The result shows that alumina aerogel has excellent creep resistance, thermal stability and heat insulation properties at high temperature (above 800 °C), and it has a good application prospect in high temperature insulation fields, while the ceramic fiber-reinforced silica aerogel, limited by the sintering and poor creep resistance under high temperature, is more suitable for low temperature (below 600 °C) insulation field.

  17. ZrO2包覆CaO-MgO-SiO2陶瓷纤维的制备及其性能%Preparation and properties of ZrO2 coated CaO-MgO-SiO2 ceramic fiber

    Institute of Scientific and Technical Information of China (English)

    刘浩; 王玺堂; 王周福; 张保国

    2012-01-01

    为了解决CaO-MgO-SiO2陶瓷纤维在使用过程中析晶、粉化的问题,采用非均相成核法在CaO-MgO-SiO2陶瓷纤维表面制备了ZrO2涂层.用场发射扫描电子显微镜观察ZrO2包覆层,用X射线衍射仪分析800和1 000℃热处理后原始纤维和ZrO2包覆纤维的晶相变化,并检测了二者在模拟肺液中的溶解性能.结果表明:包覆处理后,CaO-MgO-SiO2陶瓷纤维表面形成了一层ZrO2包覆层;ZrO2包覆层的存在可以显著抑制800℃时纤维的析晶,1000℃时只能抑制纤维中方石英的析出,对其他物相的析晶没有明显抑制作用;ZrO2包覆层的存在降低了纤维在模拟肺液中的早期溶解速率,但对纤维的长期生物可溶性影响不大.%In order to inhibit the crystallization and pulverization of CaO-MgO-SiO2 ceramic fiber at high temperatures,the ZrO2 coating on CaO-MgO-SiOj ceramic fiber was formed by heterogeneous-nucleation method. The crystal phase compositions of the original fiber and ZrO2 coated fiber fired at 800 °C and 1 000 °C were analyzed by X-ray diffractometer.and their solubility in Gamble solution was determined. The results show that; (1) a dense ZrO2 coating is formed on the surface of fiber; (2) the coating on fiber can inhibit the precipitation of crystals at 800 °C markedly and at 1 000 °C it only can inhibit the precipitation of cristobalite and has little effects on other crystal phases; (3) the coating decreases the initial dissolution rate of the fiber in Gamble solution and has little effect on long-term bio-solubility of fiber.

  18. Preparation and characterization of photo chromic effect for ceramic tiles

    Energy Technology Data Exchange (ETDEWEB)

    Atay, B.; Goktas, A.; Dogan, A.

    2011-07-01

    Ceramic tile industry is developing due to the technological researches in scientific area and new tiles which are not only a traditional ceramic also have many multiple functionalities have been marketed nowadays. These tiles like photo catalytic, photovoltaic, antibacterial and etc. improve the quality of life and provide lots of benefits such as self cleaning, energy production, climate control. The goal of this study was to enhance the photo chromic function on ceramic tiles which is the attitude of changing color in a reversible way by electromagnetic radiation and widely used in many areas because of its aesthetic and also functional properties. High response time of photo chromic features of ceramic tiles have been achieved by employing of polymeric gel with additives of photoactive dye onto the ceramic surface. Photo chromic layer with a thickness of approximately 45- 50 {mu}m was performed by using spray coating technique which provided homogeneous deposition on surface. Photo chromic ceramic tiles with high photo chromic activity such as reversibly color change between {delta}E= 0.29 and 26.31 were obtained successfully. The photo chromic performance properties and coloring-bleaching mechanisms were analyzed by spectrophotometer. The microstructures of coatings were investigated both by stereo microscopy and scanning electron microscopy (SEM). (Author) 13 refs.

  19. Preparation of SiC Fiber Reinforced Nickel Matrix Composite

    Institute of Scientific and Technical Information of China (English)

    Lu Zhang; Nanlin Shi; Jun Gong; Chao Sunt

    2012-01-01

    A method of preparing continuous(Al+Al2O3)-coated SiC fiber reinforced nickel matrix composite was presented,in which the diffusion between SiC fiber and nickel matrix could be prevented.Magnetron sputtering is used to deposit Ni coating on the surface of the(Al+Al2O3)-coated SiC fiber in preparation of the precursor wires.It is shown that the deposited Ni coating combines well with the(Al+Al2O3) coating and has little negative effect on the tensile strength of(Al+Al2O3)-coated SiC fiber.Solid-state diffusion bonding process is employed to prepare the(Al+Al2O3)-coated SiC fiber reinforced nickel matrix with 37% fibers in volume.The solid-state diffusion bonding process is optimized and the optimum parameters are temperature of 870,pressure of 50 MPa and holding time of 2 h.Under this condition,the precursor wires can diffuse well,composite of full density can be formed and the(Al+Al2O3) coating is effective to restrict the reaction between SiC fiber and nickel matrix.

  20. The preparation, properties and application of carbon fibers for SPME.

    Science.gov (United States)

    Gierak, A; Seredych, M; Bartnicki, A

    2006-07-15

    The conditions of preparation of new types of carbon fibers for solid phase micro extraction (SPME) prepared by methylene chloride pyrolysis (at 600 degrees C) on the quartz fiber (100 microm) as well as by supporting synthetic active carbon (prepared especially for this purposes) supported in a special epoxide-acrylic polymer is described. The properties of such carbon fibers for SPME were defined by determination of the partition coefficient of the tested substances (i.e., benzene, toluene, xylenes, trichloromethane and tetrachloromethane) and by the microscopic investigations with the application of the optical and scanning electron microscope. The obtained carbon SPME fibers were applied to the analysis of some volatile organic compounds from its aqueous matrix. During chromatographic GC test, at the investigated SPME carbon fibers, we obtained different but mostly high partition coefficients for the determined compounds (Kfs from 120 for trichloromethane up to 11,500 for tetrachloromethane). Owing to the high partition coefficients of the studied substances obtained on carbon fibers, it was possible to do the analysis of organic substances occurring in trace amounts in different matrices. In this paper, we present the analysis of BTX contents in the petrol analyzed with the application carbonized with CH(2)Cl(2) SPME fiber (C1NM) and a headspace over the petrol sample (concentration of each BTX approximately g/dm(3)).

  1. Preparation and Luminescence of Er3+ Doped Oxyfluoride Glass Ceramics Containing LaF3 Nanocrystals

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Er3+ doped transparent oxyfluoride glass ceramics containing LaF3 nanocrystals were prepared and the up-con-version and near infrared luminescence behavior of Er3+ in glasses and glass ceramics were investigated. With increasing heat-treating time and temperature, the size (varied from 0 to 19 nm) and crystallinity (varied from 0 to 47%) of LaF3 nanocrystals in the glass ceramics are increased. The up-conversion luminescence intensity of Er3+ ions in the glass ceramics is much stronger than that in the glasses and increased significantly with increasing heat-treating time and temperature. The near infrared emission of Er3+ ions in the glass ceramics is found to be similar to that in the glasses.

  2. Preparation of Machinable Y-TZP/LaPO4 Composite Ceramics by Liquid Precursor Infiltration

    Institute of Scientific and Technical Information of China (English)

    周振君; 杨正方; 袁启明; 李秀华

    2002-01-01

    A machinable Y-TZP/LaPO4 composite ceramic was prepared by infiltrating LaPO4 liquid precursor into Y-TZP porous ceramic. Sintered Y-TZP ceramic preformed with 35% (volume fraction) open pore volume was made by adding graphite (30%, volume fraction). The Y-TZP/LaPO4 composite ceramics containing different LaPO4 contents were obtained by infiltration and pyrolysis cycles. The machinability and mechanical properties of materials were investigated. The results show that the machinable Y-TZP/LaPO4 composite ceramics containing 2.3% to 7.5% (volume fraction) LaPO4 has good machinability as well as outstanding mechanical properties.

  3. Fracture toughness of zirconia ceramic crowns made by feather-edge tooth preparation design

    Directory of Open Access Journals (Sweden)

    Mirković Nemanja

    2012-01-01

    Full Text Available Background/Aim. Fracture toughness determines functional crown strenght and prevents damages on ceramics during mastication. There is a lack of relevant literature data about fracture toughness of crowns made by feather-edge preparation. Mechanical testing of ceramic samples is supposed to show if feather-edge tooth preparation is a successful method for making ceramic crowns without any risk of reduction of their mechanical properties. This research was done to establish effects of feather-edge tooth preparation on fracture toughness of single zirconia ceramic crowns. Methods. The research was performed as an experimental study. Sixty (60 ceramic crowns were made on non-carious extracted human premolars. Thirty (30 crowns were made on the basis of feather-edge preparation (experimental group I. The group II included 30 crowns made on 1 mm rounded shoulder. Crowns fabrication was executed on a copy mill production system “Zirkonzahn” (Zirkonzahn GMBH, Gais, Germany. The spherical compression test was used to determine fracture toughness, using 6 mm diameter ceramic ball. Fracture load for damaging ceramic crown was recorded on a universal testing machine - Zwick, type 1464, with the speed of 0.05 mm/min. Results. The results of this research introduced significant differences between fracture toughness of ceramic samples in every examined group. However, fracture toughness of crowns from both group was above 2 000 N, what was double beyond a recommended value. The mean value of fracture toughness in the feather-edge group was 2 090 N, and in shoulder group it was 2 214 N. Conclusion. This research showed a high fracture toughness of zirconia crowns made on feather-edge preparation. The examined crowns showed a fracture resistance at a sufficient distance in relation to the minimum values of functional loads. Further research of functional loads of these crown is necessary, as well as research of marginal adaptation of cemented crowns and

  4. OptoCeramic-Based High Speed Fiber Multiplexer for Multimode Fiber Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A fiber-based fixed-array laser transmitter can be combined with a fiber-arrayed detector to create the next-generation NASA array LIDAR systems. High speed optical...

  5. Dielectric behavior of epoxy/BaTiO₃ composites using nanostructured ceramic fibers obtained by electrospinning.

    Science.gov (United States)

    Ávila, H A; Ramajo, L A; Góes, M S; Reboredo, M M; Castro, M S; Parra, R

    2013-02-01

    Composite materials made of epoxy resin and barium titanate (BT) electrospun nanostructured fibers were prepared. BT fibers were synthesized from a sol based on barium acetate, titanium isopropoxide, and poly(vinyl pyrrolidone). The fibers were heat-treated at different temperatures and characterized by X-ray diffraction, scanning electron microscopy (SEM), and Raman spectroscopy. Mats of BT fibers heat-treated at 800 °C were embedded in epoxy resin into suitable molds. The composites were characterized by SEM, and dielectric measurements were performed by means of dielectric spectroscopy. The dielectric permittivity and dielectric modulus of epoxy resin/BT-fiber composites were measured for two types of samples: with the electrodes parallel and perpendicular to the BT fiber layers. Interestingly, composite samples with electrodes perpendicular to the fiber layers and a BT content as low as 2 vol % led to dielectric permittivities three times higher than that of pure epoxy resin.

  6. Energy Saving Method of Manufacturing Ceramic Products from Fiber Glass Waste

    Energy Technology Data Exchange (ETDEWEB)

    Michael J. Haun

    2005-07-15

    The U.S. fiber glass industry disposes of more than 260,000 tons of industrial fiber glass waste in landfills annually. New technology is needed to reprocess this industrial waste into useful products. A low-cost energy-saving method of manufacturing ceramic tile from fiber glass waste was developed. The technology is based on sintering fiber glass waste at 700-900 degrees C to produce products which traditionally require firing temperatures of >1200 degrees C, or glass-melting temperatures >1500 degrees C. The process also eliminates other energy intensive processing steps, including mining and transportation of raw materials, spray-drying to produce granulated powder, drying pressed tile, and glazing. The technology completely transforms fiber glass waste into a dense ceramic product, so that all future environmental problems in the handling and disposal of the fibers is eliminated. The processing steps were developed and optimized to produce glossy and matte surface finishes for wall and floor tile applications. High-quality prototype tile samples were processed for demonstration and tile standards testing. A Market Assessment confirmed the market potential for tile products produced by the technology. Manufacturing equipment trials were successfully conducted for each step of the process. An industrial demonstration plant was designed, including equipment and operating cost analysis. A fiber glass manufacturer was selected as an industrial partner to commercialize the technology. A technology development and licensing agreement was completed with the industrial partner. Haun labs will continue working to transfer the technology and assist the industrial partner with commercialization beyond the DOE project.

  7. Improvement of anti-oxidation properties of carbon fibers by SiC/SiO2 ceramic coating.

    Science.gov (United States)

    Kim, Bo-Hye; Yang, Kap Seung; Woo, Hee-Gweon; Kim, Su Yeun

    2011-08-01

    To improve the anti-oxidation properties of carbon fibers (CFs), the sol-gel method followed by pyrolysis was used to coat CFs with SiC/SiO2 ceramic coatings. The SiO2 sol-gel coating was performed by dip coating a PAN(polyacrylonitrile)-based stabilized fiber (PSF) in a silica sol prepared by the polycondensation of tetraethylorthosilicate (TEOS) in the presence of an acidic catalyst. The PSF coated with SiO2 sol then underwent heat treatments at high temperatures in an inert atmosphere to deposit the SiC/SiO2 and carbonize the deposited fibers. The surface morphology of the CFs deposited with SiC/SiO2 was characterized using a scanning electron microscope (SEM). The relative oxidation resistance of the SiC/SiO2 layer deposited on the CFs was determined by the weight loss due to the use of a thermogravimetric analyzer (TGA) under flowing air, and the data were used to calculate the activation energies through an Arrhenius plot.

  8. Synthesis of high performance ceramic fibers by chemical vapor deposition for advanced metallics reinforcing

    Science.gov (United States)

    Revankar, Vithal; Hlavacek, Vladimir

    1991-01-01

    The chemical vapor deposition (CVD) synthesis of fibers capable of effectively reinforcing intermetallic matrices at elevated temperatures which can be used for potential applications in high temperature composite materials is described. This process was used due to its advantage over other fiber synthesis processes. It is extremely important to produce these fibers with good reproducible and controlled growth rates. However, the complex interplay of mass and energy transfer, blended with the fluid dynamics makes this a formidable task. The design and development of CVD reactor assembly and system to synthesize TiB2, CrB, B4C, and TiC fibers was performed. Residual thermal analysis for estimating stresses arising form thermal expansion mismatch were determined. Various techniques to improve the mechanical properties were also performed. Various techniques for improving the fiber properties were elaborated. The crystal structure and its orientation for TiB2 fiber is discussed. An overall view of the CVD process to develop CrB2, TiB2, and other high performance ceramic fibers is presented.

  9. SiC fibers with controllable thickness of carbon layer prepared directly by preceramic polymer pyrolysis routes

    Energy Technology Data Exchange (ETDEWEB)

    Hu Tianjiao, E-mail: tjhu617@gmail.com [College of Science, National University of Defense Technology, Changsha 410073 (China); Li Xiaodong; Li Gongyi [College of Science, National University of Defense Technology, Changsha 410073 (China); Wang Yingde; Wang Jun [State Key Laboratory of Advanced Ceramic Fibers and Composites, College of Aerospace and Materials Engineering, National University of Defense Technology, Changsha 410073 (China)

    2011-05-25

    Continuous SiC fibers with different thickness of carbon layer were prepared through three preceramic polymer pyrolysis routes. To make the carbon layer thickness controllable, a simple improvement by using a ceramic bushing was adopted to retard the deposition of the pyrolytic carbons. Auger electron spectroscopy (AES) analysis reveals that the carbon layer thickness varies from less than 5 nm to 40 nm. The specific resistivity of the fibers increases by 5 orders of magnitude as the carbon layer thickness decreases. All of the fibers exhibit a tensile strength of around 1.8 GPa which is independent of the carbon layer thickness. The formation process of the carbon layer is discussed in three steps: the decomposition, the carbonization and the deposition. The as-received fibers have a potential application as the reinforcement of functional materials.

  10. Pulmonary retention of ceramic fibers in silicon carbide (SiC) workers.

    Science.gov (United States)

    Dufresne, A; Loosereewanich, P; Armstrong, B; Infante-Rivard, C; Perrault, G; Dion, C; Massé, S; Bégin, R

    1995-05-01

    The fibrous inorganic content of post-mortem lung material obtained from 15 men who worked in the primary silicon carbide (SiC) industry was evaluated. Five men had neither lung fibrosis nor lung cancer (NFNC), six had lung fibrosis (LF), and four had lung fibrosis and lung cancer (LFLC). The workers had 23 to 32 years of exposure. Mean duration of exposure was 23.4 (SD 6.9) years in the NFNC group, 28.8 (SD 5.5) in the LF, and 32.3 (SD 9.0) in the LFLC group. Concentrations of SiC ceramic fibers and other fibrous minerals and angular particles were determined by transmission electron microscopy and energy dispersive spectroscopy. The geometric mean and geometric standard deviation lung concentrations of SiC ceramic fibers 0.1). Pulmonary retention of SiC fibers > or = 5 microns showed an excess in LF and LFLC cases combined versus NFNC that approached statistical significance (Mann-Whitney, p = 0.06). There was a somewhat greater difference for lung retention of ferruginous bodies between NFNC and either LF or LFLC cases (Mann-Whitney, p = 0.02). SiC fibers > or = 5 microns and angular particles containing Si and especially ferruginous bodies were found at higher concentrations in LF and LFLC than in NFNC cases.

  11. Preparation of Machinable Bioactive Glass-ceramics by Sol-gel Method

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The purpose of this research was to prepare machinable bioactive glass-ceramics by sol-gel method. A multi-component composite sol with great uniformity and stability was first prepared by a 2-step method.The composite sol was then transformed into gel by aging under different temperatures. The gel was dried finally by super critically drying method and sintered to obtain the machinable bioactive glass-ceramics. Effect of thermal treatment on crystallization of the glass-ceramics was investigated by X-ray diffraction (XRD) analysis. Microstructure of the glass-ceramics was observed by Scanning Electron Microscopy (SEM) and the mechanism of machinability was discussed. Phlogopite and hydroxylapatite were identified as main crystal phases by XRD analysis under thermal treatment at 750 ℃ and 950 ℃ for 1.5 h separately. The relative bulk density could achieve 99%under 1050 ℃ for 4 h. Microstructure of the glass-ceramics showed that the randomly distributed phlogopite and hydroxylapatite phases were favorable to the machinability of the glass-ceramics. A mean bending strength of about 160-180 MPa and a fracture toughness parameter KIC of about 2.1-2.3 were determined for the glass-ceramics.

  12. Controllable preparation of Ni nanoparticles for catalysis of coiled carbon fibers growth.

    Science.gov (United States)

    Jian, Xian; Zhou, Zuowan; Wu, Sixin; Chen, Lei; Zeng, Qing; Wang, Chao

    2014-01-01

    The mass preparation of high-purity coiled carbon fibers (CCFs) remains challenging due to the high complexity and low controllability of reaction. In this work, a controllable growth of Ni particles was fulfilled by liquid phase reduction of nickel sulfate with hydrazine hydrate. The impacts of the reaction temperature, NaOH concentration, and reaction time on the particle size and purity were investigated. The as-deposited Ni particles were characterized by scanning electron microscopy and X-ray diffraction. In addition, these Ni particles were also applied in preparing high-purity CCFs both on graphite and ceramic substrates. The diameter of the as-grown carbon microcoil was about 500 nm, and the related growth mechanism was discussed.

  13. Acoustic emission characterization of fracture toughness for fiber reinforced ceramic matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Hui, E-mail: phdhuimei@yahoo.com [Science and Technology on Thermostructure Composite Materials Laboratory, Northwestern Polytechnical University, Xi' an Shaanxi 710072 (China); Sun, Yuyao; Zhang, Lidong; Wang, Hongqin; Cheng, Laifei [Science and Technology on Thermostructure Composite Materials Laboratory, Northwestern Polytechnical University, Xi' an Shaanxi 710072 (China)

    2013-01-10

    The fracture toughness of a carbon fiber reinforced silicon carbide composite was investigated relating to classical critical stress intensity factor K{sub IC}, work of fracture, and acoustic emission energy. The K{sub IC} was obtained by the single edge notch beam method and the work of fracture was calculated using the featured area under the load-displacement curves. The K{sub IC}, work of fracture, and acoustic emission energy were compared for the composites before and after heat treatment and then analyzed associated with toughening microstructures of fiber pullout. It indicates that the work of fracture and acoustic emission energy can be more suitable to reflect the toughness rather than the traditional K{sub IC}, which has certain limitation for the fracture toughness characterization of the crack tolerant fiber ceramic composites.

  14. Preparation and Sintering Effect in Quartz-Barium Titanate Porous Ceramics and Permeability Modulation Using an Implanted Electrode

    Directory of Open Access Journals (Sweden)

    Ernesto Suaste Gómez

    2014-01-01

    Full Text Available Barium titanate and quartz mixed in different proportions were used to create porous piezoelectric ceramics. Three different sintering temperatures were used for the ceramics preparation; a nichrome wire was used as internal electrode in porous ceramics. Characteristics as porous area, porosity, and its relationship with quartz percentage and sintering temperatures were studied. Porous ceramics with an implanted electrode were created, by applying an alternating voltage in the internal electrode that controlled the liquid permeability coefficient, calculated by the Darcy Law.

  15. Vapour Growth of Micro-Coiled Ceramic Fibers and their Properties

    OpenAIRE

    1995-01-01

    Micro-coiled fibers of carbon, SiC, Si3N4 TiC, ZrC and HfC were prepared by a metal-impurity activated chemical vapor deposition or vapour phase metallizing of the coiled carbon fibers. The growth conditions, morphology, growth mechanism and some properties were examined. The double-coiled carbon fibers were prepared using acetylene as a carbon source and various powders or plates of transition metals, metal carbides, MoS2, Ti2O3, and Ni single crystal plate as a catalyst at 650-850°C. The tr...

  16. Preparation and Application of New Porous Environmental Ceramics Filter Medium

    Institute of Scientific and Technical Information of China (English)

    LI Meng; WU Jianfeng; JIN Jianhua; LIU Xinming

    2005-01-01

    A new kind of environmental ceramics medium which was made of industrial solid wastes discharged by Shandong Alum Corporation has been used in the process of drinking water treatment. New techniques were introduced to ensure its remarkable advantages such as high porosity and strength. The results of practical application show that this sort of filter medium has shorter filtration run, shorter mature period and higher filter deposit capability compared with traditional sand filter medium. Moreover, up to 25%- 30% of the daily running costs are expected to be reduced by using this ceramics medium.

  17. Processing and Characterization of Basalt Fiber Reinforced Ceramic Composites for High Temperature Applications Using Polymer Precursors

    Science.gov (United States)

    Cox, Sarah B.; Lui, Donovan; Gou, Jihua

    2014-01-01

    The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed and cured and then to be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The two PDCs used in this development are polysiloxane and polycarbosilane. Polysiloxanes contain a silicon oxycarbide backbone when pyrolized up to 1000C. Polycarbosilane, an organosilicon polymer, contain a silicon-carbon backbone; around 1200C, beta-SiC begins to crystallize. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in composites. Basalt is a naturally occurring material found in volcanic rock. Continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. Thermal and mechanical testing includes oxyacetylene torch testing and three point bend testing.

  18. [Exposure to ceramic fibers in the occupational environment. I. Production, kinds of ceramic fibers, changes in structure of these fibers, preliminary studies in the working environment].

    Science.gov (United States)

    Wojtczak, J

    1994-01-01

    The production of fireproof SiO2/Al2O3 ceramic fibres started in the late forties. Primarily, the production was designed entirely for the aircraft industry. In the sixties the application of ceramic fibres became more wider. The first ceramic fibrous materials were characterised by thermal resistance reaching 1200 degrees C. Certain kinds of materials produced currently can be used in the temperature accounting for 1600 degrees C. Aluminosiliceous ceramic fibres recrystallise at high temperature (above 1000 degrees C) and produce mullite and crostobalite. Ceramic fibrous material may become hazardous to workers as a source of respirable fibres. Studies, carried out in plants which manufacture products from aluminosiliceous ceramic fibres, indicated that mean concentrations of respirable fibres ranged from 0.14 to 1.13 f/cm3 while the levels of mean concentrations of total dust accounted for 0.4-13.6 mg/m3. At working posts of plants producing china, where heat-insulating materials were changed mean level of respirable fibre concentration was 0.28-1.65 f/cm3 and concentration of total dust ranged from 7.0 to 17.7 mg/m3.

  19. Preparation of high performance ceramic tiles using waste tile granules and ceramic polishing powder

    Institute of Scientific and Technical Information of China (English)

    WANG Gong-xun; SU Da-gen

    2008-01-01

    This paper presents an innovative approach to reusing waste tile granules (TG) and ceramic polishing powder (PP) to produce high performance ceramic tiles. We studied formulations each with a TG mass fraction of 25.0% and a different PP mass fraction between 1.0% and 7.0%. The formulations included a small amount of borax additive of a mass fracton between 0.2%and 1.2%. The effects of these industrial by-products on compressive strength, water absorption and microstructure of the new ceramic tiles were investigated. The results indicate that the compressive strength decreases and water absorption increases when TG with a mass fraction of 25.0% are added. Improvement of the compressive strength may be achieved when TG (up to 25.0%)and PP (up to 2.0%) are both used at the same time. In particular, the compressive strength improvement can be maximized and water absorption reduced when a borax additive of up to 0.5% is used as a flux. Scanning electron microscopy reveals that a certain amount of fine PP granules and a high content of fluxing oxides from borax avail the formation of glassy phase that fills up the pores in the new ceramic tiles, resulting in a dense product with high compressive strength and low water absorption.

  20. Preparation and Characterization of Nanotitanium Dioxide Coating Film Doped with Fe3+ Ions on Porous Ceramic

    Institute of Scientific and Technical Information of China (English)

    Kejing Xu

    2005-01-01

    The nanotitanium dioxide (TiO2) photocatalytic and porous ceramic filtering technique is one of the advanced methods to effectively treat organic wastewater. The TiO2 sol doped with Fe3+ ions was prepared by sol-gel processing. The influences of the process conditions of coating nanophotocatalytic material-Fe3+-TiO2 film on the surface of porous ceramic filter by dipping-lift method on the performance of porous ceramic filter were studied. The porous ceramic filters have two functions at the same time,filtration and photocatalytic degradation. The results of this study showed that the pH and viscosity of the sol,amount of Fe3+ ions doped as well as the coating times greatly affect the quality of coating film,the performance parameters and the photocatalytic activity of the porous ceramic filter. When the pH of the sol is 3-4,the viscosity is about 6 mPa·S,the amount of doped Fe3+ ions is about 2.0 g/L,the porous ceramic filter has been shown to have the best filtering performance and photocatalytic activity. In this condition,the porosity of porous ceramic is about 42.5%,the pore diameter is 8-10μm. The degradation of methyl-orange is 74.76% under lighting for 120 min.

  1. 钢纤维和莫来石纤维增强陶瓷基摩擦材料的性能研究%Properties of Ceramic-based Friction Material Reinforced by Steel Fiber and Mullite Fiber

    Institute of Scientific and Technical Information of China (English)

    王发辉; 刘莹

    2012-01-01

    Ceramic-based friction material reinforced by steel fiber and mullite fiber was prepared by hot-pressing sin-treing. The mechanical and friction-wear properties of ceramic-based friction materials using steel fiber reinforcement, syn ergetic reinforcement by steel fiber and mullite fiber,mullite fiber reinforcement were investigated and compared. The worn surfaces and debris particles morphology at different temperatures was observed by scanning electron microscopy (SEM) , and wear mechanisms were studied. The results show that the ceramic-based friction material using synergetic reinforcement by steel fiber and mullite fiber has the highest mechanical strength, and exhibits excellent friction stability as well as wear resistance, mullite fiber reinforced ceramic-based friction material shows severe fade and has the lowest wear resistance. SEM analysis shows that from low-temperature to high-temperature the main wear mechanism of ceramic-based friction ma terial using synergetic reinforcement by steel fiber and mullite fiber converts from adhesion wear to a mixing of adhesion wear and abrasive wear, while the main wear type of mullite fiber reinforced ceramic-based friction material is abrasive wear.%采用热压烧结法制备出钢纤维和莫来石纤维增强陶瓷基摩擦材料,对比分析钢纤维、钢纤维和莫来石纤维的混杂纤维以及莫来石纤维增强陶瓷基摩擦材料的机械性能和摩擦磨损特性.利用扫描电子显微镜( SEM)观察不同温度下的磨损表面和磨屑形貌,并研究其磨损机制.研究结果表明,钢纤维和莫来石陶瓷混杂纤维增强的陶瓷基摩擦材料具有较高的机械强度以及良好的摩擦稳定性和耐磨性能,以莫来石纤维增强的陶瓷基摩擦材料,摩擦因数表现出严重的热衰退,且具有低的耐磨损性能.SEM分析表明,在从低温到高温的摩擦过程中,钢纤维和莫来石陶瓷混杂纤维增强的陶瓷基摩擦材料的磨损形式主要由

  2. Processing of continuous fiber reinforced ceramic composites for ultra high temperature applications using organosilicon polymer precursors

    Science.gov (United States)

    Nicholas, James Robert

    The current work is on the development of continuous fiber reinforced ceramic materials (CFCCs) for use in ultra high temperature applications. These applications subject materials to extremely high temperatures(> 2000°C). Monolithic ceramics are currently being used for these applications, but the tendency to fail catastrophically has driven the need for the next generation of material. Reinforcing with continuous fibers significantly improves the toughness of the monolithic materials; however, this is a manufacturing challenge. The development of commercial, low-viscosity preceramic polymers provides new opportunities to fabricate CFCCs. Preceramic polymers behave as polymers at low temperatures and are transformed into ceramics upon heating to high temperatures. The polymer precursors enable the adaptation of well-established polymer processing techniques to produce high quality materials at relatively low cost. In the present work, SMP-10 from Starfire Systems, and PURS from KiON Corp. were used to manufacture ZrB2-SiC/SiC CFCCs using low cost vacuum bagging process in conjunction with the polymer infiltration and pyrolysis process. The microstructure was investigated using scanning electron microscopy and it was determined that the initial greenbody cure produced porosity of both closed and open pores. The open pores were found to be more successfully re-infiltrated using neat resin compared to slurry reinfiltrate; however, the closed pores were found to be impenetrable during subsequent reinfiltrations. The mechanical performance of the manufactured samples was evaluated using flexure tests and found the fiber reinforcement prevented catastrophic failure behavior by increasing fracture toughness. Wedge sample were fabricated and evaluated to demonstrate the ability to produce CFCC of complex geometry.

  3. Preparation of Polyvinylidene Fluoride (PVDF Hollow Fiber Hemodialysis Membranes

    Directory of Open Access Journals (Sweden)

    Qinglei Zhang

    2014-02-01

    Full Text Available In this study, the polyvinylidene fluoride (PVDF hollow fiber hemodialysis membranes were prepared by non-solvent induced phase separation (NIPS. The influences of PVDF membrane thickness and polyethylene glycol (PEG content on membrane morphologies, pore size, mechanical and permeable performance were investigated. It was found that membrane thickness and PEG content affected both the structure and performance of hollow fiber membranes. The tensile strength and rejection of bovine serum albumin (BSA increased with increasing membrane thickness, while the Ultrafiltration flux (UF flux of pure water was the opposite. The tensile strength, porosity and rejection of BSA increased with increasing PEG content within a certain range. Compared with commercial F60S membrane, the PVDF hollow fiber membrane showed higher mechanical and permeable performance. It was proven that PVDF material had better hydrophilicity and lower BSA adsorption, which was more suitable for hemodialysis. All the results indicate that PVDF hollow fiber membrane is promising as a hemodialysis membrane.

  4. Compound transparent ceramics and methods of preparation thereof

    Science.gov (United States)

    Hollingsworth, Joel P.; Kuntz, Joshua D.; Soules, Thomas F.; Landingham, Richard L.

    2012-12-11

    According to one embodiment, a method for forming a composite transparent ceramic preform includes forming a first suspension of oxide particles in a first solvent which includes a first dispersant but does not include a gelling agent, adding the first suspension to a first mold of a desired shape, and uniformly curing the first suspension in the first mold until stable. The method also includes forming a second suspension of oxide particles in a second solvent which includes a second dispersant but does not include a gelling agent, adding the second suspension to the stable first suspension in a second mold of a desired shape encompassing the first suspension and the second suspension, and uniformly curing the second suspension in the second mold until stable. Other methods for forming a composite transparent ceramic preform are also described according to several other embodiments. Structures are also disclosed.

  5. Effect of different ferrule designs on the fracture resistance and failure pattern of endodontically treated teeth restored with fiber posts and all-ceramic crowns

    Directory of Open Access Journals (Sweden)

    Haneef Sherfudhin

    2011-02-01

    Full Text Available OBJECTIVE: This study investigated the effect of different ferrule heights on endodontically treated premolars. MATERIAL AND METHODS: Fifty sound mandibular first premolars were endodontically treated and then restored with 7-mm fiber post (FRC Postec Plus #1 Ivoclar-Vivadent luted with self-polymerized resin cement (Multilink, Ivoclar Vivadent while the coronal section was restored with hybrid composite core build-up material (Tetric Ceram, Ivoclar-Vivadent, which received all-ceramic crown. Different ferrule heights were investigated: 1-mm circumferential ferrule without post and core (group 1 used as control, a circumferential 1-mm ferrule (group 2, non-uniform ferrule 2-mm buccally and 1-mm lingually (group 3, non-uniform ferrule 3-mm buccally and 2-mm lingually (group 4, and finally no ferrule preparation (group 5. The fracture load and failure pattern of the tested groups were investigated by applying axial load to the ceramic crowns (n=10. Data were analyzed statistically by one-way ANOVA and Tukey's post-hoc test was used for pair-wise comparisons (α=0.05. RESULTS: There were no significant differences among the failure load of all tested groups (P<0.780. The control group had the lowest fracture resistance (891.43±202.22 N and the highest catastrophic failure rate (P<0.05. Compared to the control group, the use of fiber post reduced the percentage of catastrophic failure while increasing the ferrule height did not influence the fracture resistance of the restored specimens. CONCLUSIONS: Within the limitations of this study, increasing the ferrule length did not influence the fracture resistance of endodontically treated teeth restored with glass ceramic crowns. Insertion of a fiber post could reduce the percentage of catastrophic failure of these restorations under function.

  6. Preparation and Microstructure of Porous ZrB2 Ceramics Using Reactive Spark Plasma Sintering Method

    Institute of Scientific and Technical Information of China (English)

    YUAN Huiping; LI Junguo; SHEN Qiang; ZHANG Lianmeng

    2015-01-01

    Zirconium oxide (ZrO2) and boron carbide (B4C) were added to ZrB2 raw powders to prepare ZrB2 porous ceramics by reactive spark plasma sintering (RSPS). The reactions between ZrO2 and B4C which produce ZrB2 and gas (such as CO and B2O3) result in pore formation. X-Ray Diffraction results indicated that the products phase was ZrB2 and the reaction was completed after the RSPS process. The porosity could be controlled by changing the ratio of synthesized ZrB2 to raw ZrB2 powders. The porosity of porous ceramics with 20 wt% and 40 wt% synthsized ZrB2 are 0.185 and 0.222, respectivly. And dense ZrB2-SiC ceramic with a porosity of 0.057 was prepared under the same conditions for comparison. The pores were homogeneously distributed within the microstructure of the porous ceramics. The results indicate a promising method for preparing porous ZrB2-based ceramics.

  7. Preparation and properties of highly porous, biomorphic YSZ ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Rambo, C.R.; Cao, J.; Sieber, H

    2004-10-15

    Highly porous, biomorphic YSZ (yttria-stabilized zirconia) ceramics were manufactured by infiltration of zirconium-oxychloride (ZrOCl{sub 2}{center_dot}8H{sub 2}O) sol into biological template structures derived from rattan and pine wood. 3-5 mol% yttrium nitrate (Y(NO{sub 3}){sub 3}{center_dot}5H{sub 2}O) was added to the sol to stabilize the tetragonal ZrO{sub 2} phase. After vacuum-assisted infiltration, the specimens were pyrolysed at 800 deg. C in N{sub 2} atmosphere. Repeated infiltrations and subsequent annealing in air at temperatures up to 1550 deg. C yields the burn out of the biocarbon template and resulted in the formation of biomorphous YSZ ceramics, which maintained the microstructural features of the biological preform. Depending on the type of the biological template as well as the processing parameters, biomorphic ZrO{sub 2} ceramics with an unidirected pore morphology and a large variety of microstructures can be obtained.

  8. Comparison of pleural responses of rats and hamsters to subchronic inhalation of refractory ceramic fibers.

    Science.gov (United States)

    Everitt, J I; Gelzleichter, T R; Bermudez, E; Mangum, J B; Wong, B A; Janszen, D B; Moss, O R

    1997-09-01

    In the present subchronic study, we compared pleural inflammation, visceral pleural collagen deposition, and visceral and parietal pleural mesothelial cell proliferation in rats and hamsters identically exposed to a kaolin-based refractory ceramic fiber, (RCF)-1 by nose-only inhalation exposure, and correlated the results to translocation of fibers to the pleural cavity. Fischer 344 rats and Syrian golden hamsters were exposed to 650 fibers/cc of RCF-1, for 4 hr/day, 5 days/week for 12 weeks. Following 4 and 12 weeks of exposure, and after a 12-week recovery period, pleural lavage fluid was analyzed for cytologic and biochemical evidence of inflammation. Visceral and parietal pleural mesothelial cell proliferation was assessed by immunocytochemical detection of bromodeoxyuridine incorporation. Pleural collagen was quantitated using morphometric analysis of lung sections stained with Sirius Red. Fiber-exposed rats and hamsters had qualitatively similar pleural inflammation at each time point. Mesothelial cell proliferation was more pronounced in hamsters than in rats at each time point and at each site. In both species, the mesothelial cell labeling index was highest in the parietal pleural mesothelial cells lining the surface of the diaphragm at each time point. Hamsters but not rats had significantly elevated collagen in the visceral pleura at the 12-week postexposure time point. Fibers were found in the pleural cavities of both species at each time point. These fibers were generally short and thin. These results suggest that mesothelial cell proliferation and fibroproliferative changes in the pleura of rodents following short-term inhalation exposure are associated with fiber translocation to the pleura and may be predictive of chronic pleural disease outcomes following long-term exposure.

  9. Continuous fiber ceramic composite. Phase I final report, April 1992--April 1993

    Energy Technology Data Exchange (ETDEWEB)

    Goettler, R.W.

    1995-04-01

    Babcock and Wilcox assembled a team to develop the Continuous Fiber Ceramic Composite (CFCC) processing technology, identify the industrial applications, generate design and life prediction software, and to begin the necessary steps leading to full commercialization of CFCC components. Following is a summary of Phase I activities on this program. B&W has selected an oxide-oxide composite system for development and optimization in this program. This selection was based on the results of exposure tests in combustion environments typical of the boiler and heat exchanger applications. Aluminum oxide fiber is the selected reinforcement, and both aluminum oxide and zirconium oxide matrices were selected, based on their superior resistance to chemical attack in hostile industrial service.

  10. Comparison of pulmonary and pleural responses of rats and hamsters to inhaled refractory ceramic fibers.

    Science.gov (United States)

    Gelzleichter, T R; Bermudez, E; Mangum, J B; Wong, B A; Janszen, D B; Moss, O R; Everitt, J I

    1999-05-01

    The present study was designed to determine whether pleural fiber burdens or subchronic pleural fibroproliferative and inflammatory changes can help explain the marked interspecies differences in pleural fibrosis and mesothelioma that are observed following long-term inhalation of RCF-1 ceramic fibers by rats and hamsters. Fischer 344 rats and Syrian golden hamsters were exposed to RCF-1 for 4 h per day, 5 days per week, for 12 consecutive weeks. Lung and pleural fiber burdens were characterized during and after exposure. For all time points, approximately 67% of fibers associated with lung tissues from both rats and hamsters were longer than 5 microns in length. In comparison, fibers longer than 5 microns recovered from the pleural compartment, following a 12-week exposure and 12 weeks of recovery, accounted for 13% (hamsters) and 4% (rats) of the distribution. In the 12 weeks after the cessation of exposure, the number of fibers longer than 5 microns in length remained constant in the hamster at approximately 150 fibers per cm2 pleura. This was 2 to 3 times the corresponding fiber surface density in the rat. Significant pulmonary and pleural inflammation was detected at all time points and for both species. DNA synthesis by pleural mesothelial cells was quantified by bromodeoxyuridine uptake following 3 days of labeling. Labeling indices were higher in hamsters than in rats, both for RCF-1-exposed and filtered air-control animals and was highest for the parietal surface of the pleura. Significantly greater collagen deposition was measured in the visceral pleura of hamsters 12 weeks post-exposure but was not significantly elevated in rats. These findings demonstrate that subchronic inhalation exposure to RCF-1 induces pleural inflammation, mesothelial-cell turnover, pleural fibrosis, and an accumulation of fibers with a length greater than 5 microns in the hamster. The accumulation of long fibers in the pleural space may contribute to the pathology observed in the

  11. Preparation of Long-Lasting Phosphorescence (LLP) Glass-Ceramic Materials

    Institute of Scientific and Technical Information of China (English)

    李成宇; 苏锵; 王淑彬

    2004-01-01

    Three kinds of glass-ceramics, i.e., Mn2+ doped zinc borosilicate, Eu2+, Dy3+ co-doped strontium aluminoborate and Eu2+, Nd3+ co-doped calcium aluminoborate were prepared, whose phosphorescence emission band peaks at 525, 516 and 464 nm, respectively. In preparation of these glass-ceramics the base glasses were gained by heating the mixed starting materials at high temperature to get the transparent glasses; then those glasses were heat-treated and turned to opaque glass-ceramics. X-ray diffraction(XRD) shows that the crystallites are ZnSiO4, SrAl2O4 and α-CaAl2B2O7, respectively. It is a useful way to get new LLP materials by the method reported in this work that may be considered as "from glass to crystal".

  12. One-Step Synthesis of Hollow Titanate (Sr/Ba Ceramic Fibers for Detoxification of Nerve Agents

    Directory of Open Access Journals (Sweden)

    Satya R. Agarwal

    2012-01-01

    Full Text Available Poly(vinyl pyrrolidone(PVP/(strontium/barium acetate/titanium isopropoxide composite fibers were prepared by electrospinning technique via sol-gel process. Diameters of fibers prepared by calcinations of PVP composite fibers were 80–140 nm (solid and 1.2-2.2 μm (hollow fibers prepared by core-shell method. These fibers were characterized using scanning electron microscope (SEM, X-ray diffraction (XRD, and transmission electron microscope (TEM analytical techniques. XRD results showed better crystalline nature of the materials when calcined at higher temperatures. SEM and TEM results clearly showed the formation of hollow submicrometer tubes. The surface area of the samples determined by BET analysis indicated that hollow fibers have ~20% higher surface area than solid fibers. The UV studies indicate better detoxification properties of the hollow fibers compared to solid fibers.

  13. Preparation and characterization of white bamboo charcoal PET fiber

    Institute of Scientific and Technical Information of China (English)

    Qing Shan Li; Ming Shuang Xu; Guang Ju Zhou; Li Qiu Wang

    2010-01-01

    Bamboo charcoal polyester fiber (BC-PET) has been widely applied in home textiles, functional clothing and hydra-balance material, due to their strong adsorptivity, good resolvability, anti-statics, deodorization, antibacterial, anion releasing and far infrared emitting. But BC-PET is black and difficult to be dyed, and its application is limited. In this article, nitric acid was used to treat the surface of bamboo charcoal (BC) powder, and BC powder was modified by titanium dioxide sol to prepare white bamboo charcoal (white-BC) particle. White bamboo charcoal polyester fiber (white-BC-PET) was obtained by mixing white-BC and polyester (PET) resin in double screw extruder. Performance of fiber was tested referring to national standard GB/TI4464-2008 of common PET fiber and most of its indicators have already exceeded GB the level of excellent product. SEM photographs showed that the white-BC was uniformly distributed inside or on the surface of fiber. The white-BC-PET could absorb some aniline and had at least 90% anti-bacterial rate. The anti-bacterial rate could have almost been kept after it was washed 50 times. It was hopeful to be applied in various fields as functional fiber.

  14. Bismuth oxide based ceramics with improved electrical and mechanical properties: Part I. Preparation and characterisation

    NARCIS (Netherlands)

    Kruidhof, H.; Seshan, K.; Lippens Jr., B.C.; Gellings, P.J.; Burggraaf, A.J.

    1987-01-01

    A study of the preparative variables in the synthesis of ceramics based on Bi2O3-Er2O3 solid solutions has shown that the best results are obtained with a coprecipitation method. Critical parameters in the synthesis are found to be i) wet milling of the precalcined powder with an appropriate liquid

  15. Transmission Electron Microscopy Specimen Preparation Method for Multiphase Porous Functional Ceramics

    DEFF Research Database (Denmark)

    Zhang, Wei; Kuhn, Luise Theil; Jørgensen, Peter Stanley;

    2013-01-01

    An optimum method is proposed to prepare thin foil transmission electron microscopy (TEM) lamellae of multiphase porous functional ceramics: prefilling the pore space of these materials with an epoxy resin prior to focused ion beam milling. Several advantages of epoxy impregnation are demonstrated...

  16. Continuous Fiber Ceramic Composite (CFCC) Program. Inventory of federally funded CFCC R&D projects

    Energy Technology Data Exchange (ETDEWEB)

    Richlen, S. [USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States). Office of Industrial Technologies; Caton, G.M.; Karnitz, M.A.; Cox, T.D. [Oak Ridge National Lab., TN (United States); Hong, W. [Institute for Defense Analyses, Alexandria, VA (United States)

    1993-05-01

    Continuous Fiber Ceramic Composites (CFCC) are a new class of materials that are lighter, stronger, more corrosion resistant, and capable of performing at elevated temperatures. This new type of material offers the potential to meet the demands of a variety of industrial, military, and aerospace applications. The Department of Energy Office of Industrial Technologies (OIT) has a new program on CFCCs for industrial applications and this program has requested an inventory of all federal projects on CFCCs that relate to their new program. The purpose of this project is to identify all other ongoing CFCC research to avoid redundancy in the OIT Program. The inventory will be used as a basis for coordinating with the other ongoing ceramic composite projects. The inventory is divided into two main parts. The first part is concerned with CFCC supporting technologies projects and is organized by the categories listed below. (1) Composite Design; (2) Materials Characterization; (3) Test Methods; (4) Non-Destructive Evaluation; (5) Environmental Effects; (6) Mechanical Properties; (7) Database Life Prediction; (8) Fracture/Damage; and (9) Joining. The second part has information on component development, fabrication, and fiber-related projects.

  17. Preparation and characterization of alumina hollow fiber membranes

    Institute of Scientific and Technical Information of China (English)

    Tao WANG; Yuzhong ZHANG; Guangfen LI; Hong LI

    2009-01-01

    With the rapid development of membrane technology in water treatment, there is a growing demand for membrane products with high performance. The inorganic hollow fiber membranes are of great interest due to their high resistance to abrasion, chemical/thermal degradation, and higher surface area/volume ratio therefore they can be utilized in the fields of water treatment. In this study, the alumina (Al2O3) hollow fiber membranes were prepared by a combined phase-inversion and sintering method. The organic binder solution (dope) containing suspended Al2O3 powders was spun to a hollow fiber precursor, which was then sintered at elevated tempera-tures in order to obtain the Al2O3 hollow fiber membrane. The dope solution consisted ofpolyethersulfone (PES), N-methyl-2-pyrrolidone (NMP) and polyvinylpyrrolidone (PVP), which were used as polymer binder, solvent and additive, respectively. The prepared Al2O3 hollow fiber membranes were characterized by a scanning electron microscope (SEM) and thermal gravimetric analysis (TG). The effects of the sintering temperature and Al2O3/PES ratios on the morphological structure, pure water flux, pore size and porosity of the membranes were also investigated extensively. The results showed that the pure water flux, maximum pore size and porosity of the prepared membranes decreased with the increase in Al2O3/PES ratios and sintering temperature. When the Al2O3/PES ratio reached 9, the pure water flux and maximum pore size were at 2547L/m2·h and 1.4μm, respectively. Under 1600℃ of sintering temperature, the pure water flux and maximum pore size reached 2398 L/(m2·h) and 2.3 μm, respectively. The results showed that the alumina hollow fiber membranes we prepared were suitable for the microfiltration process. The morphology investigation also revealed that the prepared Al2O3 hollow fiber membrane retained its'asymmetric structure even after the sintering process.

  18. High temperature properties of ceramic fibers and insulations for thermal protection of atmospheric entry and hypersonic cruise vehicles

    Science.gov (United States)

    Kourtides, Demetrius A.; Pitts, William C.; Araujo, Myrian; Zimmerman, R. S.

    1988-01-01

    Multilayer insulations (MIs) which will operate in the 500 to 1000 C temperature range are being considered for possible applications on aerospace vehicles subject to convective and radiative heating during atmospheric entry. The insulations described consist of ceramic fibers, insulations, and metal foils quilted together with ceramic thread. As these types of insulations have highly anisotropic properties, the total heat transfer characteristics must be determined. Data are presented on the thermal diffusivity and thermal conductivity of four types of MIs and are compared to the baseline Advanced Flexible Reusable Surface Insulation currently used on the Space Shuttle Orbiter. In addition, the high temperature properties of the fibers used in these MIs are discussed. The fibers investigated included silica and three types of aluminoborosilicate (ABS). Static tension tests were performed at temperatures up to 1200 C and the ultimate strain, tensile strength, and tensile modulus of single fibers were determined.

  19. Full-field characterization of thermal diffusivity in continuous- fiber ceramic composite materials and components

    Energy Technology Data Exchange (ETDEWEB)

    Steckenrider, J.S.; Ellingson, W.A. [Argonne National Lab., IL (United States); Rothermel, S.A. [South Dakota State Univ., Brookings, SD (United States)

    1995-05-01

    Continuous-fiber ceramic matrix composites (CFCCs) are currently being developed for various high-temperature applications, including use in advanced heat engines. Among the material classes of interest for such applications are silicon carbide (SiC)-fiber-reinforced SiC (SiC{sub (f)}/SiC), SiC-fiber-reinforced silicon nitride (SiC {sub (f)}/Si{sub 3}N{sub 4}), aluminum oxide (Al{sub 2}O{sub 3})-fiber-reinforced Al{sub 2}O{sub 3} (Al{sub 2}O{sub 3}{sub (f)}/Al{sub 2}O{sub 3}), and others. In such composites, the condition of the interfaces (between the fibers and matrix) are critical to the mechanical and thermal behavior of the component (as are conventional mechanical defects such as cracks, porosity, etc.). For example, oxidation of this interface (especially on carbon coated fibers) can seriously degrade both mechanical and thermal properties. Furthermore, thermal shock damage can degrade the matrix through extensive crack generation. A nondestructive evaluation method that could be used to assess interface condition, thermal shock damage, and to detect other ``defects`` would thus be very beneficial, especially if applicable to full-scale components. One method under development uses infrared thermal imaging to provide ``single-shot`` full-field assessment of the distribution of thermal properties in large components by measuring thermal diffusivity. By applying digital image filtering, interpolation, and least-squares-estimation techniques for noise reduction, we can achieve acquisition and analysis times of minutes or less with submillimeter spatial resolution. The system developed at Argonne has been used to examine the effects of thermal shock, oxidation treatment, density variations, and variations in oxidation resistant coatings in a full array of test specimens. Subscale CFCC components with nonplanar geometries have also been studied for manufacturing-induced variations in thermal properties.

  20. [Exposure to ceramic fibers in the work environment. II. Occupational exposure to dust in plants producing ceramic fiber; fibrogenic effect of the fibers].

    Science.gov (United States)

    Wojtczak, J; Lao, I; Krajnow, A

    1996-01-01

    The aim of the work was to assess the exposure to dust containing ceramic fibres among workers employed in the plant producing aluminosilicate fibres, and to investigate fibrogenic properties of produced ceramic aluminosilicate fibres (L-1). The studies carried out in the work environment revealed that workers were exposed to dust containing respirable fibres from materials produced (fibres, mats). Mean concentrations of these fibres ranged from 0.07 to 0.37 f/cm3 and they were considerably lower than MAC value (1 f/cm3) proposed for respirable ceramic fibres. Mean total dust concentrations ranged from 0.4 to 2.9 mg/m3, and at two working posts they exceeded the proposed MAC value (2 mg/m3). In animal experiments (Wistar female rats) a single dose (25 mg) of L-1 fibres administered intratracheally induced pathological symptoms in lungs, limited to reactive changes in the form of granuloma with weakly pronounced cytolysis, and mean levels of hydroxyproline in the lungs did not differ significantly from the physiological level. The L-1 fibre was classified in the group of dusts with insignificant fibrogenic effects.

  1. One-Step Synthesis of Hollow Titanate (Sr/Ba) Ceramic Fibers for Detoxification of Nerve Agents

    OpenAIRE

    2012-01-01

    Poly(vinyl pyrrolidone)(PVP)/(strontium/barium acetate)/titanium isopropoxide composite fibers were prepared by electrospinning technique via sol-gel process. Diameters of fibers prepared by calcinations of PVP composite fibers were 80–140 nm (solid) and 1.2-2.2 μm (hollow fibers prepared by core-shell method). These fibers were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD), and transmission electron microscope (TEM) analytical techniques. XRD results showed ...

  2. A controlled wet-spinning and dip-coating process for preparation of high-permeable TiO2 hollow fiber membranes.

    Science.gov (United States)

    Zhang, Qi; Wang, Hua; Fan, Xinfei; Chen, Shuo; Yu, Hongtao; Quan, Xie

    2016-01-01

    In order to improve the permeate flux of photocatalytic membranes, we present an approach for coupling TiO2 with ceramic hollow fiber membranes. The ceramic hollow fiber membranes with high permeate flux were fabricated by a controlled wet-spinning process using polyethersulfone (PESf) and ceramic powder as precursors and 1-methyl-2-pyrrolidinone as solvent, and the subsequent TiO2 coating was performed by a dip-coating process using tetra-n-butyl titanate as precursor. It has been found that the PESf/ceramic powder ratio could influence the structure of the membranes. Here the as-prepared TiO2 hollow fiber membranes had a pure water flux of 4,450 L/(m(2)·h). The performance of the TiO2 hollow fiber membrane was evaluated using humic acid (HA) as a test substance. The results demonstrated that this membrane exhibited a higher permeate flux under UV irradiation than in the dark and the HA removal efficiency was enhanced. The approach described here provides an operable route to the development of high-permeable photocatalytic membranes for water treatment.

  3. Preparation and Drug-release Behavior of β-TCP Ceramics Drug Carrier in vitro

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qihuan; YAN Xin; YAN Yuhua; DAI Honglian; JIANG Xin; LI Shipu

    2012-01-01

    β-TCP ceramics drug carrier was first prepared and characterized.SEM showed that β-TCP carrier was in porous amorphous structure with diameters around 10 μm.The physical properties including apparent porosity,volume-weight,tensile strength and the permeability were measured and the results indicated those properties fit the clinical usage of β-TCP drug carrier.Furthermore,drug release experiment in vitro showed that the carrier could prolong drug release in simulated body fluid which provides basis for the clinical use of β-TCP ceramics as drug carrier.

  4. Preparation and characterization of ceramic/carbon coated Fe₃O₄ magnetic nanoparticle nanocomposite as a solid-phase microextraction adsorbent.

    Science.gov (United States)

    Heidari, Hassan; Razmi, Habib; Jouyban, Abolghasem

    2012-07-06

    A novel solid-phase microextraction (SPME) fiber based on a glass tube coated with ceramic/carbon coated Fe₃O₄ magnetic nanoparticle nanocomposite (C-Fe₃O₄/C MNP) was prepared by sol-gel technique. The carbon coated Fe₃O₄ magnetic nanoparticles were synthesized by a simple hydrothermal reaction and the resultant powder was mixed with sol-gel precursors to prepare C-Fe₃O₄/C MNP. The prepared C-Fe₃O₄/C MNP was deposited on surface of glass tubes as new substrate with a simple method. The results revealed that this procedure was a simple and reproducible technique for the preparation of SPME fibers coated with magnetic nanoparticles. The scanning electron micrographs of the fiber surface revealed a three-dimensional structure which is suitable as SPME adsorbents. Some polycyclic aromatic hydrocarbons (PAHs) were selected as model compounds for evaluating performance of the designed SPME fiber. The analytes were extracted with SPME, and desorbed using acetonitrile via ultrasonication. The extracts were analyzed by high performance liquid chromatography (HPLC) with fluorescence detection. The results demonstrated that the proposed method based on the C-Fe₃O₄/C MNP fiber had wide dynamic linear range (0.01-350 μg L⁻¹) with good linearity (R²>0.990) and low detection limits (0.7-50 pg mL⁻¹). The relative standard deviation ranged from 6.9% to 12.2% for inter-day variations. These fibers were successfully used for the analysis of spiked water samples, which demonstrating the applicability of the home-made C-Fe₃O₄/C MNP fibers.

  5. Processes for preparing carbon fibers using gaseous sulfur trioxide

    Energy Technology Data Exchange (ETDEWEB)

    Barton, Bryan E.; Lysenko, Zenon; Bernius, Mark T.; Hukkanen, Eric J.

    2016-01-05

    Disclosed herein are processes for preparing carbonized polymers, such as carbon fibers, comprising: sulfonating a polymer with a sulfonating agent that comprises SO.sub.3 gas to form a sulfonated polymer; treating the sulfonated polymer with a heated solvent, wherein the temperature of said solvent is at least 95.degree. C.; and carbonizing the resulting product by heating it to a temperature of 500-3000.degree. C.

  6. Cross-sectional AEM preparation technique for ceramic-coated WC-Co cutting tools.

    Science.gov (United States)

    Ostreicher, K; Sung, C

    1993-04-15

    The preparation of cross-sectional specimens for AEM studies of materials such as ceramic coated tungsten carbide presents some unique problems. Pieces joined by the use of epoxides often separate at the interface between the WC and ceramic coating during the initial mechanical grinding and subsequent thinning process as a result of the vibration and physical strain placed on the sample. These problems have been overcome through the use of a preparation process which essentially encapsulates the sample within the confines of an epoxy filled quartz tube. This preparation process has allowed for facile AEM cross-sectional analysis of TiN/TiCN coatings on WC-Co substrates, and has revealed two distinct grain morphologies within the TiCN coating.

  7. Preparation and Characteristic of Glass-Ceramics with Super Low Thermal Expansion Coefficient

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The preparation technics of glass-ceramics with super low coefficient of thermal expansion containing β-quartz solid solution as a main crystal phase based on the glass in the system Li2O-Al2O3-SiO2 was introduced. The composition of base glass, technics of melting and heat treatment effecting on characteristic of glass-ceramics was described. Specimens were prepared by melting, anneal and controlled two steps heat treatment. Crystal phase, microstructure and elementary distributing were studied by using XRD, SEM and EDS respectively. Prepared specimens show excellent transparency and super low thermal expansion coefficient of 2×10-8 ·K-1, which reaches international advanced level.

  8. Preparation of cross-sectional specimens of ceramic thermal barrier coatings for transmission electron microscopy.

    Science.gov (United States)

    Unal, O; Heuer, A H; Mitchell, T E

    1990-04-01

    During the microstructural examination of ceramic thermal barrier coatings by transmission electron microscopy (TEM), initial efforts for the preparation of cross-sectional thin foils from interface regions by conventional means were mostly failures. Delamination of the Y2O3-stabilized ZrO2 ceramic coating from the nickel-base alloy substrate sometimes occurred during fine polishing at around 80 microns thickness but mostly occurred during dimpling. Because of this sensitivity, special techniques for mechanical handling were developed so that ion milling could give thin enough regions of the metal-ceramic interface. TEM showed convincingly that the highly fragile nature of the coatings is in fact due to the extensive porosity at the interface developed as a result of heat treatment.

  9. Cervical end preparation design on collarless metal ceramic crown to the decrease of bacterial colony

    Directory of Open Access Journals (Sweden)

    Edy Machmud

    2010-09-01

    Full Text Available Background: Cervical end preparation design is an important procedure in fixed partial denture. If the cervical end preparation design is inadequate, dental plaque will easily be formed and this may indicate the beginning of periodontal disease. Purpose: This study was aimed to analyze the effect of cervical end preparation design on collarless metal ceramic crown towards the decrease of bacterium colony number. Methods: This study was quasi-experimental study applying pre and post test on a control group involving 48 subjects with shoulder, bevel shoulder, and deep chamfer cervical end preparation. The bacterium colonies were examined on the 1st, 7th, and 21st days after the insertion of collarless metal ceramic crown. Results: The study showed that bacterium colony increased significantly in deep chamfer and bevel shoulder preparation design between the treatment group and the control group (p<0.05. In shoulder preparation there was not significant different between the treatment group and the control group (p>0.05. Conclusion: Compared to the bevel shoulder and deep chamfer, shoulder design is the best design for collarless metal ceramic crown restoration.Latar belakang: Desain preparasi tepi servikal merupakan suatu tahap yang sangat menentukan dalam pembuatan gigi tiruan cekat. Apabila desain preparasi tepi servikal tidak adekuat dapat menyebabkan pembentukan plak gigi pada daerah tersebut. Keadaan ini merupakan tahap awal terjadinya penyakit periodontal. Tujuan: Untuk menganalisis pengaruh desain preparasi tepi servikal yang dibuat pada mahkota collarless metal ceramic untuk mengurangi jumlah bakterium koloni. Metode: Penelitian ini adalah penelitian eksperimental semu dengan metode pre and post test dan kelompok kontrol terhadap 48 subyek penelitian. Dilakukan preparasi gigi dan pembuatan akhiran preparasi tepi servikal shoulder, bevel shoulder, dan deep chamfer pada subyek penelitian. Pemeriksaan koloni bakteri dilakukan pada hari ke-1

  10. A new class of boron nitride fibers with tunable properties by combining an electrospinning process and the polymer-derived ceramics route.

    Science.gov (United States)

    Salles, Vincent; Bernard, Samuel; Brioude, Arnaud; Cornu, David; Miele, Philippe

    2010-02-01

    Novel boron nitride (BN) fibers have been developed with diameters ranging from the nano- to microscale by thermal conversion of as-electrospun fibers from polyacrylonitrile and poly[B-(methylamino)borazine] blend solutions. Such a new class of ceramic fibers is seen as potential candidate for thermal management applications and filtration systems in harsh environments.

  11. Preparation and characterization of nanocrystalline barium ferrite ceramic

    Science.gov (United States)

    Saeedi, Majid; Abdellahi, Majid; Rahimi, Alireza; Khandan, Amirsalar

    2016-09-01

    In this work, nanocrystalline BaFe12O19 hexaferrite ceramic was synthesized via high-energy ball milling and subsequent sintering from the mixed powders of Fe2O3 and BaCO3. X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), differential thermal analysis (DTA) and scanning electron microscopy (SEM) were utilized to understand the structural evolution during the synthesis process. Vibrating sample magnetometer (VSM) was also used to investigate the magnetic properties of the samples as a function of sintering process. DTA analysis suggested that the initial high-energy milling of the precursors helps the formation of single domain magnetic particles. According to the results obtained, BaFe12O19 can be formed via two main steps, during which BaFe2O4 is formed initially that eventually turns into BaFe12O19. VSM-based findings showed that the ratio of remanent magnetization to magnetization value (Mr/Ms) is around 0.5 which is the expected value for randomly oriented assembly of uniaxial single-domain particles undergoing magnetization reversal by coherent rotation. The observed magnetic parameters (Mr and Ms) are much higher than the previously reported values, due to the reduction in particle size as a result of ball milling.

  12. Structural, dielectric and magnetic properties of cobalt ferrite prepared using auto combustion and ceramic route

    Energy Technology Data Exchange (ETDEWEB)

    Murugesan, C., E-mail: murugesanscience@gmail.com; Perumal, M.; Chandrasekaran, G.

    2014-09-01

    Cobalt ferrite is synthesized by using low temperature auto combustion and high temperature ceramic methods. The prepared samples have values of lattice constant equal to 8.40 Å and 8.38 Å for auto combustion and ceramic methods respectively. The FTIR spectrum of samples of the auto combustion method shows a high frequency vibrational band at 580 cm{sup −1} assigned to tetrahedral site and a low frequency vibrational band at 409 cm{sup −1} assigned to octahedral site which are shifted to 590 cm{sup −1} and 412 cm{sup −1} for the ceramic method sample. SEM micrographs of samples show a substantial difference in surface morphology and size of the grains between the two methods. The frequency dependent dielectric constant and ac conductivity of the samples measured from 1 Hz to 2 MHz at room temperature are reported. The room temperature magnetic hysteresis parameters of the samples are measured using VSM. The measured values of saturation magnetization, coercivity and remanent magnetization are 42 emu/g, 1553 Oe, 18.5 emu/g for the auto combustion method, 66.7 emu/g, 379.6 Oe, and 17.3 emu/g for the ceramic method, respectively. The difference in preparation methods and size of the grains causes interesting changes in electrical and magnetic properties.

  13. Biomorphous SiC ceramics prepared from cork oak as precursor

    Science.gov (United States)

    Yukhymchuk, V. O.; Kiselov, V. S.; Valakh, M. Ya.; Tryus, M. P.; Skoryk, M. A.; Rozhin, A. G.; Kulinich, S. A.; Belyaev, A. E.

    2016-04-01

    Porous ceramic materials of SiC were synthesized from carbon matrices obtained via pyrolysis of natural cork as precursor. We propose a method for the fabrication of complex-shaped porous ceramic hardware consisting of separate parts prepared from natural cork. It is demonstrated that the thickness of the carbon-matrix walls can be increased through their impregnation with Bakelite phenolic glue solution followed by pyrolysis. This decreases the material's porosity and can be used as a way to modify its mechanical and thermal characteristics. Both the carbon matrices (resulted from the pyrolysis step) and the resultant SiC ceramics are shown to be pseudomorphous to the structure of initial cork. Depending on the synthesis temperature, 3C-SiC, 6H-SiC, or a mixture of these polytypes, could be obtained. By varying the mass ratio of initial carbon and silicon components, stoichiometric SiC or SiC:C:Si, SiC:C, and SiC:Si ceramics could be produced. The structure, as well as chemical and phase composition of the prepared materials were studied by means of Raman spectroscopy and scanning electron microscopy.

  14. DEVELOPMENT OF NOVEL CERAMIC NANOFILM-FIBER INTEGRATED OPTICAL SENSORS FOR RAPID DETECTION OF COAL DERIVED SYNTHESIS GAS

    Energy Technology Data Exchange (ETDEWEB)

    Junhang Dong; Hai Xiao; Xiling Tang; Hongmin Jiang; Kurtis Remmel; Amardeep Kaur

    2012-09-30

    The overall goal of this project is to conduct fundamental studies on advanced ceramic materials and fiber optic devices for developing new types of high temperature (>500{degree}C) fiber optic chemical sensors (FOCS) for monitoring fossil (mainly coal) and biomass derived gases in power plants. The primary technical objective is to investigate and demonstrate the nanocrystalline doped-ceramic thin film enabled FOCS that possess desired stability, sensitivity and selectivity for in-situ, rapid gas detection in the syngas streams from gasification and combustion flue gases. This report summarizes research works of two integrated parts: (1) development of metal oxide solid thin films as sensing materials for detection and measurement of important gas components relevant to the coal- and biomass-derived syngas and combustion gas streams at high temperatures; and (2) development of fiber optic devices that are potentially useful for constructing FOCS in combination with the solid oxide thin films identified in this program.

  15. Preparation of Ln3-xEuxS4 (Ln=Ce,Pr,and Nd) ceramics by pressureless sintering

    Institute of Scientific and Technical Information of China (English)

    YUAN HaiBin; ZHANG JianHui; YU RuiJin; SU Oiang

    2009-01-01

    The preparation of ternary rare earth sulfides of Ln3-xEuxS4(Ln = Ce,Pr,and Nd) ceramics was investigated,and the effect of Eu substitution on Ln3-xEuxS4 ceramics was also studied.Ln3-xEuxS4 powders were synthesized by the sulfurization of their oxide powders using carbon disulfide gas.Ln3-xEuxS4 ceramics were sintered by pressure-less sintering method.All pressureless sintered Ln3-xEuxS4 ceramics crystallized in y-phase.It was found that Eu substitution could improve the density of Ln3-xEuxS4 ceramics.Furthermore,Eu substitution might narrow the optical band gaps of Ln3-xEuxS4 ceramics.

  16. Preparation of AZO Nanoparticles, Ceramic Targets and Thin Films by a Co-precipitaition Method

    Institute of Scientific and Technical Information of China (English)

    XIU Sanmu; WEI Tiefeng; YANG Ye; ZHANG Ting; LI Jia; SONG Weijie

    2015-01-01

    We comprehensively study the co-precipitation preparation of aluminum doped zinc oxide (AZO) nanoparticles, ceramic target and thin iflm deposition. The nanoparticles calcined below 700℃possessed pure wurtzite structure of ZnO. When the calcination temperature exceeded 700℃, ZnAl2O4 phase appeared. The resistivity and relative density of the AZO target pressed from nanoparticles were 3×10-3Ω∙cm and 99.1%, respectively. The minimum resistivity of AZO thin films prepared by DC sputtering of the ceramic target reached 4.1×10–4Ω∙cm with the mobility of 33 cm2/v∙s and the carrier concentration of 4.5 ×1020 cm-3. The average optical transmittance of the AZO thin iflms in the visible wavelength range (400-800 nm) was more than 80%.

  17. Coal Fly Ash Ceramics: Preparation, Characterization, and Use in the Hydrolysis of Sucrose

    Directory of Open Access Journals (Sweden)

    Ricardo Pires dos Santos

    2014-01-01

    Full Text Available Coal ash is a byproduct of mineral coal combustion in thermal power plants. This residue is responsible for many environmental problems because it pollutes soil, water, and air. Thus, it is important to find ways to reuse it. In this study, coal fly ash, obtained from the Presidente Médici Thermal Power Plant, was utilized in the preparation of ceramic supports for the immobilization of the enzyme invertase and subsequent hydrolysis of sucrose. Coal fly ash supports were prepared at several compaction pressures (63.66–318.30 MPa and sintered at 1200°C for 4 h. Mineralogical composition (by X-ray diffraction and surface area were studied. The ceramic prepared with 318.30 MPa presented the highest surface area (35 m2/g and amount of immobilized enzyme per g of support (76.6 mg/g. In assays involving sucrose inversion, it showed a high degree of hydrolysis (around 81% even after nine reuses and 30 days’ storage. Therefore, coal fly ash ceramics were demonstrated to be a promising biotechnological alternative as an immobilization support for the hydrolysis of sucrose.

  18. Study of Large-Scale Aluminium-Doped Zinc Oxide Ceramic Targets Prepared by Slip Casting

    Directory of Open Access Journals (Sweden)

    Ling-yun Han

    2016-01-01

    Full Text Available Aluminium-doped zinc oxide (AZO ceramic green compacts at a size of 170 × 340 × 17 mm have been prepared by slip casting. An AZO slurry with good fluidity and viscosity was obtained when 1.2 wt% of dispersant was added, which indicates that the slurry prepared with micrometre particles is more suitable for slip casting. The densification and electrical properties of the AZO targets prepared by particles with different sizes were investigated after sintering from 1380 to 1460°C. The results showed that the relative density of the AZO target prepared with 45 nm particles could reach nearly 98% at 1380°C; the resistivity of the AZO target prepared with nanometre particles could be as low as 1.6 × 10−3 Ω·cm at 1400°C; and the average transmittance of the AZO film prepared with nanometre particles could reach a maximum value of 93.73% in the visible region at 250 W. In this study, the correlation between the density, resistivity, and grain growth of AZO ceramic green compacts was studied.

  19. Quantitative assessment of the risk of lung cancer associated with occupational exposure to refractory ceramic fibers.

    Science.gov (United States)

    Moolgavkar, S H; Luebeck, E G; Turim, J; Hanna, L

    1999-08-01

    We present the results of a quantitative assessment of the lung cancer risk associated with occupational exposure to refractory ceramic fibers (RCF). The primary sources of data for our risk assessment were two long-term oncogenicity studies in male Fischer rats conducted to assess the potential pathogenic effects associated with prolonged inhalation of RCF. An interesting feature of the data was the availability of the temporal profile of fiber burden in the lungs of experimental animals. Because of this information, we were able to conduct both exposure-response and dose-response analyses. Our risk assessment was conducted within the framework of a biologically based model for carcinogenesis, the two-stage clonal expansion model, which allows for the explicit incorporation of the concepts of initiation and promotion in the analyses. We found that a model positing that RCF was an initiator had the highest likelihood. We proposed an approach based on biological considerations for the extrapolation of risk to humans. This approach requires estimation of human lung burdens for specific exposure scenarios, which we did by using an extension of a model due to Yu. Our approach acknowledges that the risk associated with exposure to RCF depends on exposure to other lung carcinogens. We present estimates of risk in two populations: (1) a population of nonsmokers and (2) an occupational cohort of steelworkers not exposed to coke oven emissions, a mixed population that includes both smokers and nonsmokers.

  20. Preparation of Hydroxyapatite Fibers by the Homogeneous Precipitation Method

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper discussed the preparing process of hydroxyapatite fibers which were widely used as reinforcement for biomedical materials by homogeneous precipitation method.The needle-like hydroxyapatite crystals were synthesized in an aqueous system.They were transferred from precursors-dicalcium phosphate anhydrate and octacalcium phosphate crystals.The reaction conditions were well controlled in order to obtain crystals in given morphology.The products were characterized by X-ray powder diffractometry(XRD),scanning electron microscopy (SEM) and infrared spectroscopy(IR).They were verified to be hydroxyapatite crystals with needle-like in shape.

  1. Preparation and Photocatalytic Property of TiO2/Diatomite-Based Porous Ceramics Composite Materials

    Directory of Open Access Journals (Sweden)

    Shuilin Zheng

    2012-01-01

    Full Text Available The diatomite-based porous ceramics was made by low-temperature sintering. Then the nano-TiO2/diatomite-based porous ceramics composite materials were prepared by hydrolysis deposition method with titanium tetrachloride as the precursor of TiO2 and diatomite-based porous as the supporting body of the nano-TiO2. The structure and microscopic appearance of nano-TiO2/diatomite-based porous ceramics composite materials was characterized by XRD and SEM. The photocatalytic property of the composite was investigated by the degradation of malachite green. Results showed that, after calcination at 550°C, TiO2 thin film loaded on the diatomite-based porous ceramics is anatase TiO2 and average grain size of TiO2 is about 10 nm. The degradation ratio of the composite for 5 mg/L malachite green solution reached 86.2% after irradiation for 6 h under ultraviolet.

  2. Preparation of Neodymium-Doped Yttrium Aluminum Garnet Transparent Ceramics by Homogeneous Precipitation Method

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Neodymium doped-yttrium aluminum garnet (Nd: YAG) transparent polycrystalline ceramics already become substitutes of single crystals because they are provided with easy fabrication, low cost, large size, highly doped concentration, high heat conductivity, mass fabrication, multi-layers and multi-functions. The Nd: YAG precursor powders with loosely dispersed, slightly agglomerated, super fine and YAG cubic crystal phase were synthesized at 1100 ℃ by the hocal stabilizer, TEOS as sintering additive. The Nd:YAG transparent ceramics were prepared after being vacuum sintered at 1700 ℃ for 5 h. The Nd:YAG ceramic materials were characterized by the TG-DTA, XRD, FT-IR, TEM, FEG-ESEM and FT-PL. The results show that the crystallization temperature of YAG is 850 ℃ and the intermediate crystal phase YAP forming during the heat treatment transforms to YAG cubic crystal phase at 1050 ℃. The lasing wavelength of (Nd0.01Y0.99)3Al5O12 transparent ceramics is 1.065 μm and there exists a slight red-shift compared to the single crystal with the same chemical composition. The optical transmittance is 45% in the visible light and 58% in the near infrared light and the optical transmittance descends with the decreasing the wavelength.

  3. All- Ceramic Crown Preparation and the Remained wall Thickness of the Pulp Chamber

    Directory of Open Access Journals (Sweden)

    Mohammadzadeh Akhlaghi N.

    2012-12-01

    Full Text Available tatement of Problem: A minimally invasive method of preparation is essential to prevent tooth structure weakening and pulp irritation; especially for mandibular anterior single-tooth all-ceramic crowns. According to many investigations, one of the most important reasons of pulp injury caused by tooth preparation for different restorative procedures is reduced “remained wall thickness” (RWT. In order to protect the pulp from irritation, it is necessary to maintain a 0.5 mm of RWT.Purpose: The purpose of the present study was to evaluate the effect of all-ceramic crown preparation on pulp chamber RWT of mandibular incisors.Materials and Method: Mesiodistal and buccolingual initial images of 24 ex-tracted mandibular incisors were provided. The pulp chamber initial wall thick-nesses of buccal, lingual and proximal surfaces of cervical, 1and 2 mm above the cervical areas and also the incisal surfaces of incisal sections were measured using digital radiography and Photoshop software. After all-ceramic crown preparation, images were provided at the same initial positions. The initial and remained pulp chamber wall thicknesses were statistically evaluated and analyzed by ANOVA, paired t-test and a post hoc Tukey test.Results: Repeated measures ANOVA showed that the mean of pre- or post-preparation wall thicknesses were not significantly different for each surface at the three horizontal levels (p> 0.05. However, there were significant differences between the surfaces for each section. Comparison of pre- and post-preparation wall thicknesses revealed significant differences (p< 0.05. Proximal surfaces of cervical sections had the least RWT (0.42±0.12.Conclusion: According to the results of the present study, the least amount of initial and remained wall thicknesses of pulp chamber were related to the proximal surfaces, particularly in cervical areas. Therefore a reduction of preparation to 0.7 mm is suggested to prevent future pulp injury for

  4. Exposures to refractory ceramic fibers in manufacturing and related operations: a 10-year update.

    Science.gov (United States)

    Rice, Carol H; Levin, Linda S; Borton, Eric K; Lockey, James E; Hilbert, Timothy J; Lemasters, Grace K

    2005-09-01

    Refractory ceramic fiber (RCF) is a man-made vitreous fiber used for its insulating properties. Since 1987, the work environment of approximately 800 persons employed in fiber manufacture or production operations directly related to manufacturing has been monitored to evaluate exposure levels. Samples were collected quarterly from the breathing zones of randomly selected workers. The measurements from those working in areas of similar activities and exposure controls (dust zones or homogeneous exposure groups) were used to calculate a mean exposure during identified time periods. Persons who spent all of their work time in one zone/group were assigned this mean exposure; those with responsibilities in more than one area were assigned an exposure based on a time-weighted formula. A total of 3213 measurements were used to estimate exposure for 130 job titles; because of the mobile jobs, many samples contribute to the estimates of exposure for multiple job titles. The majority of exposure estimates (53%) have remained stable over the operational history of the plant reported here. For 32 job titles (25%) exposures have decreased, and for 28 job titles (22%) exposures have increased. Of the 122 job titles active in 2001, 97 (79%) exposures were estimated to be at 0.25 f/cc or lower; 8 (7%) had an exposure exceeding 0.5 f/cc (range 0.51-0.80) and 17 (14%) of these exposure estimates were in the range of > 0.25 f/cc to 0.5 f/cc. The continuing program to measure exposure supports a respiratory health surveillance program in these facilities.

  5. Preparation of array of long carbon nanotubes and fibers therefrom

    Science.gov (United States)

    Arendt, Paul N.; DePaula, Ramond F.; Zhu, Yuntian T.; Usov, Igor O.

    2015-11-19

    An array of carbon nanotubes is prepared by exposing a catalyst structure to a carbon nanotube precursor. Embodiment catalyst structures include one or more trenches, channels, or a combination of trenches and channels. A system for preparing the array includes a heated surface for heating the catalyst structure and a cooling portion that cools gas above the catalyst structure. The system heats the catalyst structure so that the interaction between the precursor and the catalyst structure results in the formation of an array of carbon nanotubes on the catalyst structure, and cools the gas near the catalyst structure and also cools any carbon nanotubes that form on the catalyst structure to prevent or at least minimize the formation of amorphous carbon. Arrays thus formed may be used for spinning fibers of carbon nanotubes.

  6. Preparation technology and anti-corrosion performances of black ceramic coatings formed by micro-arc oxidation on aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    CHEN Ling; HAN Jing; YU Shengxue

    2006-01-01

    In order to prepare ornamental and anti-corrosive coating on aluminum alloys, preparation technology of black micro-arc ceramic coatings on Al alloys in silicate based electrolyte was studied.The influence of content of Na2WO4 and combination additive in solution on the performance of black ceramic coatings was studied; the anticorrosion performances of black ceramic coatings were evaluated through whole-immersion test and electrochemical method in 3.5% NaCl solution at different pH value; SEM and XRD were used to analyze the surface morphology and phase constitutes of the black ceramic coatings.Experimental results indicated that, without combination additives, with the increasing of Na2WO4 content in the electrolyte, ceramic coating became darker and thicker, but the color was not black; after adding combination additive, the coating turned to be black; the black ceramic coating was multi-hole form in surface.There was a small quantity of tungsten existing in the black ceramic coating beside α-Al2O3 phase and β-Al2O3 phase.And aluminum alloy with black ceramic coating exhibited excellent anti-corrosion property in acid, basic and neutral 3.5% NaCl solution.

  7. Surface reactivity, cytotoxicity, and transforming potency of iron-covered compared to untreated refractory ceramic fibers.

    Science.gov (United States)

    Elias, Zoé; Poirot, Odile; Danière, Marie-Céleste; Terzetti, Francine; Binet, Stéphane; Tomatis, Maura; Fubini, Bice

    2002-12-13

    Untreated and iron-coated refractory ceramic fibers (RCFs) 1, 3, and 4 were examined for their potential to generate free radicals and to catalyze hydrogen peroxide decomposition in cell-free assays and were compared for cytotoxic and transforming potencies in Syrian hamster embryo (SHE) cell system. Coating with a high quantity of iron increased the capability of RCFs to generate hydroxyl radicals and to catalyze the decomposition of hydrogen peroxide. In the SHE cells, the untreated RCFs had varying ability to induce inhibition of cell proliferation, cytotoxicity (as measured by the colony-forming efficiency, CE) and morphological transformation, in a concentration-dependent manner. According to cytotoxic and transforming potencies, they ranged as follows: RCF3 > RCF1 > RCF4. The lethal concentration 50 (LC50; decrease of CE to 50% of controls after 7 d of treatment) expressed per number of RCF3 and RCF1/cm(2) of culture dish was 2.5 x 10(4) and 3.7 x 10(4), respectively, whereas RCF4 was not cytotoxic up to the highest concentration tested (23.7 x 10(4) fibers/cm(2)). At LC50, RCF3 was 1.4-fold more transforming than RCF1, and the weakest, RCF4, induced less than 1% transformation. Iron coating of RCF1 and RCF3 markedly attenuated their cytostatic, cytotoxic, and transforming potencies without a linear concentration-transformation relationship. In contrast, iron coating of RCF4 affected slightly its low transforming potency, although the growth inhibitory effect was reduced. The observed decrease rather than increase in the cytotoxic and transforming potencies of the active samples RCF1 and RCF3 by their coating with large amounts of ferric iron suggests that it is not the quantity or any form of iron on the surface of fibers but the iron, even in trace, in a particular redox and coordinate state that might play a role in the fiber's surface reactivity with regard to the biological material. Surface chemical functions involved in the interaction with the cell

  8. Preparation of neodymium-doped yttrium aluminum garnet powders and fibers

    Institute of Scientific and Technical Information of China (English)

    R.López; J.Zárate; E.A.Aguilar; J.Mu(n)oz-Salda(n)a

    2008-01-01

    Using nitrate precursors, a novel spray-drying assisted citrate gel process for the preparation of neodymium-doped yttrium alumi-num garnet (YAG) phase was developed. Synthesis of single-phase polycrystalline YAG was achieved at temperatures as low as 800 ℃ us-ing the spray-drying methodology whilst conventional approaches currently available require 1000 ℃. Initially, a solution was prepared by mixing aluminum and yttrium nitrates, citric acid, etilenglycol and neodymium oxide. This solution was dried by pulverization (spray dryer) to obtain aggregated precursor powders of the compound. These aggregates were calcined at 800, 850 and 900 ℃ to determine the phase evolution from amorphous to crystalline by X-ray diffraction (XRD). The morphology of aggregates was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Moreover, through XRD it was determined that the crystallization of YAG phase started at about 800 ℃ without any intermediate phases. The powders were composed of spherical aggregates with an average diame-ter of 1 μm. From these powders, ceramic fibers with additions of 2at.% and 5at.% Nd, were extracted from the melt with diameters ranging from 30 μm to 50 μm.

  9. Preparation and Characterization of Nylon 6/Silver Nanocomposite Fibers for Permanent Antibacterial Effect

    Directory of Open Access Journals (Sweden)

    Laleh Maleknia

    2015-03-01

    Full Text Available The nylon 6/silver nano composite fibers were prepared for the attainment of permanent antibacterial activity to common synthetic textile. The fibers prepared by melt spinning and nylon 6/ Silver nanocomposite were prepared by a modular twin screw extruder.. The antibacterial activities of nano silver in fibers were calculated by percent reduction of two kinds of bacteria staphylococcus aurous and klebsiela peneumoniae. Scanning electron microscopy (SEM was carried out to observe particle distribution on the nanocomposite fibers. All the nanocomposite fibers were characterized by instron machine.

  10. Actuation Behavior of Polylactic Acid Fiber Films Prepared by Electrospinning.

    Science.gov (United States)

    Nobeshima, Taiki; Ishii, Yuya; Sakai, Heisuke; Uemura, Sei; Yoshida, Manabu

    2016-04-01

    A poly-DL-lactide (PLA) fiber film was prepared using the electrospinning method. This film consisted of randomly oriented PLA nanofibers. Consequently, it had sponge-like structure and was quite soft compared to PLA films prepared by spin coating. The average diameter of the fibers and the density of the film were 730 nm and 20%, respectively. By applying a voltage, the PLA film was subjected to electric-field-induced strain: expansion and compression in the thickness direction. When a voltage of -200 V was applied to the film, its thickness shrank from 13.5 µm to 10.0 µm (a 26% reduction). Electric-field-induced strain can occur via two different mechanisms: The first is electrostrictive behavior. That. is, in a highly electric field region, a change of film thickness occurs (compression only) from the electrostatic force between electrodes. The second mechanism is piezoelectric-like behavior that occurs in racemic PLA, wherein a PLA nanofiber is expanded and compressed by applying positive and negative voltage. Such piezoelectric-like behavior was not observed in spin-coated PLA films.

  11. Preparation of Zeolite X Membranes on Porous Ceramic Substrates with Zeolite Seeds

    Institute of Scientific and Technical Information of China (English)

    Zhongqiang Xu; Qingling Chen; Guanzhong Lu

    2002-01-01

    Zeolite X membranes were investigated by in-situ hydrothermal synthesis on porous ceramic tubes precoated with zeolite X seeds or precursor amorphous aluminosilicate, and porous α-Al2O3 ceramic tubes with a pore size of 50 200 nm were employed as supports. Zeolite X crystals were synthesized by the classic method and mixed into deionized water as a slurry with a concentration of 0.2 0.5wt%, having a range of crystal sizes from 0.2 to 2μm. Crystal seeds were pressed into the pores near the inner surface of the ceramic tubes, and crystallization took place at 95℃ for 24-96 h. It was also investigated that Boehmite sol added with zeolite X seeds was precoated on ceramic supports to form a layer of γ-Al2O3 by heating, and hydrothermal crystallization could then take place to prepare the zeolite membranes on the composite ceramic tubes. The crystal species were characterized by XRD, and the morphology of the supports subjected to crystallization was characterized by SEM. The composite zeolite membranes have zeolitic top-layers with a thickness of 10-25 μm, and zeolite crystals can be intruded into pores of the supports as deeply as 100μm. The experimental results indicate that the precoating of zeolitic seeds on supports is beneficial to crystallization by shortening the synthesis time and improving the membrane strength. The resulting zeolite X membrane shows permselectivity to tri-n-butylamine((C4H9)3N) over perfluro-tributyl-amine ((C4Fg)3N), and a permeance ratio of 57 for ((C4Hg)3N to (C4F9)3N could be reached at 350℃. Permeances of BZ, EB and TIPB through the zeolite membrane were also measured and were found to slightly increase with temperature.

  12. Investigation of pitch-sulphur mixtures used as binder in the preparation of black ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Clausse, V.; Bastien, T.; Hoppe, S.; Mareche, J.F.; Fierro, V.; Celzard, A. [Nancy University, Nancy (France)

    2009-08-15

    Since tens of years, sulphur is a very classical additive in the composition of black ceramics because, if added in small amounts (i.e., less than 10 wt.% of the binder), it improves their mechanical properties without strongly degrading their graphitability and their conductivity. Macroscopic properties of black ceramics strongly depend on the quality of the interfaces between grains of solid filler (graphite, carbon black) and coke originating from the pyrolysis of the binder; thus, the binder should correctly wet the filler prior to the carbonisation process. Coal-tar pitch usually exhibits a high affinity for carbon grains. In the effect of the amount of sulphur on the viscosity of the molten binder and on the way the present work, it wets the solid filler was investigated. For that purpose, the penetration of mixtures of coal-tar pitch and sulphur inside a bed of carbon particles was studied as a function of temperature. The influence of the sulphur content on composition, optical texture, and transport properties of the derived black ceramics, as well as the way it was mixed with the other constituents, were also examined. It was found that the preparation of black ceramics may be achieved easily and in safe conditions, without evolution of H{sub 2}S, using pitch-sulphur mixtures first molten in a bladed mixer, and having sulphur contents within the range 10-20 wt.%. The presence of sulphur increases the coke yield but lowers the ability to graphitise, thus limiting the transport properties of the resultant black ceramic. The optimal concentration of sulphur should thus be a compromise between mechanical strength and other physical properties.

  13. Students’ evaluation of preclinical simulation for all ceramic preparation (In Faculty of Dentistry Universiti Kebangsaan Malaysia

    Directory of Open Access Journals (Sweden)

    Natasya Ahmad Tarib

    2008-06-01

    Full Text Available The purpose of the study is to evaluate all ceramic crown (ACC preparations those were made by dental undergraduate students during the preclinical sessions. 104 plastic teeth were prepared by 4th year dental undergraduates during the preclinical session for ACC crown examined. The teeth were placed on the frasaco arches and were mounted in the frasaco head. The preparations were examined for the tapering, presence of undercuts, incisal and cingulum reductions as well as preparation of shoulder margin. Preparations were examined using hand instruments and visual. The sample size was 92 plastic teeth. Most of the preparations were acceptable with acceptable placement and types of margins, adequate axial and incisal reductions and acceptable tapered of the axial walls. On the other hand, most of the teeth showed absence of cingulum wall. Most of the crowns prepared by the students were acceptable. It showed that they understood the principles of crown preparation. Cingulum wall preparation has to be given greater emphasis as it is important in the retention and resistance of the restoration.

  14. Preparation and luminescence properties of Ce3+/Dy3+-codoped fluorosilicate glass ceramics

    Institute of Scientific and Technical Information of China (English)

    CUI Shuo; ZHAO Daliang; Huang Jinglu; FU Hengyi; QIAN Jiangyun; LUO Qun; Qiao Xusheng; FAN Xianping; ZHANG Xianghua

    2012-01-01

    The Ce3+and Dy3+ co-doped fluorosilicate glass and glass ceramics containing SrF2 or CeF3 nanocrystals were prepared under reducing atmosphere.The precipitated nano-crystalline phase shifted from cubic SrF2 to hexagonal CeF3 gradually with the heat treatment temperature increasing from 620 to 680 ℃.The glass and glass ceramics emitted white light,deriving from a combination of the Ce3+ blue and the Dy3+ yellow light.The CIE coordinates could be tuned by adjusting the ratio of Ce3+/Dy3+ concentration.The luminescence could be enhanced significantly by annealing the samples at the temperatures lower than 640 ℃.

  15. Preparation of Lanthanum-Doped Pb(Zr,Ti)O3 Ceramics Sheets by Tape Casting

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The physical and electrical properties of lanthanum doped Pb(Zr,Ti)O3 ceramic sheets (PLZT) which were prepared by tape casting method were carried out. Tape casting of lanthanum modified PZT was performed using commercial cellulose acetate binders and poly(ethylene glycol) plasticizers in ethanol solvent. Tapes from these slips were casted on a polymer substrate. The PLZT green tapes were stacked for 5 units and sintered in air at 1050℃ for 1 h with heating rate 5℃/min. SEM micrographs show that the tape is dense (90.26% of theoretical density) and rather uniform with grain size of approximately 1.1 ? m. The dielectric permittivity and loss tangent of PLZT ceramics as a function of temperature at 1 kHz suggest that the compounds exhibit a phase transition of diffuse type. The transition temperature (Tm) and piezoelectric coefficient (d33) were 110℃ and 117 pC/N, respectively.

  16. Influences of Mechanical Vibration on Rapidly Solidified Al2O3/YSZ Ceramics Prepared by Combustion Synthesis

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zhong-min; ZHANG Long; WANG Wei-guo; ZHANG Shi-yue

    2006-01-01

    Al2O3/YSZ composite ceramics was fabricated with combustion synthesis technology, and the influences of mechanical vibration on its microstructures and properties were investigated. It is found that under the mechanical vibration of ever-increasing frequency, increasing combustion temperature, accelerating ceramics/metal liquid-liquid separation and quickening ceramic solidification could not only reduce the average diameter and the size distribution of aligned ZrO2 nano-micron fibers in rod-shaped Al2O3 matrix grains, but also make the randomly-oriented rod-shaped grains finer and increase their aspect ratios. As a result, a remarkable increase in flexural strength and fracture toughness of the ceramics can be observed.

  17. Ultra high strain properties of lanthanum substituted PZT electro-ceramics prepared via mechanical activation

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Ajeet, E-mail: jkajeet@yahoo.co.in [Ceramics and Composites Group, Defence Metallurgical Research Laboratory, Hyderabad 500058 (India); School of Physics, University of Hyderabad, Hyderabad 500046 (India); Bhanu Prasad, V.V., E-mail: bhanu@dmrl.drdo.in [Ceramics and Composites Group, Defence Metallurgical Research Laboratory, Hyderabad 500058 (India); James Raju, K.C., E-mail: kcjrsp@yahoo.com [School of Physics, University of Hyderabad, Hyderabad 500046 (India); James, A.R., E-mail: james@dmrl.drdo.in [Ceramics and Composites Group, Defence Metallurgical Research Laboratory, Hyderabad 500058 (India)

    2014-06-25

    Highlights: • PLZT comparable with PMN–PT and their hot-pressed counterparts synthesized. • HEM applied for ceramic preparation at reduced sintering temperature. • Strain value (0.27%) comparable to previous reported values for PLZT 8/60/40. • The electric field induced (strain) hysteresis loss was also found to be very less. - Abstract: Substitution of lanthanum at the A sites of perovskite lead zirconate titanate ceramics shows an improvement in the structural and electrical properties. (Pb{sub 0.92}La{sub 0.08})(Zr{sub 0.60}Ti{sub 0.40})O{sub 3} (PLZT 8/60/40) was prepared using high energy mechano-chemical milling. The effect of milling on the microstructure and electrical properties of PLZT 8/60/40 has been studied. X-ray diffraction shows the phase formation after milling itself. TEM was used to measure the particle size. The SEM image of the sintered pellet shows a dense microstructure and the average grain size was found to be <1.5 μm. Electrical properties of the ceramics were characterized. Piezoelectric charge coefficient (d{sub 33}) was found to be 561 pC/N. Resonance studies were performed on poled ceramics and the electromechanical coupling factor was calculated by the resonance method. The PLZT 8/60/40 composition showed a well saturated and uniform P–E hysteresis loop with remanent polarization (P{sub r}) of 33.29 μC/cm{sup 2} and a coercive field (E{sub c}) of 10.57 kV/cm. Electric field induced strain (S–E loop) shows a value of ∼0.27% with minimum loss.

  18. Effects of Fiber Content on Mechanical Properties of CVD SiC Fiber-Reinforced Strontium Aluminosilicate Glass-Ceramic Composites

    Science.gov (United States)

    Bansal, Narottam P.

    1996-01-01

    Unidirectional CVD SiC(f)(SCS-6) fiber-reinforced strontium aluminosilicate (SAS) glass-ceramic matrix composites containing various volume fractions, approximately 16 to 40 volume %, of fibers were fabricated by hot pressing at 1400 C for 2 h under 27.6 MPa. Monoclinic celsian, SrAl2Si2O8, was the only crystalline phase formed, with complete absence of the undesired hexacelsian phase, in the matrix. Room temperature mechanical properties were measured in 3-point flexure. The matrix microcracking stress and the ultimate strength increased with increase in fiber volume fraction, reached maximum values for V(sub f) approximately equal to 0.35, and degraded at higher fiber loadings. This degradation in mechanical properties is related to the change in failure mode, from tensile at lower V(sub f) to interlaminar shear at higher fiber contents. The extent of fiber loading did not have noticeable effect on either fiber-matrix debonding stress, or frictional sliding stress at the interface. The applicability of micromechanical models in predicting the mechanical properties of the composites was also examined. The currently available theoretical models do not appear to be useful in predicting the values of the first matrix cracking stress, and the ultimate strength of the SCS-6/SAS composites.

  19. Effect of Annealing on Ferroelectric Properties of Nanometre BaTiO3 Ceramics Prepared by High Pressure Sintering Method

    Institute of Scientific and Technical Information of China (English)

    LI Peng-Fei; JIN Chang-Qing; XIAO Chang-Jiang; WANG Feng-Ping; WANG Xiao-Hui; LI Long-Tu

    2007-01-01

    @@ Dense nanocrystalline BaTiO3 ceramics with a grain size of 50nm are prepared under 6 GPa at 1273K using a high pressure sintering method. The sintered bulk is uniform and the relative density is above 97%. We anneal the ceramic samples in oxygen with various temperatures and for different times without apparent grain growth. After the annealing, several broadened peaks can be observed at about 378K by dielectric measurements. However,these peaks are very different from those of coarser-grained ceramics. It is indicated that both the elimination of oxygen vacancies and the release of residual stresses caused by high pressure greatly improve the overall ferroelectric properties of BaTiO3 ceramics. The observation of nearly linear polarization hysteresis loop after anneal provides the solid evidence of ferroelectricity in these nano-sized BaTiO3 ceramics.

  20. Cellulose nanowhiskers from coconut husk fibers: effect of preparation conditions on their thermal and morphological behavior

    Science.gov (United States)

    Cellulose nanowhiskers were prepared by sulfuric acid hydrolysis from coconut husk fibers which had previously been submitted to a delignification process. The effects of preparation conditions on the thermal and morphological behavior of the nanocrystals were investigated. Cellulose nanowhisker sus...

  1. Preparation of PVA/ H3PW12O40 Fiber Mats

    Institute of Scientific and Technical Information of China (English)

    Jian GONG; Chang Lu SHAO; Guo Cheng YANG; Yan PAN; Lun Yu QU

    2004-01-01

    Poly(vinyl alcohol) (PVA) fiber mats containing 20 and 80 wt% H3PW12O40 were prepared by using electrospinning technique. The fiber mats were characterized by IR, XRD spectra and scanning electron microscope (SEM). The diameter of the fiber mats is ca. 400 nm.

  2. In Situ Preparation of Titanium Carbide Ceramic Layer on Grey Cast Iron

    Directory of Open Access Journals (Sweden)

    Lisheng ZHONG

    2015-11-01

    Full Text Available In this article, we report the in situ synthesis of TiC ceramic layer between titanium plate and graphite phases in grey cast iron using heat treatment method. The microstructure of the compound region was characterized by X-ray diffraction (XRD and scanning electron microscopy (SEM, and the kinetics of the TiC ceramic layer was analyzed. The results revealed that the as-prepared TiC samples were irregularly shaped particles with a size of 1 ~ 8 μm and gradient distribution on the surface of grey cast iron. The thickness of the reaction layers increased gradually as the incubation continued, which were 62, 81, 95 and 108 μm after incubation at 1164 °C for 1, 2, 3 and 4 hours, respectively. Also, it can be recognized that the layer thickness changes in a parabolic style with incubation duration. The formation process of TiC ceramic layer consists of diffusion and in situ reaction of carbon and titanium atoms.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9700

  3. A novel method for preparing microfibrillated cellulose from bamboo fibers

    Science.gov (United States)

    Dat Nguyen, Huu; Thanh Thuy Mai, Thi; Bich Nguyen, Ngoc; Duy Dang, Thanh; Loan Phung Le, My; Dang, Tan Tai; Tran, Van Man

    2013-03-01

    The bamboo fiber is a potential candidate for biomass and power source application. In this study, microfibrillated cellulose (MFC) is prepared from raw fibers of bamboo tree (Bambusa Blumeana J A & J H Schultes) by an alkali treatment at room temperature in association with a bleaching treatment followed by a sulfuric acid hydrolysis. Field-emission scanning electron microscopy (FESEM) images indicated that final products ranged from 20 to 40 nm in diameter. The chemical composition measurement and Fourier transform infrared (FTIR) spectroscopy showed that both hemicellulose and lignin are mostly removed in the MFC. The x-ray diffraction (XRD) results also show that MFC has crystallinity of more than 70%. The thermogravimetric analysis (TGA) curves revealed that cellulose microfibers have a two-step thermal decomposition behavior owing to the attachment of sulfated groups onto the cellulose surface in the hydrolysis process with sulfuric acid. The obtained MFCs may have potential applications in alternative power sources as biomass, in pharmaceutical and optical industries as additives, as well as in composite fields as a reinforcement phase.

  4. Preparation and Properties of Carbon Fiber Chiral Materials

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ping; HUANG Zhixin; WANG Guoqing

    2008-01-01

    The chiral materials were prepared by using the carbon fiber helices as chiral inclusions,and the composite of Fe3O4 and polyaniline as matrix.The electromagnetic properties,including the rotation angles,the axial ratios and the complex chirality parameters,were measured by using a circular waveguide method in the 8.5-11.0 GHz frequency range.The dependence of these electromagnetic properties on the frequency and the concentration of the Fe3O4 in the composite matrix were analyzed.The results show that an appropriate concentration of Fe3O4 in the matrix is useful in improving the electromagnetic properties of the chiral material.

  5. Technical progress report during Phase 1 of the continuous fiber ceramic composites program

    Energy Technology Data Exchange (ETDEWEB)

    Richerson, D.W.

    1994-03-15

    United States industry has a critical need for materials that are lightweight, strong, tough, corrosion resistant and capable of performing at high temperatures; such materials will enable substantial increase in energy efficiency and reduction in emissions of pollutants. Continuous fiber ceramic composites (CFCCs) are an emerging class of materials which have the potential for the desired combination of properties to meet the industrial needs. A $10 billion annual market has been estimated for CFCC products by the year 2010, which equates to over 100,000 industrial sector jobs. The CFCC program began in the spring of 1992 as a three-phase 10-year effort to assess potential applications of CFCC materials, develop the necessary supporting technologies to design, analyze and test CFCC materials, conduct materials and process development guided by the applications assessment input, fabricate test samples and representative components to evaluate CFCC material capabilities under application conditions, and analyze scaleability and manufacturability plus demonstrate pilot-scale production engineering. DOE awarded 10 Phase I cooperative agreements to industry-lead teams plus identified generic supporting technology projects. This document highlights the broad progress and accomplishments on these contracts and support technology projects during Phase I.

  6. 增强纤维对陶瓷基摩擦材料摩擦磨损性能的影响%Effects of Reinforced Fibers on Friction and Wear Properties of Ceramic-based Friction Material

    Institute of Scientific and Technical Information of China (English)

    刘莹; 王发辉

    2012-01-01

    采用热压烧结法制备纤维增强陶瓷基摩擦材料,研究了钢纤维、钢纤维/莫来石纤维、莫来石纤维、钢纤维/硅酸铝纤维以及硅酸铝纤维增强陶瓷基摩擦材料的摩擦磨损特性.研究结果表明:不同纤维对陶瓷基摩擦材料摩擦系数的影响较为复杂.相比较添加单一纤维增强摩擦材料的情况,钢纤维增强的试样具有较好的耐磨性能,其次为莫来石纤维增强的试样,硅酸铝纤维增强的试样表现出最差的耐磨性能,钢纤维/莫来石纤维和钢纤维/硅酸铝纤维增强试样的磨损均低于相应的陶瓷纤维增强的试样;在高温下以莫来石纤维增强的试样,其磨损形式以磨粒磨损为主,而以硅酸铝纤维和钢纤维/硅酸铝纤维增强的试样的主要磨损形式为黏着磨损,钢纤维和钢纤维/莫来石纤维增强的试样的磨损属于磨粒磨损和黏着磨损.%Ceramic-based friction materials with different reinforced fibers was prepared by hot-pressing.The effects of steel fiber,steel/mullite fiber,mullite fiber,steel/aluminium-silicate fiber and aluminium-silicate fiber as reinforcing materials on the friction and wear properties of ceramic-based friction material were investigated.The results show a complex relationship between different kinds of reinforced fibers and the friction coefficients.For friction material reiforced by single fiber,steel fiber reinforced sample had the highest wear resistance,while aluminium-silicate fiber reinforced sample had the poorest wear resistance,mullite fiber reinforced sample had the moderate wear resistance.The wear rates of sample with steel/mullite fiber or steel/aluminium-silicate fiber were lower than that of the samples reinforced by the corresponding ceramic fibers.The friction and wear tests at elevated temperature reveal that the main wear mechanism of mullite fiber reinforced ceramic-based friction material was abrasive wear while the main wear mecanism for friction

  7. Preparation of Electrospun Polymer Fibers Using a Copper Wire Electrode in a Capillary Tube

    Science.gov (United States)

    Shinbo, Kazunari; Onozuka, Shintaro; Hoshino, Rikiya; Mizuno, Yoshinori; Ohdaira, Yasuo; Baba, Akira; Kato, Keizo; Kaneko, Futao

    2010-04-01

    Polymer fibers were prepared by an electrospinning method utilizing a copper wire electrode in a capillary tube. The morphology of electrospun poly(vinyl alcohol) (PVA) fibers was observed, and was found to be dependent on the wire electrode tip position in the capillary tube, the concentration of the polymer solution, the distance between the electrodes, and the applied voltage. By using the wire electrode, the experimental setup is simple and the distance between the electrodes and the applied voltage can be easily reduced. Furthermore, the preparation of poly(3-hexylthiophene) (P3HT) fibers was carried out. P3HT fibers were successfully prepared by mixing poly(ethylene oxide) (PEO) in P3HT solution. Orientation control was also carried out by depositing the fibers on a rotating collector electrode, and the alignment of the P3HT:PEO fibers was confirmed. Anisotropy of the optical absorption spectra was also observed for the aligned fibers.

  8. A new class of boron nitride fibers with tunable properties by combining an electrospinning process and the polymer-derived ceramics route

    Science.gov (United States)

    Salles, Vincent; Bernard, Samuel; Brioude, Arnaud; Cornu, David; Miele, Philippe

    2010-02-01

    Novel boron nitride (BN) fibers have been developed with diameters ranging from the nano- to microscale by thermal conversion of as-electrospun fibers from polyacrylonitrile and poly[B-(methylamino)borazine] blend solutions. Such a new class of ceramic fibers is seen as potential candidate for thermal management applications and filtration systems in harsh environments.Novel boron nitride (BN) fibers have been developed with diameters ranging from the nano- to microscale by thermal conversion of as-electrospun fibers from polyacrylonitrile and poly[B-(methylamino)borazine] blend solutions. Such a new class of ceramic fibers is seen as potential candidate for thermal management applications and filtration systems in harsh environments. Electronic supplementary information (ESI) available: Experimental details and EDX results. See DOI: 10.1039/b9nr00185a

  9. Fiber-reinforced resin coating for endocrown preparations: a technical report.

    Science.gov (United States)

    Rocca, G T; Rizcalla, N; Krejci, I

    2013-01-01

    Coronal rehabilitation of endodontically treated posterior teeth is still a controversial issue. Although the use of classical crowns supported by radicular metal posts remains widespread in dentistry, their invasiveness has been largely criticized. New materials and therapeutic options based entirely on adhesion are available nowadays, from direct composite resins to indirect endocrowns. They allow for a more conservative, faster, and less expensive dental treatment. However, the absence of a metal or high-strength ceramic substructure as in full-crown restorations can expose this kind of restoration to a higher risk of irreversible fracture in case of crack propagation. The aim of this case report is to present a technique to reinforce the cavity of an endodontically treated tooth by incorporating a fiber-reinforced composite (FRC) layer into the resin coating of the tooth preparation, before the final impressions of the cavity. This technique allows the use of FRCs in combination with any kind of restorative material for an adhesive overlay/endocrown.

  10. Physiological function of insoluble dietary fiber prepared from exploded oak wood (Quercus mongolica).

    Science.gov (United States)

    Yang, Jae-Kyung; Choi, Myung-Suk; Kim, Chang-Joon; Shin, Yong-Seung; Han, Dae-Yong; Han, Sang-Woo; Lim, Bu-Kug; Lee, Jong-Yoon; Rhee, Soon-Jae; Kim, Eun-Hee; Kim, Gon-Sup

    2006-01-01

    This study investigated the production of insoluble dietary fiber using exploded and chemically treated oak wood (Quercus mongolica) and the physiological functions of prepared insoluble dietary fiber in laboratory animals. To produce high quality insoluble dietary fiber, the steam explosion treatment was performed at 25 kgf/cm2 pressure for 6 minutes. In the chemical analysis of insoluble dietary fiber, exploded oak wood was pretreated by 1% sodium hydroxide solution. The insoluble dietary fiber contained 7.6% residual lignin and 61.7% of alpha-cellulose. In order to compare the physiological functions of prepared insoluble dietary fiber with those of commercial insoluble dietary fiber, Sprague-Dawley male rats weighing 100 +/- 10 g were randomly assigned to one normal diet and five high cholesterol diets, containing 1% cholesterol. The high cholesterol diet groups were classified as the fiber-free diet (FF group), 5% commercial alpha-cellulose diet group (5C group), 10% commercial alpha-cellulose group (10C group), 5% insoluble dietary fiber group (5M group) and 10% insoluble dietary fiber group (10M group). Food intake, weight gain and food efficiency ratio in high cholesterol groups were significantly higher than those of the normal group, but there were no significant differences among the high cholesterol diet groups. In addition, there were no significant differences in the weights of liver, kidney and small intestine in insoluble dietary fiber-supplemented groups. Cecum weights in all insoluble dietary fiber groups were significantly higher than those of the FF group. There were no significant differences in the activities of the glutamic pyruvic transaminase (GPT) and glutamic oxaloacetic transaminase (GOT) among the insoluble dietary fiber-supplemented groups. In conclusion, the prepared insoluble dietary fiber and the commercially available insoluble fiber showed the same physiological effects. Moreover, the preparation method for the insoluble dietary

  11. All-ceramic single-tooth restorations: choosing the material to match the preparation--preparing the tooth to match the material.

    Science.gov (United States)

    Baltzer, A

    2008-01-01

    The shape of a crown preparation is the prime determinant for the choice of material for an all-ceramic restoration. One essential factor is the available space for the restoration, which requires a certain occlusal thickness. The dentist's preparation design determines the available vertical clearance, and the dental technician has the responsibility of advising the dentist with regard to either choosing the right material to match the preparation or to preparing the tooth to match the material. Assuming a minimum static fracture strength of > 2000 N, the following materials can be used for all-ceramic crowns: Laboratory surveys have shown that in most situations, the available occlusal clearance in clinical reality is only 0.8 to 0.9 mm (after cementing). This shows that the available space will often be insufficient for providing monoblock crowns and still on the tight side for veneered oxide ceramics (In Ceram, zirconia, etc.). However, crowns made of veneered oxide ceramics are much more complex to fabricate and much more expensive. By simply providing a minimal occlusal thickness of 1.5 mm, the treatment provider could therefore easily facilitate the use of the much more economical monoblock crowns without compromising either esthetics or strength. Actually, crowns with veneered oxide ceramic copings do not offer any higher fracture resistance compared to Mark II crowns as long as the minimum thickness requirements are met. The flexural strength of CAD/CAM-fabricated lithium disilicate rods is about twice that of CAD/CAM-fabricated Mark II rods. When used for crowns with a wall thickness of 1.5 mm, however, both materials exhibit the same fracture strength of between 2000 and 2500 N. This is related to the different reinforcing action of the adhesive luting agent, which is essentially required for both these materials. When choosing a material, preparation shapes, technical complexity and cost should be thoroughly compared and scrutinized and should figure

  12. Preparation of BN/SiO2 ceramics by PIP method

    Institute of Scientific and Technical Information of China (English)

    WANG Jing; WEN Guang-wu; MENG Qing-chang

    2005-01-01

    The precursor infiltration and pyrolysis(PIP) method for preparation of BN/SiO2 composites was used to improve mechanical properties, dielectric properties and feasibility of high temperature dielectric parts with large dimensions and complex shapes. In the processing procedure, the porous BN ceramic matrix was first successfully prepared by compacting the mixed powders of B and BN and then sintering them at a certain temperature under normal pressure of N2.The polycarbosilane(PCS) solution was vacuum infiltrated into porous BN ceramics at the room temperature and then at 800 ℃ in the air to depolimerize out amorphous SiO2, and sintered further at 1 300 ℃ in N2 to get BN/SiO2 composites. The microstructure of materials was studied by means of X-ray diffraction and electron probe micro analysis. The thermo-decomposition mechanism of PCS was investigated by a TG-DTA and infrared (IR) spectrum analysis. The flexural strengths were measured by the three-point bending method. The dielectric constant and the loss tangent were measured by the wave-guide method. The results show BN/SiO2 composites were fabricated. The obtained composites posses a flexural strength of 61.9693.31 MPa, the dielectric constant in the range of 3.503.78 and the order of magnitude of the loss tangent at 10-3, which are good for the high temperature dielectric parts with large size and complex shapes.

  13. Characterization of Ceramic Composite-Membranes Prepared by ORMOSIL Coating Sol

    Institute of Scientific and Technical Information of China (English)

    Goo-Dae Kim; Tae-Bong Kim

    2004-01-01

    Sol-gel methods offer many advantages over conventional slip-casting, including the ability to produce ceramic membranes. They are purer, more homogeneous, more reactive and contain a wider variety of compositions. We produced ormosil sol using sol-gel process under different molecular weight of polymer species [polyethylene glycol (PEG) ] in total system [Tetraethyl ortho silicate(TEOS)-polyethylene glycol (PEG)]. The properties of as-prepared ormosil sol such as,viscosity, gelation time were characterized. Also, the ceramic membrane was prepared by dip-coating with synthetic sol and its micro-structure was observed by scanning electron microscopy. The permeability and rejection efficiency of membrane for oil/water emulsion were evaluated as cross-flow apparatus. The ormosil sol coated Membrane is easily formed by steric effect of polymer and it improves flux efficiency because infiltration into porous support decreased. Its flux efficiency is elevated about 200(1/m2·h) compared with colloidal sol coated membrane at point of five minutes from starting test.

  14. Eco prep: the economical preparation of ceramic bodies; Ecoprep: la preparacion rentable de masas ceramicas

    Energy Technology Data Exchange (ETDEWEB)

    Luders, M.; Walter, H. J.; Nold, P.; Lobe, R.; Muller, M.; Gerl, S.

    2012-07-01

    Eco prep (Economic Preparation) is the sustainable technology for preparing ceramic bodies with a minimum consumption of resources. It has a huge impact on the energy balance and eliminates the need for additives to generate a high-quality slip to make granules. In consequence Eco prep delivers a significant reduction in production costs, bringing an investment in this technology to the break-even point after a very short time. Reduction in water consumption and additives and the use of new raw materials are other advantages that impulse the implementation of this production technology, as well as important reduction of CO{sub 2} emissions, contributing to meeting the goals of the Kyoto Protocol. In short: A technology already successfully applied in different industries for decades, that includes a compendium of measures based on saving reductions in a range from 66% (energy, water,) and 100% (additives, deflocculants, etc.) and will mark the future in micro granulation processes also in the ceramic industry. (Author)

  15. Optical fibers of As2S3 glasses: preparation and characterization

    Science.gov (United States)

    Podrazký, Ondřej; Matějec, Vlastimil; Kostka, Petr; Pedliková, Jitka; Bašinová, Nikola; Zavadil, Jiří

    2015-01-01

    Chalcogenide glasses based on arsenic sulfide (As2S3), arsenic selenide or telluride are known to exhibit high optical nonlinearities which are necessary for advanced applications in telecommunications. Both, standard optical fibers and microstructured fibers have been fabricated from chalcogenide glasses. In this paper we deal with As2S3 solid core fibers and capillary fibers coated with a polymer jacket of UV acrylate. The guiding mechanism employing the reflection on boundary of high-index glass (a refractive index of about 2.4) and hollow cavity (n=1) was confirmed by ray-optic calculations. Fibers were drawn from input As2S3 rods and tubes. The rods were prepared from extra pure arsenic and sulfur by their melting in an evacuated ampoule. The tubes were prepared by using rotational melting technique in an evacuated ampoule rotating at 1600 rpm. Rods and tubes were elongated into fibers by using a fiber drawing facilities for preparation of optical fibers from soft optical glasses. Temperatures in a range 300-400 °C and drawing velocities of about 0.1 m/s were used. Fibers were prepared either without any polymeric jacket or they were provided by a jacket of UV acrylate (n ˜ 1.5). Fibers with diameters from 0.2 to 0.4 mm were fabricated. Dimensions of prepared fibers were measured by optical microscopy without prior polishing. Transmission properties of prepared fibers were characterized by measuring angular distributions of output power at the wavelength of 670 nm. Optical losses of fibers exceeding 2 dB/m were determined by using the cut back method.

  16. [The evaluation of carcinogenic effect in rats and mice after intraperitoneal administration of refractory ceramic fibers].

    Science.gov (United States)

    Krajnow, A; Lao, I; Stetkiewicz, J; Wiecek, E

    1998-01-01

    The carcinogenic effect of Langfaser and Thermowool ceramic fibres was assessed in Wistar rats and BALB/C mice. Fibres were administered into the animal peritoneal cavity in doses of 25 and 5 mg, and the animals were left for survival. Langfaser and Thermowool ceramic fibres were found carcinogenic. The carcinogenic properties of Thermowool ceramic fibre can be compared to those of Krokidoit UICC asbestos.

  17. 新型耐高温氮化物陶瓷纤维研究进展%Research progress in new high temperature resistant nitride ceramic fiber

    Institute of Scientific and Technical Information of China (English)

    彭雨晴; 韩克清; 赵曦; 袁佳; 余木火

    2011-01-01

    介绍了耐高温氮化物陶瓷纤维的种类及制备方法即有机聚合物先驱体转化法;综述了Si3N4,BN,SiBN,SiBN(C)陶瓷纤维的研究进展;重点介绍了SiBN(C)陶瓷纤维的研究现状,并与SiC纤维进行性能对比.指出具有耐高温、透波性等功能结构一体化的SiBN(C)陶瓷纤维是陶瓷纤维的重要发展方向,简化先驱体的合成过程及降低制备成本是技术关键,聚合物分子结构设计和纺丝工艺还有待深入研究.%Hie variety and the production technology, I.e. Organic polymer precursor conversion method, of high temperature resistant nitride ceramic fiber was introduced. The research progress in Si3N4, BN, SiBN and SiBN(C) ceramic fibers was reviewed. The research situation of SiBN(C) ceramic fiber was emphatically introduced. And the properties of SiBN( C) ceramic fiber were compared with those of SiC fiber. It was pointed out that the development trend of ceramic fibers would focus on the function-structure integrated SiBN(C) ceramic fiber with high temperature resistance and wave transmissivity, the key technology should be the simplification of precursor synthesis process and the reduction of production cost, and the polymer molecular structure design and the spinning process should be studied further.

  18. Preparation and characterization of microporous fibers for sample preparation and LC-MS determination of drugs.

    Science.gov (United States)

    Buszewski, Boguslaw; Nowaczyk, Jacek; Ligor, Tomasz; Olszowy, Pawel; Ligor, Magdalena; Wasiniak, Bartlomiej; Miekisch, Wolfram; Schubert, Jochen K; Amann, Anton

    2009-07-01

    The aim of this study was the preparation of polypyrrole (PPy) fibers for solid phase microextraction (SPME). PPy coatings were obtained during the electrochemical polymerization process. The utility of various metal wires (Fe, Cu, Ag, Cu/Ag, kanthal and medical stainless steel) as a support for polymers was compared. Various experimental conditions of the synthesis process such as scan rate, voltage limits and number of scans and deposition time were applied. The average polymer thickness was in the range of 7-125 microm and its weight was in the scope of 0.65-5.6 mg. Different techniques, mainly elemental analysis, Fourier transform infrared spectroscopy, microscopy, and chromatography were performed for the characterization of obtained fibers with microporous structure. The extraction efficiency of cardiovascular drugs (metoprolol, propranolol, oxprenolol, propafenone and mexiletine) by means of fibers was tested. The concentration of mentioned compounds in standard solution was in the span of 10-150 ng/mL. LC-MS was employed for determination of drugs in desorption solution. LODs varied from 0.013 to 1.51 ng/mL for metoprolol and mexiletine respectively. The repeatability of extraction was obtained with the RSD values lower than 10%.

  19. Preparation of Paper Mulberry Fibers and Possibility of Cotton/Paper Mulberry Yarns Production

    Directory of Open Access Journals (Sweden)

    Manoon Jitjaicham

    2016-01-01

    Full Text Available The novelty of yarn production from cotton/paper mulberry fiber blends was reported. The objective of this research was to prepare the paper mulberry fibers and study the possibility of production of yarns from cotton/paper mulberry fibers. For preparation of paper mulberry fibers, the inner bark was first immersed in water for 24 h. Then, the fibers were treated with sodium hydroxide at concentration of 5–10% (w/v for 1–3 h. After that, the bleaching process was conducted with hydrogen peroxide at concentration of 5–25% (v/v for different temperature and time. Finally, the fibers were washed with 10% (v/v of nonionic surfactant at temperature of 90°C for 30 minute to remove the residual gum from the fibers. The results showed that optimum condition for scouring of the paper mulberry fibers was 15% (w/v sodium hydroxide at 90°C for 2 h. The bleaching process with 15% (v/v H2O2 at 90°C for 90 minute was suitable. The obtained fibers were blended with the cotton fibers to produce yarns by open-end spinning method. The % elongation and tenacity of the blended yarns increased with the increasing of the paper mulberry ratio. Also, the antifungal property of yarns was improved by the blending of cotton fibers with the paper mulberry fibers.

  20. Research & Development of Materials/Processing Methods for Continuous Fiber Ceramic Composites (CFCC) Phase 2 Final Report.

    Energy Technology Data Exchange (ETDEWEB)

    Szweda, A.

    2001-01-01

    The Department of Energy's Continuous Fiber Ceramic Composites (CFCC) Initiative that begun in 1992 has led the way for Industry, Academia, and Government to carry out a 10 year R&D plan to develop CFCCs for these industrial applications. In Phase II of this program, Dow Corning has led a team of OEM's, composite fabricators, and Government Laboratories to develop polymer derived CFCC materials and processes for selected industrial applications. During this phase, Dow Corning carried extensive process development and representative component demonstration activities on gas turbine components, chemical pump components and heat treatment furnace components.

  1. Electrostatic Assembly Preparation of High-Toughness Zirconium Diboride-Based Ceramic Composites with Enhanced Thermal Shock Resistance Performance.

    Science.gov (United States)

    Zhang, Baoxi; Zhang, Xinghong; Hong, Changqing; Qiu, Yunfeng; Zhang, Jia; Han, Jiecai; Hu, PingAn

    2016-05-11

    The central problem of using ceramic as a structural material is its brittleness, which associated with rigid covalent or ionic bonds. Whiskers or fibers of strong ceramics such as silicon carbide (SiC) or silicon nitride (Si3N4) are widely embedded in a ceramic matrix to improve the strength and toughness. The incorporation of these insulating fillers can impede the thermal flow in ceramic matrix, thus decrease its thermal shock resistance that is required in some practical applications. Here we demonstrate that the toughness and thermal shock resistance of zirconium diboride (ZrB2)/SiC composites can be improved simultaneously by introducing graphene into composites via electrostatic assembly and subsequent sintering treatment. The incorporated graphene creates weak interfaces of grain boundaries (GBs) and optimal thermal conductance paths inside composites. In comparison to pristine ZrB2-SiC composites, the toughness of (2.0%) ZrB2-SiC/graphene composites exhibited a 61% increasing (from 4.3 to 6.93 MPa·m(1/2)) after spark plasma sintering (SPS); the retained strength after thermal shock increased as high as 74.8% at 400 °C and 304.4% at 500 °C. Present work presents an important guideline for producing high-toughness ceramic-based composites with enhanced thermal shock properties.

  2. Effects of single pulse energy on the properties of ceramic coating prepared by micro-arc oxidation on Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun-Hua [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023 (China); Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming 650500 (China); Wang, Jin [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control, Beijing 100084 (China); Lu, Yan [School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023 (China); Du, Mao-Hua [Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming 650500 (China); Han, Fu-Zhu, E-mail: hanfuzhu@mail.tsinghua.edu.cn [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control, Beijing 100084 (China)

    2015-01-01

    Highlights: • Single pulse energy remarkably influences the properties of ceramic coating prepared by MAO on Ti alloy. • The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. • The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. • Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. • The effects of single pulse energy on the micro-hardness and phase composition of ceramic coating are not as evident as those of frequency and duty cycle. - Abstract: The effects of single pulse energy on the properties of ceramic coating fabricated on a Ti–6Al–4V alloy via micro-arc oxidation (MAO) in aqueous solutions containing aluminate, phosphate, and some additives are investigated. The thickness, micro-hardness, surface and cross-sectional morphology, surface roughness, and compositions of the ceramic coating are studied using eddy current thickness meter, micro-hardness tester, JB-4C Precision Surface roughness meter, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Single pulse energy remarkably influences the ceramic coating properties. The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. The sizes of oxide particles, micro-pores and micro-cracks slightly increase with impulse width and single pulse energy. The main surface conversion products generated during MAO process in aqueous solutions containing aluminate are rutile TiO{sub 2}, anatase TiO{sub 2}, and a large amount of Al{sub 2}TiO{sub 5}. The effects of

  3. Rheological Behavior of Slurries Containing Short Glass Fibers for Preparation of Investment Casting Shell

    Directory of Open Access Journals (Sweden)

    MA Hai-jiao

    2016-08-01

    Full Text Available The short glass fibers were introduced into the slurries by 0%-0.5% (mass fraction of refractory powders for preparation of fiber-reinforced shells for investment casting. The rheological properties of coatings containing different amounts of glass fibers were measured by R/S rheometer and the rheological behaviors of coatings were investigated. The results show that the apparent viscosities of coatings containing different amounts of glass fibers decrease with increasing shear rate, i.e., shear thinning behavior, similar to that of the coating without fibers. At the same shear rate, the apparent viscosities of coatings containing fibers are higher than that of the coating without fibers and the apparent viscosities of coatings containing 0.3% (mass fraction fibers are higher than that of the others. The high shear viscosities of coatings containing fibers increase initially, but later decrease, with increasing amount of fibers. The high shear viscosity of the coating containing 0.3% fibers reaches a maximum value of 102.6×10-3Pa·s, increased by about 31.9%, in comparison to the coating without fibers. And this coating with a maximum thixotropical loop area value of 11.8Pa·s-1 exhibits an excellent thixotropical behavior. However, it is not found that there is a noticeable effect of the amount of glass fibers on the yield stress or suspensibility of coatings.

  4. Preparation and characterization of novel glass-ceramic tile with microwave absorption properties from iron ore tailings

    Science.gov (United States)

    Yao, Rui; Liao, SongYi; Dai, ChangLu; Liu, YuChen; Chen, XiaoYu; Zheng, Feng

    2015-03-01

    A novel glass-ceramic tile consisting of one glass-ceramic layer (GC) attaining microwave absorption properties atop ceramic substrate was prepared through quench-heat treatment route derived from iron ore tailings (IOTs) and commercial raw materials (purity range 73-99%). X-ray diffraction (XRD), SEM, Energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), Physical property measurement system (PPMS) and Vector network analyzer (VNA) measurements were carried out to investigate phase, microstructure, magnetic and microwave absorption aspects of the glass-ceramic layer. Roughly 80.6±1.7 wt% borosilicate glass and 19.4±1.7 wt% spinel ferrite with chemical formula of (Zn2+0.17Fe3+0.83)[Fe3+1.17Fe2+0.06Ni2+0.77]O4 were found among the tested samples. Absorption of Electromagnetic wave by 3 mm thick glass-ceramic layer at frequency of 2-18 GHz reached peak reflection loss (RL) of -17.61 dB (98.27% microwave absorption) at 10.31 GHz. Altering the thickness of the glass-ceramic layer can meet the requirements of different level of microwave absorption.

  5. Joining of SiC Fiber-Bonded Ceramics using Silver, Copper, Nickel, Palladium, and Silicon-Based Alloy Interlayers

    Energy Technology Data Exchange (ETDEWEB)

    Asthana, Rajiv [University of Wisconsin-Stout, Menomonie; Singh, Mrityunjay [NASA-Glenn Research Center, Cleveland; Lin, Hua-Tay [ORNL; Matsunaga, Kenji [Ube Industries, Ltd.; Ishikawa, Toshihiro [Ube Industries, Ltd.

    2013-01-01

    SiC fiber-bonded ceramics, SA-Tyrannohex, (SA-THX) with perpendicular and parallel fiber orientations were brazed using Ag-, Ni- and Pd-base brazes, and four Si X (X: Ti, Cr, Y, Ta) eutectics. Outcomes were variable, ranging from bonded joints through partially bonded to un-bonded joints. Prominent Ti- and Si-rich interfaces developed with Cusil-ABA, Ticusil, and Copper-ABA and Ni- and Si-rich layers with MBF-20. Stress rupture tests at 650 and 750 C on Cusil-ABA-bonded joints revealed a temperature-dependent behavior for the perpendicular joints but not for the parallel joints with failure occurring at brazed interface. Higher-use temperatures can be targeted with eutectic Si Ti and Si Cr alloys.

  6. Development of Nano-crystalline Doped-Ceramic Enabled Fiber Sensors for High Temperature In-Situ Monitoring of Fossil Fuel Gases

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Hai [Missouri Univ. of Science and Technology, Rolla, MO (United States); Dong, Junhang [Univ. of Cincinnati, OH (United States); Lin, Jerry [Arizona State Univ., Tempe, AZ (United States); Romero, Van [New Mexico Institute of Mining and Technology, Socorro, NM (United States)

    2012-03-01

    This is a final technical report for the first project year from July 1, 2005 to Jan 31, 2012 for DoE/NETL funded project DE-FC26-05NT42439: Development of Nanocrystalline Doped-Ceramic Enabled Fiber Sensors for High Temperature In-Situ Monitoring of Fossil Fuel Gases. This report summarizes the technical progresses and achievements towards the development of novel nanocrystalline doped ceramic material-enabled optical fiber sensors for in situ and real time monitoring the gas composition of flue or hot gas streams involved in fossil-fuel based power generation and hydrogen production.

  7. 陶瓷纤维炉衬表面防护技术%Surface Protection Technology for Ceramic Fiber Furnace Lining

    Institute of Scientific and Technical Information of China (English)

    侯世英

    2013-01-01

    通过分析陶瓷纤维制品作为工业炉炉衬的优缺点,综述了常用的陶瓷纤维表面防护技术的几种应用形式及其优缺点,同时提出了优化设计的一些建议.%Through analyzing the merits and demerits of ceramic fiber products for industry furnace lining, some application forms and their advantages and disadvantages of the commonly used ceramic fiber surface protection technology were summarized, and some suggestions of optimization design were given out.

  8. Characterization of Green-Emitting Translucent Zinc Oxide Ceramics Prepared Via Spark Plasma Sintering

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Mei [University of California; DeVito, David M [ORNL; Howe, Jane Y [ORNL; Yang, Xiaocheng [West Virginia University; Giles, Nancy C. [Air Force Institute of Technology; Neal, John S [ORNL; Munir, Zuhair [University of California

    2011-01-01

    Translucent, green-emitting zinc oxide (ZnO) bodies, 19 mm in diameter and 0.72 mm in thickness, have been prepared via spark plasma sintering method. The consolidation of ZnO powders was investigated over the temperature range of 550-1050 C and the pressure range of 55-530 MPa. Samples sintered at temperatures >850 C and pressures of {approx}120 MPa were translucent and had densities of {approx}100%. Samples sintered at 950 C and 130 MPa showed a higher maximum transmittance than the samples sintered at higher or lower temperatures or pressures, with an excellent in-line transmission of 70% in the IR region around 2330 nm. The dense ZnO ceramics exhibited a strong green emission and a weak ultraviolet emission, and the relative intensity of the green emission increased with increasing sintering temperature.

  9. Low Temperature Preparation and Cold Manufacturing Techniques for Femoral Head of Al2O3 Ceramic

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The hip joint femoral head prosthesis was prepared using the Al2O3 material, which was synthesized by high purity alumina micro-powder and Mg- Zr- Y composite additives, the cold manufacturing techniques of lathe turning, grade polishing and the matching size correction of the sintered femoral head were studied. The results showed, after being pressed under 200 MPa cold isostatic pressure and being pre-sintered at 1 150 ℃, the biscuit' s strength can meet the demands of lathe turning; After being grade polished by SiC micro-powder and diamond abrading agent and being size corrected by special instruments, the femoral head prosthesis of Al2O3 ceramic has good surface degree of finish and articulates tightly with femoral handle.

  10. Preparation for femur prosthesis of ceramic-metal combination artificial hip joint

    Institute of Scientific and Technical Information of China (English)

    王欣宇; 李世普; 陈晓明; 贺建华

    2002-01-01

    Al2O3 material was synthesized by using high purity alumina micro-powder and Mg-Zr-Y composite additives at temperature of 1600℃, which had good mechanics property of 416MPa bending strength and 5.46MPa*m1/2 fracture toughness. Femur head prosthesis of hip joint was prepared by using this material; Ti alloy femur handle was sprayed bioactive hydroxyapatite (HA) by plasma on surface, which improves the chemistry stability and biocompatibility of Ti alloy; ceramic-metal combination artificial hip joint femur prosthesis was made by combining Al2O3 femur head with Ti alloy femur handle, so the manufacturing process is improved and the property and application flexibility are advanced.

  11. Preparation and Mechanical Properties of Al2O3/Al Laminated Ceramic Matrix Composites

    Institute of Scientific and Technical Information of China (English)

    HUANG Kangming; LI Weixin; XIE Binhuan; RAO Pinggen; PENG Cheng; CHEN Dabo; WU Jianqing

    2011-01-01

    Three series of Al2O3/Al laminated ceramic matrix composites,named SPA,SPV and HP,were fabricated by different methods.SPA and SPV were prepared using Al2O3 slices and Al slurry via screen printing and subsequent heat treatment in air or vacuum.HP samples were made by hot pressing the layered stack of Al foils and Al2O3 slices.SEM and XRD were applied to analyze the microstructure and the interlayer crystal phase.The bending strength,fracture toughness and fracture work of the samples made by the three methods were measured and compared.The results show that the composites have much better toughness and higher fracture work than the Al2O3 slice.Among the samples made by the three methods,the samples made by hot pressing have the optimum mechanical performance.The displacement-load curves and fracture mechanism were analyzed.

  12. PROCESSING AND CHARACTERIZATION OF TUBULAR CERAMIC SUPPORT FOR MICROFILTRATION MEMBRANE PREPARED FROM PYROPHYLLITE CLAY

    Directory of Open Access Journals (Sweden)

    Abedallah Talidi

    2011-09-01

    Full Text Available Tubular macroporous support for ceramic microfiltration membranes were prepared by extrusion followed by sintering of the low cost pyrophyllite clay. Clay powders mixed with some organic additives can be extruded to form a porous tubular support. The average pore size of the membrane is observed to increase from 5 µm to 10.8 µm when sintering temperature increase from 900 °C to 1200 °C. However, with the increase in temperature from 900 °C to 1200 °C, the support porosity is reduced from 47% to 30% and flexural strength is increased from 4 MPa to 17 MPa. The fabricated macro-porous supports are expected to have potential applications in the pre-treatment and also can be used like support for membranes of ultra-filtration.

  13. A new method of preparing fiber-optic DNA biosensor and its array for gene detection

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new method of preparing fiber-optic DNA biosensor and its arrayfor the simultaneous detection of multiple genes is described. The optical fibers were first treated with poly-l-lysine, and then were made into fiber-optic DNA biosensors by adsorbing and immobilizing the oligonucleotide probe on its end. By assembling the fiber-optic DNA biosensors in a bundle in which each fiber carried a different DNA probe, the fiber-optic DNA biosensor array was well prepared. Hybridization of fluorescent- labeled cDNA of p53 gene, N-ras gene and Rb1 gene to the DNA array was monitored by CCD camera. A good result was achieved.

  14. INVESTIGATION OF SOFTENING AGENT PREPARATION AND PERFORMANCE OF HANDMADE ECOCOMPOSITES WITH CONIFEROUS WOOD AND BASALT FIBERS

    Institute of Scientific and Technical Information of China (English)

    GuangjianWang; DekuShang; KailiangZhang; LinnaHu; ZhenhuaGuo

    2004-01-01

    In this investigation, basalt mineral fiber softening agent was prepared in order to obtain desirable flexible performance. Stability and physical chemistry natures of softening agent were evaluated by particle size distribution, dilution, storage and folding endurance etc. Constitutes of basalt and wood fibers were determined by energy dispersion analysis X-ray which served as an accessory of scanning electron microscopy (SEM-EDAX). Naturally degradable ecocomposite was prepared by basalt and wood fibers. The results of SEM observation illustrated that the wood and basalt fibers were blended uniformly. The impact factors of beating degree, content of wood fibers and adhesive etc. were discussed. The structure of the naturally degradable ecocomposite was contrasted with that of pure wood fibers and the cause of excellent filtration performance was analyzed. Compared with traditional methods, it was of saving wood resource, a large amount of water and reducing second pollution. As a consequence, the ecocomposite harmonized with environment and accorded with requirement of benignly friendly environment.

  15. Preparation and characterization of novel glass–ceramic tile with microwave absorption properties from iron ore tailings

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Rui; Liao, SongYi [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Dai, ChangLu [Guangdong Bode Fine Building Material Co. Ltd., Foshan 528000 (China); Liu, YuChen; Chen, XiaoYu [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Zheng, Feng, E-mail: fzheng@csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Phase diagrams and materials design center, Central South University, Changsha 410083 (China)

    2015-03-15

    A novel glass–ceramic tile consisting of one glass–ceramic layer (GC) attaining microwave absorption properties atop ceramic substrate was prepared through quench-heat treatment route derived from iron ore tailings (IOTs) and commercial raw materials (purity range 73–99%). X-ray diffraction (XRD), SEM, Energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), Physical property measurement system (PPMS) and Vector network analyzer (VNA) measurements were carried out to investigate phase, microstructure, magnetic and microwave absorption aspects of the glass–ceramic layer. Roughly 80.6±1.7 wt% borosilicate glass and 19.4±1.7 wt% spinel ferrite with chemical formula of (Zn{sup 2+}{sub 0.17}Fe{sup 3+}{sub 0.83})[Fe{sup 3+}{sub 1.17}Fe{sup 2+}{sub 0.06}Ni{sup 2+}{sub 0.77}]O{sub 4} were found among the tested samples. Absorption of Electromagnetic wave by 3 mm thick glass–ceramic layer at frequency of 2–18 GHz reached peak reflection loss (RL) of −17.61 dB (98.27% microwave absorption) at 10.31 GHz. Altering the thickness of the glass–ceramic layer can meet the requirements of different level of microwave absorption. - Highlights: • Iron ore tailings (IOTs) have been used as one of the main raw materials. • Glass–ceramic tile contains spinel ferrite has been prepared. • The cation distribution of the spinel ferrite has been calculated. • The intrinsic complex permeability and permittivity have been evaluated.

  16. Microanalytical investigations of fiber-reinforced ceramic materials. Mikroanalytische Untersuchungen faserverstaerkter keramischer Werkstoffe

    Energy Technology Data Exchange (ETDEWEB)

    Meier, B.; Grathwohl, G. (Karlsruhe Univ. (T.H.) (Germany, F.R.). Inst. fuer Werkstoffkunde 2)

    1990-03-01

    Microanalytical investigations have been made on samples of ceramic fibres (SiC-fibres (Nicalon), C-fibre coated with TiN) and fibre-reinforced ceramics (SiC- and glass-matrices). High resolution Auger electron spectroscopy (HRAES), electron probe microanalysis (EPMA) and scanning electron microscopy were employed for these examinations. Analysis was best performed with HRAES on account of its lateral and depth resolution. AES depth profiles of ceramic fibres are reported and compared with the surface analysis of fibres in the composites after being broken in situ. (orig.).

  17. Tensile strain measurements of ceramic fibers using scanning laser acoustic microscopy

    Science.gov (United States)

    Kent, Renee M.; Vary, Alex

    1992-01-01

    A noncontacting technique using scanning laser acoustic microscopy for making in situ tensile strain measurements of small diameter fibers was implemented for the tensile strain analysis of individual Nicalon SiC fibers (nominal diameter 15 microns). Stress vs strain curves for the fibers were plotted from the experimental data. The mean elastic modulus of the fibers was determined to be 185.3 GPa. Similar measurements were made for Carborundum SiC fibers (nominal diameter 28 microns) and Saphikon sapphire fibers (nominal diameter 140 microns).

  18. Preparation and Characterization of M-Type Barium Ferrite Fibers via Aqueous Sol-Gel Process

    Institute of Scientific and Technical Information of China (English)

    GONG Cairong; FAN Guoliang; SONG Chonglin; L(U) Gang

    2007-01-01

    BaFe12O19 fibers was prepared via an aqueous sol-gel process using Fe(OH)( HCOO)2 synthesized in laboratory and Ba(CH3COO)2 as the original materials and citrate as the chelate. The rheological behaviour of spinnable sol was characterized on rheometer, and the development of gel fibers to barium ferrite fibers was studied by IR, TG and XRD. Morphology observation of the fibers was given on SEM, and the diameter of the obtained fibers was between 5 and 10 μm corresponding to different additives. The additives affected the surface tension of the precursor sol which had close relation to the microstructure of fibers. Sucrose and hydroxyethylic cellulose could improve the surface tension while diethanolamine and hexadecylamine reduce that of the precursor sol. And using diethanolamine or hexadecylamine as an additive, well-structured BaFe12O19 fibers could be obtained.

  19. Microstructure and properties of SiC-coated carbon fibers prepared by radio frequency magnetron sputtering

    Science.gov (United States)

    Cheng, Yong; Huang, Xiaozhong; Du, Zuojuan; Xiao, Jianrong; Zhou, Shan; Wei, Yongshan

    2016-04-01

    SiC-coated carbon fibers are prepared at room temperature with different radio-frequency magnetron sputtering powers. Results show that the coated carbon fibers have uniform, continuous, and flawless surfaces. The mean strengths of the coated carbon fibers with different sputtering powers are not influenced by other factors. Filament strength of SiC-coated carbon fibers increases by approximately 2% compared with that of uncoated carbon fibers at a sputtering power of coated fibers increase by 9.3% and 12% at sputtering powers of 250 and 300 W, respectively. However, the mean strength of the SiC-coated carbon fibers decreased by 8% at a sputtering power of 400 W.

  20. Oxidation of Carbon Fibers in a Cracked Ceramic Matrix Composite Modeled as a Function of Temperature

    Science.gov (United States)

    Halbig, Michael C.; Cawley, James D.; Eckel, Andrew J.

    2003-01-01

    The oxidation model simulates the oxidation of the reinforcing carbon fibers within a ceramic matrix composite material containing as-fabricated microcracks. The physics-based oxidation model uses theoretically and experimentally determined variables as input for the model. The model simulates the ingress of oxygen through microcracks into a two-dimensional plane within the composite material. Model input includes temperature, oxygen concentration, the reaction rate constant, the diffusion coefficient, and the crack opening width as a function of the mechanical and thermal loads. The model is run in an iterative process for a two-dimensional grid system in which oxygen diffuses through the porous and cracked regions of the material and reacts with carbon in short time steps. The model allows the local oxygen concentrations and carbon volumes from the edge to the interior of the composite to be determined over time. Oxidation damage predicted by the model was compared with that observed from microstructural analysis of experimentally tested composite material to validate the model for two temperatures of interest. When the model is run for low-temperature conditions, the kinetics are reaction controlled. Carbon and oxygen reactions occur relatively slowly. Therefore, oxygen can bypass the carbon near the outer edge and diffuse into the interior so that it saturates the entire composite at relatively high concentrations. The kinetics are limited by the reaction rate between carbon and oxygen. This results in an interior that has high local concentrations of oxygen and a similar amount of consumed carbon throughout the cross section. When the model is run for high-temperature conditions, the kinetics are diffusion controlled. Carbon and oxygen reactions occur very quickly. The carbon consumes oxygen as soon as it is supplied. The kinetics are limited by the relatively slow rate at which oxygen is supplied in comparison to the relatively fast rate at which carbon and

  1. Relationship Between Hysteresis Dissipated Energy and Temperature Rising in Fiber-Reinforced Ceramic-Matrix Composites Under Cyclic Loading

    Science.gov (United States)

    Longbiao, Li

    2016-06-01

    In this paper, the relationship between hysteresis dissipated energy and temperature rising of the external surface in fiber-reinforced ceramic-matrix composites (CMCs) during the application of cyclic loading has been analyzed. The temperature rise, which is caused by frictional slip of fibers within the composite, is related to the hysteresis dissipated energy. Based on the fatigue hysteresis theories considering fibers failure, the hysteresis dissipated energy and a hysteresis dissipated energy-based damage parameter changing with the increase of cycle number have been investigated. The relationship between the hysteresis dissipated energy, a hysteresis dissipated energy-based damage parameter and a temperature rise-based damage parameter have been established. The experimental temperature rise-based damage parameter of unidirectional, cross-ply and 2D woven CMCs corresponding to different fatigue peak stresses and cycle numbers have been predicted. It was found that the temperature rise-based parameter can be used to monitor the fatigue damage evolution and predict the fatigue life of fiber-reinforced CMCs.

  2. Preparation and Properties of Iminodiacetic Acid Chelate Fiber

    Directory of Open Access Journals (Sweden)

    QIAN Jin-xin

    2016-07-01

    Full Text Available The iminodiacetic acid chelate fiber(IDACF which has a property of selective adsorption, was fabricated by amination and carboxylation using chloramethylated polypropylene grafted styrene fiber as raw material. Orthogonal experiment was adopted to study the effect of temperature, time, liquor ratio and the amount of chloroacetic acid on carboxylation reaction. The maximum adsorption capacity of iminodiacetic acid chelate fiber to Cu2+ is 65.54mg·g-1, which is 10.52 times of that of Fe3+. Elementary analysis(EA, Fourier transform infrared spectrum(FT-IR, scanning electron microscopy(SEM and thermogrametry(TG were used to characterize the structure and the properties of the iminodiacetic acid chelate fiber. The results show that iminodiacetic acid has been transformed to the raw fiber successfully after amination and carboxymethylation, and IDACF has good thermal stability.

  3. PREPARATION OF ACTIVATED CARBON FIBERS AND THEIR XENON ADSORPTION PROPERTIES (Ⅰ)-PREPARATION AND PORE STRUCTURE CHARACTERIZATION

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A series of sisal based activated carbon fibers were prepared with steam activation attemperature from 750 ℃ to 900 ℃. Their pore structures were characterized through their nitrogenadsorption isotherms at 77K using different theories. The results showed that t-plot method andDR-plot method could suitably be used to characterize the mesopore structure and the multi-stagedistribution of pore size of activated carbon fibers. It also showed that the pore size widens with theincrease of activation temperature.

  4. High efficient preparation of carbon nanotube-grafted carbon fibers with the improved tensile strength

    Science.gov (United States)

    Fan, Wenxin; Wang, Yanxiang; Wang, Chengguo; Chen, Jiqiang; Wang, Qifen; Yuan, Yan; Niu, Fangxu

    2016-02-01

    An innovative technique has been developed to obtain the uniform catalyst coating on continuously moving carbon fibers. Carbon nanotube (CNT)-grafted carbon fibers with significantly improved tensile strength have been succeeded to produce by using chemical vapor deposition (CVD) when compared to the tensile strength of untreated carbon fibers. The critical requirements for preparation of CNT-grafted carbon fibers with high tensile strength have been found, mainly including (i) the obtainment of uniform coating of catalyst particles with small particle size, (ii) the low catalyst-induced and mechano-chemical degradation of carbon fibers, and (iii) the high catalyst activity which could facilitate the healing and strengthening of carbon fibers during the growth of CNTs. The optimum growth temperature was found to be about 500 °C, and the optimum catalyst is Ni due to its highest activity, there is a pronounced increase of 10% in tensile strength of carbon fibers after CNT growth at 500 °C by using Ni catalyst. Based on the observation from HRTEM images, a healing and crosslink model of neighboring carbon crystals by CNTs has been formulated to reveal the main reason that causes an increase in tensile strength of carbon fibers after the growth of CNTs. Such results have provided the theoretical and experimental foundation for the large-scale preparation of CNT-grafted carbon fibers with the improved tensile strength, significantly promoting the development of CNT-grafted carbon fiber reinforced polymer composites.

  5. SiBN陶瓷纤维的高温抗氧化性研究%High temperature oxidation resistance of SiBN ceramic fiber

    Institute of Scientific and Technical Information of China (English)

    王会峰; 唐彬彬; 牟世伟; 星禧; 柯盛包; 韩克清; 刘勇; 余木火

    2015-01-01

    The chemical structure and the thermal stability of SiBN ceramic fibers were investigated by FTIR and TG. SiBN ceramic fibers were treated under air atmosphere at 1 400℃. The structure and the element contents along the radius of SiBN ceramic fibers after the air⁃oxidation treatment were characterized by means of SEM,XRD and EDS. The results show that SiBN ceramic fibers exhibit good thermal stability at high temperature,which contain Si⁃N bonds and B⁃N bonds in the back⁃bone of the fiber and low carbon content (0.1%). After the air⁃oxidation treatment,the ceramic fibers show a skin⁃core structure. Oxygen mainly exists in the form of SiO2 in the skin of fiber,which can prevent the air from the interior of the fibers, thus providing the high temperature stability. In addition,after air⁃oxidation treatment,the SiBN ceramic fibers maintain their fiber shape and still show compact structure without micropores and amorphous character.%采用FTIR及TG对SiBN陶瓷纤维的结构及高温稳定性进行分析,在空气气氛中1400℃下对其进行高温氧化处理,并利用SEM、XRD、EDS等手段对高温处理后陶瓷纤维的结构及元素分布情况进行表征。结果表明:SiBN陶瓷纤维具有良好的高温稳定性,Si—N键、B—N键构成了SiBN陶瓷纤维的骨架架构,其碳的质量分数仅为0.1%;经高温氧化处理后SiBN纤维出现明显的皮芯结构,其中O元素以SiO2的形式主要富集在皮层,隔绝了纤维内部与空气的接触,从而保证了纤维的高温稳定性。另外,高温氧化处理后仍保持其纤维形状,结构致密,无明显孔洞,且仍为无定型结构。

  6. Preparation of Composite Charge-mosaic Hollow Fiber Membrane by Interfacial Polymerization

    Institute of Scientific and Technical Information of China (English)

    Hao Qin ZHANG; Jin Dun LIU

    2004-01-01

    The preparation of composite charge-mosaic membrane included spinning of hollow fiber as the supporting membrane, preparing a selective layer on the inside surface of the fiber by interfacial polymerization. The charge-mosaic membranes show a high salt permeability while retaining sucrose. The charge-mosaic membrane can be effectively used to separate multivalent salts with organic matter of molecular weight great than 300 g/mol in industry.

  7. Effects of Steel Fiber on Tribological Properties of Ceramic -Based Friction Material%钢纤维对陶瓷基摩擦材料摩擦学性能的影响

    Institute of Scientific and Technical Information of China (English)

    王发辉; 刘莹

    2012-01-01

    以钢纤维为增强材料,采用氮气保护烧结方法制备出了钢纤维增强陶瓷基摩擦材料,用XD-MSM型定速摩擦磨损试验机对比研究了不同钢纤维含量对陶瓷基摩擦材料的热衰退性能、恢复性能以及磨损性能的影响,利用扫描电子显微镜(SEM)观察磨损表面形貌,并探讨了其磨损机理.研究结果表明:钢纤维的添加量(质量百分数)为24%时,钢纤维同陶瓷基体界面结合良好,陶瓷基摩擦材料的耐磨性能有所提高,热衰退率仅为5.8%,恢复率达到了107.8%,表明此配方陶瓷基摩擦材料具有较高的抗热衰退性能和恢复性能;钢纤维的含量影响陶瓷基摩擦材料的磨损形式,当含钢纤维含量较少时,陶瓷基摩擦材料以脆性脱落和疲劳磨损混合磨损形式为主;而随添加钢纤维含量的增多,其磨损形式转变为磨粒磨损;钢纤维过量加入时,则主要磨损形式为脆性脱落和疲劳磨损,并伴有黏着磨损.%Steel fiber reinforced ceramic -based friction material is prepared by nitrogen protection sintering method. The effects of steel fiber content on fade, recovery and wear performance of the ceramic - based friction material are studied and compared using XD - MSM constant speed friction tester. The worn surface morphology is observed by using scanning electron microscopy (SEM) , and wear mechanism is discussed. The results show that the interface between steel fiber and ceramic matrix is good, the wear resistance of the friction material with a steel fiber content of 24% is improved. The fade ratio is as low as 5.8% and the recovery ratio is 107.8%, showing the excellent performances of heat fading resistance and recovery of the friction material. SEM analysis shows that steel fiber content has impact on the main wear mechanism of ceramic - based friction material. The main wear mechsanisms of ceramic - based friction material with a low

  8. INFLUENCE OF REOXIDATION ON SILICA-CONTAINING BARIUM TITANATE CERAMICS FOR PTCR THERMISTORS PREPARED BY TAPE CASTING

    Directory of Open Access Journals (Sweden)

    Jianqiao Liu

    2016-03-01

    Full Text Available Silica-containing barium-rich BaTiO₃ ceramics for thermistors with a positive temperature coefficient of resistance are prepared by a tape-casting technique. The ceramics are sintered in a reducing atmosphere at low temperatures of 1175-1225°C. The influences of reoxidation are investigated after the reduced ceramics are reoxidized in air at 700-900°C. An anomalous correlation is illustrated between room temperature resistivity and reoxidation temperature. The anomaly results from the ferroelectricity rebuilding mechanism, which includes the spontaneous polarization theory and the ferroelectricity degradation caused by oxygen vacancies. The acceptor-state densities are estimated from the temperature-dependent resistivity. A critical temperature of 750-800°C is concluded for the grain boundary reoxidation.

  9. Preparation,Characterization and Dielectric Property of Sr5LaTi3Nb7O30 Ceramic

    Institute of Scientific and Technical Information of China (English)

    ZHUO Rong-hui; ZHANG Hui; YANG Jun-feng; HUANG Tao-hua; YUAN Run-zhang

    2004-01-01

    Sr5LaTi3Nb7O30 ceramic was prepared by the conventional high temperature solid-state reaction route. The sintered samples were characterized by X-ray diffraction, scanning electron microscopy (SEM), differential thermal calorimetry (DSC) and dielectric measurements.The results show Sr5LaTi3Nb7O30 belongs to paraelectric phase of filled tetragonal TB structure at room temperature, and undergoes a diffuse phase transition in the temperature range of -54-34 ℃.And Sr5LaTi3Nb7O30 ceramic shows a high dielectric constant of 479 with a low dielectric loss of 0.005 at 1MHz. In comparison with Ba-based ceramics with TB structure, the temperature coefficients of the dielectric constant (τε) is significantly reduced.

  10. Density variation and piezoelectric properties of Ba(Ti1−Sn)O3 ceramics prepared from nanocrystalline powders

    Indian Academy of Sciences (India)

    A K Nath; Nirmali Medhi

    2012-10-01

    Nanocrystalline powders of tin-doped barium titanate with different concentrations of tin have been synthesized by a combination of solid state reaction and high-energy ball milling. The average particle size of the milled powders as determined from TEM analysis was about 5.96 nm. Analysis of all the milled powders using X-ray diffraction method showed single phase perovskite structure. The density variation of the ceramics with sintering temperature has been studied by sintering the samples at different temperatures. Density variation results show that 1350°C is the optimum sintering temperature for tin-doped barium titanate ceramics. SEM micrographs show high density and increasing trend of grain size with increasing content of Sn. The ferroelectricity decreases with increasing concentration of Sn. The electromechanical coupling coefficient also decreases with increasing Sn content corroborating decreasing trend of ferroelectricity. The bipolar strain curves show piezoelectric properties of the prepared ceramics.

  11. Preparation of A New Fiber by Sol-gel Technology in Solid-phase Microextraction (SPME)

    Institute of Scientific and Technical Information of China (English)

    Li Ming WEI; Qing Yu OU; Ju Bai LI

    2004-01-01

    The sol-gel technology is applied for the preparation of solid-phase microextraction (SPME) fiber. The fiber demonstrates high thermal stability, efficient extraction rate and the selectivity for non-polar or low-polar analytes. Efficient SPME-GC-FID analyses of benzene- toluene-ethylbenzene-xylenes (BTEXs) and low-polar halocarbon were achieved by the sol-gel coated DSDA-DDBT-TiO2 fiber. Some parameters of the SPME fiber for the determination of halocarbon in aqueous sample were investigated.

  12. Development of Boron-Containing Silicon Carbide Precursor for Ceramic Fibers%纤维用含硼 SiC 陶瓷先驱体的研究进展

    Institute of Scientific and Technical Information of China (English)

    朱旖华; 王浩; 邵长伟

    2013-01-01

    综述了硅硼碳(SiBC)先驱体、硅硼碳氧(SiBCO)先驱体和硅硼碳氮(SiBCN)先驱体等纤维用含硼碳化硅( SiC)陶瓷先驱体的合成方法,分析了不同陶瓷先驱体的组成、结构和性能,比较了几种合成含硼SiC先驱体方法的优缺点,提出了纤维用含硼SiC陶瓷先驱体的合成新思路。%The present paper gives an overview of the synthesis strategies from the polymeric precursors which are used to prepare boron-containing SiC ceramic fibers , such as SiBC , SiBCO and SiBCN .The struc-tures and the properties of the derived fibers are discussed , and the advantage and disadvantage of the different methods for synthesizing boron-containing silicon carbide precursor are compared .A novel route for preparing boron-containing SiC ceramic precursor is proposed .

  13. [Preparation and photoluminescence study of Er3+ : Y2O3 transparent ceramics].

    Science.gov (United States)

    Luo, Jun-ming; Li, Yong-xiu; Deng, Li-ping

    2008-10-01

    Y2O3 acted as the matrix material, which was doped with different concentrations of Er3+, Er3+ : Y2O3 nanocrystalline powder was prepared by co-precipitation method, and Er3+ : Y2O3 transparent ceramics was fabricated by vacuum sintering at 1700 degrees C, 1 x 10(-3) Pa for 8 h. By using the X-ray diffraction (D/MAX-RB), transmission electron microscopy(Philips EM420), automatic logging spectrophotometer(DMR-22), fluorescence analyzer (F-4500) and 980 nm diode laser, the structural, morphological and luminescence properties of the sample were investigated. The results show that Er3+ dissolved completely in the Y2O3 cubic phase, the precursor was amorphous, weak diffraction peaks appeared after calcination at 400 degrees C, and if calcined at 700 degrees C, the precursor turned to pure cubic phase. With increasing the calcining temperature, the diffraction peaks became sharp quickly, and when the calcining temperature reached 1100 degrees C, the diffraction peaks became very sharp, indicating that the grains were very large. The particles of Er+ : Y2O3 is homogeneous and nearly spherical, the average diameter of the particles is in the range of 40-60 nm after being calcined at 1000 degrees C for 2 h. The relative density of Er3+ : Y2O3 transparent ceramics is 99.8%, the transmittance of the Er2+ : Y2O3 transparent ceramics is markedly lower than the single crystal at the short wavelength, but the transmittance is improved noticeably with increasing the wavelength, and the transmittance exceeds 60% at the wavelength of 1200 nm. Excited under the 980 nm diode laser, there are two main up-conversion emission bands, green emission centers at 562 nm and red emission centers at 660 nm, which correspond to (4)S(3/2) / (2)H(11/2) - (4)I(15/2) and (4)F(9/2) - (4)I(15/2) radiative transitions respectively. By changing the doping concentrations of Er3+, the color of up-conversion luminescence can be tuned from green to red gradually. The luminescence intensity is not reinforce

  14. Preparation and performance of thin-layered PdAu/ceramic composite membranes

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Lei; Goldbach, Andreas; Zeng, Gaofeng; Xu, Hengyong [Dalian Institute of Chemical Physics, Chinese Academy of Science, Zhongshan Road 457, Dalian 116023 (China)

    2010-05-15

    Preparation of 3-5 {mu}m thick, hydrogen-selective PdAu layers via sequential electroless plating of Pd and Au onto ceramic microfiltration membranes was investigated employing a cyanide-free Au plating bath. The Au deposition rate was strongly dependent on bath temperature and alkalinity reaching an optimum at 333 K and pH 10. Homogenous alloying of the separate metal layers under atmospheric H{sub 2} proved to be a protracted process and required approximately a week at 873 K for a PdAu layer as thin as 3 {mu}m. After 300 h annealing at 823 K the 5 {mu}m thick PdAu layer of a composite membrane still exhibited a Au gradient declining from 7.4 at.% at the top surface to 5.5 at.% at the support interface despite that the H{sub 2} permeation rate had become stable. Nonetheless, the membrane exhibited a very high H{sub 2} permeability of e.g. 1.3 x 10{sup -8} mol m m{sup -2} s{sup -1} Pa{sup -0.5} at 673 K, but it decreased much faster with temperature below 573 K than above, likely due to a change from bulk H diffusion-controlled to H{sub 2} adsorption or desorption-limited transport. The composite membrane withstood cycling between 523 and 723 K in H{sub 2} well showing that differing thermal expansion of the joined metallic and ceramic materials stayed within the tolerance range up to 723 K. (author)

  15. Structural, dielectric and piezoelectric properties of aluminium doped PLZT ceramics prepared by sol-gel route

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Soma [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)]. E-mail: dutta_som@yahoo.co.in; Choudhary, R.N.P. [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India); Sinha, P.K. [Department of Aerospace Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)

    2007-03-14

    Nanosized piezoelectric ceramics for vibration sensor applications have been prepared by mixing the ferroelectric PLZT (8:60:40) with variable doping fractions of trivalent aluminium ion (Al{sup 3+}). Samples have been prepared through a standard sol-gel route. X-ray diffraction and scanning electron microscopy (SEM) have been used to determine the phase and morphological modifications. Transmission electron microscopy (TEM) studies reveal the microstructure with nanosized well-dispersed homogeneous spherical particles. The vibrational infra-red (IR) spectroscopy record is taken to locate the position of the doping Al{sup 3+} ion. Using electrical impedance spectroscopy, the resonance and anti-resonance frequencies of the Al modified PLZT system have been determined and analysed. Al addition in PLZT has left a profound effect in its dielectric and piezoelectric properties. An interpretation of the role of Al addition is proposed in terms of structure modification. The sensing power of the investigated material was found useful for the vibration control of a cantilever beam.

  16. Preparation and Characteristic of Self-regulation Water-transmitting Coating Fiber

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zengzhi; GU Na; ZHANG Jifei

    2009-01-01

    Common clay,Kaolin and Bentonite were used as additives to prepare wa-ter-transmitting coating fiber,respectively,and the water-transmitting characteristic of coating fiber was studied.Different water-transmitting coating fibers were prepared by coating fiber using coating material with different mass proportions of additives to adhesive.And the coating materials were made from three kinds of inorganic clays as additives respectively and polyvinyl alcohol(PVA)as adhesive.Furthermore,the surface morphology and water-transmitting capacity of coating fiber were studied by SEM,Perkin Elmer Diamond SⅡ thermal multi-analyzer and instrument for quick measurement moisture M30.The experimental results indicate that water-transmitting coating fibers made from three kinds of clays all have water-transmitting capacity.The surface of water-transmitting coating fiber prepared by common clay T is continuous and compact,and the water-transmitting effect is better than coating fibers made from other clays.

  17. Preparation and Characterization of Bragg Fibers for Delivery of Laser Radiation at 1064 nm

    Directory of Open Access Journals (Sweden)

    V. Matejec

    2013-04-01

    Full Text Available Bragg fibers offer new performance for transmission of high laser energies over long distances. In this paper theoretical modeling, preparation and characterization of Bragg fibers for delivery laser radiation at 1064 nm are presented. Investigated Bragg fibers consist of the fiber core with a refractive index equal to that of silica which is surrounded by three pairs of circular layers. Each pair is composed of one layer with a high and one layer with a low refractive index and characterized by a refractive-index difference around 0.03. Propagation constants and radiation losses of the fundamental mode in such a structure were calculated on the basis of waveguide optics. Preforms of the Bragg fibers were prepared by the MCVD method using germanium dioxide, phosphorous pentoxide and fluorine as silica dopants. The fibers with a diameter of 170 m were drawn from the preforms. Refractive-index profiles, angular distributions of the output power and optical losses of the prepared fibers were measured. Results of testing the fibers for delivery radiation of a pulse Nd:YAG laser at 1064 nm are also shown.

  18. A structured analysis of in vitro failure loads and failure modes of fiber, metal, and ceramic post-and-core systems.

    NARCIS (Netherlands)

    Fokkinga, W.A.; Kreulen, C.M.; Vallittu, P.K.; Creugers, N.H.J.

    2004-01-01

    PURPOSE: This study sought to aggregate literature data on in vitro failure loads and failure modes of prefabricated fiber-reinforced composite (FRC) post systems and to compare them to those of prefabricated metal, custom-cast, and ceramic post systems. MATERIALS AND METHODS: The literature was sea

  19. Preparation and Properties of Antibacterial Lyocell Fibers Containing Chitosan Derivative

    Institute of Scientific and Technical Information of China (English)

    ZHUANG Xu-pin; LIU Xiao-fei; CHENG Bo-wen; KANG Wei-min

    2006-01-01

    The O-carboxymethyl chitosan sodium salt, NaCMCh, was initially synthesized and analyzed with better antibacterial activity than chitosan. Then NaCMCh was dissolved in the N-methylmorpholine-N- oxide, NMMO, solution with cellulose for spinning of the lyocell fiber. The results showed that the lyocell fibers modified with over 2 wt% NaCMCh has good antibacterial activity in against the E. coli and with NaCMCh content below 6 wt% has considerable mechanical properties.

  20. Preparation of ZnO nanorods on conductive PET-ITO-Ag fibers

    Science.gov (United States)

    Li, Yiwen; Ji, Shuai; Chen, Yuanyu; Zhang, Hong; Gong, Yumei; Guo, Jing

    2016-12-01

    We studied the vertical ZnO nanorods grown on conductive conventional polyethylene terephthalate (PET) fibers which are prepared by electroless silver depositing on tin-doped indium oxide (ITO) coated PET fibers through an efficient and low-cost green approach. The PET fibers were firstly functionalized with a layer of ITO gel synthesized through a sol-gel process at rather low temperature, simply by immersing the fibers into ITO sol for several minutes followed by gelation at 120 °C. Once the ITO gel layer surface was activated by SnCl2, a continuous, uniform, and compact layer of silver was carried out on the surface of the PET-ITO fibers through electroless plating operation at room temperature. The as-prepared PET-ITO-Ag fibers had good electrical conductivity, with surface resistivity as low as 0.23 mΩ cm. The overall procedure is simple, efficient, nontoxic, and controllable. The conductive PET-ITO-Ag fiber was used successfully as a flexible basal material to plant vertical ZnO nanorods through controlling the seeding and growth processes. The morphology of the PET-ITO, PET-ITO-Ag, and PET-ITO-Ag-ZnO fibers were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Undergone the whole process, although the tensile strength of the fiber decreased slightly, they may still exert their applications in flexible electronic such as photovoltaic and piezoelectric devices.

  1. Sample Preparation for Headspace GC Analysis of Residual Solvents in Hyaluronic Acid Derivative Fiber

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hoon Joo; Kim, Dong Min; Yang, Jeong Soo [LG life Sciences, Ltd./R and D Park, Daejeon (Korea, Republic of); Kim, Chan Wha [Korea University, Seoul (Korea, Republic of)

    2006-02-15

    The aim of this study is to develop efficient sample preparation method for HS-GC analysis of residual solvents in HA derivative fiber. Compared to direct extraction of residual solvents from HA derivative fiber, the extraction through the hydrolysis of HA derivative fiber by HAse gave more complete and higher reproducible quantification of residual solvent. To validate HS-GC analysis method of residual solvents, specificity, limits of detection and quantification, linearity, accuracy and precision are investigated in the study. HA derivative fiber was hydrolyzed using HAse for headspace gas chromatographic analysis of residual solvents of ethanol, acetone and isopropanol in HA derivative fiber. This study showed that the developed method had specificity, linearity, accuracy and precision. In addition, it demonstrated that HS-GC coupled with matrix-breaking method such as hydrolysis was available for the determination of residual solvents in a matrix like HA derivative fiber.

  2. Preparation and characterization of chitosan/poly(Vinyl alcohol)/poly(Vinyl pyrrolidone) electrospun fibers

    Institute of Scientific and Technical Information of China (English)

    MA Guiping; YANG Dongzhi; ZHOU Yingshan; JIN Yu; NIE Jun

    2007-01-01

    Ultrafine fibers of chitosan/poly(vinyl alcohol)/poly(vinyl pyrrolidone) (CS/PVA/PVP) were prepared via electrospinning.The structure and morphology of CS/PVA/PVP ultrafine fibers was characterized by the Fourier transform inflared (FT-IR) spectroscope and scanning electron microscope (SEM).Furthermore.the effects of the concentration of PVA,PVP and the electrospinning voltage on the morphology of ultrafine fibers were investigated by the SEM.When the concentration of PVA was at the range of 30wt%-40wt%,ultrafine fibers could be obtained.The diameter distributions of ultrafine fibers decreased when the electrospinning voltage increased from 20to 30kV. The rough surface fibers could be obtained after etching with CHCl3.

  3. Preparation and characterization of aligned carbon nanotubes/polylactic acid composite fibers

    Energy Technology Data Exchange (ETDEWEB)

    Kong Yuxia; Yuan Jie [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Qiu Jun, E-mail: qiujun@tongji.edu.cn [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Key Laboratory of Advanced Civil Engineering Materials of Education of Ministry, Shanghai 201804 (China)

    2012-07-01

    Aligned functionalized multiwalled carbon nanotubes/polylactic acid (MWNTs-PCL/PLA) composite fibers were successfully prepared by electrospinning processing. The MWNTs bonded with the polycaprolactone chains exhibited excellent uniform dispersion in PLA solution by comparing with the acid-functionalized MWNTs and amino-functionalized MWNTs. Optical microscopy was used to study the aligned degree of the fibers and to investigate the influences of the electrodes distance on the alignment and structure of the fibers, and results showed that the best quality of aligned fibers with dense structure and high aligned degree were obtained at an electrodes distance of 3 cm. Moreover, the MWNTs embedded inside the MWNTs-PCL/PLA fibers displayed well orientation along the axes of the fibers, which was demonstrated by field emission scanning electron microscopy, transmission electron microscopy and Raman spectroscopy.

  4. EFFECTS OF THE PULP PREPARATION AND PAPERMAKING PROCESSES ON THE PROPERTIES of OCC FIBERS

    Directory of Open Access Journals (Sweden)

    Jinquan Wan

    2011-03-01

    Full Text Available Changes of the pore structure of recycled fibers and the strength properties of papers produced by old corrugated container (OCC recycled fibers were studied, after they were subjected to different stock preparation and papermaking processes. In this paper, the effects of beating, sizing, pressing, and drying on fiber properties were investigated, and the porous structure of fibers was analyzed by nitrogen adsorption technique. The results showed that beating, pressing, and other physical processes significantly influenced the fiber properties, whereas the effects of sizing were minor. Significant changes of water retention value (WRV, crystallinity index, and paper strength were observed after those processes. Further, an effort has been made to show relationships between pore structure and macroscopic properties (WRV, crystallinity index of recycled fibers.

  5. Energy saving by optimization of wall construction of industrial furnaces using ceramics and mullite fibers

    Energy Technology Data Exchange (ETDEWEB)

    Zander, H.

    1984-01-01

    A change to better insulation, using ceramic fibre, not only reduces energy consumption but can raise productivity to levels higher than ever before. To design ceramic fibre into a furnace, calculations are made based on VDI standard 2055, in unsteady and constant conditions for different refractory materials. The results show the difference in wall to wall temperature drop and energy requirements, depending on the process conditions. A newly developed mullite fibre has recently been introduced. This material has all the well-known ceramic fibre advantages of light weight, good insulating properties and excellent thermal shock resistance. As a mullite fibre it also has higher refractoriness, negligible shrinkage and much improved resistance to chemical attack.

  6. Non-destructive mechanical characterization of (nano-sized) ceramic fibers

    Energy Technology Data Exchange (ETDEWEB)

    Colomban, P.; Gouadec, G. [CNRS, Thiais (France). LADIR

    2002-07-01

    SiC and C fibres are produced from polymeric precursor. This synthesis route leads to a nano-sized materials with very smooth surface, the lack of defects explaining tensile strengths as high as 3 GPa. A high correlation is expected between short-range-ordering, nanostructure and macroscopic properties, like in any nano-sized ceramic issued from liquid routes (sol-gel, polymer precursors). The paper provides a comprehensive study on Raman spectroscopy versatility as a fast and non-destructive tool for the study of ceramic fibres nano/micro-structures and the prediction of their mechanical properties. We show how the results of very simple spectra fitting are correlated with E and {sigma}{sub r} in NLM, Hi, Hi-S, SA, SCS-6 and Sylramic (trademarks) SiC fibres. The reason why such a correlation exists, the common dependency of Raman signal and mechanical behaviour to the nano/microstructure of ceramics, is discussed. (orig.)

  7. Comparison between the preparation, structure and mechanical properties of long fiber reinforced thermoplastics and short fiber reinforced thermoplastic

    Institute of Scientific and Technical Information of China (English)

    Fang Kun; Yang Jie; Wu Sizhu; Li Mei; Ma Mingtu

    2012-01-01

    This article summarizes the comparison between the preparation, structure and mechanical properties of long fiber reinforced thermoplastics (LFT) and short fiber reinforced thermoplastics (SFT). Both of the experiment and theory results showed that the mechanical properties of long glass fiber reinforced thermoplastics pellets (LGFRT) have been enhanced better than that of short glass fiber reinforced thermoplastics pellets (SGFRT) manufactured by molding procession. After regulation of the relative humidity by 50 % , the mechanical properties of 30 % ( weight percent) short glass fiber content in SFT ( SFT-PA6-SGF30 ) are similar to that of 40 % long glass fiber content in LFT. Howev- er, the density of the latter is about 17 % lower than that of the former. Thus, the corresponding weight of products is reduced by 13 % ;output rate is increased by 21% , and the cost is therefore significantly lowered. And it has the fol- lowing advantages: impact strength is increased by 87 % ; the proportion is reduced by 20 % ; molding cycle is short- ened by 10 % ;materials cost is saved by 20 % -30 % and the final total cost is saved by 30 % -40 %. So LFT (LFT-PP-LGF40) can replace SFT (SFT-PA6-SGF30) with the similar basic mechanical properties under normal tem- perature or 160 ℃ lower.

  8. Preparation and characterization of porous carbon material-coated solid-phase microextraction metal fibers.

    Science.gov (United States)

    Zhu, Fang; Guo, Jiaming; Zeng, Feng; Fu, Ruowen; Wu, Dingcai; Luan, Tiangang; Tong, Yexiang; Lu, Tongbu; Ouyang, Gangfeng

    2010-12-10

    Two kinds of porous carbon materials, including carbon aerogels (CAs), wormhole-like mesoporous carbons (WMCs), were synthesized and used as the coatings of solid-phase microextraction (SPME) fibers. By using stainless steel wire as the supporting core, six types of fibers were prepared with sol-gel method, direct coating method and direct coating plus sol-gel method. Headspace SPME experiments indicated that the extraction efficiencies of the CA fibers are better than those of the WMC fibers, although the surface area of WMCs is much higher than that of CAs. The sol-gel-CA fiber (CA-A) exhibited excellent extraction properties for non-polar compounds (BTEX, benzene, toluene, ethylbenzene, o-xylene), while direct-coated CA fiber (CA-B) presented the best performance in extracting polar compounds (phenols). The two CA fibers showed wide linear ranges, low detection limits (0.008-0.047μgL(-1) for BTEX, 0.15-5.7μgL(-1) for phenols) and good repeatabilities (RSDs less than 4.6% for BTEX, and less than 9.5% for phenols) and satisfying reproducibilities between fibers (RSDs less than 5.2% for BTEX, and less than 9.9% for phenols). These fibers were successfully used for the analysis of water samples from the Pearl River, which demonstrated the applicability of the home-made CA fibers.

  9. Nanostructured zirconium titanate fibers prepared by particulate sol–gel and cellulose templating techniques

    Energy Technology Data Exchange (ETDEWEB)

    Rouhani, P. [Helmerich Advanced Technology Research Center, School of Electrical and Computer Engineering, Oklahoma State University, OK 74106 (United States); Salahinejad, E. [Helmerich Advanced Technology Research Center, School of Material Science and Engineering, Oklahoma State University, OK 74106 (United States); Department of Materials Science and Engineering, School of Engineering, Shiraz University, Zand Blvd., 7134851154 Shiraz (Iran, Islamic Republic of); Kaul, R. [Department of Biochemistry and Microbiology, Center for Health Sciences, Oklahoma State University, OK 74107 (United States); Vashaee, D. [Helmerich Advanced Technology Research Center, School of Electrical and Computer Engineering, Oklahoma State University, OK 74106 (United States); Tayebi, L., E-mail: lobat.tayebi@okstate.edu [Helmerich Advanced Technology Research Center, School of Material Science and Engineering, Oklahoma State University, OK 74106 (United States); School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078 (United States)

    2013-08-15

    Highlights: •A method to produce zirconium titanate fibers was introduced. •The resultant structure and photocatalytic activity of the fiber were investigated. •The fiber exhibited higher photocatalytic characteristics, compared with the powders. -- Abstract: In this paper, a method for cost-effective production of nanostructured zirconium titanate (ZrTiO{sub 4}) fibers is introduced. In this method, ZrTiO{sub 4} fibers were synthesized by a sol–gel technique using cellulose fibers as the template. The resultant structures were studied by transmission electron microscopy, X-ray diffraction, scanning electron microscopy, and Brunauer–Emmett–Teller (BET) analyses. The photocatalytic activity of the fiber was compared to that of ZrTiO{sub 4} powders prepared by the same sol–gel method, in dark and under UVA and UVC radiations. According to the results, after calcination accompanied by the template removal, the ZrTiO{sub 4} fiber consists of uniformly-deposited, crystalline nanoparticles. This nanostructured fiber exhibited a higher surface area and a higher porosity compared with the ZrTiO{sub 4} powders, resulting in considerably higher photocatalytic characteristics, as confirmed by the experiment. The large surface area and the enhanced photocatalytic activity of the ZrTiO{sub 4} fibers also offer applications in sensors and bioactive films.

  10. Graphenized pencil lead fiber: facile preparation and application in solid-phase microextraction.

    Science.gov (United States)

    Liu, Qian; Cheng, Mengting; Long, Yanmin; Yu, Miao; Wang, Thanh; Jiang, Guibin

    2014-01-17

    Graphenized pencil lead fiber was facilely prepared by in situ chemical exfoliation of graphite in pencil lead fiber to few-layered graphene sheets via a one-pot, one-step pressurized oxidation reaction for the first time. This new fiber was characterized and demonstrated to be a highly efficient but low-cost solid-phase microextraction (SPME) fiber. The extraction performance of the fiber was evaluated with four bisphenol analogs [bisphenol A (BPA), bisphenol S (BPS), bisphenol AF (BPAF), and tetrabromobisphenol A (TBBPA)] as model analytes in direct SPME mode. Unlike commercially available fibers, the graphenized pencil lead fiber showed an excellent chemical stability in highly saline, acidic, alkaline and organic conditions due to its coating-free configuration. The fiber also showed a very long lifespan. Furthermore, high extraction efficiency and good selectivity for the analytes with a wide polarity range could be obtained due to the exceptional properties of graphene. The detection limits (LODs) for the analytes were in the range of 1.1-25ng/L. The fiber was successfully applied in the analysis of tap water and effluent samples from a waste water treatment plant with spike recoveries ranging from 68.5 to 105.1%. Therefore, the graphenized pencil lead fiber provides a high performance, cheap, robust, and reliable tool for SPME.

  11. Tensile Strength and Microstructural Characterization of Uncoated and Coated HPZ Ceramic Fibers

    Science.gov (United States)

    Bansal, Narottam P.; Wheeler, Donald R.; Dickerson, Robert M.

    1996-01-01

    Tensile strengths of as-received HPZ fiber and those surface coated with BN, BN/SiC, and BN/Si3N4 have been determined at room temperature using a two-parameter Weibull distribution. Nominally approx. 0.4 micron BN and 0.2 micron SiC or Si3N4 coatings were deposited on the fibers by chemical vapor deposition using a continuous reactor. The average tensile strength of uncoated HPZ fiber was 2.0 +/- 0.56 GPa (290 +/- 81 ksi) with a Weibull modulus of 4.1. For the BN coated fibers, the average strength and the Weibull modulus increased to 2.39 +/- 0.44 GPa (346 +/- 64 ksi) and 6.5, respectively. The HPZ/BN/SiC fibers showed an average strength of 2.0 +/- 0.32 GPa (290 +/- 47 ksi) and Weibull modulus of 7.3. Average strength of the fibers having a dual BN/Si3N4 surface coating degraded to 1.15 +/- 0.26 GPa (166 +/- 38 ksi) with a Weibull modulus of 5.3. The chemical composition and thickness of the fiber coatings were determined using scanning Auger analysis. Microstructural analysis of the fibers and the coatings was carried out by scanning electron microscopy and transmission electron microscopy. A microporous silica-rich layer approx. 200 nm thick is present on the as-received HPZ fiber surface. The BN coatings on the fibers are amorphous to partly turbostratic and contaminated with carbon and oxygen. Silicon carbide coating was crystalline whereas the silicon nitride coating was amorphous. The silicon carbide and silicon nitride coatings are non-stoichiometric, non-uniform, and granular. Within a fiber tow, the fibers on the outside had thicker and more granular coatings than those on the inside.

  12. Fabrication of continuous fiber-reinforced ceramics with a nanosized mullite precursor

    Energy Technology Data Exchange (ETDEWEB)

    Reese, O.; Saruhan, B.; Kanka, B.; Schneider, H. [Institute of Materials Research, Cologne (Germany)

    1995-12-01

    Chemically synthesized mullite precursor powders which are suitable materials for the production of continuous fiber-reinforced mullite composites, owing to their high sintering activity at relatively low processing temperatures were used as a matrix material. Since commercially available polycrystalline mullite fibers become instable at high temperatures, optimized slip-casting and sintering conditions were used which allowed hot-pressing of the composites at temperatures lower than 1250{degrees}C. A strong interfacial bonding between fiber and matrix has been observed due to the preferential grain growth which starts on the fiber surfaces and extends into the matrix.

  13. Preparation and Characterization of Electrospun Fibers of Poly(methyl methacrylate - Single walled carbon nano-tube Nanocomposites

    Directory of Open Access Journals (Sweden)

    Bibekananda Sundaray, Ph.D.

    2008-12-01

    Full Text Available Electrospinning is a versatile method of preparing polymer nanocmposite fibers. Electrospun nanocomposite fibers of poly(methyl methacrylate and single walled carbon nanotubes were prepared. The fibers were characterized by SEM, TEM, TGA and Raman spectroscopy. These fibers show dramatic improvement in the electrical conductivity compared to the polymer. The temperature dependent electrical resistance measurements show a one dimensional variable range hopping model (1-D VRH type of conduction mechanism operating in these types of systems.

  14. Preparation and property of polyurethane/nanosilver complex fibers

    Science.gov (United States)

    Qu, Rongjun; Gao, Jingjing; Tang, Bo; Ma, Qianli; Qu, Baohan; Sun, Changmei

    2014-03-01

    Utilizing terminal reactive groups in polyurethane, nanometer silvers were reduced in situ. The formation mechanism of nanosilver in PU was under preliminary discussion. UV-vis spectroscopy and TEM analysis were used to monitor reduction process; and the PU/nanosilver complex fibers were produced by dry spinning, which were characterized by X-ray diffraction, Fourier transform infrared spectra, thermogravimetric analysis, differential scanning calorimetry and so on. The influence of nanosilver on the thermal, mechanical and antimicrobial properties of PU was studied. It is inferred that 0.030% Ag should be a proper concentration for the PU/nanosilver complex fibers with favorable mechanical properties and highly effective antibacterial activities.

  15. Preparation and properties of hexagonal boron nitride fibers used as high temperature membrane filter

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Xinmei, E-mail: houxinmei@ustb.edu.cn; Yu, Ziyou; Li, Yang; Chou, Kuo-Chih

    2014-01-01

    Graphical abstract: - Highlights: • h-BN fibers were successfully fabricated using H{sub 3}BO{sub 3} and C{sub 3}H{sub 6}N{sub 6} as raw materials. • The obtained BN fibers were polycrystalline and uniform in morphology. • It exhibited good oxidation resistance and low thermal expansion coefficient. - Abstract: Hexagonal boron nitride fibers were synthesized via polymeric precursor method using boric acid (H{sub 3}BO{sub 3}) and melamine (C{sub 3}H{sub 6}N{sub 6}) as raw materials. The precursor fibers were synthesized by water bath and BN fibers were prepared from the precursor at 1873 K for 3 h in flowing nitrogen atmosphere. The crystalline phase and microstructures of BN fibers were examined by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and high resolution electron microscopy. The results showed that h-BN fibers with uniform morphology were successfully fabricated. The well-synthesized BN fibers were polycrystalline with 0.4–1.5 μm in diameter and 200–500 μm in length. The as-prepared samples exhibited good oxidation resistance and low thermal expansion coefficient at high temperature.

  16. Production of continuous mullite fiber via sol-gel processing

    Science.gov (United States)

    Tucker, Dennis S.; Sparks, J. Scott; Esker, David C.

    1990-01-01

    The development of a continuous ceramic fiber which could be used in rocket engine and rocket boosters applications was investigated at the Marshall Space Flight Center. Methods of ceramic fiber production such as melt spinning, chemical vapor deposition, and precursor polymeric fiber decomposition are discussed and compared with sol-gel processing. The production of ceramics via the sol-gel method consists of two steps, hydrolysis and polycondensation, to form the preceramic, followed by consolidation into the glass or ceramic structure. The advantages of the sol-gel method include better homogeneity and purity, lower preparation temperature, and the ability to form unique compositions. The disadvantages are the high cost of raw materials, large shrinkage during drying and firing which can lead to cracks, and long processing times. Preparation procedures for aluminosilicate sol-gel and for continuous mullite fibers are described.

  17. A new system for posterior restorations: a combination of ceramic optimized polymer and fiber-reinforced composite.

    Science.gov (United States)

    Rosenthal, L; Trinkner, T; Pescatore, C

    1997-01-01

    Due to the need for increased strength characteristics and enhanced aesthetic expectations of the patients, metal-free, aesthetic restorative systems for the anterior and posterior dentition are currently available. A new "space-age" restorative material has been developed that is a combination of a ceramic optimized polymer (Ceromer) (Targis/Vectris, Ivoclar Williams, Amherst, NY) and a fiber-reinforced composite framework material. The purpose of this article is to discuss the qualities that render this material particularly suitable for a variety of indications, including laboratory-fabricated restorations for the stress-bearing posterior regions. The material lends itself to diversification. Its indication for inlays, onlays, full-coverage crown restorations, and conservative single pontic inlay bridges is presented.

  18. Experimental investigation on high temperature anisotropic compression properties of ceramic-fiber-reinforced SiO{sub 2} aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Duoqi; Sun, Yantao [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China); Feng, Jian [National Key Laboratory of Science and Technology on Advanced Ceramic Fibers and Composites, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Yang, Xiaoguang, E-mail: yxg@buaa.edu.cn [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China); Han, Shiwei; Mi, Chunhu [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China); Jiang, Yonggang [National Key Laboratory of Science and Technology on Advanced Ceramic Fibers and Composites, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Qi, Hongyu [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China)

    2013-11-15

    Compression tests were conducted on a ceramic-fiber-reinforced SiO{sub 2} aerogel at high temperature. Anisotropic mechanical property was found. In-plane Young's modulus is more than 10 times higher than that of out-of-plane, but fracture strain is much lower by a factor of 100. Out-of-plane Young's modulus decreases with increasing temperature, but the in-plane modulus and fracture stress increase with temperature. The out-of-plane property does not change with loading rates. Viscous flow at high temperature is found to cause in-plane shrinkage, and both in-plane and out-of-plane properties change. Compression induced densification of aerogel matrix was also found by Scanning Electron Microscope analysis.

  19. Lithium ceramics: sol-gel preparation and tritium release; Ceramiques lithiees: elaboration sol-gel et relachement du tritium

    Energy Technology Data Exchange (ETDEWEB)

    Renoult, O.

    1994-04-01

    Ceramics based on lithium aluminate (LiA1O{sub 2}), lithium zirconate (Li{sub 2}ZrO{sub 3}) and lithium titanate (Li{sub 2}TiO{sub 3}) are candidates as tritium breeder blanket materials for forthcoming nuclear fusion reactors. Lithium silico-aluminate Li{sub 4+x}A1{sub 4-3x}Si{sub 2x}O{sub 8} (0 {<=} x {<=} 0,25) powders were synthetized from alkoxyde-hydroxyde sol-gel route. By direct sintering at 850-1100 deg C (without prior calcination), ceramics with controlled stoichiometry and homogenous microstructure were obtained. We have also prepared, using a comparable method, Li{sub 2}Zr{sub 1-x}Ti{sub x}O{sub 3} (x = 0, x = 0,1 et x = 1) materials. All these ceramics, with different microstructures and compositions, have been tested in out-of-reactor experiments. Concerning lithium aluminate microporous ceramics, the silicon substitution leads to a significant improvement of the tritrium release. Classical models taking into account independent surface mechanisms are not able to describe correctly the observed tritium release kinetics. We show, using a simple model, that the release kinetics is in fact limited by an intergranular diffusion followed by a desorption. The delay in tritium release, which occurs when the ceramic compacity increases, is explained in terms of an enhancement of the ionic T{sup +} diffusion path length. The energy required for desorption includes a leading term independent of hydrogen contained in the sweep gas. This term is attributed to the limiting recombination step of T{sup +} in molecular species HTO. For similar microstructures, the facility of tritium release for the different studied materials is explained by three properties: the crystal structure of the ceramic, the acidity of oxides and finally the presence of electronic non-stoichiometric defects. (author). 89 refs., 50 figs., 2 tabs., 1 annexe.

  20. Preparation and property of polyurethane/nanosilver complex fibers

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Rongjun, E-mail: rongjunqu@sohu.com [School of Chemistry and Materials Science, Ludong University, Yantai 264025 (China); College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250014 (China); Gao, Jingjing [School of Chemistry and Materials Science, Ludong University, Yantai 264025 (China); College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250014 (China); Tang, Bo [College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250014 (China); Ma, Qianli [Yantai Spandex Co., Ltd, Yantai 264006 (China); Qu, Baohan [College of Chemistry and Pharmacology, Qingdao Agricultural University, Qingdao 266109, Shandong (China); Sun, Changmei [School of Chemistry and Materials Science, Ludong University, Yantai 264025 (China)

    2014-03-01

    Highlights: • Utilizing terminal reactive groups in polyurethane, nanometer silvers were reduced in situ. And the PU/nanosilver complex fibers were produced by dry spinning. • The influence of nanosilver on the properties of PU was studied. • It is inferred that 0.030% Ag should be a proper concentration for the PU/nanosilver complex fibers with favorable mechanical properties and highly effective antibacterial activities. - Abstract: Utilizing terminal reactive groups in polyurethane, nanometer silvers were reduced in situ. The formation mechanism of nanosilver in PU was under preliminary discussion. UV–vis spectroscopy and TEM analysis were used to monitor reduction process; and the PU/nanosilver complex fibers were produced by dry spinning, which were characterized by X-ray diffraction, Fourier transform infrared spectra, thermogravimetric analysis, differential scanning calorimetry and so on. The influence of nanosilver on the thermal, mechanical and antimicrobial properties of PU was studied. It is inferred that 0.030% Ag should be a proper concentration for the PU/nanosilver complex fibers with favorable mechanical properties and highly effective antibacterial activities.

  1. Preparation of zein fibers using solution blow spinning method

    Science.gov (United States)

    Zein fibers were successfully fabricated via solution blow spinning (SBS) using acetic acid as solvent. Surface tension, viscosity and modulus of zein solutions were respectively determined by force tensiometer and rheometer. Increases of these properties were observed with an increase of concentrat...

  2. Preparation and antimicrobial assay of ceramic brackets coated with TiO2 thin films

    Science.gov (United States)

    Cao, Shuai; Wang, Ye; Cao, Lin; Wang, Yu; Lin, Bingpeng; Lan, Wei

    2016-01-01

    Objective Different methods have been utilized to prevent enamel demineralization and other complications during orthodontic treatment. However, none of these methods can offer long-lasting and effective prevention of orthodontic complications or interventions after complications occur. Considering the photocatalytic effect of TiO2 on organic compounds, we hoped to synthesize a novel bracket with a TiO2 thin film to develop a photocatalytic antimicrobial effect. Methods The sol-gel dip coating method was used to prepare TiO2 thin films on ceramic bracket surfaces. Twenty groups of samples were composed according to the experimental parameters. Crystalline structure and surface morphology were characterized by X-ray diffraction and scanning electron microscopy, respectively; film thickness was examined with a surface ellipsometer. The photocatalytic properties under ultraviolet (UV) light irradiation were analyzed by evaluating the degradation ratio of methylene blue (MB) at a certain time. Antibacterial activities of selected thin films were also tested against Lactobacillus acidophilus and Candida albicans. Results Films with 5 coating layers annealed at 700℃ showed the greatest photocatalytic activity in terms of MB decomposition under UV light irradiation. TiO2 thin films with 5 coating layers annealed at 700℃ exhibited the greatest antimicrobial activity under UV-A light irradiation. Conclusions These results provide promising guidance in prevention of demineralization by increasing antimicrobial activities of film coated brackets. PMID:27226960

  3. Semiconducting barium titanate ceramics prepared by using yttrium hexaboride as sintering aid

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.X.; Chan, H.L.W.; Pang, G.K.H.; Choy, C.L

    2003-07-25

    Nb-doped BaTiO{sub 3} semiconducting ceramics have been prepared at 1150 deg. C by employing YB{sub 6} as the sintering aid. The low-temperature sintered samples exhibit a positive temperature coefficient of resistivity (PTCR) effect. The room-temperature resistivity and the magnitude of PTCR effect depend on the amount of YB{sub 6} added, the Nb{sub 2}O{sub 5} content and the sintering conditions. At 1 mol% of YB{sub 6}, the sample has a low room-temperature resistivity and a resistivity jump of about 10{sup 4}. Transmission electron microscope studies revealed that the intergranular region between the crystalline BaTiO{sub 3} grains has an amorphous structure. Y, Ba and Ti are present in the intergranular region but no Y is detectable in the crystalline grains. A liquid phase is believed to be present during sintering and it helps to facilitate the densification process and to enhance the PTCR effect.

  4. Preparation,Electrochemical Behavior and Electrocatalytic Activity of a Copper Hexacyanoferrate Modified Ceramic Carbon Electrode

    Institute of Scientific and Technical Information of China (English)

    YU,Hao; ZHENG,Jian-Bin

    2007-01-01

    A copper hexacyanoferrate modified ceramic carbon electrode(CuHCF/CCE)had been prepared by two-step sol-gel technique and characterized using electrochemical methods.The resulting modified electrode showed a pair of well-defined surface waves in the potential range of 0.40 to 1.0 V with the formal potential of 0.682 V (vs.SCE)in 0.050 mol·dm-3 HOAc-NaOAc buffer containing 0.30 mol·dm-3 KCI.The charge transfer coefficient (α) and charge transfer rate constant(Ks)for the modified electrode were calculated.The electrocatalytic activity of this modified electrode to hydrazine was also investigated,and chronoamperometry was exploited to conveniently determine the diffusion coefficient(D)of hydrazine in solution and the catalytic rate constant(Kcat).Finally,hydrazine was determined with amperometry using the resulting modified electrode.The calibration plot for hydrazine determination was linear in 3.0×10-6-7.5×10-4 mol·dm-3 with the detection limit of 8.0×10-7 mol·dm-3.This modified electrode had some advantages over the modified film electrodes constructed by the conventional methods,such as renewable surface,good long-term stability,excellent catalytic activity and short response time to hydrazine.

  5. Structural and Magnetic Characterizations of Nano Sized Grain Zinc Ferrite/Hydroxyapatite Ceramic Prepared by Solid State Reaction Route.

    Science.gov (United States)

    Pankaew, Piyapong; Klumdoung, Pattarinee

    2015-11-01

    A promising composite of bioactive hydroxyapatite (HAp) and zinc ferrite (ZnFe2O4) has potentials for future bone reinforcing formation. In present study, HAp and ZnFe2O4 composite ceramic was prepared by solid state reaction route for easier control of structural and magnetic characteristics and with low cost. HAp powder was synthesized by precipitation method from chicken eggshell. Mixed powders with varying ZnFe2O4/HAp weight ratios from 2-10 wt% were milled together and uniaxially pressed and then sintered at 1200 degrees C for 3 hours. The XRD results showing no other phases of composite ceramics with only HAp and ZnFe2O4 phases were identified, indicating high stability of HAp property. Phase fractions of ZnFe2O4 were found to increase from 10.8 to 18.73 wt% with increasing content of ZnFe2O4. FT-IR results were only revealed vibration bands of standard HAp phase. SEM results revealed primary grains sizes of the prepared ceramics in nano scale. The BET surface area and pore volume increased with increasing content of ZnFe2O4 in composite ceramics. The VSM results of composites with increasing ZnFe2O4 content had been shown with increasing magnetization from 0.05 to 1.85 emu/g while their coercivities were decreased from 44 to 24 Oe. Higher magnetization as well as higher super paramagnetic behavior could be achieved with increasing the studied ZnFe2O4 weight ratios in ZnFe2O4/HAp composite ceramics, which can be tailored for specific applications.

  6. Study on the Ca doped BaTiO3 ceramic fibers%钙掺杂钛酸钡陶瓷纤维的研究

    Institute of Scientific and Technical Information of China (English)

    刘伟华; 宋双居; 刘宁

    2011-01-01

    采用溶胶-凝胶法,以醋酸钡、醋酸钙和钛酸丁酯为原料,冰醋酸为催化剂,制备了钙掺杂钛酸钡陶瓷纤维.发现当钙的掺杂量物质的量分数为0.05,0.10,0.15,0.20,0.25时溶胶具有可纺性,掺杂量物质的量分数为0.30,0.35时能形成溶胶,但溶胶不具有可纺性,掺钙量物质的量分数为0.40时不能形成溶胶.应用热分析、X射线粉末衍射、红外和扫描电子显微镜等技术对凝胶和纤维进行了较系统地研究.在1 000℃煅烧60min,升温速率为2℃/min时,得到表面形貌良好的陶瓷纤维.%The Ca doped BaTjO3 ceramic fibers were prepared by sol-gel process with Ba(CH3COO)2, Ca(CH3COO)2 and Ti(OC4 H9 )4 as precursors and CH3COOH as the catalyst. It is found that the sols are spinnable with Ca contents of 0. 05, 0. 10, 0. 15, 0. 20, 0. 25 (a-mount fraction), while not spinnable with 0. 30 and 0. 35 Ca contents, failing to form the sol of 0. 40 Ca contents. A series of researchs were carried out with TGA-DTA, XRD, FT-IR,SEM. Ceramic fibers with perfect surface were obtained under calcined time of 60 minutes held on 1 000 ℃ , at 2 ℃ /minute rate .

  7. 氧化锆纤维增强的氧化铝陶瓷的抗热震性能%Thermal Shock Resistance of Zirconia Fiber Reinforced Alumina Ceramics

    Institute of Scientific and Technical Information of China (English)

    冯帅; 王志; 丁寅森; 史国普

    2013-01-01

    Preparation of zirconia fiber reinforced alumina ceramic composite at sintering temperature of 1 650℃ and effect of zir-conia fiber content on thermal shock resistance of composite were studied. Results showed that the introduction of zirconia fiber can increase the air-cooling time of ceramic composite at the temperature difference of 1 400 ℃. When mass fraction of zirconia fiber was 15% ,the thermal shock time of the composite was 30,more than 10 times of monolithic alumina ceramics. The flexural strength and fracture toughness of the composite increased by 62.2% and 38.9% respectively than that of monolithic alumina ceramics,and its porosity was 6.71%. Increasing of mechanical properties and proper porosity contributed to the improvement of thermal shock resistance.%在1 650℃下制备氧化锆纤维增强的氧化铝陶瓷复合材料,研究氧化锆纤维添加量对氧化铝陶瓷抗热震性能的影响.结果表明,在温差为1 400℃的循环空冷条件下,加入氧化锆纤维可以明显提高氧化铝陶瓷的热震次数.当添加纤维质量分数为15%时,复合材料热震次数达到最高为30次,比纯氧化铝陶瓷提高20次;复合材料的抗弯强度和断裂韧性分别比纯氧化铝陶瓷提高62.2%和38.9%,气孔率为6.71%.复合材料力学性能的提高以及适当的气孔率是其抗热震性提高的主要原因.

  8. Synthesis and Preparation of Polysulfone Hollow Fiber Chelating Membrane Modified with Thiourea

    Institute of Scientific and Technical Information of China (English)

    WANG Bing; HUANG Lei; XIAO Feng

    2006-01-01

    Several kinds of chloromethyl polysulfones (CMPF) with different chlorinity and reactive groups were synthesized by Friedel-crafts reaction, which could be utilized as reactively matrix membrane materials. The CMPF hollow matrix membranes were prepared with phase inversion by utilization of CMPF/additive/DMAC casting solution and CMPF as membrane materials. It was found that the effects of additive content, bore liquid and dry spinning distance on the structure of CMPF hollow fiber matrix membrane were different. A high qualified polysulfone hollow fiber chelating membrane modified with thiourea as chelating groups was prepared using CMPF as membrane matrix materials,through the reaction between thiourea and CMPF hollow fiber matrix membrane to afford the methyl iso-thiourium polysulfone. The experimental results showed that thermal drawing could increase the mechanical properties of matrix membrane, and the thermal treatment could increase the homogeneity and stability of the structure of polysulfone hollow fiber chelating membrane modified with thiourea.

  9. FIBROUS CERAMIC-CERAMIC COMPOSITE MATERIALS PROCESSING AND PROPERTIES

    OpenAIRE

    1986-01-01

    The introduction of continuous fibers in a ceramic matrix can improve its toughness, if the fiber-matrix bonding is weak enough, due to matrix microcracking and fiber pull-out. Ceramic-ceramic composite materials are processed according to liquid or gas phase techniques. The most important are made of glass, carbide, nitride or oxide matrices reinforced with carbon, SiC or Al2O3 fibers.

  10. Dielectric properties of the BaTi0.85Zr 0.15O3 ceramics prepared by different techniques

    Directory of Open Access Journals (Sweden)

    Lavinia Petronela Curecheriu

    2008-12-01

    Full Text Available Three different processing routes, i.e. the classical solid state reaction technique the sol-precipitation method and the oxalate route, were employed for preparing BaTi0.85Zr0.15O3 ceramics. The dielectric properties of these ceramics are comparatively analyzed. The obtained results show that the dielectric properties of these ceramics, even having the same composition, are highly sensitive to the preparation route, causing differences in the microstructures and in the local electrical inhomogeneity, thus, causing complicated dielectric relaxation phenomena.

  11. Preparation and mechanism of calcium phosphate coatings on chemical modified carbon fibers by biomineralization

    Institute of Scientific and Technical Information of China (English)

    HUANG Su-ping; ZHOU Ke-chao; LI Zhi-you

    2008-01-01

    In order to prepare HA coatings on the carbon fibers, chemical modification and biomineralization processes were applied. The phase components, morphologies, and possible growth mechanism of calcium phosphate were studied by infrared spectroscopy(IR), X-ray diffractometry(XRD) and scanning electron microscopy(SEM). The results show that calcium phosphate coating on carbon fibers can be obtained by biomineralization. But the phase components and morphologies of calcium phosphate coatings are different due to different modification methods. Plate-like CaHPO4-2H2O (DCPD) crystals grow from one site of the active centre by HNO3 treatment. While on the para-aminobenzoic acid treated fibers, the coating is composed of nano-structural HA crystal homogeneously. This is because the -COOH functional groups of para-aminobenzoic acid graft on fibers, with negative charge and arranged structure, accelerating the HA crystal nucleation and crystallization on the carbon fibers.

  12. UTILIZATION OF BAGASSE FIBER FOR PREPARATION OF BIODEGRADABLE FLAME RETARDING COMPOSITES (BFRCS)

    OpenAIRE

    2010-01-01

    Bagasse is a renewable resource characterized by its low cost and environmental friendliness. In this work a novel technological process was proposed to make flame retarding composites (BFRCs) by using bagasse fiber. The bagasse was disintegrated by twisting it up and applying high consistency refining, and then it was used to prepare BFRCs via hot pressure. Chemical groups and thermal properties of bagasse fiber were studied through the use of FTIR spectroscopy, a universal mechanical testin...

  13. Processes for preparing carbon fibers using sulfur trioxide in a halogenated solvent

    Energy Technology Data Exchange (ETDEWEB)

    Patton, Jasson T.; Barton, Bryan E.; Bernius, Mark T.; Chen, Xiaoyun; Hukkanen, Eric J.; Rhoton, Christina A.; Lysenko, Zenon

    2015-12-29

    Disclosed here are processes for preparing carbonized polymers (preferably carbon fibers), comprising sulfonating a polymer with a sulfonating agent that comprises SO.sub.3 dissolved in a solvent to form a sulfonated polymer; treating the sulfonated polymer with a heated solvent, wherein the temperature of the solvent is at least 95.degree. C.; and carbonizing the resulting product by heating it to a temperature of 500-3000.degree. C. Carbon fibers made according to these methods are also disclosed herein.

  14. Nd-doped barium titanate ceramics with various Ti/Ba ratios prepared by sol-gel method

    Institute of Scientific and Technical Information of China (English)

    SHI Qizhen; CUI Bin; WANG Hui; TIAN Jing; CHANG Zhuguo; HOU Yudong

    2005-01-01

    The Nd-doped BaTiO3 nanocrystalline powders and ceramics with different Ti/Ba ratios were prepared by sol-gel method. Phases and microstructures of the Nd-doped BaTiO3based powders and ceramics were characterized by XRD, SEM and TEM methods. The results revealed that the powders synthesized by sol-gel method were nanometer scale (30-60 nm)and were mainly composed of cubic BaTiO3 with a small amount of BaCO3. After sintering at high temperature, both cubic BaTiO3 and BaCO3 were transformed into tetrahedron BaTiO3 phase.The dielectric properties of the ceramics were also determined and the influence of Ti/Ba ratio on the dielectric properties was discussed. The Tc did not change with the variation of Ti/Ba ratio,while the εmax increased firstly and then decreased. The excess TiO2 is benefit for the modification of ceramics' microstructure and dielectric properties.

  15. Antibacterial Properties of TiO_2 Ceramic Pellets Prepared Using Nano TiO_2 Powder

    Institute of Scientific and Technical Information of China (English)

    YAO Yadong; LI Yongdi; SHAO Wei; KANG Yunqing; WANG Hongjing; HUANG Zhongbin; LIAO Xiaoming; YIN Guangfu

    2009-01-01

    Titanium dioxide(TiO_2)porous ceramic pellets with three dimension nano-structure were prepared using nano TiO_2 powder.The TiO_2 porous ceramic pellets were composed of TiO_2 nanoparticles with 14-16 nm in diameter and had porosity of 74.85%.The mean pore size of the TiO_2 porous ceramic pellets was 20.73 nm and the main pore size ranged from 3 to 16 nm.The mass loss of the TiO_2 ceramic pellets was less than 5%after 20 d immersion in water.The antibacterial properties of the TiO_2 pellets were studied.The sterilization rate of Colibacillus(hospital polluted water with bacterium)can reach 99%after 3 h photocatalytic process and these TiO_2 pellets are easy to be re-activated and cyclically be used.The shaping mechanism and photocatalysis sterilization mechanism of the TiO_2 pellets were discussed.

  16. Biomimetic preparation and multi-scale microstructures of nano-silica/polyurethane elastomeric fibers

    Institute of Scientific and Technical Information of China (English)

    Quanyong Liu; Li Gao; Lei Jiang

    2013-01-01

    Bioinspired by the spinning of spider silks, the biomimetic preparation of nano-silica/polyurethane (nano-SiO2/TPU) elastomeric fibers with distinctive multi-scale microstructures was successfully implemented. The formation mechanism of the nano-SiO2/TPU fibers was considered as the integrated mechanism of diffusion, coagulation, self-assembly, and microphase separation, same as that of the native spider silks. The mass ratio of nano-SiO2 to TPU greatly influenced the external and inner microstructures of the nano-SiO2/TPU fibers. The formation process of the nano-SiO2/TPU fibers was simply described as three main stages, and the second stage, such as the adding of the ethanol solvents and nano-SiO2 in different diameters, was thought to be very crucial for the final external and inner microstructures of the prepared fibers. For example, the adding of the ethanol and the nano-SiO2 spheres in diameter of 10 nm resulted in the existence of many TPU-self-assembled microspheres mostly spaced apart by the nano-SiO2 aggregates in the nano-SiO2/TPU fibers, while the adding of the ethanol and the nano-SiO2 spheres in diameter of 100 nm resulted in the existence of the nano-SiO2 spheres, instead of the TPU-self-assembled microspheres, distributed in the nano-SiO2/TPU fibers.

  17. Preparation and characterization of regenerated fiber from the aqueous solution of Bombyx mori cocoon silk fibroin

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Zhenghua [Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan); Department of Application Engineering, ZheJiang Vocational College of Economic and Trade, HangZhou, ZheJiang 310018 (China); Imada, Takuzo [Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan); Asakura, Tetsuo, E-mail: asakura@cc.tuat.ac.jp [Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 (Japan)

    2009-10-15

    The regenerated silk fibers with high strength and high biodegradability were prepared from the aqueous solution of Bombyx mori silk fibroin from cocoons with wet spinning method. Although the tensile strength of the regenerated silk fibroin fiber, 210 MPa is still half of the strength of native silk fiber, the diameter of the fiber is about 100 {mu}m which is suitable for monofilament of suture together with high biodegradability. The high concentration (30%, w/v) of the aqueous solution of the silk fibroin which corresponds to the high concentration in the middle silkgland of silkworm was obtained. This was performed by adjusting the pH of the aqueous solution to 10.4 which corresponds to pK{sub a} value of the OH group of Tyr residues in the silk fibroin. The mixed solvent, methanol/acetic acid (7:3 in volume ratio) was used as coagulant solvent for preparing the regenerated fiber. The structural change of silk fibroin fiber by stretching was monitored with both {sup 13}C solid state NMR and X-ray diffraction methods, indicating that the high strength of the fiber is related with the long-range orientation of the silk fibroin chain with {beta}-sheet structure.

  18. [Assessment of carcinogenic effect of aluminosilicate ceramic fibers produced in Poland. Animal experiments].

    Science.gov (United States)

    Krajnow, A; Lao, I

    2000-01-01

    The effect of aluminosilicate ceramic fibres produced in Poland was assessed. The experiment was performed on two animal species: Wistar rats and BALB/C mice. The animals were administered intraperitoneally the studied fibres and krokidolit UICC--in doses of 25 and 5 mg and left for survival. All dead and sacrificed animals were examined histopathologically. Carcinogenic properties of ceramic aluminosilicate fibres were found to be rather weak. Only in 1 (2.5%) of 39 rats under study benign mesothelioma of tunica vagiualis testis was diagnosed. Peritoneal mesothelioma was found in none of 50 mice studied. For comparison the effect of krokidolit UICC was assessed. Krokidolit UICC is characterised by strong carcinogenic properties. It induced peritoneal mesothelioma in 43 mice (44.2%) and in 29 (80.5%) of 36 rats under study.

  19. Carbon monolith: preparation, characterization and application as microextraction fiber.

    Science.gov (United States)

    Shi, Zhi-Guo; Chen, Fei; Xing, Jun; Feng, Yu-Qi

    2009-07-10

    A carbon monolith was synthesized via a polymerization-carbonization method, styrene and divinylbenzene being adopted as precursors and dodecanol as a porogen during polymerization. The resultant monolith had bimodal porous substructure, narrowly distributed nano skeleton pores and uniform textural pores or throughpores. The carbon monolith was directly used as an extracting fiber, taking place of the coated silica fibers in commercially available solid-phase microextraction device, for the extraction of phenols followed by gas chromatography-mass spectrometry. Under the studied conditions, the calibration curves were linear from 0.5 to 50 ng mL(-1) for phenol, o-nitrophenol, 2,4-dichlorophenol and p-chlorophenol. The limits of detection were between 0.04 and 0.43 ng mL(-1). The recoveries of the phenols spiked in real water samples at 10 ng mL(-1) were between 85% and 98% with the relative standard deviations below 10%. Compared with the commercial coated ones (e.g. PDMS, CW/DVB and DVB/CAR/PDMS), the carbon monolith-based fiber had advantages of faster extraction equilibrium and higher extraction capacity due to the superior pore connectivity and pore openness resulting from its bimodal porous substructure.

  20. Creep Performance of Oxide Ceramic Fiber Materials at Elevated Temperature in Air and in Steam

    Science.gov (United States)

    2011-03-24

    boundary etching. Kronenberg et al. [74] and Castaing et al. [19] characterized the hydrogen impurities in hydrothermally annealed ceramics and...pp. 257-264, 1987. 19. J. Castaing, A. K. Kronenberg , S. H. Kirby and T. E. Mitchell, "Hydrogen defects in α-Al2O3 and water weakening of...2003. 74. A. K. Kronenberg , J. Castaing, T. E. Mitchell and S. H. Kirby, "Hydrogen defects in α-Al2O3 and water weakening of sapphire and

  1. [Assessment of exposure to ceramic fibers during insulation operations in a thermoelectric power plant].

    Science.gov (United States)

    Marconi, A; Cavariani, F; Carai, A; Cacchioli, G; Papandrea, F; Cacchioli, E

    2001-01-01

    Refractory ceramic fibre concentrations were measured during renewal of the insulation lining of a turbine located in a large power plant. Personal and stationary samples were collected during operations, which involved installing and ripping out standard and pre-coated and pre-shaped ceramic fibre blankets. Operation-length average (OLA) and TWA exposure levels were about 500 F/l and about 100 F/l, respectively, for installing and ripping out operations where non-coated blankets were handled. In these cases specific task-associated personal exposure levels up to 1000 F/l were measured. Personal exposure levels up to as much as 10 times lower were observed in operations involving pre-coated and pre-shaped blankets. The average concentration levels from area samples were always lower than those from personal samples, and showed a downward gradient with the distance from the source. Given the current carcinogenic classification of refractory ceramic fibres (class 2, European), the necessity is stressed of introducing adequate working practices and control measures (adoption of pre-coated and pre-shaped fibrous materials whenever possible, confinement of working area, use of local air extractions ventilation with HEPA filter unit, use of garments for personal protection and respirators, use of wetting or binding liquids prior to removal, quick cleaning of debris from working area), in order to keep the exposure levels and the number of potentially exposed workers to the minimum.

  2. A modified diffuse reflectance infrared Fourier transform spectroscopy cell for depth profiling of ceramic fibers.

    Science.gov (United States)

    Fondeur, F; Mitchell, B S

    2000-02-15

    A modified diffused reflectance infrared Fourier transformed spectroscopy (DRIFTS) accessory was used to analyze the surface properties of alumino-silicate fibers. The modifications are simple and involve a different way of performing depth-profiling from traditional DRIFTS by removing approximately 2 mm of salt from a full cup prior to placing the sample in for depth profiling. This method proved successful in elucidating the effects of quenching alumino-silicate fibers in mineral oil versus quenching in an air stream.

  3. Preparation of ceramic-corrosion-cell fillers and application for cyclohexanone industry wastewater treatment in electrobath reactor

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Suqing; Qi, Yuanfeng; Gao, Yue; Xu, Yunyun; Gao, Fan; Yu, Huan; Lu, Yue [Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, 250100 Jinan (China); Yue, Qinyan, E-mail: qyyue58@yahoo.com.cn [Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, 250100 Jinan (China); Li, Jinze [Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, 250100 Jinan (China)

    2011-11-30

    Highlights: Black-Right-Pointing-Pointer Dried sewage sludge and scrap iron used as raw materials for sintering ceramics. Black-Right-Pointing-Pointer The new media ceramics used as fillers in electrobath of micro-electrolysis. Black-Right-Pointing-Pointer Modified micro-electrolysis used in cyclohexanone industry wastewater treatment. Black-Right-Pointing-Pointer This modified micro-electrolysis could avoid failure of the electrobath reactor. - Abstract: As new media, ceramic-corrosion-cell fillers (Cathode Ceramic-corrosion-cell Fillers - CCF, and Anode Ceramic-corrosion-cell Fillers - ACF) employed in electrobath were investigated for cyclohexanone industry wastewater treatment. 60.0 wt% of dried sewage sludge and 40.0 wt% of clay, 40.0 wt% of scrap iron and 60.0 wt% of clay were utilized as raw materials for the preparation of raw CCF and ACF, respectively. The raw CCF and ACF were respectively sintered at 400 Degree-Sign C for 20 min in anoxic conditions. The physical properties (bulk density, grain density and water absorption), structural and morphological characters and toxic metal leaching contents were tested. The influences of pH, hydraulic retention time (HRT) and the media height on removal of COD{sub Cr} and cyclohexanone were studied. The results showed that the bulk density and grain density of CCF and ACF were 869.0 kg m{sup -3} and 936.3 kg m{sup -3}, 1245.0 kg m{sup -3} and 1420.0 kg m{sup -3}, respectively. The contents of toxic metal (Cu, Zn, Cd, Pb, Cr, Ba, Ni and As) were all below the detection limit. When pH of 3-4, HRT of 6 h and the media height of 60 cm were applied, about 90% of COD{sub cr} and cyclohexanone were removed.

  4. Continuous Fiber Wound Ceramic Composite (CFCC) for Commercial Water Reactor Fuel. Technical progress report for period ending April 1, 2000

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-04-01

    Our program began on August 1, 1999. As of April 1, 2000, the progress has been in materials selection and test planning. Three subcontracts are in place (McDermott Technologies Inc. for continuous fiber reinforced ceramic tubing fabrication, Swales Aerospace for LOCA testing of tubes, and Massachusetts Institute of Technology for In Reactor testing of tubes). With regard to materials selection we visited McDermott Technologies Inc. a number of times, including on February 23, 2000 to discuss the Draft Material Selection and Fabrication Report. The changes discussed at this meeting were implemented and the final version of this report is attached (attachment 1). McDermott Technologies Inc. will produce one type of tubing: Alumina oxide (Nextel 610) fiber, a carbon coating (left in place), and alumina-yttria matrix. A potentially desirable CFCC material of silicon carbide fiber with spinel matrix was discussed. That material selection was not adopted primarily due to material availability and cost. Gamma Engineering is exploring the available tube coatings at Northwestern University as a mechanism for reducing the permeability of the tubes, and thus, will use coating as a differentiating factor in the testing of tubing in the LOCA test as well as the In-Reactor Test. The conclusion of the Material Selection and Fabrication Report lists the possible coatings under evaluation. With regard to Test Planning, the MIT and Swales Aerospace have submitted draft Test Plans. MIT is attempting to accommodate an increased number of test specimens by evaluating alternative test configurations. Swales Aerospace held a design review at their facilities on February 24, 2000 and various engineering alternatives and safety issues were addressed. The final Test Plans are not expected until just before testing begins to allow for incorporation of changes during ''dry runs.''

  5. 苎麻织物制备多孔氧化铝遗态陶瓷%Preparation of porous alumina ceramics by morph-genetic process

    Institute of Scientific and Technical Information of China (English)

    王蒙; 刘江南; 贺辛亥; 王俊勃; 江燕; 李冰

    2014-01-01

    以苎麻织物为生物模板,聚合氯化铝溶液为浸渍液,经浸渍、干燥获得前驱体,将前驱体经有氧煅烧制备出具有苎麻织物结构的 Al2 O3遗态材料.采用 TG 、XRD 、TEM 、SEM 和比表面积等检测技术,分别对材料的热失重、物相组成和显微结构进行了表征与分析.结果表明,1200℃下制备的 Al2 O3陶瓷成功地保留了苎麻织物的结构.不同浓度下制得的 Al2 O3具有不同的微观形貌.Al2 O3比表面积为9.94~30.07m 2・ g-1;平均孔径为5.02~6.2nm .%Based on bio-templating ,a new kind of Al2 O3 morph-genetic ceramic materials with the struc-ture of ramie fibers was prepared by calcining under aerobic environment from precursors ,which were prepared by impregnating poly-aluminum chloride solution .The phase composition and micro-structure of the materials were analyzed and characterized respectively by using thermo -gravimetric analysis (TG) ,X-ray diffraction (XRD) ,transmission electron microscope (TEM ) ,scanning electron micro-scope (SEM ) and H-2000PS2 system .The experimental results show that the Al2 O3 morph-genetic ce-ramic successfully reserved the ramie fibers structure .Under different concentration of aluminum ,the products have different morphology . BET test shows that the specific surface area is 9.94 ~30.07m2 ・ g- 1 and the average pore diameter is 5.02 ~ 6.2nm .

  6. Effect of particle size on microstructure and strength of porous spinel ceramics prepared by pore-forming in situ technique

    Indian Academy of Sciences (India)

    Wen Yan; Nan Li; Yuanyuan Li; Guangping Liu; Bingqiang Han; Juliang Xu

    2011-08-01

    The porous spinel ceramics were prepared from magnesite and bauxite by the pore-forming in situ technique. The characterization of porous spinel ceramics was determined by X-ray diffractometer (XRD), scanning electron microscopy(SEM), mercury porosimetry measurement etc and the effects of particle size on microstructure and strength were investigated. It was found that particle size affects strongly on the microstructure and strength. With decreasing particle size, the pore size distribution occurs from multi-peak mode to bi-peak mode, and lastly to mono-peak mode; the porosity decreases but strength increases. The most apposite mode is the specimens from the grinded powder with a particle size of 6.53 m, which has a high apparent porosity (40%), a high compressive strength (75.6MPa), a small average pore size (2.53 m) and a homogeneous pore size distribution.

  7. PREPARATION MICRO-FILTRATION CERAMIC MEMBRANE FROM NATURAL ZEOLITE FOR PROCION RED MX8B AND METHYLENE BLUE FILTRATION

    Directory of Open Access Journals (Sweden)

    Dyah Choiriyah

    2015-12-01

    Full Text Available The study of ceramic membrane fabrication from natural zeolite and its utilization for filtration of procion red MX8B and methylene blue has been investigated. The purposes of this study are to determine the effect of pressure on membrane permeability and selectivity and utilize natural zeolite as ceramic membranes procion red MX8B and methylene blue filtration. The membrane was prepared by metide press pellets and then calcined at 850 oC. The membranes were characterized by mechanical test, flux and rejection of dye. The compression test of the membrane found the values of 1369.178 psi in dry conditions to 1388.933 psi in wet conditions. The flux test found that the higher the pressure applied, the flux was increase. However, the high pressure also decreased the selectivity. Rejection test found that the rejection of methylene blue filtration up to 70 %. Meanwhile, procion red MX8B filtration has rejectivity less than 20 %.

  8. Preparation of α-Al2O3 base ceramic coating on aluminum alloy via thermo-decomposition of diaspore

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The aim of this work is to describe the possibilities of preparing a corundum coating onaluminum alloy through in-situ chemical reaction at a relative low temperature. The transformationconditions of diaspore (β-AIOOH) to corundum (α-Al2O3 ) are studied using X-ray diffraction analy-sis. Temperature and heating time are two main factors influencing the transformation. Suitableheating parameters can lower the transformation temperature. On this basis, a new process isdeveloped to produce corundum ceramic coating on an aluminum alloy substrate. The phasecomposition and microstructure of the coating are studied using X-ray diffraction analysis andScanning Electron Microscopy. Abrasion properties of the coating are evaluated by ring-block tri-botester. The results show that it is feasible to obtain ceramic coatings on aluminum alloy sub-strates by means of thermo-decomposition of diaspore.

  9. Rapid preparation of ceramic moulds for medium-sized superalloy castings with magnesia-phosphate-bonded bauxite-mullite investments

    Directory of Open Access Journals (Sweden)

    Li Tingzhong

    2010-11-01

    Full Text Available Phosphate-bonded investments have already been widely utilized in dental restoration and micro-casting of artistic products for its outstanding rapid setting and high strength. However, the rapid setting rate of investment slurry has up to now been a barrier to extend the use of such slurry in preparation of medium-sized ceramic moulds. This paper proposes a new process of rapid fabrication of magnesia-phosphate-bonded investment ceramic moulds for medium-sized superalloy castings utilizing bauxite and mullite as refractory aggregates. In order to determine the properties of magnesia-phosphate-bonded bauxite-mullite investments (MPBBMI, a series of experiments were conducted, including modification of the workable time of slurry by liquid(mL/powder(g(L/P ratio and addition of boric acid as retard agent and sodium tri-polyphosphate (STP as strengthening agent, and adjustment of bauxite (g/mullite(g(B/M ratio for mechanical strength. Mechanical vibration was applied to improve initial setting time and fluidity when pouring investment slurry; then an intermediate size ceramic mould for superalloy castings was manufactured by means of this rapid preparing process with MPBBMI material. The results showed that the MPBBMI slurry exhibits proper initial setting time and excellent fluidity when the L/P ratio is 0.64 and the boric acid content is 0.88wt.%. The fired specimens made from the MPBBMI material demonstrated adequate compression strength to withstand impact force of molten metal when the B/M ratio is 0.89 and the STP content is 0.92wt.%. The experimental results confirmed the feasibility of the proposed rapid fabricating process for medium-sized ceramic moulds with MPBBMI material by appropriate measures.

  10. High Temperature Advanced Structural Composites. Volume 2. Ceramic Matrix Composites, Fiber Processing and Properties, and Interfaces

    Science.gov (United States)

    1993-04-02

    h. Arrow shows AI,0 3 precipitate. 500x. Alumina-Silica Syvstem 33 Table 4 Hydrated Alumina and Aluminosilicates Name Chemical compound Diaspore ...Contracts and Grants It is my understanding that I will be notified in writing as to the action which the Institute intends to take in the disposition of...0.8(m P~ ~ re(m fl04 10 3a92-50 /mn 2e0h0.410 INTERFACES IN INTERMETALLIC AND CERAMIC MATRIX COMPOSITES peratures or to write fines on substrates".,r

  11. Bibliography on Ceramic Matrix Composites and Reinforcing Whiskers, Platelets, and Fibers, 1970-1990

    Science.gov (United States)

    1993-08-01

    1990 Loewenstein , P. Zenuk, C. (AD D250 757 Whittaker Corporation; Nuclear Metals Division, West Concord, MA 1.4.1.27 Final Report Strength Enhancement... Karl M. AFIT/GAE/ENY/90D-30, 1990 Pantano, Carlo G. (AD A230 470) Carbon 27 (5), 717-27, 1989 (AD D250 862) * Export Control **Distribution Limited...An Overview German, Randall M. Hens, Karl F. Rice, Roy W. Lin, Shun-Tian P. AIChE J. Am. Ceram. Soc. Bull. 36 (4), 481-510, Apr 1990 70 (8), 1294

  12. 陶瓷窑炉中硅酸铝纤维的老化机理%The Aging Mechanisms of Aluminosilicate Fiber Used in Ceramic Kiln

    Institute of Scientific and Technical Information of China (English)

    曾令可; 黄浪欢; 孙宇彤

    2001-01-01

    模拟卫生瓷用窑炉的工作环境,将陶瓷纤维置于各种温度场、气氛场(还原及氧化气氛)及腐蚀性介质中加热,并借助XRD、TEM、DTA等分析测试手段,分析概括了陶瓷纤维使用寿命与工作环境间的关系.%Simulating the working environment in the sanitary ware kiln, ceramic fiber samples are disposed in temperature field,caustic medium or atmosphere field(oxidizing or reducing) and then processed samples are tested through methods such as XRD,TEM,DTA and so on. The relations between ceramic fiber's aging and its working environment are summarized.

  13. 氧化锆耐火纤维在卷取炉上的应用%The Application of Zirconia Ceramic Fiber to the Coihing Furnace

    Institute of Scientific and Technical Information of China (English)

    邓小元; 高燕; 肖永良; 刘伟云

    2011-01-01

    This article describes the situation of zirconia ceramic fiber for Coiling furnace liner in Anyang Iron & Steel Co. Ltd., The liner of Coiling furnace was constructed with zirconium oxide ceramic fiber and paste molded. The purposes of energy saving and extending furnace life achieve, while improving the production quality and the operating environment.%介绍氧化锆耐火纤维在安钢卷取炉上使用情况.采用氧化锆耐火纤维和压模粘贴的施工方法进行了卷取炉炉衬施工,达到了节能降耗、延长炉体寿命的目的,并改善了产品质量与生产操作环境.

  14. INVESTIGATION OF SOFTENING AGENT PREPARATION AND PERFORMANCE OF HANDMADE ECOCOMPOSITES WITH CONIFEROUS WOOD AND BASALT FIBERS

    Institute of Scientific and Technical Information of China (English)

    Guangjian Wang; Deku Shang; Kailiang Zhang; Linna Hu; Zhenhua Guo

    2004-01-01

    In this investigation, basalt mineral fiber softening agent was prepared in order to obtain desirable flexible performance. Stability and physical chemistry natures of softening agent were evaluated by particle size distribution, dilution, storage and folding endurance etc. Constitutes of basalt and wood fibers were determined by energy dispersion analysis X-ray which served as an accessory of scanning electron microscopy (SEM-EDAX). Naturally degradable ecocomposite was prepared by basalt and wood fibers. The results of SEM observation illustrated that the wood and basalt fibers were blended uniformly. The impact factors of beating degree, content of wood fibers and adhesive etc. were discussed. The structure of the naturally degradable ecocomposite was contrasted with that of pure wood fibers and the cause of excellent filtration performance was analyzed. Compared with traditional methods, it was of saving wood resource,a large amount of water and reducing second pollution. As a consequence, the ecocomposite harmonized with environment and accorded with requirement of benignly friendly environment.

  15. Processing and mechanical properties of short fibers/Si{sub 3}N{sub 4p} reinforced BaO.Al{sub 2}O{sub 3}.2SiO{sub 2} ceramic matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Ma Jingmei [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Ye Feng, E-mail: yf306@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Liu Limeng; Zhang Haijiao [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2009-09-15

    Dense short silicon carbide (SiC{sub sf}) and carbon fibers (C{sub sf}) reinforced BaAl{sub 2}Si{sub 2}O{sub 8} (BAS) glass-ceramic composites with silicon nitride were fabricated by hot-pressing technique. The phase characterization, microstructure, mechanical properties and fracture behavior of the composites were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and three-point bending tests. The results showed that short silicon carbide and carbon fibers disperse homogeneously in BAS matrix, and had good chemical compatibility with the glass-ceramic matrix. The addition of Si{sub 3}N{sub 4} could successfully eliminate the microcracks in the BAS matrix induced by the thermal mismatch between the fiber and matrix. Both the added short fibers could effectively reinforce the BAS glass-ceramic by the associated toughening mechanisms such as crack deflection, fiber bridging and pullout effects.

  16. Preparation and characterization of activated carbon fiber (ACF) from cotton woven waste

    Energy Technology Data Exchange (ETDEWEB)

    Jieying Zheng,; Zhao, Quanlin; Ye, Zhengfang, E-mail: zhengfangye@163.com

    2014-04-01

    Highlights: • Cotton woven waste can be recycled as precursor to produce activated carbon fiber. • The optimum carbonization and activation temperature are 700 °C and 800 °C. • The prepared ACF is in the form of fiber, with the surface area of 789 m{sup 2}/g. • The prepared ACF can be used to remove over 80% of COD from oilfield wastewater. - Abstract: In this study, the activated carbon fibers (ACFs) were prepared using cotton woven waste as precursor. The cotton woven waste was first partly dissolved by 80% phosphoric acid and then was pre-soaked in 7.5% diammonium hydrogen phosphate solution. Finally, carbonization and activation were proceeded to get ACF. The optimum preparation conditions, including carbonization temperature, carbonization time, activation temperature and activation time, were chosen by orthogonal design. Nitrogen adsorption/desorption test was conducted to characterize the prepared ACF's pore structure. Fourier transform infrared spectroscopy (FTIR) analysis, X-ray photoelectron spectroscopy (XPS) and environmental scanning electron microscope (ESEM) were employed to characterize its chemical properties and morphology. Adsorption of oilfield wastewater was used to evaluate its adsorption properties. The results show that the prepared ACF is in the form of fiber, with the sectional diameters of 11.7 × 2.6 μm and the surface area of 789 m{sup 2}/g. XPS results show that carbon concentration of the prepared ACF is higher than that of the commercial ACF. When the prepared ACF dosage is 6 g/L, over 80% of COD and over 70% of chrominance can be removed after 24 h of adsorption at 18 °C.

  17. Deposition and Characterization of Sisal Fiber Composite Prepare By Iron Oxide Synthesis.

    Directory of Open Access Journals (Sweden)

    Asif Jehan

    2015-02-01

    Full Text Available Iron oxide synthesized through sintering route. The present research work deals with ferrite composite prepared using chemical reactions. Ferric nitrates and ammonium chloride doped with sisal fiber has been prepared. The comparative studies of ferric oxide were examined through few characterizations. The structural behavior of iron oxide was studied in XRD, FT/IR, TEM and SEM. This behavior showed ferrite nature of the sample.

  18. 陶瓷纤维织物保暖性能研究%STUDY ON THE THERMAL INSULATION PROPERTY OF FABRICS WITH CERAMIC FIBER

    Institute of Scientific and Technical Information of China (English)

    来侃; 张保国; 孙润军

    2001-01-01

    The thermal insulation property of fabrics with ceramic fiber is studied,the rule of structure of fabric is discussed.The result of test is accordant with the theoretic analysis.%对含碳化锆为主的陶瓷纤维织物保暖机理进行了分析,从理论上探讨了此类织物结构参数设计的规律。

  19. 改善SiC陶瓷纤维吸波性能途径∗%The Way of Improve SiC Ceramic Fiber Absorbing Performance

    Institute of Scientific and Technical Information of China (English)

    康永

    2015-01-01

    介绍了 SiC陶瓷吸波材料的吸波机理,并分析了改 SiC陶瓷硅纤维吸波性能的途径。%In this paper,the absorbing mechanism of silicon carbide ceramic absorbing materials is introduced,and the way to improve the performance of SiC fiber is analyzed.

  20. Carbon molecular sieve membranes prepared from porous fiber precursor

    NARCIS (Netherlands)

    Barsema, Jonathan N.; Vegt, van der N.F.A.; Koops, G.H.; Wessling, M.

    2002-01-01

    Carbon molecular sieve (CMS) membranes are usually prepared from dense polymeric precursors that already show intrinsic gas separation properties. The rationale behind this approach is that the occurrence of any kind of initial porosity will deteriorate the final CMS performance. We will show that i

  1. [Preparation of carbon fiber reinforced fluid type resin denture (author's transl)].

    Science.gov (United States)

    Kasuga, H; Sato, H; Nakabayashi, N

    1980-01-01

    Transverse strength of cured fluid resins is weaker than that of the heat cured. We have studied to improve the mechanical strength of self-cured acrylic resin by application of carbon fibers as reinforcement and simple methods which must be acceptable for technicians are proposed. A cloth type carbon fiber was the best reinforcement among studied carbon fibers such as chopped or mat. The chopped fibers were difficult to mix homogeneously with fluid resins and effectiveness of the reinforcement was low. Breaking often occurred at the interface between the reinforcement and resin in the cases of mat which gave defects to the test specimens. To prepare reinforced denture, the cloth was trimmed on the master cast after removal of wax and the prepreg was formed with the alginate impression on the cast by Palapress and the cloth. Other steps were same as the usual fluid resin.

  2. Preparation of ferromagnetic binary alloy fine fibers byorganic gel-thermal reduction process

    Institute of Scientific and Technical Information of China (English)

    SHEN Xiang-qian; CAO Kai; ZHOU Jian-xin

    2006-01-01

    Ferromagnetic metal fibers with a high aspect ratio (length/diameter) are attractive for use as high performance electromagnetic interference shielding materials. Ferromagnetic binary alloy fine fibers of iron-nickel, iron-cobalt and cobalt-nickel were prepared by the organic gel-thermal reduction process from the raw materials of critic acid and metal salts. These alloy fibers synthesized were featured with a diameter of about 1 μm and a length as long as 1 m. The structure, thermal decomposition process and morphologies of the gel precursors and fibers derived from thermal reduction of the gel precursors were characterized by FTIR, XRD, TG/DSC and SEM. The gel spinnability largely depends on the molecular structure of metal- carboxylates formed during the gel formation. The gel consisting of linear-type structural molecules shows good spinnability.

  3. Preparation and supercapacitor performance of assembled graphene fiber and foam

    Directory of Open Access Journals (Sweden)

    Jing Li

    2016-06-01

    Full Text Available Graphene-based materials have been full of vigor and tremendous potentiality for application in supercapacitors due to its variety of unique properties such as electronic properties, simple synthesis, etc. In developing new macroscopic nanostructured graphene materials for supercapacitors, considerable efforts have been made by the scientist including our research group. In this account, we describe our development of the construction of the assembled graphene especially fiber and foam, which have great potential in addressing the challenges in the synthesis of graphene-based electrode materials for supercapacitors. As the supercapacitors are reviewed in this article, they are accordant with the rapid development of flexible, lightweight, and wearable-electronic devices, overcoming the major some drawbacks of conventional bulk supercapacitors. We hope that this summary will benefit the further research of graphene-based materials for the applications in electrochemical energy storage devices and beyond.

  4. Preparation and supercapacitor performance of assembled graphene fiber and foam

    Institute of Scientific and Technical Information of China (English)

    Jing Li; Xianke Huang; Linfan Cui; Nan Chen n; Liangti Qu n

    2016-01-01

    Graphene-based materials have been full of vigor and tremendous potentiality for application in su-percapacitors due to its variety of unique properties such as electronic properties, simple synthesis, etc. In developing new macroscopic nanostructured graphene materials for supercapacitors, considerable efforts have been made by the scientist including our research group. In this account, we describe our development of the construction of the assembled graphene especially fiber and foam, which have great potential in addressing the challenges in the synthesis of graphene-based electrode materials for su-percapacitors. As the supercapacitors are reviewed in this article, they are accordant with the rapid development of flexible, lightweight, and wearable-electronic devices, overcoming the major some drawbacks of conventional bulk supercapacitors. We hope that this summary will benefit the further research of graphene-based materials for the applications in electrochemical energy storage devices and beyond.

  5. 银纤维的制备和应用%Preparation and Application of Silver Fiber

    Institute of Scientific and Technical Information of China (English)

    毛俊峰; 李可欣

    2013-01-01

    The characteristics including antibacterial, deodorant, antistatic, electromagnetic shielding and attemperation of silver fiber are introduced. The fiber preparation methods with the popularly applications attracted much attention are also described. Finally, the existing problems and predicts prospect of the preparation and application of silver fiber are pointed out.%介绍了银纤维的抗菌、除臭、抗静电、电磁波屏蔽等特性;同时叙述了银纤维的制备方法,以及银纤维作为备受关注的功能性纤维的应用;最后指出了目前银纤维制备和应用中存在的问题,并对其前景进行了展望.

  6. Physical and Degradable Properties of Mulching Films Prepared from Natural Fibers and Biodegradable Polymers

    Directory of Open Access Journals (Sweden)

    Zhijian Tan

    2016-05-01

    Full Text Available The use of plastic film in agriculture has the serious drawback of producing vast quantities of waste. In this work, films were prepared from natural fibers and biodegradable polymers as potential substitutes for the conventional non-biodegradable plastic film used as mulching material in agricultural production. The physical properties (e.g., mechanical properties, heat preservation, water permeability, and photopermeability and degradation characteristics (evaluated by micro-organic culture testing and soil burial testing of the films were studied in both laboratory and field tests. The experimental results indicated that these fiber/polymer films exhibited favorable physical properties that were sufficient for use in mulching film applications. Moreover, the degradation degree of the three tested films decreased in the following order: fiber/starch (ST film > fiber/poly(vinyl alcohol (PVA film > fiber/polyacrylate (PA film. The fiber/starch and fiber/PVA films were made from completely biodegradable materials and demonstrated the potential to substitute non-biodegradable films.

  7. Preparation and characterization of gas separation hollow fiber membranes based on polyethersulfone-polyimide miscible blends

    NARCIS (Netherlands)

    Kapantaidakis, G.C.; Koops, G.H.; Wessling, M.

    2002-01-01

    In this work the preparation and characterization of gas separation hollow fibers based on polyethersulfone Sumikaexcel (PES) and polyimide Matrimid 5218 (PI) blends are reported. Scanning Electron Microscopy (SEM) was used to investigate the morphological characteristics and structure of the asymme

  8. Experimental observations of thermal spikes in microwave processing of ceramic oxide fibers

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, G.J.; Unruh, W.P. [Los Alamos National Lab., NM (United States); Thomas, J.R. Jr. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)

    1994-04-01

    Microwave heating of alumina/silica fiber tows in a single-mode microwave cavity at 2.45 GHz have produced a surprising thermal spike behavior on the fiber bundles. During a thermal spike, a ``hot spot`` on the tow brightens rapidly, persists for a few seconds, and rapidly extinguishs. A hot spot can encompass the entire tow in the cavity or just a localized portion of the tow. Some local hot spots propagate along the fiber. Thermal spikes are triggered by relatively small (<15%) increases in power, thus having obvious implications for the development of practical microwave fiber processing systems. A tow can be heated through several successive thermal spikes, after which the tow is left substantially cooler than it was originally, although the applied microwave electric field is much larger. X-ray diffraction studies show that after each temperature spike there is a partial phase transformation of the tow material into mullite. After several excursions the tow has been largely transformed to the new, less lossy phase and is more difficult to heat. Heating experiments with Nextel 550 tows are examined for a pausible explanation of this microwave heating behavior.

  9. 陶瓷纤维模块在工业炉中的应用%Application of Ceramic Fiber Module in Industrial Furnace

    Institute of Scientific and Technical Information of China (English)

    王鲁

    2011-01-01

    以冷轧带钢退火炉为例,介绍了陶瓷纤维模块炉内衬的应用以及安装方法,并对模块化内衬和层铺毯式内衬的炉壁温度进行对比分析.结果表明,陶瓷纤维模块用于炉内衬显示了众多的优越性.在新型炉窑设计或旧炉窑的改造中,陶瓷纤维模块应该成为首选的设计方案.%The application and installation methods of the furnace lined with ceramic fiber module were introduced by taking the example of continuous annealing furnace, and the furnace wall temperature with different lining was analyzed. The results showed that the ceramic fiber modules show much superiorities as furnace lining. The ceramic fiber module should be the preferred solution in the new furnace design or in the old furnace reform.

  10. Comparison of the properties of tonpilz transducers fabricated with 001 fiber-textured lead magnesium niobate-lead titanate ceramic and single crystals.

    Science.gov (United States)

    Brosnan, Kristen H; Messing, Gary L; Markley, Douglas C; Meyer, Richard J

    2009-11-01

    Tonpilz transducers are fabricated from 001 fiber-textured 0.72Pb(Mg(1/3)Nb(2/3))O(3)-0.28PbTiO(3) (PMN-28PT) ceramics, obtained by the templated grain growth process, and PMN-28PT ceramic and Bridgman grown single crystals of the same composition. In-water characterization of single element transducers shows higher source levels, higher in-water coupling, and more usable bandwidth for the 81 vol % textured PMN-28PT device than for the ceramic PMN-28PT element. The 81 vol % textured PMN-28PT tonpilz element measured under large signals shows linearity in sound pressure levels up to 0.23 MV/m drive field but undergoes a phase transition due to a lowered transition temperature from the SrTiO(3) template particles. Although the textured ceramic performs well in this application, it could be further improved with compositional tailoring to raise the transition temperature and better processing to improve the texture quality. With these improvements textured piezoelectric ceramics will be viable options for medical ultrasound, actuators, and sonar applications because of their ease of processing, compositional homogeneity, and potentially lower cost than single crystal.

  11. INVESTIGATION OF BONDING IN OXIDE-FIBER (WHISKER) REINFORCED METALS.

    Science.gov (United States)

    CERAMIC FIBERS , BONDING), (*COMPOSITE MATERIALS, BONDING), (*BONDING, CERAMIC FIBERS ), ALUMINUM COMPOUNDS, OXIDES, ZIRCONIUM, NICKEL, TITANIUM, CHROMIUM, SINGLE CRYSTALS, VACUUM, SHEAR STRESSES, SURFACE PROPERTIES, ADDITIVES.

  12. Study on Physical and Chemical Behaviors of Rare Earths in Preparing Ceramic Tube Supported Palladium Film by Electroless Plating

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The rare earths of ytterbium, lanthanum, praseodymium, neodymium and their binary mixtures were respectively added into the traditional electroless plating solution to prepare thin palladium film on the inner surface of porous ceramic tube. The experimental results shows that the addition of rare earths increases palladium deposition rates and the binary mixtures are superior to the single rare earths and the mixture of ytterbium-lanthanum is the most efficient. Adding the mixture of ytterbium-lanthanum can also reduce the plating temperature by 10~20 ℃, shrink the metal crystal size and improve the film densification compared to those by traditional electroless plating. A thin palladium film with 5 μm was prepared and the film made a highly pure hydrogen with a molar fraction of more than 99.97% from a H2-N2 gas mixture. More attentions were paid to analyze the physical and chemical behaviors of the rare earths in palladium film preparation.

  13. The effect of preparation under vacuum and microwave drying on the mechanical properties of porcelain ceramic foam via polymeric sponge method

    Science.gov (United States)

    Shahatha, S. H.; Mohammed, M. A.

    2016-04-01

    In this paper was demonstrated the effect of preparation condition under vacuum and microwave drying on the mechanical properties of porcelain ceramic foam. The study was based on five different polymeric foam templates with thickness ranging from 0.5 to 4 cm. The templates were impregnated in ceramic slurry with solid loading ranging from 35 to 55 wt. % under vacuum pressure 10-1 Torr and then sintered to 1250°C. Effects of polymeric foam template thickness and solid loading quantity were evaluated based on porosity, density and mechanical properties (compressive and flexural strengths) of the ceramic foam.

  14. Preparation and properties of gradient Al2O3-ZrO2 ceramic foam by centrifugal slip casting method

    Directory of Open Access Journals (Sweden)

    Li Qiang

    2012-11-01

    Full Text Available The aim of the present research is to provide a novel technique for preparing gradient Al2O3-ZrO2 ceramic foams. This technique used epispastic polystyrene spheres to array templates and centrifugal slip casting to obtain cell struts with gradient distribution of Al2O3 and ZrO2 particles and high packing density. Aqueous Al2O3-20vol.% ZrO2 slurries with 20vol.% solid contents were prepared and the dispersion and rheological characteristics of the slurries were investigated. The settling velocity and mass segregation of Al2O3 and ZrO2 particles at different centrifugal accelerations were calculated and studied. The drying behavior, macrostructure, microstructure, compressive property and resistance to thermal shock of the sintered products were also investigated. The results show that the difference of settling velocity of Al2O3 and ZrO2 particles increases and mass segregation becomes acute with an increase in centrifugal acceleration. The cell struts prepared at a centrifugal acceleration of 1,690 g have high sintered density (99.0% TD and continuous gradient distribution of Al2O3 and ZrO2 particles. When sintered at 1,550 oC for 2 h, the cell size of gradient Al2O3-ZrO2 foam is approximately uniform, about 1.1 mm. With the porosity of gradient Al2O3-ZrO2 ceramic foams increasing from 75.3% to 83.0%, the compressive strength decreases from 4.4 to 2.4 MPa, and the ceramic foams can resist 8-11 repeated thermal shock from 1,100 oC to room temperature.

  15. Preparation and laser performance of Nd-doped yttrium lanthanum oxide transparent ceramic

    Science.gov (United States)

    Yang, Qiuhong; Lu, Shenzhou; Zhang, Bin; Zhang, Haojia; Zhou, Jun; Yuan, Zhijun; Qi, Yunfeng; Lou, Qihong

    2011-03-01

    1.5 at.% Nd:Y 1.8La 0.2O 3 transparent ceramic was fabricated by a solid-state reaction method and sintered at 1650-1700 °C for 40-50 h under H 2 atmosphere. The spectroscopic properties were investigated at room temperature. The transparent ceramic has excellent spectroscopic properties, with the absorption cross section of 1.50 × 10 -20 cm 2 and broad full width at half maximum (FWHM) of about 8 nm at LD wavelength 806 nm, the emission cross section of 2.03 × 10 -20 cm 2 at 1079 nm, and the decay lifetime of 200 μs. Laser performance was carried out using an uncoated Nd:Y 1.8La 0.2O 3 ceramic plate under laser diode end-pumping without any water cooling device. The room temperature thermal conductivity of this ceramic is 6.20 W/mK. For Nd:Y 1.8La 0.2O 3 ceramic laser, a maximum output power of 62 mW was obtained at 1079 nm under a 808 nm diode pump.

  16. Effect of Sintering Temperature on the Properties of Fused Silica Ceramics Prepared by Gelcasting

    Science.gov (United States)

    Wan, Wei; Huang, Chun-e.; Yang, Jian; Zeng, Jinzhen; Qiu, Tai

    2014-07-01

    Fused silica ceramics were fabricated by gelcasting, by use of a low-toxicity N' N-dimethylacrylamide gel system, and had excellent properties compared with those obtained by use of the low-toxicity 2-hydroxyethyl methacrylate and toxic acrylamide systems. The effect of sintering temperature on the microstructure, mechanical and dielectric properties, and thermal shock resistance of the fused silica ceramics was investigated. The results showed that sintering temperature has a critical effect. Use of an appropriate sintering temperature will promote densification and improve the strength, thermal shock resistance, and dielectric properties of fused silica ceramics. However, excessively high sintering temperature will greatly facilitate crystallization of amorphous silica and result in more cristobalite in the sample, which will cause deterioration of these properties. Fused silica ceramics sintered at 1275°C have the maximum flexural strength, as high as 81.32 MPa, but, simultaneously, a high coefficient of linear expansion (2.56 × 10-6/K at 800°C) and dramatically reduced residual flexural strength after thermal shock (600°C). Fused silica ceramics sintered at 1250°C have excellent properties, relatively high and similar flexural strength before (67.43 MPa) and after thermal shock (65.45 MPa), a dielectric constant of 3.34, and the lowest dielectric loss of 1.20 × 10-3 (at 1 MHz).

  17. Preparation of ceramic-corrosion-cell fillers and application for cyclohexanone industry wastewater treatment in electrobath reactor.

    Science.gov (United States)

    Wu, Suqing; Qi, Yuanfeng; Gao, Yue; Xu, Yunyun; Gao, Fan; Yu, Huan; Lu, Yue; Yue, Qinyan; Li, Jinze

    2011-11-30

    As new media, ceramic-corrosion-cell fillers (Cathode Ceramic-corrosion-cell Fillers - CCF, and Anode Ceramic-corrosion-cell Fillers - ACF) employed in electrobath were investigated for cyclohexanone industry wastewater treatment. 60.0 wt% of dried sewage sludge and 40.0 wt% of clay, 40.0 wt% of scrap iron and 60.0 wt% of clay were utilized as raw materials for the preparation of raw CCF and ACF, respectively. The raw CCF and ACF were respectively sintered at 400°C for 20 min in anoxic conditions. The physical properties (bulk density, grain density and water absorption), structural and morphological characters and toxic metal leaching contents were tested. The influences of pH, hydraulic retention time (HRT) and the media height on removal of COD(Cr) and cyclohexanone were studied. The results showed that the bulk density and grain density of CCF and ACF were 869.0 kg m(-3) and 936.3 kg m(-3), 1245.0 kg m(-3) and 1420.0 kg m(-3), respectively. The contents of toxic metal (Cu, Zn, Cd, Pb, Cr, Ba, Ni and As) were all below the detection limit. When pH of 3-4, HRT of 6h and the media height of 60 cm were applied, about 90% of COD(cr) and cyclohexanone were removed.

  18. Comparative study of dielectric properties of MgNb2O6 prepared by molten salt and ceramic method

    Indian Academy of Sciences (India)

    Vishnu Shanker; Ashok K Ganguli

    2003-12-01

    Magnesium niobate (MgNb2O6) powder was synthesized by the conventional ceramic route as well as by the molten salt route using a eutectic mixture of NaCl–KCl as the salt and Mg(NO3)$_2\\cdot$6H2O and TiO2 as the starting materials. Pure phase of MgNb2O6 could be obtained by the molten salt method at 1100°C. However, in ceramic method the pure phase of MgNb2O6 was obtained by heating at 1025°C for 20 h. On sintering at 1100°C the dielectric constant and dielectric loss of MgNb2O6 obtained by the molten salt method was found to be 19.5 and 0.004 at 100 kHz at room temperature. Lower values were obtained for these oxides prepared by the ceramic route, 16.6 and 0.000518, respectively. In both cases the dielectric constant was quite stable with frequency.

  19. Preparation of Silver- and Zinc-Doped Mullite-Based Ceramics Showing Anti-Bacterial Biofilm Properties

    Directory of Open Access Journals (Sweden)

    Suhair Saleh

    2011-03-01

    Full Text Available Zinc- and silver-doped mullite ceramic discs were prepared and tested as potentially resistant materials against bacterial adhesion and biofilm formation. Elemental analysis and X-ray diffraction studies showed that zinc ions were incorporated in the structural framework of the mullite, while silver ions remained outside the mullite crystal lattice, which allowed their slow (0.02 ppm/24 hours leaching into the surrounding aqueous environment. In agreement with this behavior, silver-doped mullite showed potent resistance against surface attachment of Pseudomonas aeruginosa, while on the other hand, zinc-doped mullite failed to stop bacterial attachment.

  20. Oxidation Kinetics and Strength Degradation of Carbon Fibers in a Cracked Ceramic Matrix Composite

    Science.gov (United States)

    Halbig, Michael C.

    2003-01-01

    Experimental results and oxidation modeling will be presented to discuss carbon fiber susceptibility to oxidation, the oxidation kinetics regimes and composite strength degradation and failure due to oxidation. Thermogravimetric Analysis (TGA) was used to study the oxidation rates of carbon fiber and of a pyro-carbon interphase. The analysis was used to separately obtain activation energies for the carbon constituents within a C/SiC composite. TGA was also conducted on C/SiC composite material to study carbon oxidation and crack closure as a function of temperature. In order to more closely match applications conditions C/SiC tensile coupons were also tested under stressed oxidation conditions. The stressed oxidation tests show that C/SiC is much more susceptible to oxidation when the material is under an applied load where the cracks are open and allow for oxygen ingress. The results help correlate carbon oxidation with composite strength reduction and failure.

  1. Preparation and properties of nano-composite ceramic coating by thermo chemical reaction method

    Institute of Scientific and Technical Information of China (English)

    MA Zhuang; SUN Fang-hong; LI Zhi-chao

    2007-01-01

    Nano-composite ceramic coating was fabricated on Q235 steel through thermo chemical reaction method. Structure of the coating was analyzed and the properties were tested. The results show that a few of new ceramic phases, such as MgAl2O4, ZnAl2O4,Al2SiO5, Ni3Fe and Fe3Al, are formed on the coating during the process of solidifying at 600 ℃. The ceramic coating is dense and the high bonding strength is obtained. The average bonding strength between the coating and matrix could be 14.22 MPa. The acid resistance of the coating increase by 8.8 times, the alkali resistance by 4.1 times, the salt resistance by 10.3 times, and the wear resistance by 2.39 times.

  2. 莫来石纤维含量对陶瓷基摩擦材料摩擦磨损性能的影响%Effects of Mullite Fiber Content on Friction and Wear Properties of Ceramic-based Friction Material

    Institute of Scientific and Technical Information of China (English)

    王发辉; 刘莹

    2012-01-01

    Ceramic-based friction material with 0%-24% (mass fraction) mullite fiber reinforcement was prepared by nitrogen protection hot-pressing sintering. The effect of mullite fiber content on friction and wear properties of ceramic-based friction material was studied on the XD-MSM constant speed friction tester. The worn surfaces morphology after tests was observed by scanning electron mic'rosco-py (SEM), and wear mechanism was discussed. The results show that mullite fiber could increase friction coefficients of ceramic-based friction material, and with increasing mullite fiber contents, friction coefficients continuously increase. While the wear rates also increase with increasing mullite fiber contents at high temperature. The dominant wear mechanism of ceramic-based friction material without mullite fiber is brittle spalling and fatigue wear, accompanying with abrasive wear; the main wear type converts into adhesion wear and abrasive wear when adding mullite fiber into ceramic friction material.%利用氮气保护热压烧结法制备含0%~24%(质量分数)莫来石纤维增强陶瓷基摩擦材料,采用XD-MSM型定速摩擦试验机研究莫来石纤维含量对摩擦材料摩擦磨损性能的影响,借助于扫描电子显微镜观察实验后试样的磨损表面形貌,并探讨其磨损机理.结果表明:莫来石纤维的加入能够显著提高陶瓷基摩擦材料的摩擦因数,且随莫来石纤维含量增加而增大.在高温下,陶瓷基摩擦材料的磨损率随莫来石纤维含量增加而增大.未添加莫来石纤维的陶瓷基摩擦材料磨损形式主要是脆性脱落和疲劳磨损,伴有磨粒磨损;而添加莫来石纤维的陶瓷基摩擦材料磨损形式转化为黏着磨损和磨粒磨损.

  3. Microstructure characterization of PAN preoxidation fibers prepared with radio frequency plasma

    Institute of Scientific and Technical Information of China (English)

    FU Weibiao; XU Haiping; GONG Jingsong; SUN Yanping; HOU Lingyun; CHEN Xinmou

    2006-01-01

    The microstructures of preoxidation fibers prepared with radio frequency plasma were characterized in terms of micron, nano and atomic scales through scanning electron microscopy (SEM), high resolving transmission electron microscopy (HRTEM), scanning tunneling microscopy (STM), X-ray diffraction (XRD), etc. The polyacrylonitrile (PAN) precursors were first soaked in the oxygen-enriched solvent and polarized in radio frequency electric field, and then were oxidized in the atmosphere of oxygen plasma. The morphology of SEM at micron scales shows that the wrinkles on the surface of preoxidation fibers prepared with plasma are shallower, and the surfaces are more tidy and smoother than the unsoaked samples prepared with usual electric furnace, and the uneven radial structure is improved. The results of XRD calculation show that the graphitization degree and microcrystalline size get larger and the interlayer spacing gets smaller. Also, the lattice stripe and edge of bedding plane (002) can be observed from HRTEM at nano scales. From STM images at nano and atom scales, the microfibrils were found to be composed of ultrafibrils that closely twined and arranged, forming the left spiral structures spreading to fiber axis, and the carbon atoms on the surface of microcrystalline were found to have the trend of directional arrangement. All the above characterization results indicate that the plasma method effectively makes the internal and external oxidation of PAN precursors at the same level, so that the radial structure difference of preoxidation fibers is reduced.

  4. Preparation and mechanical property of core-shell type chitosan/calcium phosphate composite fiber

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Atsushi [Japan Society for the Promotion of Science, Ikenohata1-1-1, Daitou-ku, Tokyo 110-0008 (Japan) and Creative Research Initiative ' Sousei' , Hokkaido University, Sapporo, Hokkaido 001-0021 (Japan)]. E-mail: MATSUDA.Atsushi@nims.go.jp; Ikoma, Toshiyuki [Biomaterials Research Center, National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044 (Japan); Kobayashi, Hisatoshi [Biomaterials Research Center, National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044 (Japan)]. E-mail: Kobayashi.Hisatoshi@nims.go.jp; Tanaka, Junzo [Creative Research Initiative ' Sousei' , Hokkaido University, Sapporo, Hokkaido 001-0021 (Japan); Biomaterials Research Center, National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044 (Japan)

    2004-12-01

    Core-shell type chitosan/calcium phosphate composite fibers were prepared by a facile wet spinning method; the chitosan aqueous solution with PO{sub 4} ions was dropped and coagulated in the ethanol/calcium hydroxide solutions at different mixed ratio. X-ray diffraction (XRD) patterns indicated that the crystal phases of calcium phosphates in the composite fibers were a low-crystalline hydroxyapatite (HAp; Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2})or the low-crystalline hydroxyapatite/brushite mixture depended on the ratio of ethanol/calcium hydroxide solutions. The inorganic contents were ca. 60 wt.% by using the TG-DTA analysis. The energy-dispersive X-ray spectroscopy (EDS) analysis indicated that Ca and P atoms were mainly distributed on the outer layer of the composite fiber to grow calcium phosphate crystals; however, a little amount of P atom still remained at the inside of the fiber. This indicated that the composite fibers formed a unique core-shell structure with shell of calcium phosphate and core of chitosan. The mechanical property of the fibers was reinforced by the initial concentration of chitosan solution.

  5. KINETICS OF GRAIN-GROWTH OF YTTRIUM ALUMINUM GARNET FIBERS PREPARED BY SOL-GEL METHOD

    Directory of Open Access Journals (Sweden)

    Tan H.

    2013-12-01

    Full Text Available The yttrium aluminum garnet (YAG long fibers were prepared by the sol-gel method using aluminum chloride, aluminum powder, yttrium oxide and acetic acid as raw materials. The grain growth law is given by Dn – D0n = Kt (D0 = initial grain size, D = average grain size at time t, n = grain growth exponent and K = reaction constant. The grain growth exponent and activation energy of YAG fibers are ≈ 3 and 200 kJ/mol, respectively. The grain-growth behaviors of YAG were influenced by experimental conditions such as raw materials, initial particle size, initial particle distribution, etc.

  6. PREPARATION AND CHARACTERIZATION OF MODIFIED STARCH-BASED BIODEGRADABLE MATERIALS REINFORCED WITH PULP FIBER

    Institute of Scientific and Technical Information of China (English)

    LingfangJi; ShucaiLi

    2004-01-01

    Native corn starch and hydroxypropyl starch (HPS) based plastic films were prepared using the short pulp fiber as reinforcement and the glycerol as the plasticizer. The results of tensile test showed that the tensile strength and the elongation at break increased with the pulp contents. With the glycerol contents, the elongation at break increased considerably, but the tensile strength decreased. The water uptake of the films decreased with the pulp contents and hydroxypropylation, but increased with the glycerol contents. So it is concluded that the films was reinforced by pulp fiber and hydroxypropylation.

  7. PREPARATION AND CHARACTERIZATION OF MODIFIED STARCH-BASED BIODEGRADABLE MATERIALS EINFORCED WITH PULP FIBER

    Institute of Scientific and Technical Information of China (English)

    Lingfang Ji; Shucai Li

    2004-01-01

    Native com starch and hydroxypropyl starch (HPS)based plastic films were prepared using the short pulp fiber as reinforcement and the glycerol as the plasticizer. The results of tensile test showed that the tensile strength and the elongation at break increased with the pulp contents. With the glycerol contents,the elongation at break increased considerably, but the tensile strength decreased. The water uptake of the films decreased with the pulp contents and hydroxypropylation, but increased with the glycerol contents. So it is concluded that the films was reinforced by pulp fiber and hydroxypropylation.

  8. Nanoscale multilayered and porous carbide interphases prepared by pressure-pulsed reactive chemical vapor deposition for ceramic matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Jacques, S., E-mail: jacques@lcts.u-bordeaux1.fr [LCTS, University of Bordeaux 1, CNRS, Herakles-Safran, CEA, 3 allee de la Boetie, F-33600 Pessac (France); Jouanny, I.; Ledain, O.; Maillé, L.; Weisbecker, P. [LCTS, University of Bordeaux 1, CNRS, Herakles-Safran, CEA, 3 allee de la Boetie, F-33600 Pessac (France)

    2013-06-15

    In Ceramic Matrix Composites (CMCs) reinforced by continuous fibers, a good toughness is achieved by adding a thin film called “interphase” between the fiber and the brittle matrix, which acts as a mechanical fuse by deflecting the matrix cracks. Pyrocarbon (PyC), with or without carbide sub-layers, is typically the material of choice to fulfill this role. The aim of this work was to study PyC-free nanoscale multilayered carbide coatings as interphases for CMCs. Nanoscale multilayered (SiC–TiC){sub n} interphases were deposited by pressure-Pulsed Chemical Vapor Deposition (P-CVD) on single filament Hi-Nicalon fibers and embedded in a SiC matrix sheath. The thicknesses of the carbide interphase sub-layers could be made as low as a few nanometers as evidenced by scanning and transmission electron microscopy. By using the P-ReactiveCVD method (P-RCVD), in which the TiC growth involves consumption of SiC, it was not only possible to obtain multilayered (SiC–TiC){sub n} films but also TiC films with a porous multilayered microstructure as a result of the Kirkendall effect. The porosity in the TiC sequences was found to be enhanced when some PyC was added to SiC prior to total RCVD consumption. Because the porosity volume fraction was still not high enough, the role of mechanical fuse of the interphases could not be evidenced from the tensile curves, which remained fully linear even when chemical attack of the fiber surface was avoided.

  9. Preparation of Biomorphic SiC/C Ceramics from Pine Wood via Supercritical Ethanol Infiltration

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Biomorphic (wood derived) carbide ceramics with an overall composition in the SiC/C was produced by supercritical ethanol infiltration of low viscosity tetraethylorthosilicate/supercritical ethanol into biologically derived carbon templates (CB-templates) and in situ hydrolysis into Si(OH)4-gel, the Si(OH)4-gel was calcined at 1400℃ to promote the polycondensation of Si(OH)4-gel into SiO2-phase and then carbonthermal reduction of the SiO2 with the biocarbon template into highly porous, biomorphic SiC/C ceramics. The phases and morphology conversion mechanism of resulting porous SiC/C ceramics have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR). Experimental results showed that the biomorphic cellular morphology of pinewood charcoal was remained in the porous SiC/C ceramic with high precision that consisted of β-SiC with minority of α-SiC and the remain free carbon existed in amorphous phase.

  10. Preparation and luminescence properties of Eu3+ doped oxyfluoride borosilicate glass ceramics

    Institute of Scientific and Technical Information of China (English)

    LI Yanhong; ZHAO Li; ZHANG Yongming; MA Jing

    2012-01-01

    Oxyfluoride borosilicate glass with the molar composition of60SiO2-15B2O3-15Na2O-8CaF2-2NaF-0.25Eu2O3 was synthesized by a traditional glass melting method.Glass ceramics containing CaF2 nanocrystals were preparcd by heat treating the glass samples at a temperature in the range of 620-680℃.The results of X-ray diffraction (XRD) indicated that the average crystallite size and the lattice constant of CaF2 nanocrystals increased with the heat treatment temperature incrcasing.The luminescence spectra showed that the emission intensity of Eu3+ doped glass ceramics was stronger than that of the glass matrix,and increased with the heat treatment temperature increasing.The left edge of excitation band shifted to shorter wavelength in the glass ceramics.The local environments of Eu3+ ions in the glass and glass ceramics were different.

  11. Preparation of Gd2O2S:Pr Scintillation Ceramics by Pressureless Reaction Sintering Method

    Institute of Scientific and Technical Information of China (English)

    Jingbao Lian; Xudong Sun; Tie Gao; Qiang Li; Xiaodong Li; Zhigang Liu

    2009-01-01

    Fabrication of Gd2O2S:Pr scintillation ceramics by pressureless reaction sintering was investigated. The 2Gd2O3.(Gd,Pr)2(SO4)3.mH2O precursor was made by hydrotherrnal reaction using commercially available Gd2O3, Pr6O11 and H2SO4 as the starting materials. Then single phase Gd2O2SO4:Pr powder was obtained by calcining the precursor at 750℃ for 2 h. The Gd2O2SO4:Pr powder compacts can be sintered to single phase Gd2O2S:Pr ceramics with a relative density of 99% and mean grain size of 30 μm at 1750℃ for 2 h in flowing hydrogen atmosphere. Densification and microstructural development of the Gd2O2S:Pr ceramics were examined. Luminescence spectra of the Gd2O2S:Pr ceramic under 309 nm UV excitation and X-ray excitation show a green emission at 511 nm as the most prominent peak, which corresponds to the 3P0-ZH4 transition of Pr3+ ions.

  12. Preparation of TiN Ceramic Collector for Sodium Sulfur Battery

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Hao; MA; Jun-ping; TANG; Xian

    2015-01-01

    As an energy storage technology,sodium sulfur battery is used in many areas.It uses beta alumina ceramic as electrolytes,sodium and sulfur as electrode,the working temperature is350℃,which can get heat from radioisotopes.Traditional battery uses stainless steel and Al as collector,which are easily eroded by sodium.As

  13. Pyrochlore free 0.67PMN-0.33PT ceramics prepared by particle-coating method

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Ruiqing; Li, Yan [College of Materials Science and Engineering, Liaocheng University, Liaocheng 252059 (China); Gong, Shuwen [College of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059 (China); Liu, Yong [College of Materials Science and Engineering, Liaocheng University, Liaocheng 252059 (China); Li, Guorong [The State Key Lab of High Performance Ceramics and Superfinemicrostructure, Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai 200050 (China); Xu, Zhijun, E-mail: zhjxu@lcu.edu.cn [College of Materials Science and Engineering, Liaocheng University, Liaocheng 252059 (China)

    2012-08-20

    Highlights: Black-Right-Pointing-Pointer Pyrochlore-free PMN-PT powders were obtained by two-step particle-coating method. Black-Right-Pointing-Pointer Mg-citric acid polymeric complex coatings avoid the formation of pyrochlore phase. Black-Right-Pointing-Pointer Pyrochlore-free PMN-PT powders have been successfully prepared at 800 Degree-Sign C. Black-Right-Pointing-Pointer The PMN-PT ceramics sintered at 1150 Degree-Sign C exhibited excellent electrical properties. - Abstract: In present study, pyrochlore-free 0.67Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.33PbTiO{sub 3} (0.67PMN-0.33PT) powders and ceramics have been successfully prepared. Using oxides as raw materials, pyrochlore-free 0.67PMN-0.33PT powders were obtained by two-step particle-coating method. The XRD and EDS results confirmed that the Mg-citric acid polymeric complex coatings effectively prevent the direct contact between PbO and Nb{sub 2}O{sub 5} and thus avoid the formation of pyrochlore phase. The obtained pyrochlore-free 0.67PMN-0.33PT powders at 800 Degree-Sign C showed uniform and even grain size. The 0.67PMN-0.33PT ceramics sintered at 1150 Degree-Sign C for 2 h exhibited 99% of relative density and a piezoelectric coefficient (d{sub 33}) of 576pC/N, a remnant polarization (P{sub r}) of 28.4 {mu}C/cm{sup 2}, a planar electromechanical coupling factor (k{sub p}) of 0.55 and a mechanical quality factor (Q{sub m}) of 90.

  14. Synthesis of ceramic hollow fiber supported zeolitic imidazolate framework-8 (ZIF-8) membranes with high hydrogen permeability

    KAUST Repository

    Pan, Yichang

    2012-12-01

    Purification and recovery of hydrogen from hydrocarbons in refinery streams in the petrochemical industry is an emerging research field in the study of membrane gas separation. Hollow fiber membrane modules can be easily implemented into separation processes at the industrial scale. In this report, hollow yttria-stabilized zirconia (YSZ) fiber-supported zeolitic imidazole framework-8 (ZIF-8) membranes were successfully prepared using a mild and environmentally friendly seeded growth method. Our single-component permeation studies demonstrated that the membrane had a very high hydrogen permeance (~15×10 -7mol/m 2sPa) and an ideal selectivity of H 2/C 3H 8 of more than 1000 at room temperature. This high membrane permeability and selectivity caused serious concentration polarization in the separation of H 2/C 3H 8 mixtures, which led to almost 50% drop in both the H 2 permeance and the separation factor. Enhanced mixing on the feed side could reduce the effect of the concentration polarization. Our experimental data also indicated that the membranes had excellent reproducibility and long-term stability, indicating that the hollow fiber-supported ZIF-8 membranes developed in this study have great potential in industry-scale separation of hydrogen. © 2012 Elsevier B.V.

  15. Preparation of LuAG Powders with Single Phase and Good Dispersion for Transparent Ceramics Using Co-Precipitation Method

    Directory of Open Access Journals (Sweden)

    Liangjie Pan

    2015-08-01

    Full Text Available The synthesis of pure and well dispersed lutetium aluminum garnet (LuAG powder is crucial and important for the preparation of LuAG transparent ceramics. In this paper, high purity and well dispersed LuAG powders have been synthesized via co-precipitation method with lutetium nitrate and aluminum nitrate as raw materials. Ammonium hydrogen carbonate (AHC was used as the precipitant. The influence of aging time, pH value, and dripping speed on the prepared LuAG powders were investigated. It showed that long aging duration (>15 h with high terminal pH value (>7.80 resulted in segregation of rhombus Lu precipitate and Al precipitate. By decreasing the initial pH value or accelerating the dripping speed, rhombus Lu precipitate was eliminated and pure LuAG nano powders were synthesized. High quality LuAG transparent ceramics with transmission >75% at 1064 nm were fabricated using these well dispersed nano LuAG powders.

  16. Effect of organic additives on mechanical properties of SiC ceramics prepared by a modified gelcasting method

    Directory of Open Access Journals (Sweden)

    Feng Wang

    2016-12-01

    Full Text Available A novel and simple gel system of isobutylene and maleic anhydride (PIBM was used to prepare SiC ceramics. The rheological behaviour of the SiC slurries was investigated as function of organic additives. The SiC slurries with 0.2 wt.% PIBM and 0.2 wt.% tetramethylammonium hydroxide (TMAH showed low viscosity, which was favourable for casting SiC green bodies. In order to obtain homogeneous green bodies, polyvinyl alcohol (PVA was used to assist the dispersion of carbon black in the slurries, and polyethylene glycol (PEG was added to inhibit the surface exfoliation of green bodies. The content of PVA was controlled carefully to avoid the warpage of green bodies during the drying process. Finally, homogeneous defect-free SiC green bodies were successfully fabricated via aqueous gelcasting. The SiC ceramics sintered at 2100 °C (prepared from slurries with solid content of 60 wt.% showed an average flexural strength of 305.7 MPa with porosity of 19.92%.

  17. Flaw strength distributions and statistical parameters for ceramic fibers: The normal distribution

    Science.gov (United States)

    R'Mili, M.; Godin, N.; Lamon, J.

    2012-05-01

    The present paper investigates large sets of ceramic fibre failure strengths (500 to 1000 data) produced using tensile tests on tows that contained either 500 or 1000 filaments. The probability density function was determined through acoustic emission monitoring which allowed detection and counting of filament fractures. The statistical distribution of filament strengths was described using the normal distribution. The Weibull equation was then fitted to this normal distribution for estimation of statistical parameters. A perfect agreement between both distributions was obtained, and a quite negligible scatter in statistical parameters was observed, as opposed to the wide variability that is reported in the literature. Thus it was concluded that flaw strengths are distributed normally and that the statistical parameters that were derived are the true ones. In a second step, the conventional method of estimation of Weibull parameters was applied to these sets of data and, then, to subsets selected randomly. The influence of other factors involved in the conventional method of determination of statistical parameters is discussed. It is demonstrated that selection of specimens, sample size, and method of construction of so-called Weibull plots are responsible for statistical parameters variability.

  18. Properties of amorphous SiBNC-ceramic fibres

    Energy Technology Data Exchange (ETDEWEB)

    Baldus, H.-P. [Bayer AG, Leverkusen (Germany); Passing, G. [Bayer AG, Leverkusen (Germany); Scholz, H. [Fraunhofer-Institut fuer Silicatforschung (ISC), Wuerzburg (Germany); Sporn, D. [Fraunhofer-Institut fuer Silicatforschung (ISC), Wuerzburg (Germany); Jansen, M. [Bonn Univ. (Germany). Inst. fuer Anorganische Chemie; Goering, J. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Koeln (Germany). Inst. fuer Werkstoff-Forschung

    1997-06-01

    A new amorphous ceramic material consisting of Si, N, C, and B can be synthesized by pyrolysis of a preceramic polyborosilazane (PBS-Me) made of the ``single source`` precursor Cl{sub 3}Si-NH-BCl{sub 2} (TADB). Novel ceramic fibers consisting of borosilicon carbonitride (SiBN{sub 3}C) can be synthesized from this polymer by using a simple melt spinning process, followed by an intermediate curing step and successive pyrolysis of the obtained infusible green fibers. In the present paper we report on the preparation of the ceramic fibres, as well as their thermal stability, and their mechanical behaviour, including high temperature creep data. The reported mechanical data will be correlated to the microstructure of the fibers. (orig.)

  19. Reduced leakage current and improved ferroelectricity in magneto-electric composite ceramics prepared with microwave assisted radiant hybrid sintering

    Directory of Open Access Journals (Sweden)

    Sanjay Kumar Upadhyay

    2015-04-01

    Full Text Available Structural, electrical and magnetic properties of magneto-electric composite ceramics viz., 0.9 BaTi0.95Sn0.05O3 (BTSO- 0.1 Ni0.8Zn0.2Fe2O4 (NZFO prepared with microwave assisted radiant hybrid sintering (MARH are reported. Phase purity and isovalent substitution of Ti4+ by Sn4+ of the samples is confirmed from x-ray diffraction and 119Sn Mossbauer measurements respectively. Significant suppression of leakage current and improvement of ferroelectricity is observed for the composites prepared with MARH. The observed results are explained in terms of uniform dispersion of ferrite (NZFO phase in the ferroelectric (BTSO matrix as evidenced from back-scattered scanning electron micrographs.

  20. The Preparation of Soft Magnetic Composites Based on FeSi and Ferrite Fibers

    Science.gov (United States)

    Strečková, Magdaléna; Fáberová, Mária; Bureš, Radovan; Kurek, Pavel

    2016-12-01

    The fields of soft magnetic composites and powder metallurgy technologies have a powerful potential to redesign the way of electric motor preparation, and will continue to grow for years to come. A design of the novel soft microcomposite material composed of spherical FeSi particles and Ni0.3Zn0.7Fe2O4 ferrite nanofibers is reported together with a characterization of basic mechanical and electrical properties. The needle-less electrospinning method was used for a preparation of Ni0.3Zn0.7Fe2O4 ferrite nanofibers, which has a spinel-type crystal structure as verified by XRD and TEM analysis. The dielectric coating was prepared by mixing of nanofibers with glycerol and ethanol because of safe manipulation with fumed fibers and homogeneous distribution of the coating around the FeSi particle surface. The final microcomposite samples were prepared by a combination of the traditional PM compaction technique supplemented with a conventional sintering process of the prepared green compacts. The composition and distribution of the secondary phase formed by the spinel ferrite fibers were examined by SEM. It is demonstrated that the prepared composite material has a tight arrangement without any significant porosity, which manifest itself through superior mechanical properties (high mechanical hardness, Young modulus, and transverse rupture strength) and specific electric resistivity compared to the related composite materials including resin as the organic binder.

  1. Preparation and characterization of boron nitride/carbon fiber composite with high specific surface area

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yan; Fan, Mingwen [Wuhan Univ. (China). Key Laboratory for Oral Biomedical Engineering; Yuan, Songdong; Xiong, Kun; Hu, Kunpeng; Luo, Yi [Hubei Univ. of Technology, Wuhan (China). School of Chemistry and Chemical Engineering; Li, Dong [Hubei Univ. of Technology, Wuhan (China). School of Chemistry and Chemical Engineering; Oxford Univ. (United Kingdom). Chemistry Research Lab.

    2014-06-15

    Boron nitride can be used as a good catalyst carrier because of its high thermal conductivity and chemical stability. However, a high specific surface area of boron nitride is still desirable. In this work, a carbon fiber composite coated with boron nitride villous nano-film was prepared, and was also characterized by means of scanning electron microscopy, high resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller analysis. The results indicated that the carbon fibers were covered by uniform villous boron nitride films whose thickness was about 150 - 200 nm. The specific surface area of the boron nitride/carbon fiber composite material was 96 m{sup 2} g{sup -1}, which was markedly improved compared with conventional boron nitride materials. (orig.)

  2. Cellulose acetate fibers prepared from different raw materials with rapid synthesis method.

    Science.gov (United States)

    Chen, Jinghuan; Xu, Jikun; Wang, Kun; Cao, Xuefei; Sun, Runcang

    2016-02-10

    Transesterification is a mild process to prepare cellulose acetate (CA) as compared with the traditional method. In this study, CA fibers were produced from six cellulose raw materials based on a simple and rapid transesterification method. The properties of the CA solutions and the obtained CA fibers were investigated in detail. Results showed that all of the cellulose raw materials were esterified within 15 min, and spinning dopes could be obtained by concentrating the CA solutions via vacuum distillation. The XRD, FT-IR, (1)H, (13)C and HSQC NMR analysis confirmed the successful synthesis of CA. The degree of substitution (DS) of the obtained CA was significantly affected by the degree of polymerization (DP) of cellulose raw materials, which further influenced the viscosity of CA solutions as well as the structural, thermal and mechanical properties of the CA fibers.

  3. Preparation of ferromagnetic metal fine fibers by organic gel-thermal reduction process

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The organic gel-thermal reduction process was used for the preparation of ferromagnetic metal Ni, Co and Fe fine fibers from the raw materials of citric acid, lactic acid and metal salts. The structure, thermal decomposition process and morphologies of the gel precursors and fibers derived from thermal reduction of these gel precursors were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermo-gravimetric/differential scanning calorimetry and scanning electron microscopy. The results show that spinnability of gel largely depends on molecular structure of metal-carboxylate complex that is a linear-type structure formed in the gel. As a result, the gels exhibit a good spinnability. Metal Ni, Co and Fe fine fibers are featured with diameters of around 1 urn and a high aspect ratio up to 1×106.

  4. Nanocelluloses from jute fibers and their nanocomposites with natural rubber: Preparation and characterization.

    Science.gov (United States)

    Thomas, Martin George; Abraham, Eldho; Jyotishkumar, P; Maria, Hanna J; Pothen, Laly A; Thomas, Sabu

    2015-11-01

    Nanocellulose fibers having an average diameter of 50nm were isolated from raw jute fibers by steam explosion process. The isolation of nanocellulose from jute fibers by this extraction process is proved by SEM, XRD, FTIR, birefringence and TEM characterizations. This nanocellulose was used as the reinforcing agent in natural rubber (NR) latex along with crosslinking agents to prepare crosslinked nanocomposite films. The effects of nanocellulose loading on the morphology and mechanics of the nanocomposites have been carefully analyzed. Significant improvements in the Young's modulus and tensile strength of the nanocomposite were observed because of the reinforcing ability of the nanocellulose in the rubber matrix. A mechanism is suggested for the formation of the Zn-cellulose complex. The three-dimensional network of cellulose nanofibers (cellulose/cellulose network and Zn/cellulose network) in the NR matrix plays a major role in improving the properties of the crosslinked nanocomposites.

  5. Preparation of a sol-gel-derived carbon nanotube ceramic electrode by microwave irradiation and its application for the determination of adenine and guanine

    Energy Technology Data Exchange (ETDEWEB)

    Abbaspour, Abdolkarim, E-mail: abbaspour@chem.susc.ac.i [Department of Chemistry, College of Sciences, Shiraz University, Shiraz, Fars 71456-85464 (Iran, Islamic Republic of); Ghaffarinejad, Ali [Department of Chemistry, College of Sciences, Shiraz University, Shiraz, Fars 71456-85464 (Iran, Islamic Republic of)

    2010-01-01

    In this study, microwave irradiation was used for the fast preparation (min) of a sol-gel-derived carbon nanotube ceramic electrode (MW-CNCE). For confirmation of the preparation of the ceramic by MW irradiation, Fourier transform infrared, X-ray diffraction spectra and scanning electron microscopy images of the produced ceramic were compared with those of conventional ceramic (which is produced by drying the ceramic in air for 48 h). The electrochemical behavior of MW-CNCE in nicotinamide adenine dinucleotide, L-cysteine, adenine and guanine was compared with that of a conventional sol-gel-derived carbon nanotube ceramic electrode (CNCE). In all systems, similar peak potentials and lower background currents were obtained with respect to CNCE. Finally, the MW-CNCE was used for the simultaneous determination of adenine and guanine using differential pulse voltammetry. The linear ranges of 0.1-10 and 0.1-20 muM were obtained for adenine and guanine, respectively. These results are comparable with some modified electrodes that have recently been reported for the determination of adenine and guanine, with the advantage that the proposed electrode did not contain modifier. In addition, the proposed electrode was successfully used for the oxidation of adenine and guanine in DNA, and the detection limit for this measurement was 0.05 mug mL{sup -1} DNA.

  6. Combustion chemical vapor deposition (CCVD) of LaPO{sub 4} monazite and beta-alumina on alumina fibers for ceramic matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, T.J.; Hendrick, M.R.; Shao, H.; Hornis, H.G.; Hunt, A.T. [MicroCoating Technol., Chamblee, GA (United States)

    1998-03-31

    This research used the low cost, open atmosphere combustion chemical vapor deposition (CCVD{sup SM}) method to efficiently deposit protective coatings onto alumina fibers (3M Nextel{sup TM}610) for use in ceramic matrix composites (CMCs). La-monazite (LaPO{sub 4}) and beta-alumina were the primary candidate debonding coating materials investigated. The coated fibers provide thermochemical stability, as well as desired debonding/sliding interface characteristics to the CMC. Dense and uniform La-phosphate coatings were obtained at deposition temperatures as low as 900-1000 C with minimal degradation of fibers. However, all of the {beta}-alumina phases required high deposition temperatures and, thus, could not be applied onto the Nextel{sup TM}610 alumina fibers. The fibers appeared to have complete and relatively uniform coatings around individual filaments when 420 and 1260 filament tows were coated via the CCVD process. Fibers up to 3 feet long were fed through the deposition flame in the laboratory of MicroCoating Technologies (MCT). TEM analyses performed at Wright-Patterson AFB on the CCVD coated fibers showed a 10-30 nm thick La-rich layer at the fiber/coating interface, and a layer of columnar monazite 0.1-1 {mu}m thick covered with sooty carbon of <50 nm thick on the outside. A single strength test on CCVD coated fibers performed by 3M showed that the strength value fell in the higher end of data from other CVD coated samples. (orig.) 7 refs.

  7. Preparation, microstructure and oxidation resistance of SiCN ceramic matrix composites with glass-like carbon interface

    Directory of Open Access Journals (Sweden)

    Yi Xia

    2009-02-01

    Full Text Available Glass-like carbon (GC interface was successfully introduced into carbon fiber-reinforced SiCN ceramic matrix composite (C/GC/SiCN by polymer infiltration and pyrolysis using phenolic resin as precursor. In order to highlight the Oxidation resistance of GC interface, the Oxidation behavior of GC, carbon fiber (Cf containing approximately 0.3 μm GC coating and C/GC/SiCN was investigated by means of weight changes and residual strength ratio before and after oxidizing, and the results were also compared with that of Cf containing Pyrocarbon (PyC coating and C/PyC/SiCN composite. Scanning electron microscopy displays homogeneous, adherent GC coating on Cf. Weight loss rate of Cf containing GC coating is lower than that of Cf containing PyC coating. The residual stress ratio of C/GC/SiCN was higher than that of C/PyC/SiCN. The results indicate that GC interface can improve anti-oxidation of Cf-reinforced composite than PyC interface.

  8. Preparation of amine group-containing chelating fiber for thorough removal of mercury ions.

    Science.gov (United States)

    Ma, Nianfang; Yang, Ying; Chen, Shuixia; Zhang, Qikun

    2009-11-15

    An aminated chelating fiber (AF) with high adsorption capacity for mercury ions was prepared by grafting copolymerization of acrylonitrile onto polypropylene fiber, followed by aminating with chelating molecule diethylenetriamine. Effects of reaction conditions such as temperature, reaction time, bath ratio and dosage of catalyst on the grafting yield were studied. Chemical structure, tensile strength and thermal stability of AF were characterized. The adsorption performances for mercury were evaluated by batch adsorption experiments and kinetic experiments. The results show that AF is effective for the removal of mercury over a wide range of pH. The chelating fiber also shows much higher adsorption capacities for mercury, the equilibrium adsorption amount could be as high as 657.9 mg/g for mercury. The high adsorption capacity of Hg(2+) on AF is resulted from the strong chelating interaction between amine groups and mercury ions. Two amine groups coordinate with one mercury ion could be speculated from the adsorption capacity and amine group content on AF. The kinetic adsorption results indicate that the adsorption rates of AF for mercury are very rapid. Furthermore, the residual concentration was less than 1 microg/L with feed concentration of mercury below 1mg/L, which can meet the criterion of drinking water, which indicates that the chelating fiber prepared in this study could be applied to low-level Hg contaminated drinking water purification.

  9. Preparation of active 3D film patches via aligned fiber electrohydrodynamic (EHD) printing

    Science.gov (United States)

    Wang, Jun-Chuan; Zheng, Hongxia; Chang, Ming-Wei; Ahmad, Zeeshan; Li, Jing-Song

    2017-03-01

    The design, preparation and application of three-dimensional (3D) printed structures have gained appreciable interest in recent times, particularly for drug dosage development. In this study, the electrohydrodynamic (EHD) printing technique was developed to fabricate aligned-fiber antibiotic (tetracycline hydrochloride, TE-HCL) patches using polycaprolactone (PCL), polyvinyl pyrrolidone (PVP) and their composite system (PVP-PCL). Drug loaded 3D patches possessed perfectly aligned fibers giving rise to fibrous strut orientation, variable inter-strut pore size and controlled film width (via layering). The effect of operating parameters on fiber deposition and alignment were explored, and the impact of the film structure, composition and drug loading was evaluated. FTIR demonstrated successful TE-HCL encapsulation in aligned fibers. Patches prepared using PVP and TE-HCL displayed enhanced hydrophobicity. Tensile tests exhibited changes to mechanical properties arising from additive effects. Release of antibiotic from PCL-PVP dosage forms was shown over 5 days and was slower compared to pure PCL or PVP. The printed patch void size also influenced antibiotic release behavior. The EHDA printing technique provides an exciting opportunity to tailor dosage forms in a single-step with minimal excipients and operations. These developments are crucial to meet demands where dosage forms cannot be manufactured rapidly or when a personalized approach is required.

  10. Fundamental studies on the nature and properties of ceramic fiber insulation

    Science.gov (United States)

    Mueller, J. I.; Whittemore, O. J., Jr.; Scott, W. D.; Miller, A. D.; Smiser, L. W.; Leiser, D. B.

    1975-01-01

    Silica and mullite fibers used to fabricate reusable surface insulation (RSI) for the space shuttle orbiter may devitrify/recrystallize within the temperature range anticipated upon reentry. This is shown to be dependent upon impurity level, temperature, and time at temperature. It is determined that the effects of the material improvement and optimization program are positive. The degree of crystallinity is shown to have a predominant effect upon the strength of fabricated RSI tile, and limits are determined. Models are developed to predict tensile strengths and shrinkage rates of silica tile based upon readily measurable parameters. Thermal cycling which simulates reentry results in an increase in the crystallinity and in the porosity of tile coatings.

  11. Preparation and application of cationized pulp fiber as a papermaking wet-end additive

    Institute of Scientific and Technical Information of China (English)

    XIE Wei; FENG Hai-li; QIAN Xue-ren

    2008-01-01

    Cationized pulp fibers (CPF) were prepared by the adsorption of a novel biodegradable cationic ester quaternary ammonium salt (31441) on bleached softwood kraft pulp fibers. The optimized conditions for the CPF preparation were: 4% of 31441 (based on oven-dry pulp), 80°C and 30 min. The CPF was characterized by FT-IR, SEM and XPS. Experimental results showed that the CPF improved the retention of precipitated calcium carbonate (PCC) filler significantly. With 0.9% CPF (based on oven-dry pulp), the retention of PCC increased from 57.53% to 72.21%. The physical properties of paper were also slightly improved. The tensile strength and burst strength of the paper with CPF were higher than those with CPAM. CPF addition had no effect on the stock drainage.

  12. Carob pulp preparation rich in insoluble dietary fiber and polyphenols enhances lipid oxidation and lowers postprandial acylated ghrelin in humans.

    Science.gov (United States)

    Gruendel, Sindy; Garcia, Ada L; Otto, Baerbel; Mueller, Corinna; Steiniger, Jochen; Weickert, Martin O; Speth, Maria; Katz, Norbert; Koebnick, Corinna

    2006-06-01

    Ghrelin is an orexigenic hormone that may affect substrate utilization in humans. Ghrelin is influenced by macronutrients, but the effects of insoluble dietary fiber and polyphenols are unknown. We investigated the effects of a polyphenol-rich insoluble dietary fiber preparation from carob pulp (carob fiber) on postprandial ghrelin responses and substrate utilization. Dose-dependent effects of the consumption of carob fiber were investigated in a randomized, single-blind, crossover study in 20 healthy subjects, aged 22-62 y. Plasma total and acylated ghrelin, triglycerides, and serum insulin and nonesterified fatty acids (NEFA) levels were repeatedly assessed before and after ingestion of an isocaloric standardized liquid meal with 0, 5, 10, or 20 g of carob fiber over a 300-min period. The respiratory quotient (RQ) was determined after consumption of 0 or 20 g of carob fiber. Carob fiber intake lowered acylated ghrelin to 49.1%, triglycerides to 97.2%, and NEFA to 67.2% compared with the control meal (P fiber-enriched liquid meal. Postprandial energy expenditure was increased by 42.3% and RQ was reduced by 99.9% after a liquid meal with carob fiber compared with a control meal (P pulp preparation, an insoluble dietary fiber rich in polyphenols, decreases postprandial responses of acylated ghrelin, triglycerides, and NEFA and alters RQ, suggesting a change toward increased fatty acid oxidation. These results indicate that carob fiber might exert beneficial effects in energy intake and body weight.

  13. Preparation and properties of rare earth luminous fiber containing red organic fluorescent pigment

    Institute of Scientific and Technical Information of China (English)

    朱亚楠; 葛明桥; 陈志

    2013-01-01

    Rare earth luminous fiber was prepared by method of melt spinning. X-ray diffraction (XRD), scanning electron micros-copy (SEM), and fluorescence spectrophotometer as well as afterglow brightness tester were used to characterize the resulting sam-ples. Results from XRD and SEM demonstrated that the phase of SrA12O4:Eu2+,Dy3+in the fiber was not destroyed in the manufac-turing process and the as-formed luminous fiber consisted of irregular particles. Under ultraviolet excitation, the luminous fiber exhib-ited a yellow-green and orange-red emission band with a maximum at 520 nm and around 600 nm originating from SrAl2O4:Eu2+, Dy3+and red organic fluorescent pigments. The energy transfer process was further studied. Furthermore, the emission colors of lu-minous fibers could be tuned from yellow-green to orange-red easily by doping red organic fluorescent pigment, making the materials have potential application in many areas.

  14. Physical and Degradable Properties of Mulching Films Prepared from Natural Fibers and Biodegradable Polymers

    OpenAIRE

    Zhijian Tan; Yongjian Yi; Hongying Wang; Wanlai Zhou; Yuanru Yang; Chaoyun Wang

    2016-01-01

    The use of plastic film in agriculture has the serious drawback of producing vast quantities of waste. In this work, films were prepared from natural fibers and biodegradable polymers as potential substitutes for the conventional non-biodegradable plastic film used as mulching material in agricultural production. The physical properties (e.g., mechanical properties, heat preservation, water permeability, and photopermeability) and degradation characteristics (evaluated by micro-organic cultur...

  15. Light element ceramics

    OpenAIRE

    Rao, KJ; Varma, KBR; Raju, AR

    1988-01-01

    An overview of a few structually important light element ceramics is presented. Included in the overview are silicon nitide, sialon, aluminium nitride, boron carbide and silicon carbide. Methods of preparation, characterization and industrial applications of these ceramics are summarized. Mechanical properties, industrial production techniques and principal uses of these ceramics are emphasized.

  16. Properties of sintered glass-ceramics prepared from plasma vitrified air pollution control residues.

    Science.gov (United States)

    Roether, J A; Daniel, D J; Rani, D Amutha; Deegan, D E; Cheeseman, C R; Boccaccini, A R

    2010-01-15

    Air pollution control (APC) residues, obtained from a major UK energy from waste (EfW) plant, processing municipal solid waste, have been blended with silica and alumina and melted using DC plasma arc technology. The glass produced was crushed, milled, uni-axially pressed and sintered at temperatures between 750 and 1150 degrees C, and the glass-ceramics formed were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Mechanical properties assessed included Vickers's hardness, flexural strength, Young's modulus and thermal shock resistance. The optimum sintering temperature was found to be 950 degrees C. This produced a glass-ceramic with high density (approximately 2.58 g/cm(3)), minimum water absorption (approximately 2%) and relatively high mechanical strength (approximately 81+/-4 MPa). Thermal shock testing showed that 950 degrees C sintered samples could withstand a 700 degrees C quench in water without micro-cracking. The research demonstrates that glass-ceramics can be readily formed from DC plasma treated APC residues and that these have comparable properties to marble and porcelain. This novel approach represents a technically and commercially viable treatment option for APC residues that allow the beneficial reuse of this problematic waste.

  17. Preparation of MgTiO3 Ceramics by High Energy Ball Milling

    Institute of Scientific and Technical Information of China (English)

    TAO Zhendong; ZHANG Ying; YANG Zhongxi; WANG Yingzi; MENG Shanshan; TENG Tieli

    2006-01-01

    MgTiO3 precursor was mechanochemically synthesized by high-energy ball milling of MgO and TiO2. The sintering characteristic of the resulted MgTiO3 precursor was investigated. The experimental results indicate that particles of both MgO and TiO2 powders become smaller rapidly, and then the crystalline structures of MgO and TiO2 change significantly. MgTiO3 was observed by XRD after 30 hours of ball milling. Strong diffraction peaks of MgTiO3 were observed after 50 hours of ball milling. HRTEM observation proves that dense MgTiO3 ceramics with a compact crystalline structure can be sintered from mechanochemically activated MgTiO3 precursor, the volume density of the resulting ceramic is as high as 95% of the theoretical density, the porosity and average pore diameter of the ceramic are measured as 4.95% and 50 nm respectively, and the transverse strength exceeded 500 MPa.

  18. Properties of ceramics prepared using dry discharged waste to energy bottom ash dust.

    Science.gov (United States)

    Bourtsalas, Athanasios; Vandeperre, Luc; Grimes, Sue; Themelis, Nicolas; Koralewska, Ralf; Cheeseman, Chris

    2015-09-01

    The fine dust of incinerator bottom ash generated from dry discharge systems can be transformed into an inert material suitable for the production of hard, dense ceramics. Processing involves the addition of glass, ball milling and calcining to remove volatile components from the incinerator bottom ash. This transforms the major crystalline phases present in fine incinerator bottom ash dust from quartz (SiO(2)), calcite (CaCO(3)), gehlenite (Ca(2)Al(2)SiO(7)) and hematite (Fe(2)O(3)), to the pyroxene group minerals diopside (CaMgSi(2)O(6)), clinoenstatite (MgSi(2)O(6)), wollastonite (CaSiO(3)) together with some albite (NaAlSi(3)O(8)) and andradite (Ca(3)Fe(2)Si(3)O(12)). Processed powders show minimal leaching and can be pressed and sintered to form dense (>2.5 g cm(-3)), hard ceramics that exhibit low firing shrinkage (ceramic tiles that have potential for use in a range of industrial applications.

  19. Preparation of transparent Y2O3 ceramic by slip casting and vacuum sintering

    Institute of Scientific and Technical Information of China (English)

    HUO Di; ZHENG Yanchun; SUN Xudong; LI Xiaodong; LIU Shaohong

    2012-01-01

    In the present work transparent Y2O3 ceramics were made by slip casting and vacuum sintering of nanopowders with sodium polyacrylic acid (PAA-Na) as dispersant.The rheological properties of Y2O3 nanopowder slurry were investigated using different amounts of dispersant and solid contents.The microstructures and transmittance of the sintered ceramics were also studied by means of scauning electron microscopy (SEM) and ultra-violet visible spectrometry.The results showed that rheological behaviors of the Y2O3 nanopowder slurry were effectively promoted by sodium polyacrylic acid.Highly dispersive and stable slurries were obtained as the dispersant was added over 1.0dwb% under the fixed conditions of pH 11 and 45 wt.% solid content.All the slip cast green bodies were sintered into highly dense ceramics after sintering at 1700 ℃ for 5 h in vacuum,wherein the sample added with 1.1% sodium polyacrylic acid exhibited the highest relative density of 99.36% and transmission of 30% at 800 nm wavelength.

  20. [Composition, physico-chemical properties and molecular superstructure of dietary fiber preparations of the cellan type].

    Science.gov (United States)

    Dongowski, G; Frigge, K; Zenke, I

    1995-07-01

    Dietary fiber preparations of "cellan" type were prepared from apples, white cabbage, sugar beet pulp, soy hulls and wheat bran by treatment with amylolytic and proteolytic enzymes as well as by chemical extractions. Scanning electron microscopic examinations show different morphological structures of the preparations and a high maintenance of native biomolecular superstructure. The content of pectin, protein, polysaccharide-hexoses and -pentoses and the composition of monosaccharides (also after their treatment with 4 or 8% sodium hydroxide) were determined. The cellans possess waterbinding capacities (WBC) between 25 g H2O/g and waterholding capacities between 50 g H2O/g. The WBC is related to the internal surface; it diminishes after treatment with NaOH. The interactions between the cellans and the adsorbed water were characterized by NMR-spin-lattice relaxation time T1. The molecular mobility increases as the water content grows. The T1-values of dried cellans decreased with increasing degree of moisture before drying. The supermolecular structure is comparatively disordered. Only in case of soy cellan a crystalline cellulose-I-modification could be identified by X-ray-diffraction pattern, esp. after NaOH treatment. The low degree of order of cellans was observed in the 13C-NMR spectra, too. Only the soy hull preparation resulted in a spectrum corresponding to well-ordered cellulose. The botanic source has an essential influence on the physico-chemical properties of dietary fiber preparations of cellan type.

  1. A simple sample preparation method for measuring amoxicillin in human plasma by hollow fiber centrifugal ultrafiltration.

    Science.gov (United States)

    Dong, Wei-Chong; Hou, Zi-Li; Jiang, Xin-Hui; Jiang, Ye

    2013-02-01

    A simple sample preparation method has been developed for the determination of amoxicillin in human plasma by hollow fiber centrifugal ultrafiltration (HF-CF-UF). A 400-μL plasma sample was placed directly into the HF-CF-UF device, which consisited of a slim glass tube and a U-shaped hollow fiber. After centrifugation at 1.25 × 10(3) g for 10 min, the filtrate was withdrawn from the hollow fiber and 20 µL was directly injected into the high-performance liquid chromatography (HPLC) for analysis. The calibration curve was linear over the range of 0.1-20 µg/mL (r = 0.9996) and the limit of detection was as low as 0.025 µg/mL. The average recovery and absolute recovery were 99.9% and 84.5%, respectively. Both the intra-day and inter-day precisions (relative standard deviation) were less than 3.1% for three concentrations (0.25, 2.5 and 10 µg/mL). The sample preparation process was simplified. Only after a single centrifugal ultrafiltration can the filtrate be injected directly into HPLC. The present method is simple, sensitive and accurate. It could be effective for the analysis of biological samples with high protein contents, especially for the biopharmaceutical analysis of drugs that use traditional isolation techniques for sample preparation such as the protein precipitation method.

  2. OPTIMAL PREPARATION JUNCTIONS FOR ALL-CERAMIC FIXED RESTORATIONS MADE BY CAM 5 – S 2 IMPRESSION, VHF

    Directory of Open Access Journals (Sweden)

    Angelina Vlahova

    2015-12-01

    Full Text Available Introduction: The type of the preparation junction is determined by a number of factors that need to be taken in consideration with CAD/CAM Fixed Prosthodontics: the material of which the construction will be made; the type and condition of the retainer teeth, of their periodontium and the occlusion; the design software, the CAM setting and the type of drills; the working protocol; the type of the cement and the method of cementation.Purpose: The aim of this publication is to describe the optimal preparation junctions for all-ceramic crown and bridge restorations made by CAM 5 - S 2 Impression, VHF.Materials and methods: Suitable are chamfer and shoulder preparation junction with rounded inner angle (width 1 - 1, 5 mm. Trimming of 1.5 – 2 mm dental tissues is necessary on the occlusal surface. The homothetic reduction of teeth is optimal.Results and discussion: The width depends on the size and vitality of the tooth. In stained teeth and those built with metal pins the removal of more tissues provides a greater volume needed to disguise the dark color. Vestibular preparation under the level of the gingiva is preferable to ensure optimal aesthetics. Preparation junction is determined also by the CAD/CAM technology - the type of drills and protocol of impression taking (classical or digital. The creation of a working model with TRIOS, 3Shape intraoral scanner is greatly facilitated by preparation junctions made above the gingival margin.Conclusion: Knowledge about the criteria for selection the preparation junctions is essential for fabrication accurate and aesthetic CAD/CAM restorations.

  3. Study of the Powdering Mechanisms of Ceramic Fiber and the Anti-powdering Methods%陶瓷纤维粉化及抗粉化方法的研究

    Institute of Scientific and Technical Information of China (English)

    黄浪欢; 曾令可; 孙宇彤

    2001-01-01

    The common silicate-alumina fiber were studied in this paper. The powdering mechanisms of ceramic fibers in ceramic kiln and the methods of anti-powdering were discussed. Artificial neural network was used to forecast the lifespan of ceramic fibers. The study is meaningful to prolong the lifespan of ceramic kiln and optimize the kiln structure%本文以普通硅酸铝纤维为研究对象,探讨了陶瓷窑炉内陶瓷纤维粉化的机理以及用人工神经网络的方法对陶瓷纤维使用寿命进行预测,并提出抗粉化的方法,对延长陶瓷纤维使用寿命及优化窑炉结构意义深远。

  4. Thin film ceramic thermocouples

    Science.gov (United States)

    Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

    2011-01-01

    A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

  5. In vitro hypoglycemic and cholesterol lowering effects of dietary fiber prepared from cocoa (Theobroma cacao L.) shells.

    Science.gov (United States)

    Nsor-Atindana, John; Zhong, Fang; Mothibe, Kebitsamang Joseph

    2012-10-01

    Three dietary fiber (DF) powders; soluble dietary fiber (SDF), insoluble dietary fiber (IDF) and total dietary fiber (TDF) were prepared from cocoa bean shells (CBS) by enzymatic treatment. These DFs were evaluated for their effects on glucose adsorption, glucose diffusion, starch hydrolysis, cholesterol binding, sodium cholate binding and oil binding capacities using in vitro model systems by simulating gastric intestinal conditions. The results showed that SDF generally exhibited significantly (p 0.05) glucose dialysis retardation index (GDRI) and oil binding capacity, when compared with IDF and TDF which both showed similar effects. Moreover, it was discovered that the three CBS dietary fiber powders contained intrinsic antioxidants (phenolic compounds). The study suggested that CBS could be an alternative cheap source of DF with additional benefits. Thus, CBS fibers could be incorporated as low calorie bulk ingredients in high-fiber diet to reduce calorie and cholesterol levels and control blood glucose level.

  6. ZrC Ceramics Prepared by Self-propagating High-temperature Synthesis/Single Action Pressing

    Directory of Open Access Journals (Sweden)

    CHENG Yong

    2017-01-01

    Full Text Available ZrC ceramics were prepared by mechanical axial compression of self-propagating high-temperature synthesis/single action pressing (SHS/SAP.The effects of pressure on microstructure and densification of the products,as well as the relationship between displacement/variation of the load curve and SHS reaction,were studied.The structure and properties of the products were investigated by XRD and SEM.In addition,the density was measured by the drain away liquid method.Meanwhile,universal testing machine was used to record the displacement and load curve alternations.The results indicate that products are mainly composed of ZrC phase,the process of exhaust are accelerated as the increasing of pressure as well,leading to the smaller size of porosity and crystal particles.Density manifested as an increasing pattern by the elevated pressure with no longer change at 80MPa.Due to the strong attenuation of pressure at the peak of temperature,the density of the production is only 65.7% in 120MPa.The end point of the SHS reaction and the plastic time of the products can be monitored by displacement and load curve.The results provide evidence for the application of self-propagating high-temperature synthesis/pseudo-hot isostatic pressing to further improve the density of ceramics.

  7. Preparation and photo-catalytic activity of TiO2-coated medical stone-based porous ceramics

    Science.gov (United States)

    Gao, Ru-qin; Hou, Xin-mei

    2013-06-01

    Medical stone-based porous ceramics as a carrier were prepared by ultra-fine grinding and low-temperature sintering method. Nano-TiO2 thin films were loaded on the carrier by chemical liquid deposition method using titanium tetrachloride as a precursor. The micro-morphology and microstructure of the synthesized samples were characterized using X-ray diffraction, scanning electron microscopy with energy dispersive spectrometry, and mercury injection method. The photo-catalytic activity of the TiO2 thin films was investigated by degrading formaldehyde. The main crystalline phase in the TiO2 thin films calcined at 550°C is anatase with the average particle size about 10 nm. The specific surface area of the carrier-coated nano-TiO2 increases from 3.68 to 5.32 m2/g. The formaldehyde removal rate of the TiO2/medical stone-based porous ceramics irradiated under an ultraviolet lamp for 120 min reaches 85.6%.

  8. Processing, Mechanical and Optical Properties of Additive-Free ZrC Ceramics Prepared by Spark Plasma Sintering

    Directory of Open Access Journals (Sweden)

    Clara Musa

    2016-06-01

    Full Text Available In the present study, nearly fully dense monolithic ZrC samples are produced and broadly characterized from microstructural, mechanical and optical points of view. Specifically, 98% dense products are obtained by Spark Plasma Sintering (SPS after 20 min dwell time at 1850 °C starting from powders preliminarily prepared by Self-propagating High-temperature Synthesis (SHS followed by 20 min ball milling. A prolonged mechanical treatment up to 2 h of SHS powders does not lead to appreciable benefits. Vickers hardness of the resulting samples (17.5 ± 0.4 GPa is reasonably good for monolithic ceramics, but the mechanical strength (about 250 MPa up to 1000 °C could be further improved by suitable optimization of the starting powder characteristics. The very smoothly polished ZrC specimen subjected to optical measurements displays high absorption in the visible-near infrared region and low thermal emittance at longer wavelengths. Moreover, the sample exhibits goodspectral selectivity (2.1–2.4 in the 1000–1400 K temperature range. These preliminary results suggest that ZrC ceramics produced through the two-step SHS/SPS processing route can be considered as attractive reference materials for the development of innovative solar energy absorbers.

  9. Preparation of Silicon Carbide Reticulated Ceramics%碳化硅网眼多孔陶瓷的制备

    Institute of Scientific and Technical Information of China (English)

    朱新文; 江东亮; 谭寿洪

    2000-01-01

    本工作采用有机泡沫浸渍工艺制备了具有相互贯通气孔的碳化硅网眼多孔陶瓷.通过选择合适的流变剂获得了对海绵具有良好涂覆性能的浆料.探讨了粘结剂对网眼多孔陶瓷性能的影响,结果表明:硅溶胶是一种比较理想的粘结剂.XRD、SEM研究了烧结制品的晶相组成及显微结构,同时还对烧结制品的孔筋密度、气孔率、力学性能等进行了表征.本工作在1450℃下保温1h获得了气孔率为75%~85%、抗弯强度达2.5MPa以上的碳化硅网眼多孔陶瓷,其主要晶相由α-SiC、α-Al2O3、方石英和莫来石组成.%The open cell silicon carbide reticulated ceramics were prepared by impregnating a polyurethane sponge with aqueous ceramic slurry. TG-DTA analysis of the polyurethane sponge was used to determine the global thermal cycle for the consolidation of the porous ceramic bodies.A thixotropical slurry by adding effective rheological agents was optimized to uniformly coat the polyurethane sponge. The effect of processing conditions on properties of the sintered was studied.The effect of binders on processing was discussed in detail and it was found that colloidal silica is an effective binder. The structure of the sintered bodies were characterized by SEM and the phases of the sintered bodies were determined by XRD. Some properties including bulk density,strut density, porosity and strength of the sintered bodies, were characterized. The SiC reticulated ceramics, having 75%~85% porosity and bending strength as high as 2.5MPa, can be obtained under firing temperature 1450℃ for lh. The phases of the fired bodies are composed of α-SiC,α-Al2O3, cristobalite and mullite.

  10. STUDY OF CERAMIC TILE PREPARATION WITH HIGH CONTENT OF CINDER%高掺量煤渣制备陶瓷釉面砖的研究

    Institute of Scientific and Technical Information of China (English)

    程小苏; 陈倩

    2011-01-01

    Ceramic glazed tile was prepared by low temperature biscuit fire and high temperature glost fire using cinder from a ceramic factory' coal gasifier as the ceramic raw material. The phase composition and microstructure of ceramic glazed tile were analyzed by testing strength, water absorption, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of Albite and Black Talc to strength of ceramic body were discussed. When the content of cinder was 50%, the strength of ceramic tile was more than 35Mpa.%以煤气发生炉的煤渣为主要原料,辅以钠长石和黑滑石等其他原料,经低温素烧、高温釉烧的二次烧结工艺在辊道窑烧制成陶瓷釉面砖.测试其强度和吸水率,并采用X射线衍射(XRD)仪和扫描电子显微镜(SEM)分析了煤渣陶瓷釉面砖的物相组成及微观结构,探讨了配方中钠长石和黑滑石含量对陶瓷坯体强度的影响,制备出的陶瓷釉面砖强度大于35Mpa,且煤渣利用量可达50%.

  11. Investigation on Structural and Optical Properties of Willemite Doped Mn2+ Based Glass-Ceramics Prepared by Conventional Solid-State Method

    Directory of Open Access Journals (Sweden)

    Nur Farhana Samsudin

    2015-01-01

    Full Text Available Mn-doped willemite (Zn2SiO4:Mn2+ glass-ceramics derived from ZnO-SLS glass system were prepared by a conventional melt-quenching technique followed by a controlled crystallization step employing the heat treatment process. Soda lime silica (SLS glass waste, ZnO, and MnO were used as sources of silicon, zinc, and manganese, respectively. The obtained glass-ceramic samples were characterized using the X-ray diffraction (XRD, Field Emission Scanning Electron Microscopy (FESEM, Fourier Transform Infrared (FTIR, UV-Visible (UV-Vis, and photoluminescence (PL spectroscopy. The results of XRD revealed that ZnO crystal and willemite (β-Zn2SiO4 were presented as major embedded crystalline phases. This observation was consistent with the result of FESEM which showed the presence of irregularity in shape and size of willemite crystallites. FTIR spectroscopy exhibits the structural evolution of willemite based glass-ceramics. The optical band gap shows a decreasing trend as the Mn-doping content increased. Photoluminescent technique was applied to characterize the role of Mn2+ ions when entering the willemite glass-ceramic structure. By measuring the excitation and emission spectra, the main emission peak of the glass-ceramic samples located at a wavelength of 585 nm after subjecting to 260 nm excitations. The following results indicate that the obtained glass-ceramics can be applied as phosphor materials.

  12. STUDIES ON PAN MACROMOLECULAR SEMICONDUCTING FIBER 1. PREPARATION OF PAN CONDUCTING FIBER TREATED BY STANNIC CHLORIDE AND ITS SEMICONDUCTING BEHAVIOUR

    Institute of Scientific and Technical Information of China (English)

    WANG Dexi; CUI Dayuan; LUO Boliang; WANG Xiugang; WU Renjie

    1984-01-01

    The PAN fiber treated by Lewis acid (e.g. stannic chloride) could be transformed into a macromolecular conducting fiber by further thermal treatment. Depending on thermal treatment condition the resistance of the fiber varied from 103 to 1012 Ω and kept stable after hydrolysis. The fiber has enough strength to be processed by various means. This is a new kind of macromolecular semiconducting fiber having some characteristics similar to those of organic semiconductors.

  13. Preparation and Characterization of Zirconium Boride Precursor Fiber%二硼化锆陶瓷前驱体纤维的制备及表征

    Institute of Scientific and Technical Information of China (English)

    贾军; 孙泽玉; 耿冉; 胡建建; 韩克清; 余木火

    2013-01-01

    In this paper,ZrOCl2·8H2O,boric acid,sucrose,citric acid were used as inorganic substances,ZrB2 precursor solution was prepared via the mixing of inorganic and PVA,precursor fibers were obtained through dry spinning.Microstructure was observed by SEM,reactions and series changes were studied by FT-IR,DSC and TG.The results showed reactions happened among inorganic substances and polyvinyl alcohol and PVA stabilized owing to these reactions.The precursor fiber showed a smooth and intact appearance and provided a basic study for the preparation of ZrB2 ceramic fibers.%利用八水合氧氯化锆、硼酸、蔗糖和柠檬酸为无机原料,聚乙烯醇为有机原料,采用有机、无机共混反应制得前驱体溶液,并利用干法纺丝制得前驱体纤维,通过红外光谱(IR)、差示扫描(DSC)、热失重(TG)分析表征发生的反应及产生的一系列变化,利用扫描电镜(SEM)观察纤维的形态结构.结果表明:无机成分与聚乙烯醇发生了反应并使聚乙烯醇变得稳定,制得了光滑致密的纤维,为下一步制得ZrB2陶瓷纤维做好了准备.

  14. Preparation and pharmaceutical evaluation of acetaminophen nano-fiber tablets: Application of a solvent-based electrospinning method for tableting.

    Science.gov (United States)

    Hamori, Mami; Nagano, Kana; Kakimoto, Sayaka; Naruhashi, Kazumasa; Kiriyama, Akiko; Nishimura, Asako; Shibata, Nobuhito

    2016-03-01

    In this study, we developed nano-fiber-based tablets with acetaminophen (AAP; LogPow=0.51) for controlled-release delivery systems and evaluated in vitro drug dissolution and in vivo pharmacokinetics in rats. Nano-fibers made from methacrylic acid copolymer S (MAC; EUDRAGIT S100) and containing AAP were prepared using a solvent-based electrospinning (ES) method. In vitro dissolution rate profiles of AAP showed tableting pressure-dependent decreases and pH-dependent increases. The results of tablet tracking by X-ray irradiation showed tablets based on MAC nano-fibers did not disintegrate in the upper intestinal lumen and had the properties of a long-term-acting tablet. In addition, the in vitro release profiles of AAP from nano-fiber tablets prepared by dissolving MAC with AAP (NFT), nano-fiber tablets prepared by adsorbing AAP to drug-free MAC nano-fibers (NFTadso), and tablets prepared by adsorbing half the amount of AAP to MAC nano-fibers containing the remaining amount of AAP (NFThalf) showed independent controlled-release aspects of AAP compared with physical mixture tablets (PMT). In vivo pharmacokinetic studies in rats after intraduodenal administration of 14 mg/rat AAP in NFT, NFTadso, and NFThalf demonstrated that all these tablets based on MAC nano-fibers showed sustained-release profiles compared with PMT, and showed ultra-sustained release properties for AAP. These new tablets based on MAC nano-fibers did not disintegrate in the intestine in the lower pH region, and the tablets could regulate the release of AAP in a pH-dependent manner. The ES method is a useful technique to prepare nano-fibers and showed promising results as an oral delivery system for sustained-release regulation.

  15. Preparation and characterization of regenerated cellulose membranes from natural cotton fiber

    Directory of Open Access Journals (Sweden)

    Yanjuan CAO

    2015-06-01

    Full Text Available A series of organic solutions with different cellulose concentrations are prepared by dissolving natural cotton fibers in lithium chloride/dimethyl acetamide (LiCl/DMAC solvent system after the activation of cotton fibers. Under different coagulating bath, the regenerated cellulose membranes are formed in two kinds of coagulation baths, and two coating methods including high-speed spin technique (KW-4A spin coating machine and low-speed scraping (AFA-Ⅱ Film Applicator are selected in this paper. The macromolecular structure, mechanical properties, crystallinity, thermal stability and wetting property of the regenerated cellulose membrane are characterized by Scanning Electron Microscope(SEM, Fourier Transform Infrared Spectroscopy (FT-IR,X-ray diffraction (XRD, Thermogravimetric analysis (TG and contacting angle tester. The effects of mass fraction, coagulation bath type, membrane forming process on the regenerated membrane properties are investigated. Experimental results show that the performance of regenerated cellulose membrane is relatively excellent under the condition of using the KW-4A high-speed spin method, water coagulation bath, and when mass fraction of cellulose is 3.5%. The crystallinity of the regenerated cellulose membrane changes a lot compared with natural cotton fibers. The variation trend of thermal stability is similar with that of cotton fiber. But thermal stability is reduced to some degree, while the wetting ability is improved obviously.

  16. A modified coaxial electrospinning for preparing fibers from a high concentration polymer solution

    Directory of Open Access Journals (Sweden)

    2011-08-01

    Full Text Available A new process technology modified from conventional coaxial electrospinning process has been developed to prepare polymer fibers from a high concentration solution. This process involves a pure solvent concentrically surrounding polymer fluid in the spinneret. The concentric spinneret was constructed simply by inserting a metal needle through a high elastic silica gel tube. Two syringe pumps were used to drive the core polymer solution and the sheath solvent. Using polyvinylpyrrolidone (PVP as the polymer model, which normally has an electrospinnable concentration of 10% w/v in ethanol, it was possible to electrospin 35% w/v of PVP in the same solvent, when pure N, N-dimethylacetamide (DMAc was used as sheath fluid. The resultant fibers have a smooth surface morphology and good structural uniformity. The diameter of the fibers was 2.0±0.25 µm when the DMAc-to-polymer-solution flow rate ratio was set as 0.1. The process technology reported here opens a new window to tune the polymer fibers obtained by the electrospinning, and is useful for improving productivity of the electrospinning process.

  17. PREPARATION AND THEIR ANTIBACTERIAL ACTIVITY OF ACTIVATED CARBON FIBER CONTAINING SILVER

    Institute of Scientific and Technical Information of China (English)

    CHENShuixia; LUOYing; 等

    2000-01-01

    Several kinds of activated carbon fiber(ACF),Granule Activated carbon(AC) containing silver ion or fine silver particle(Ag-ACF/AC) have been prepared by soaking ACF or AC in the salt solution of silver.Ag,AgCl and AgI compounds have been loaded onto the fibers:The stucture of the fibers was measured by scanning electron microscopy(SEM) and power X-ray diffraction(XRD),THe Ag content in the fiber was obtained by an Atomic absorption spectroscopy(AAS),The Ag+ content in water after the antibacterial test was measured by an Inductively Coupled plasma(ICP) emission spectroscopy.Antibacterial test was carried out against Escherichia coli(E.coli) and Staphylococcus aureus(S.aureus).The results show that Ag-ACF/AC have strong antibacterial activity against E.Coli and S.aureus.After dealt with ACF/AC loading Ag,AgCl,AgI,no E.coli and S.aureus alive in solution can be detected.The analysis of Agcontent in water after antibacterial test showed that the content of Ag meet the quality requirement of the National Potable Water Standrd,It is indicated that ACF/AC-Ag in this experiment would be a safe antibacterial agent.

  18. Preparation of hydrophilic vinyl chloride copolymer hollow fiber membranes with antifouling properties

    Science.gov (United States)

    Rajabzadeh, Saeid; Sano, Rie; Ishigami, Toru; Kakihana, Yuriko; Ohmukai, Yoshikage; Matsuyama, Hideto

    2015-01-01

    Hydrophilic vinyl chloride copolymer hollow fiber membranes with antifouling properties were prepared from brominated vinyl chloride-hydroxyethyl methacrylate copolymer (poly(VC-co-HEMA-Br)). The base membrane was grafted with two different zwitterionic monomers, (2-methacryloyloxyethylphosphorylcholine) (MPC) and [2-(methacryloyloxy) ethyl] dimethyl (3-sulfopropyl) ammonium hydroxide) (MEDSAH), and poly(ethylene glycol) methyl ether methacrylate (PEGMA). The effect of the grafting on the base membrane hydrophilicity and antifouling properties was investigated. For comparison of the results, the pure water permeabilities and pore sizes at the outer surfaces of the grafted hollow fiber membranes were controlled to be similar. A poly(VC-co-HEMA-Br) hollow fiber membrane with similar pure water permeability and pore size was also prepared as a control membrane. A BSA solution was used as a model fouling solution for evaluation of the antifouling properties. Grafting with zwitterionic monomers and PEGMA improved the antifouling properties compared with the control membrane. The PEGMA grafted membrane showed the best antifouling properties among the grafted membranes

  19. Wheat bran stabilization and its use in the preparation of high-fiber pasta.

    Science.gov (United States)

    Sudha, M L; Ramasarma, P R; Venkateswara Rao, G

    2011-02-01

    Wheat bran was explored as a source of fiber in the preparation of high-fiber pasta. Ground raw wheat bran having an ash content 5.99%, crude protein 15.1% and fat content 5.83% was subjected to moist heat treatment (steam heat-treated bran) and dry heat treatment (dry heat-treated bran), wherein the lipase activity was reduced by 50%. Treated bran samples were stable for 3 months without developing any rancid flavor and bitterness. Pasta samples were prepared by substituting semolina with 40% and 50% of bran samples. There was no further significant inactivation of lipase activity upon extrusion followed by drying of pasta, irrespective of the type and the amount of bran sample used. The cooked weights of the pasta were in the range 257-268 g/100 g, whereas the cooking loss decreased from 12.8% to 9.3% for treated bran-incorporated pasta. Sensory scores for pasta containing treated bran samples were higher. The total dietary fiber increased by 5.2 times upon replacement of semolina by 40% of treated wheat bran. Sodium dodecyl sulfate polyacrylamide gel electrophoresis studies showed faint bands in treated bran samples as well as treated bran-incorporated pasta samples.

  20. Preparation and characterizations of bioglass ceramic cement/Ca-P coating on pure magnesium for biomedical applications.

    Science.gov (United States)

    Zhang, Xue; Li, Xiao-Wu; Li, Ji-Guang; Sun, Xu-Dong

    2014-01-08

    Magnesium has been recently recognized as a biodegradable metal for bone substitute applications. In order to improve the biocompatibility and osteointegration of pure Mg, two kinds of coatings, i.e., the Ca-P coating and bioglass ceramic cement (BGCC)/Ca-P coating, were prepared on the pure Mg ribbons in the present work. The Ca-P coating was obtained by aqueous solution method. Subsequently, Ca-P coated Mg was immersed into the BGCC slurry, which was prepared by the mix of SiO2-CaO-P2O5 bioglass ceramic (BGC) powders and phosphate liquid with a liquid-to-solid ratio (L/S) of 1.6, to obtain BGCC/Ca-P coating by a dipping-pulling method. The microstructures, morphologies, and compositions of these coatings have been characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). The effect of these coatings on the mineralization activity of pure Mg has been investigated. The results indicated that both the Ca-P coating and BGCC/Ca-P coating could promote the nucleation of osteoconductive minerals, i.e., bone-like apatite, and the hydroxyapatite (HA) layer formed on the surface of the BGCC/Ca-P coating is obviously more dense, thick, and stable than that formed on the Ca-P coating after immersion in SBF solution for 15 days. The potentiodynamic polarization test indicated that the corrosion current density of the BGCC/Ca-P coated Mg is obviously lower than that of the Ca-P coating and 10 times lower than that of uncoated Mg. These results demonstrated that the BGCC/Ca-P coating can increase significantly the corrosion resistance of Mg and introduce a high biocompatibility of the bone-Mg substrate interface. In summary, the newly developed BGCC/Ca-P coated Mg has a good potential for biomedical applications.

  1. 墙地砖胶粘剂的研制%Preparation of ceramic tile adhesive

    Institute of Scientific and Technical Information of China (English)

    赵卫国; 俞永涵; 钱翠英; 蒋中南

    2001-01-01

    A fine water resisting styrene-acrylic emulsion was synthesized by adding silane coupling agent in the polymerization.By using this emulsion,a waterproof and weather fastness ceramic tile adhesive was produced successfully.The experimental results show that the silane dosage and its adding method have great effects on the product,and the property of the ceramic tile was good when using propylene-glycol butyl ether and methyl hydroxypropyl cellulose as film-forming agent and thickener respectively.%通过在聚合过程中加入硅烷偶联剂,制得一种耐水性优良的苯丙乳液,并用该乳液制得耐水、耐候性优良的即用型墙地砖胶粘剂。实验表明,硅烷偶联剂的加入量和加入方式对产品耐水性的影响较大,同时,以丙二醇丁醚和甲基羟丙基纤维素分别作为产品的成膜助剂及增稠剂,产品的综合性能较佳。

  2. Optimization of the preparation conditions of ceramic products using drinking water treatment sludges.

    Science.gov (United States)

    Zamora, R M Ramirez; Ayala, F Espesel; Garcia, L Chavez; Moreno, A Duran; Schouwenaars, R

    2008-11-01

    The aim of this work is to optimize, via Response Surface Methodology, the values of the main process parameters for the production of ceramic products using sludges obtained from drinking water treatment in order to valorise them. In the first experimental stage, sludges were collected from a drinking water treatment plant for characterization. In the second stage, trials were carried out to elaborate thin cross-section specimens and fired bricks following an orthogonal central composite design of experiments with three factors (sludge composition, grain size and firing temperature) and five levels. The optimization parameters (Y(1)=shrinking by firing (%), Y(2)=water absorption (%), Y(3)=density (g/cm(3)) and Y(4)=compressive strength (kg/cm(2))) were determined according to standardized analytical methods. Two distinct physicochemical processes were active during firing at different conditions in the experimental design, preventing the determination of a full response surface, which would allow direct optimization of production parameters. Nevertheless, the temperature range for the production of classical red brick was closely delimitated by the results; above this temperature, a lightweight ceramic with surprisingly high strength was produced, opening possibilities for the valorisation of a product with considerably higher added value than what was originally envisioned.

  3. Preparation of Micro-Porous Alumina Sheet Support for Ceramic Membrane by Extrusion

    Science.gov (United States)

    Hemra, Khanthima; Atong, Duangduen; Aungkavattana, Pavadee

    Among several types of ceramic membrane developed for a half of century, alumina is the most extensive advantage. In this study, many types of alumina with different particle size distributions were used as a starting material for fabrication of support sheet ceramic membrane using extrusion process. The investigation focused on the alumina dough components composed of some organic binders and water. The organic binder of about 12 wt. % was required in order for dough to be easily extruded, while the amount of water added to the dough depended on the particle size of alumina powder. The particle size and size distribution of starting powder showed strong effects on pore size of sintered alumina support. The pore size decreased when smaller particle size of starting powder was used. In addition, the pore volume of the sintered alumina decreased with increasing the sintering temperature due to improvement in densification, while pore size remained the same. The mechanical strength of alumina supports was also influenced by the particle size of starting powder; the finer particle size resulted in the higher mechanical strength. However, in order to obtain a good flux for the membrane, a high mechanical strength of the support along with its effective porosity is critical concerns. In this work, the support sintered at 1450°C provided a proper porosity of approximately 40% with an acceptable mechanical strength of 30-45MPa.

  4. Proton conductivity in tungsten and antimony-modified titania ceramics prepared by the sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Vichi, Flavio Maron [Departamento de Quimica Fundamental, Instituto de Quimica, Universidade de Sao Paulo, Av. Prof, Lineu Prestes, 748, Butanta, Sao Paulo, SP (Brazil); Tejedor-Tejedor, Maria Isabel; Anderson, Marc A. [Environmental Chemistry and Technology Program, University of Wisconsin-Madison, 660 N. Park St., Madison, WI 53706 (United States)

    2005-03-15

    Titania ceramic materials modified with 5% antimony and 5% tungsten were prepared by the sol-gel method. For the antimony-modified material, a treatment with H{sub 2}O{sub 2} was also performed, in order to obtain antimonic acid. The electric conductivity of the xerogels was measured at 25 {sup o}C in the relative humidity (RH) range 33-81%. At 25 {sup o}C, the electrical conductivity of the 'as prepared' 5% Sb ceramic varies from 2.02x10{sup -5} S cm{sup -1} at 33% RH to 1.12x10{sup -2} S cm{sup -1} at 81% R.H. For the material treated with H{sub 2}O{sub 2}, the conductivity varies from 1.56x10{sup -5} to 2.37x10{sup -2} S cm{sup -1} for 33% and 81% R.H., respectively. For the tungsten-modified material, the conductivity varies from 1.02x10{sup -5} to 2.66x10{sup -3} S cm{sup -1} for 33% and 81% R.H., respectively. The activation energies observed for proton conduction were 23.5 kJ mol{sup -1} for TiO{sub 2}/W 5%, 22.9 kJ mol{sup -1} for TiO{sub 2}/Sb 5% and 20.6 kJ mol{sup -1} for the material treated with H{sub 2}O{sub 2}. The highest activation energy was observed for untreated TiO{sub 2}:24.8 kJ mol{sup -1}. The conductivity values for the Sb-modified ceramics are superior to those reported previously for antimonic acid films, and approach the values reported for proton-conducting polymers, such as Nafion(R), making them a potential candidate for application as electrolytes in fuel cell systems.

  5. Synergistic Effects of Stress-Rupture and Cyclic Loading on Strain Response of Fiber-Reinforced Ceramic-Matrix Composites at Elevated Temperature in Oxidizing Atmosphere

    Directory of Open Access Journals (Sweden)

    Longbiao Li

    2017-02-01

    Full Text Available In this paper, the synergistic effects of stress rupture and cyclic loading on the strain response of fiber-reinforced ceramic-matrix composites (CMCs at elevated temperature in air have been investigated. The stress-strain relationships considering interface wear and interface oxidation in the interface debonded region under stress rupture and cyclic loading have been developed to establish the relationship between the peak strain, the interface debonded length, the interface oxidation length and the interface slip lengths. The effects of the stress rupture time, stress levels, matrix crack spacing, fiber volume fraction and oxidation temperature on the peak strain and the interface slip lengths have been investigated. The experimental fatigue hysteresis loops, interface slip lengths, peak strain and interface oxidation length of cross-ply SiC/MAS (magnesium alumino-silicate, MAS composite under cyclic fatigue and stress rupture at 566 and 1093 °C in air have been predicted.

  6. Influence of morphology of ceramic fibers in catalytic combustion of methane; Influencia da morfologia de fibras ceramicas na combustao catalitica do metano

    Energy Technology Data Exchange (ETDEWEB)

    Tabarelli, A.C.; Alves, A.K.; Bergmann, C.P., E-mail: andretabarelli@gmail.com [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Departamento de Materiais

    2012-07-01

    Methane, considered as the main constituent of natural gas has been widely used as an energy source. During its combustion are produced pollutants that cause concern and necessity to eliminate or reduce the emission of these agents in the atmosphere. One of the main means of controlling emissions is the use of catalysts. In order to contribute to the development of new catalysts, this study analyzed the morphology of ceramic fibers of cerium oxide (ceria) doped with copper fabricated by electrospinning, in order to verify their effects on catalytic activity. Parameters were varied in distance from the electrodes, the diameter of the capillary and applied voltage between electrodes. The characterizations were performed: scanning electron microscopy, thermogravimetric analysis, BET and Xray diffraction (DXR). The results indicate that after the thermal treatment there was a reduction of approximately 40% fiber diameter and specific surface area ranging between 28.929 and 34.501 m{sup 2}/g. (author)

  7. Preparation and Application of Ceramic Coating on Magnesium Alloy%镁合金陶瓷涂层制备工艺及应用

    Institute of Scientific and Technical Information of China (English)

    赵斌; 李欣棉; 陶莹; 李智超

    2012-01-01

    The characteristics and research status of preparation technology of ceramic coating on Mg alloy (including methods of thermochemical reaction, thermal spray and so on) were introduced, and the application prospect of ceramic coating on Mg alloy in the production practice was pointed out.%介绍了镁合金陶瓷涂层的制备工艺(包括热化学反应法、热喷涂法及其他方法)的特点及研究现状,并指岀了镁合金陶瓷涂层在生产实践中的应用前景.

  8. Preparation and Properties of Macroporous Silicon Nitride Ceramics by Gelcasting and Carbonthermal Reaction

    Institute of Scientific and Technical Information of China (English)

    Wen ZHANG; Hongjie WANG; Zhihao JIN

    2005-01-01

    Macroporous silicon nitride (Si3N4) ceramics with high strength, uniform structure and relatively high porosity were obtained by gelcasting and carbonthermal reaction in a two-step sintering technique. Microstructure and composition were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction(XRD). Open porosity, pore size distribution and basic mechanical performance were measured by Archimedes method,mercury intrusion porosimetry and three-point bending methods, respectively. SEM and TEM results revealed that pores were formed by elongated β-Si3N4. SADP measurement proved the formation of SiC particles. The SiC granules were beneficial for the formation of high ratio elongated β-Si3N4, and at proper amount, they also acted as reinforcement phase. Thermodynamic analysis indicated that the mechanisms of the reactions were mainly associated with liquid-solid reaction and gas-liquid reaction.

  9. Piezoelectric Ceramic Characteristics Using Fiber Grating Sensor%用光纤光栅传感器研究压电陶瓷的特性

    Institute of Scientific and Technical Information of China (English)

    余有龙; 谭玲; 邹李刚; 王浩

    2011-01-01

    提出了一种利用光纤光栅传感器研究压电陶瓷特性的新方法.该方法采用非平衡Michelson扫描干涉仪对光纤光栅传感信号进行相位解调,通过观测波长漂移引起的相移,从而获得压电陶瓷的位移量与所加电压间的关系.实验分析了迟滞特性和蠕变现象,得到了压电陶瓷的电压-位移特性曲线以及蠕变特性曲线.实验表明,光源功率的波动对压电陶瓷迟滞特性不能造成影响且压电陶瓷的蠕变特性与电压方向无关.%A method for characteristics of piezoelectric ceramics was presented using a fiber Bragg grating sensor. An unbalanced Michelson interferometer was utilized to demodulate the fiber Bragg grating sensor signals. The relationship between the displacement of piezoelectric ceramic and the applied voltage was shown by observing the phase-shift induced by wavelength-shift. The hysteretic and creep properties of the piezoelectric ceramic were demonstrated experimentally,and the applied voltage-displacement curve and the creep curve were obtained. The results show that the fluctuations of light power had no effect on hysteretic,and the voltage direction has nothing with creep.

  10. Adsorption of SO2 on bituminous coal char and activated carbon fiber prepared from phenol formaldehyde

    Science.gov (United States)

    DeBarr, Joseph A.; Lizzio, Anthony A.; Daley, Michael A.

    1996-01-01

    Carbon-based materials are used commercially to remove SO2 from coal combustion flue gases. Historically, these materials have consisted of granular activated carbons prepared from lignite or bituminous coal. Recent studies have reported that activated carbon fibers (ACFs) may have potential in this application due to their relatively high SO2 adsorption capacity. In this paper, a comparison of SO2 adsorption for both coal-based carbons and ACFs is presented, as well as ideas on carbon properties that may influence SO2 adsorption

  11. Preparation and properties of Nd{sup 3+}:SrAlF{sub 5} nanocrystals embedded fluorophosphate transparent glass-ceramic with long fluorescence lifetime

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Ruilin; Wang, Jinlong; Zhang, Liaolin; Liu, Chunxiao; Wei, Wei [Nanjing University of Posts and Telecommunications, School of Optoelectronic Engineering, Nanjing (China)

    2016-07-15

    Nd{sup 3+}:SrAlF{sub 5} nanocrystals embedded fluorophosphate glass-ceramics were prepared by the melt quenching and subsequent thermal treatment method. The formation of SrAlF{sub 5} nanocrystals in the glass was confirmed by X-ray diffraction and scanning electron microscope. The fluorescence intensity and lifetime of the glass-ceramics increased with the increase of size of nanocrystals. Importantly, by controlling growth of nanocrystals, an obvious enhancement of lifetime (725 μs) emerged in the glass-ceramics heat-treated at 510 C and the transmittance can reach to 72.2 % at 1049 nm. The enhanced fluorescence intensity and lifetime were ascribed to the comfortable local environment to the Nd{sup 3+} ion and scattering of the nanoparticle embedded into the glass matrix. (orig.)

  12. Induction of micronuclei, hyperdiploidy and chromosomal breakage affecting the centric/pericentric regions of chromosomes 1 and 9 in human amniotic fluid cells after treatment with asbestos and ceramic fibers.

    Science.gov (United States)

    Dopp, E; Schuler, M; Schiffmann, D; Eastmond, D A

    1997-06-09

    This article describes the induction of micronuclei, hyperdiploidy and chromosome breakage in human amniotic cells in vitro by amosite, chrysotile and crocidolite asbestos, and ceramic fibers. The response of human (amniotic fluid cells) and rodent (Syrian hamster embryo fibroblasts, SHE) cells to fiber treatment was compared using the micronucleus assay. The data of the rodent studies were taken from a previous investigation (Dopp, E. et al. (1995) Environ. Health Perspect., 103, 268-271). All types of mineral fibers caused a significant increase of micronucleated cells. The kinetochore analysis revealed that all three types of asbestos and ceramic fibers yielded similar effects. Approximately 50% of the induced micronuclei were kinetochore-negative indicating formation through clastogenic events. Human amniotic cells were much less susceptible than SHE cells to the induction of micronuclei by mineral fibers. This again demonstrates that SHE cells are more susceptible to chromosomal changes than human amniotic fluid cells. The application of fluorescence in situ hybridization (FISH) with tandem DNA probes yielded more detailed information about specific structural chromosome aberrations in the 1 (cen-q12) and 9 (cen-q12) regions and about abnormal numbers of chromosomes in interphase human amniotic fluid cells. Using this FISH approach we found a statistically significant increase of chromosomal breakage in the pericentric heterochromatin regions of chromosomes 1 and 9 in interphase human amniotic cells after exposure to asbestos and ceramic fibers compared to control cells. The number of hyperdiploid cells was also significantly increased. Our results show that asbestos fibers as well as ceramic fibers are inducers of structural and numerical chromosomal aberrations in human amniotic fluid cells.

  13. Microstructure, bonding strength and thermal shock resistance of ceramic coatings on steels prepared by plasma electrolytic oxidation

    Science.gov (United States)

    Wang, Yunlong; Jiang, Zhaohua; Yao, Zhongping

    2009-11-01

    Ceramic coatings were successfully prepared on steel by plasma electrolytic oxidation (PEO) in aluminate electrolyte and silicate electrolyte, respectively. The microstructure of the coatings including surface morphology, phase and element composition were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The bonding strength between the ceramic coating and the substrate was tested using different methods including tensile tests and shearing tests. The thermal shock resistance of the coatings was also evaluated. The results indicated that coatings obtained in both electrolytes were porous and coarse. The average diameters of the pores were below 10 μm. PEO coatings obtained in aluminate electrolyte were composed of Fe 3O 4 and FeAl 2O 4, while those obtained in silicate electrolyte were in a noncrystal state. PEO coatings obtained in aluminate electrolyte showed similar change trend of tensile strength and shearing strength with increasing treating time, namely, a relatively high values with middle time treating and low value with short and long time treating. The best coating was the samples treated with 30 min, whose tensile strength was 20.6 MPa and shearing strength was 16 MPa. The tensile strength and shearing strength of coatings obtained in silicate electrolyte were not strongly influenced by the treating time, the values of which were range in 14 ± 2 MPa and 11 ± 2 MPa, respectively. Coatings obtained in both electrolytes showed the best thermal shock resistance with middle time treating. Coatings obtained in silicate electrolyte show a little better thermal shock resistance than those obtained in aluminate electrolyte.

  14. Functional properties of Sm{sub 2}NiMnO{sub 6} multiferroic ceramics prepared by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Gheorghiu, Felicia, E-mail: felicia.gheorghiu@uaic.ro [Dielectrics, Ferroelectrics & Multiferroics Group, Department of Physics, “Al. I. Cuza” Univ., 11 Blvd. Carol I, 700506 Iasi (Romania); RAMTECH Centre, Interdisciplinary Research Department-Field Science, “Al. I. Cuza” Univ., Blvd. Carol I, Nr. 11, 700506 Iasi (Romania); Curecheriu, Lavinia [Dielectrics, Ferroelectrics & Multiferroics Group, Department of Physics, “Al. I. Cuza” Univ., 11 Blvd. Carol I, 700506 Iasi (Romania); Lisiecki, Isabelle [CNRS, Univ Paris 06, UMR 7070, LM2N, bât. F, B.P. 52, 4 place Jussieu, Paris F-75231, Cedex 05 (France); Beaunier, Patricia [UPMC, Univ Paris 06, UMR 7197, LRS, Le Raphaël, 3 rue Galilée, 94200 Ivry (France); Feraru, Simona; Palamaru, Mircea N. [Faculty of Chemistry, “Al. I. Cuza” Univ., 11 Blvd. Carol I, 700506 Iasi (Romania); Musteata, Valentina [“Petru Poni” Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda 41A, 700487 Iasi (Romania); Lupu, Nicoleta [National Institute of Research and Development for Technical Physics, 700050 Iasi (Romania); Mitoseriu, Liliana, E-mail: lmtsr@uaic.ro [Dielectrics, Ferroelectrics & Multiferroics Group, Department of Physics, “Al. I. Cuza” Univ., 11 Blvd. Carol I, 700506 Iasi (Romania)

    2015-11-15

    In the present work, it was reported for the first time the new synthesis of Sm{sub 2}NiMnO{sub 6} double perovskite oxides by sol–gel auto-combustion method. The Rietveld analysis of the X-ray ceramics diffraction pattern recorded at room temperature for Sm{sub 2}NiMnO{sub 6} ceramics sintered at 1000 °C/5 min from powders obtained at 700 °C/7 h confirm the formation of the double perovskite with a monoclinic structure and the space group P2{sub 1}/n. The HRTEM analysis shows clear lattice fringes that confirm a high crystallinity level of the material corresponding to the monoclinic structure. The non-linear dielectric character was checked for the first time in Sm{sub 2}NiMnO{sub 6} double perovskite and the results reveals a strong nonlinearity and a small hysteretic behaviour. The present structural, magnetic and dielectric data make the Sm{sub 2}NiMnO{sub 6} system due to its multiferroic character a promising candidate to different modern electronic devices applications. - Highlights: • The Sm{sub 2}NiMnO{sub 6} double perovskite were prepared by sol–gel auto-combustion method. • The Rietveld and HRTEM analysis confirm a double perovskite monoclinic structure. • The non-linear character reveals a strong nonlinearity. • The magnetic transitions indicate a change in the spin ordering. • The Sm{sub 2}NiMnO{sub 6} system is a promising multiferroic candidate to modern applications.

  15. Preparation of Fe-Al Intermetallic / TiC-Al2O3 Ceramic Composites from Ilmenite by SHS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Fe-Al intermetallic/TiC-Al2O3 ceramic composites were successfully prepared by self-propagating high-temperature synthesis (SHS) from natural ilmenite, aluminium and carbon as the raw materials. The effects of carbon sources, preheating time and heat treatment temperature on synthesis process and products were investigated in detail, and the reaction process of the FeTiO3-Al-C system was also discussed.It is shown that the temperature and velocity of the combustion wave are higher when graphite is used as the carbon source, which can reflect the effect of the carbon source structure on the combustion synthesis;Prolonging the preheating time or heat treatment temperature is beneficial to the formation of the ordered intermetallics; The temperature and velocity of the combustion wave arc improved, but the disordered alloys are difficult to eliminate with the preheating time prolonged. The compound powders mainly containing ordered Fe3Al intermetallic can be prepared through heat treatment at 750 ℃.

  16. The effect of firing conditions on phase formation, microstructure and dielectric properties of BNKTNb-LSb ceramics prepared via the combustion technique

    Science.gov (United States)

    Yotthuan, Surirat; Kornphom, Chittakorn; Bongkarn, Theerachai

    2015-10-01

    The fabrication of 0.99[Bi0.5(Na0.82K0.18)0.5Ti0.995Nb0.005O3]-0.01LiSbO3 ceramics (BNKTNb-LSb) prepared by the combustion technique was studied. A single perovskite phase of BNKTNb-LSb powder was observed by the powders calcined at 700 °C for 2 h, which was lower than the solid-state reaction technique ∼150 °C. The BNKTNb-LSb ceramics showed the coexistence of a rhombohedral and tetragonal phase at a low sintering temperature. Then, the phase formation changed from a tetragonal to a pseudocubic phase when sintered at higher temperatures. The grain morphology of the BNKTNb-LSb ceramics exhibited a rather square shape and the average grain size of the ceramics was increased with increased sintering temperatures. The density, linear shrinkage, ɛr and ɛmax of the BNKTNb-LSb ceramics tended to increase with increasing sintering temperatures up to 1125 °C and then decreased. At 1125 °C, the highest density, shrinkage, ɛr and ɛmax were about 5.82 g/cm3, 18.7%, 1625 and 4465, respectively. The dielectric behavior corresponded with the XRD, density and the microstructure results.

  17. Preparation and properties of CaO-Al2O3-SiO2 glass-ceramics by sintered frits particle from mining wastes

    Directory of Open Access Journals (Sweden)

    He F.

    2014-01-01

    Full Text Available The paper reports on some experimental results obtained from the production of glass-ceramics containing gold tailings powder (GTP. Frits particle sintered technology was used to prepare glass ceramic products. SiO2, CaO, ZnO, BaO and B2O3 were selected to adjust the composition of the glass. Based on the results of differential thermal analysis (DTA, the nucleation and crystallization temperature of parent glass samples with different schedule were identified, respectively. X-ray diffraction (XRD analysis of the produced glass-ceramics materials revealed that the main crystalline phase was β-wollastonite. With the increasing of CaO content, the intensity of crystal diffractive peaks also increases. The formation of β-wollastonite crystal could be accelerated by the increasing of CaO. The glass-ceramics with fine microstructure showed better physical, mechanical properties and chemical resistance. Overall results indicated that it was a feasible attempt to produce glass-ceramics for building and decorative materials from waste materials. The amount of GTP used in the glass batches was more than 65 wt% of the whole raw.

  18. UTILIZATION OF BAGASSE FIBER FOR PREPARATION OF BIODEGRADABLE FLAME RETARDING COMPOSITES (BFRCS

    Directory of Open Access Journals (Sweden)

    Wenjia Han

    2010-06-01

    Full Text Available Bagasse is a renewable resource characterized by its low cost and environmental friendliness. In this work a novel technological process was proposed to make flame retarding composites (BFRCs by using bagasse fiber. The bagasse was disintegrated by twisting it up and applying high consistency refining, and then it was used to prepare BFRCs via hot pressure. Chemical groups and thermal properties of bagasse fiber were studied through the use of FTIR spectroscopy, a universal mechanical testing machine, and TGA, while properties of BFRCs were also analyzed by SEM, and the surface water resistance and burning characteristics were measured. Results showed the pyrolysis temperature of bagasse fibers to be about 273oC. Chemical groups were not changed, while the content of groups was reduced a little during the manufacturing process. The BFRCs showed good performance for water resistance, and the optimum value was 1.7g. They also had good flame retardant performance. The index of flame spread was 13.6 and the smoke index was 108, which reaches Class A by the ASTM E84-08 Standard.

  19. Influence of electron beam Irradiation on PP/Piassava fiber composite prepared by melt extrusion process

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Michelle G.; Ferreira, Maiara S.; Oliveira, Rene R.; Silva, Valquiria A.; Teixeira, Jaciele G.; Moura, Esperidiana A.B., E-mail: michellegoncalvesgomes@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    In the latest years, the interest for the use of natural fibers in materials composites polymeric has increased significantly due to their environmental and technological advantages. Piassava fibers (Attalea funifera) have been used as reinforcement in the matrix of thermoplastic and thermoset polymers. In the present work (20%, in mass), piassava fibers with particle sizes equal or smaller than 250 μm were incorporated in the polypropylene matrix (PP) no irradiated and polypropylene matrix containing 10 % and 30 % of polypropylene treated by electron-beam radiation at 40 kGy (PP/PPi/Piassava). The composites PP/Piassava and PP/PPi/Piassava were prepared by using a twin screw extruder, followed by injection molding. The composite material samples obtained were treated by electron-beam radiation at 40 kGy, using a 1.5 MeV electron beam accelerator, at room temperature, in presence of air. After irradiation treatment, the irradiated and non-irradiated specimens tests samples were submitted to thermo-mechanical tests, melt flow index (MFI), sol-gel analysis, X-Ray diffraction (XRD) and scanning electron microscopy (SEM). (author)

  20. Diffusion and Interface Effects during Preparation of All-Solid Microstructured Fibers

    Directory of Open Access Journals (Sweden)

    Kobelke Jens

    2014-09-01

    Full Text Available All-solid microstructured optical fibers (MOF allow the realization of very flexible optical waveguide designs. They are prepared by stacking of doped silica rods or canes in complex arrangements. Typical dopants in silica matrices are germanium and phosphorus to increase the refractive index (RI, or boron and fluorine to decrease the RI. However, the direct interface contact of stacking elements often causes interrelated chemical reactions or evaporation during thermal processing. The obtained fiber structures after the final drawing step thus tend to deviate from the targeted structure risking degrading their favored optical functionality. Dopant profiles and design parameters (e.g., the RI homogeneity of the cladding are controlled by the combination of diffusion and equilibrium conditions of evaporation reactions. We show simulation results of diffusion and thermal dissociation in germanium and fluorine doped silica rod arrangements according to the monitored geometrical disturbances in stretched canes or drawn fibers. The paper indicates geometrical limits of dopant structures in sub-µm-level depending on the dopant concentration and the thermal conditions during the drawing process. The presented results thus enable an optimized planning of the preform parameters avoiding unwanted alterations in dopant concentration profiles or in design parameters encountered during the drawing process.

  1. The preparation of albumin as a biological drug from human plasma by fiber filtration

    Directory of Open Access Journals (Sweden)

    Mousavi Hosseini K

    2011-08-01

    Full Text Available "nBackground: In recent years, consumption of whole-blood for the treatment of patients has decreased but use of biological plasma-derived medicines such as albumin, immunoglobulin and coagulation factors have increased instead. Paying attention to albumin molecular structure is important for its isolation from human plasma. Albumin is a single-chain protein consisting of about 585 amino acids and a molecular weight of 66500 Daltons. Albumin is a stable molecule and it is spherical in shape. There are different methods for human albumin preparation. Considering the large consumption of this biological drug in clinical settings, methods with fewer steps in production line are of big advantage in saving time and manufacturing more products."n "nMethods: In this project, we prepared human albumin using hollow fiber cartridges in order to omit the rework on fraction V+VI. Human albumin is usually produced by the application of cold ethanol method, where albumin is obtained from fraction V by doing a rework on fraction V+VI to separate fraction V."n "nResults: In the current work, human albumin was prepared from fraction V+VI by the help of hollow fiber cartridges. With a concentration of 20%, the obtained albumin had 96.5% of monomer and 3.5% of polymer and polymer aggregate."n "nConclusion: Comparing the obtained human albumin with a number of commercial human albumin samples by the use of SDS-page, the results were satisfactory regarding the 3.5 percent polymer and aggregate rate for the prepared albumin.

  2. Activated carbon fibers/poly(lactic-co-glycolic) acid composite scaffolds: preparation and characterizations.

    Science.gov (United States)

    Shi, Yanni; Han, Hao; Quan, Haiyu; Zang, Yongju; Wang, Ning; Ren, Guizhi; Xing, Melcolm; Wu, Qilin

    2014-10-01

    The present work is a first trial to introduce activated carbon fibers (ACF) with high adsorption capacity into poly(lactic-co-glycolic) acid (PLGA), resulting in a novel kind of scaffolds for tissue engineering applications. ACF, prepared via high-temperature processing of carbon fibers, are considered to possess bioactivity and biocompatibility. The ACF/PLGA composite scaffolds are prepared by solvent casting/particulate leaching method. Increments in both pore quantity and quality over the surface of ACF as well as a robust combination between ACF and PLGA matrix are observed via scanning electron microscopy (SEM). The high adsorption capacity of ACF is confirmed by methylene blue solution absorbency test. The surfaces of ACF are affiliated with many hydrophilic groups and characterized by Fourier transform infrared spectroscopy. Furthermore, the SEM images show that cells possess a favorable spreading morphology on the ACF/PLGA scaffolds. Besides, vivo experiments are also carried out to evaluate the histocompatibility of the composite scaffolds. The results show that ACF have the potential to become one of the most promising materials in biological fields.

  3. Activated carbon fibers/poly(lactic-co-glycolic) acid composite scaffolds: Preparation and characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Yanni [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China); Han, Hao [College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China); Bayer Material Science China Co., Ltd, Shanghai 200120 (China); Quan, Haiyu; Zang, Yongju; Wang, Ning; Ren, Guizhi [College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China); Xing, Melcolm [Department of Mechanical Engineering, Faculty of Engineering and Department of Biochemistry and Genetics, Faculty of Medicine P.I., Manitoba Institute of Child Health, University of Manitoba, Winnipeg, Manitoba (Canada); Wu, Qilin, E-mail: wql@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China)

    2014-10-01

    The present work is a first trial to introduce activated carbon fibers (ACF) with high adsorption capacity into poly(lactic-co-glycolic) acid (PLGA), resulting in a novel kind of scaffolds for tissue engineering applications. ACF, prepared via high-temperature processing of carbon fibers, are considered to possess bioactivity and biocompatibility. The ACF/PLGA composite scaffolds are prepared by solvent casting/particulate leaching method. Increments in both pore quantity and quality over the surface of ACF as well as a robust combination between ACF and PLGA matrix are observed via scanning electron microscopy (SEM). The high adsorption capacity of ACF is confirmed by methylene blue solution absorbency test. The surfaces of ACF are affiliated with many hydrophilic groups and characterized by Fourier transform infrared spectroscopy. Furthermore, the SEM images show that cells possess a favorable spreading morphology on the ACF/PLGA scaffolds. Besides, vivo experiments are also carried out to evaluate the histocompatibility of the composite scaffolds. The results show that ACF have the potential to become one of the most promising materials in biological fields. - Highlights: • ACF with strong adsorption capacity and porous structure for enhanced surface area • The incorporation of ACF promoting the porosity of composite scaffolds • The composite scaffolds having no side effect on cell adhesion and proliferation • The composite scaffolds presenting good biocompatibility in vivo.

  4. Preparation and Characterization of Andalusite Ceramic Used for Solar Thermal Power Generation

    Institute of Scientific and Technical Information of China (English)

    WU Jianfeng; CHENG Hao; XU Xiaohong; ZHOU Yang; HE Dezhi; LIU Yi

    2014-01-01

    High-temperature thermal storage material is one of the critical materials of solar thermal power generation system. Andalusite, kaolin, talc,γ-Al2O3 and partially stabilized zirconia were used as the raw materials, and in-situ synthesis of cordierite was adopted to fabricate thermal storage material for solar thermal power generation via pressureless sintering. The phase compositions, microstructures and thermal shock resistances of the sintered samples were analyzed by XRD, SEM and EDS, and the corresponding mechanical properties were measured. The results show that the major phases of the samples are mullite and zirconium silicate, and the pores distribute uniformly. After being sintered at 1 460 ℃, A4 sample exhibits a better mechanical performance and thermal shock resistance, its loss rate of bending strength after 30 cycles thermal shock is 3.04%, the bulk density and bending strength are 2.86 g·cm-3 and 139.66 MPa, respectively. The better thermal shock resistance of the sample is closely related to the effect of zirconium silicate, such as its uniform distribution, nested growth with mullite, low thermal expansion coefficient, high thermal conductivity, etc. This ceramic can be widely used as one of potential thermal storage materials of solar thermal power generation system.

  5. PREPARATION OF RECYCLING CERAMIC TILES USING CERAMIC INDUSTRIAL WASTE%利用陶瓷工业废料制备再生陶瓷墙地砖

    Institute of Scientific and Technical Information of China (English)

    王功勋

    2011-01-01

    Recycling ceramic tile was made from raw materials using waste ceramic polishing powder(PP),and waste tiles,and using borax was added as a supplementary flux.Effects of PP sintering property on the strength of recycling ceramic tiles were investigated.Effects of PP on microstructure were detected by SEM tests.Results show that PP is beneficial to improve the sintering property because of its fine particle and glass phase.Strength of recycling ceramic tiles is increased by adding PP and borax compound.In the experimental,borax mass fraction of 0.5%,PP mass fraction of 2% and ceramic tile granule mass fraction of 25%,the strength of recycling ceramic tiles is the highest.This treatment technology features large integrated utilization efficiency for ceramic industrial waste and high strength of recycle ceramic tiles.%以废弃陶瓷抛光砖粉、陶瓷墙地砖烧成废料为原材料,硼砂作辅助熔剂制备再生陶瓷墙地砖,研究陶瓷抛光砖粉的高温烧结性能及其对再生墙地砖强度的影响,采用SEM测试分析陶瓷抛光砖粉对再生陶瓷制品微观结构的影响。结果表明:抛光砖粉含玻璃相、颗粒细小,有利坯体烧结密实;复掺少量抛光砖粉和硼砂,可提高制品强度。在硼砂掺量为0.5%,陶瓷抛光砖粉为2%、烧成废料为25%的实验条件下,所得再生陶瓷制品强度最高。该方法具有陶瓷工业废料的综合利用率高,制得的再生陶瓷制品强度高等特点。

  6. Influence of aluminium nitride as a foaming agent on the preparation of foam glass-ceramics from high-titanium blast furnace slag

    Institute of Scientific and Technical Information of China (English)

    Huan Shi; Ke-qin Feng; Hai-bo Wang; Chang-hong Chen; Hong-ling Zhou

    2016-01-01

    To effectively reuse high-titanium blast furnace slag (TS), foam glass-ceramics were successfully prepared by powder sintering at 1000°C. TS and waste glass were used as the main raw materials, aluminium nitride (AlN) as the foaming agent, and borax as the fluxing agent. The influence of the amount of AlN added (1wt%-5wt%) on the crystalline phases, microstructure, and properties of the produced foam glass-ceramics was studied. The results showed that the main crystal phases were perovskite, diopside, and augite. With increasing AlN content, a transformation from diopside to augite occurred and the crystallinity of the pyroxene phases slightly decreased. Initially, the aver-age pore size and porosity of the foam glass-ceramics increased and subsequently decreased; similarly, their bulk density and compressive strength decreased and subsequently increased. The optimal properties were obtained when the foam glass-ceramics were prepared by adding 4wt% AlN.

  7. Influence of aluminium nitride as a foaming agent on the preparation of foam glass-ceramics from high-titanium blast furnace slag

    Science.gov (United States)

    Shi, Huan; Feng, Ke-qin; Wang, Hai-bo; Chen, Chang-hong; Zhou, Hong-ling

    2016-05-01

    To effectively reuse high-titanium blast furnace slag (TS), foam glass-ceramics were successfully prepared by powder sintering at 1000°C. TS and waste glass were used as the main raw materials, aluminium nitride (AlN) as the foaming agent, and borax as the fluxing agent. The influence of the amount of AlN added (1wt%-5wt%) on the crystalline phases, microstructure, and properties of the produced foam glass-ceramics was studied. The results showed that the main crystal phases were perovskite, diopside, and augite. With increasing AlN content, a transformation from diopside to augite occurred and the crystallinity of the pyroxene phases slightly decreased. Initially, the average pore size and porosity of the foam glass-ceramics increased and subsequently decreased; similarly, their bulk density and compressive strength decreased and subsequently increased. The optimal properties were obtained when the foam glass-ceramics were prepared by adding 4wt% AlN.

  8. Preparation and characterization of continuous high-temperature resistant Si-Al-C fibers by one-step method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Using polymer-derived technology, continuous high-temperature resistant Si-Al-C fibers were prepared by one step method, which included melt-spinning of polya-luminocarbosilane (PACS), curing of continuous PACS fibers, and sintering of the cured products. The results show that the average diameter and tensile strength of continuous Si-Al-C fibers are 11 to 12 μm and 1.8 to 2.0 GPa, respectively. The chemical formula of Si-Al-C fibers is SiC1.01O0.0400Al0.024, which is nearly stoichometric. The fibers are mainly composed of β-SiC crystalline, small amount of α-SiC, and amorphous SiC. Continuous Si-Al-C fibers exhibit excellent thermal stability. When the fibers were exposed in argon for 1 h, the tensile strength did not decrease until 1500℃. After heat treatment at 1800℃ in argon for 1 h, the fibers maintained about 80% of the initial strength. It was higher than that of Nicalon and Hi-Nicalon fibers.

  9. Preparation and characterization of activated carbon fiber (ACF) from cotton woven waste

    Science.gov (United States)

    Zheng, Jieying; Zhao, Quanlin; Ye, Zhengfang

    2014-04-01

    In this study, the activated carbon fibers (ACFs) were prepared using cotton woven waste as precursor. The cotton woven waste was first partly dissolved by 80% phosphoric acid and then was pre-soaked in 7.5% diammonium hydrogen phosphate solution. Finally, carbonization and activation were proceeded to get ACF. The optimum preparation conditions, including carbonization temperature, carbonization time, activation temperature and activation time, were chosen by orthogonal design. Nitrogen adsorption/desorption test was conducted to characterize the prepared ACF's pore structure. Fourier transform infrared spectroscopy (FTIR) analysis, X-ray photoelectron spectroscopy (XPS) and environmental scanning electron microscope (ESEM) were employed to characterize its chemical properties and morphology. Adsorption of oilfield wastewater was used to evaluate its adsorption properties. The results show that the prepared ACF is in the form of fiber, with the sectional diameters of 11.7 × 2.6 μm and the surface area of 789 m2/g. XPS results show that carbon concentration of the prepared ACF is higher than that of the commercial ACF. When the prepared ACF dosage is 6 g/L, over 80% of COD and over 70% of chrominance can be removed after 24 h of adsorption at 18 °C. We demonstrated the catalytic growth of m-axial InxGa1-xN (0.10 ≤ x ≤ 0.17) nanocolumn arrays with high crystallinity on silicon substrates using metal-organic chemical vapor deposition with trimethylindium (TMIn), triethylgallium (TEGa), and ammonia as precursors. The high quality of InGaN nanocolumns (NCs) were believed to be due to the utilization of TEGa that achieved less carbon impurities and offered more comparable vapor pressure with that of TMIn at low temperature. In addition, these NCs were grown in non-polar m-axis, which the internal electric field of the InGaN that often deteriorates the device performances might be able to be eliminated. Furthermore, the bandgap of this InGaN can be modulated from

  10. Preparation of electrospun fiber mats using siloxane-containing vaterite and biodegradable polymer hybrids for bone regeneration.

    Science.gov (United States)

    Fujikura, Kie; Lin, Sen; Nakamura, Jin; Obata, Akiko; Kasuga, Toshihiro

    2013-11-01

    An electrospun fiber mat using a new composite consisting of siloxane-containing vaterite (SiV) and poly(lactic-co-glycolic acid) (PLGA) (denoted by SiPLGVH) was prepared with the aim of applying it as a membrane for use in a guided bone regeneration (GBR) system. Another electrospun fiber mat using a previously described composite consisting of SiV and poly(L-lactic acid) (denoted by SiPVH) was also prepared as a comparative sample. SiPLG VH fiber mats showed superior results in terms of mechanical tensile properties and cellular behavior. Their elongation before failure was about eight times higher than that of SiPVH. The numbers of osteoblast-like cells that proliferated on the SiPLGVH fiber mats, regardless of the hydroxyapatite coating, were comparable to that of SiPVH. The cells spread more, two dimensionally, on the SiPLGVH fiber mats, since the pores between fibers were narrowed down because of swelling of the PLGA matrix during cell culture. This two-dimensional cellular proliferation quality on the SiPLGVH fiber mats is expected to be suitable for materials used in GBR, leading to control of infiltration of the soft tissue and great tissue integration with the surrounding tissue.

  11. A low-cost mullite-titania composite ceramic hollow fiber microfiltration membrane for highly efficient separation of oil-in-water emulsion.

    Science.gov (United States)

    Zhu, Li; Chen, Mingliang; Dong, Yingchao; Tang, Chuyang Y; Huang, Aisheng; Li, Lingling

    2016-03-01

    Oil-in-water (O/W) emulsion is considered to be difficult to treat. In this work, a low-cost multi-layer-structured mullite-titania composite ceramic hollow fiber microfiltration membrane was fabricated and utilized to efficiently remove fine oil droplets from (O/W) emulsion. In order to reduce membrane cost, coal fly ash was effectively recycled for the first time to fabricate mullite hollow fiber with finger-like and sponge-like structures, on which a much more hydrophilic TiO2 layer was further deposited. The morphology, crystalline phase, mechanical and surface properties were characterized in details. The filtration capability of the final composite membrane was assessed by the separation of a 200 mg·L(-1) synthetic (O/W) emulsion. Even with this microfiltration membrane, a TOC removal efficiency of 97% was achieved. Dilute NaOH solution backwashing was used to effectively accomplish membrane regeneration (∼96% flux recovery efficiency). This study is expected to guide an effective way to recycle waste coal fly ash not only to solve its environmental problems but also to produce a high-valued mullite hollow fiber membrane for highly efficient separation application of O/W emulsion with potential simultaneous functions of pure water production and oil resource recovery.

  12. Use of the Materials Genome Initiative (MGI approach in the design of improved-performance fiber-reinforced SiC/SiC ceramic-matrix composites (CMCs

    Directory of Open Access Journals (Sweden)

    Jennifer S. Snipes

    2016-07-01

    Full Text Available New materials are traditionally developed using costly and time-consuming trial-and-error experimental efforts. This is followed by an even lengthier material-certification process. Consequently, it takes 10 to 20 years before a newly-discovered material is commercially employed. An alternative approach to the development of new materials is the so-called materials-by-design approach within which a material is treated as a complex hierarchical system, and its design and optimization is carried out by employing computer-aided engineering analyses, predictive tools and available material databases. In the present work, the materials-by-design approach is utilized to design a grade of fiber-reinforced (FR SiC/SiC ceramic matrix composites (CMCs, the type of materials which are currently being used in stationary components, and are considered for use in rotating components, of the hot sections of gas-turbine engines. Towards that end, a number of mathematical functions and numerical models are developed which relate CMC constituents’ (fibers, fiber coating and matrix microstructure and their properties to the properties and performance of the CMC as a whole. To validate the newly-developed materials-by-design approach, comparisons are made between experimentally measured and computationally predicted selected CMC mechanical properties. Then an optimization procedure is employed to determine the chemical makeup and processing routes for the CMC constituents so that the selected mechanical properties of the CMCs are increased to a preset target level.

  13. Preparation and microwave characterization of BaNd{sub 2-x}Sm{sub x}Ti{sub 4}O{sub 12} (0 {<=} x {<=} 2) ceramics and their effect on the temperature coefficient of dielectric constant in polytetrafluoroethylene composites

    Energy Technology Data Exchange (ETDEWEB)

    Stanly Jacob, K.; Satheesh, R. [Centre for Materials for Electronics Technology, Department of Information Technology, Ministry of Communication and Information Technology, Govt. of India, M.G. Kavu, Athani P.O., Thrissur 680771, Kerala (India); Ratheesh, R., E-mail: ratheeshr@yahoo.com [Centre for Materials for Electronics Technology, Department of Information Technology, Ministry of Communication and Information Technology, Govt. of India, M.G. Kavu, Athani P.O., Thrissur 680771, Kerala (India)

    2009-10-15

    High dielectric and temperature-stable ceramic compositions have been prepared through solid-state ceramic route. The structure and microstructure of the ceramics have been studied using powder X-ray diffraction and scanning electron microscopic techniques. The dielectric properties of well-sintered ceramics are studied in the microwave frequency region using Hakki and Coleman post-resonator technique. The samples exhibited high dielectric constant (>77), relatively high quality factor (>1500) and near zero temperature coefficient of resonant frequency. Phase pure calcined ceramic materials are incorporated in the polytetrafluoroethylene matrix through a proprietary process comprising of sigma mixing, extrusion, calendering followed by hot pressing for the fabrication of planar circuit laminates. The effect of temperature coefficient of dielectric constant of the resultant polytetrafluoroethylene/ceramic composite materials is studied with respect to compositional variation of the filler materials.

  14. High-Temperature Properties of Ceramic Fibers and Insulations for Thermal Protection of Atmospheric Entry and Hypersonic Cruise Vehicles

    Science.gov (United States)

    Kourtides, Demetrius A.; Pitts, William C.; Araujo, Myrian; Zimmerman, R. S.

    1988-01-01

    Multilayer insulations which will operate in the 500C to 1000C temperature range are being considered for possible applications on aerospace vehicles subject to convective and radiative heating during atmospheric entry. The insulations described in this paper consist of ceramic fabrics, insulations, and metal foils quilted together using ceramic thread. As these types of insulations have highly anisotropic properties, the total heat transfer characteristics of these insulations must be determined. Data are presented on the thermal diffusivity and thermal conductivity of four types of multilayer insulations and are compared to the baseline Advanced Flexible Reusable Surface Insulation

  15. High tenacity regenerated chitosan fibers prepared by using the binary ionic liquid solvent (Gly·HCl)-[Bmim]Cl.

    Science.gov (United States)

    Ma, Bomou; Qin, Aiwen; Li, Xiang; He, Chunju

    2013-09-12

    A binary ionic liquid system was confirmed to be a promising solvent to dissolve chitosan, and the regenerated chitosan fibers were prepared by wet and dry-wet spinning technique respectively. The SEM results show that the chitosan fibers prepared by wet spinning technique present striated surface and round cross section, and the chitosan fibers prepared by dry-wet spinning technique present smooth surface and irregular cross section. The mechanical testing results show that the regenerated chitosan fibers present relatively high tenacity, especially, these prepared by dry-wet spinning process present excellent strength and initial modulus, i.e. 2.1cN/dtex and 83.5cN/dtex, which is stronger than that of most reported chitosan fibers. The FT-IR results show that the dissolution of chitosan in the binary ionic liquid system is due to the protonation of NH₂ groups in the chitosan chains. Furthermore, a possible reaction during the dissolution and regeneration process is proposed.

  16. Preparation methodology and possible treatments for improved ceramics for high voltage vacuum applications

    CERN Document Server

    Tan, J

    1998-01-01

    The flashover characteristics of an insulator bridged high voltage vacuum gap can play an important role in the overall performance of a high voltage device, for example in the extreme environments of high energy particle accelerators. The detailed preparation of the insulators is, at present, governed by the commercial production methods and by standard bulk cleaning processes, which for a particular application may be far from optimum. The influence of the mechanical preparation, thermal history and particular cleaning technique have been investigated for commercially available alumina samples, with measurement of surface characteristics by scanning electron microscopy and laser diffraction, measurement of the secondary electron emission curve and analysis of the high voltage performance with the possibility of applied fields up to 200kV/cm. The results of the different measurements are discussed in the overall context of the problems encountered in the full sized high voltage devices, and suggestions are m...

  17. Effect of preparation method on the anti-corrosive properties of nanocrystalline Zn-CoO ceramic pigments

    Energy Technology Data Exchange (ETDEWEB)

    Rasouli, S. [Department of Nanotechnology, Institute for Color Science and Technology (ICST), 55 Vafamanesh Ave., HosseinAbad Square, Pasdaran St., 1668814811 Tehran (Iran, Islamic Republic of); Danaee, I. [Abadan Faculty of Petroleum, Petroleum University of Technology (PUT), Abadan (Iran, Islamic Republic of)

    2011-05-15

    Zn-CoO green ceramic pigments were synthesized by two different methods; high energy ball milling and solution combustion, with two different fuels; citric acid and glycine. Products were characterized by X-ray diffraction and scanning-transmission electron microscopy (TEM). The anti-corrosive properties of the obtained pigments were investigated by electrochemical impedance spectroscopy (EIS) techniques. Results have shown that either by solid state reaction or combustion by citric acid, a calcination step was needed to obtain the desired phase whereas by glycine fuel, pure ZnO phase was obtained directly. TEM showed particles with mean particle size of about 70, 150, and 180 nm for glycine, citric acid, and solid state reaction samples, respectively. The corrosion performance of the coating in 3% w/v NaCl solution was evaluated by EIS and polarization measurements. According to the measurements of EIS and electrochemical polarization, the coatings with glycine-based pigment showed the highest corrosion resistance among the prepared coatings. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Novel texturing method for sputtered zinc oxide films prepared at high deposition rate from ceramic tube targets

    Directory of Open Access Journals (Sweden)

    Hüpkes J.

    2011-10-01

    Full Text Available Sputtered and wet-chemically texture etched zinc oxide (ZnO films on glass substrates are regularly applied as transparent front contact in silicon based thin film solar cells. In this study, chemical wet etching in diluted hydrofluoric acid (HF and subsequently in diluted hydrochloric acid (HCl on aluminum doped zinc oxide (ZnO:Al films deposited by magnetron sputtering from ceramic tube targets at high discharge power (~10 kW/m target length is investigated. Films with thickness of around 800 nm were etched in diluted HCl acid and HF acid to achieve rough surface textures. It is found that the etching of the films in both etchants leads to different surface textures. A two steps etching process, which is especially favorable for films prepared at high deposition rate, was systematically studied. By etching first in diluted hydrofluoric acid (HF and subsequently in diluted hydrochloric acid (HCl these films are furnished with a surface texture which is characterized by craters with typical diameter of around 500 − 1000 nm. The resulting surface structure is comparable to etched films sputtered at low deposition rate, which had been demonstrated to be able to achieve high efficiencies in silicon thin film solar cells.

  19. Processing and dielectric properties of ZnTiO3 ceramics prepared from nanopowder synthesised by sol-gel technique

    Directory of Open Access Journals (Sweden)

    Sophie d’Astorg

    2012-06-01

    Full Text Available ZnTiO3 nanopowders were obtained by sol-gel method. The nanopowders were characterised by means of TGA/DTA analysis, X-ray diffraction, TMA analysis and SEM characterisation. The results show that the crystalline structure of the sol-gel powders was obtained at 600 °C, with crystallite sizes of 10 nm. SEM shows that most of the prepared ZnTiO3 nanopowders are agglomerated. Since agglomeration plays an important role in the sintering of the ZnTiO3 ceramics, different deagglomeration techniques (ultrasonication, pulverisation and attrition milling were investigated. Dense ZnTiO3 structure was obtained from the attrition milled powder at 1050 °C and its dielectric characteristics were also investigated (εr =25, tε= -26 ppm/°C and tgδ < 10-3 at 1 MHz. The low sintering temperature and the good dielectric properties show promise for the manufacture of multilayered capacitors with internal copper electrodes.

  20. Effect of SiO2 on the Preparation and Properties of Pure Carbon Reaction Bonded Silicon Carbide Ceramics

    Institute of Scientific and Technical Information of China (English)

    WU Qi-de; GUO Bing-jian; YAN Yong-gao; ZHAO Xiu-jian; HONG Xiao-lin

    2004-01-01

    Effect of SiO2 content and sintering process on the composition and properties of Pure CarbonReaction Bonded Silicon Carbide (PCRBSC) ceramics prepared with C - SiO2 green body by infiltrating siliconwas presented. The infiltrating mechanism of C - SiO2 preform was also explored. The experimental results indicatethat the shaping pressure increases with the addition of SiO2 to the preform, and the pore size of the body turnedfiner and distributed in a narrower range, which is beneficial to decreasing the residual silicon content in the sin-tered materials and to avoiding shock off, thus increasing the conversion rate of SiC. SiO2 was deoxidized by car-bon at a high temperature and the gaseous SiO and CO produced are the main reason to the crack of the body atan elevated temperature. If the green body is deposited at 1800℃ in vacuum before infiltration crack will not beproduced in the preform and fully dense RBSC can be obtained. The ultimate material has the following properties:a density of3.05-3.12g/cm3 ,a strength of 580±32MPa and a hardness of (HRA)91-92.3.