WorldWideScience

Sample records for aluminates

  1. Magnesium Aluminate Spinel

    Institute of Scientific and Technical Information of China (English)

    Yu Lingyan

    2012-01-01

    1 ScopeThis standard specifies the terms, definitions,classifications,technical requirements,test methods,inspection rules, packing, marking, transportation,storage,and quality certificate of magnesium aluminate spinel.

  2. Reactive Air Aluminization

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jung-Pyung; Chou, Y. S.; Stevenson, Jeffry W.

    2011-10-28

    Ferritic stainless steels and other alloys are of great interest to SOFC developers for applications such as interconnects, cell frames, and balance of plant components. While these alloys offer significant advantages (e.g., low material and manufacturing cost, high thermal conductivity, and high temperature oxidation resistance), there are challenges which can hinder their utilization in SOFC systems; these challenges include Cr volatility and reactivity with glass seals. To overcome these challenges, protective coatings and surface treatments for the alloys are under development. In particular, aluminization of alloy surfaces offers the potential for mitigating both evaporation of Cr from the alloy surface and reaction of alloy constituents with glass seals. Commercial aluminization processes are available to SOFC developers, but they tend to be costly due to their use of exotic raw materials and/or processing conditions. As an alternative, PNNL has developed Reactive Air Aluminization (RAA), which offers a low-cost, simpler alternative to conventional aluminization methods.

  3. Calcium aluminate in alumina

    Science.gov (United States)

    Altay, Arzu

    The properties of ceramic materials are determined not only by the composition and structure of the phases present, but also by the distribution of impurities, intergranular films and second phases. The phase distribution and microstructure both depend on the fabrication techniques, the raw materials used, the phase-equilibrium relations, grain growth and sintering processes. In this dissertation research, various approaches have been employed to understand fundamental phenomena such as grain growth, impurity segregation, second-phase formation and crystallization. The materials system chosen was alumina intentionally doped with calcium. Atomic-scale structural analyses of grain boundaries in alumina were carried on the processed samples. It was found that above certain calcium concentrations, CA6 precipitated as a second phase at all sintering temperatures. The results also showed that abnormal grain growth can occur after precipitation and it is not only related to the calcium level, but it is also temperature dependent. In order to understand the formation mechanism of CA6 precipitates in calcium doped alumina samples, several studies have been carried out using either bulk materials or thin films The crystallization of CA2 and CA6 powders has been studied. Chemical processing techniques were used to synthesize the powders. It was observed that CA2 powders crystallized directly, however CA6 powders crystallized through gamma-Al 2O3 solid solution. The results of energy-loss near-edge spectrometry confirmed that gamma-Al2O3 can dissolve calcium. Calcium aluminate/alumina reaction couples have also been investigated. All reaction couples were heat treated following deposition. It was found that gamma-Al2O3 was formed at the interface as a result of the interfacial reaction between the film and the substrate. gamma-Al 2O3 at the interface was stable at much higher temperatures compared to the bulk gamma-Al2O3 formed prior to the CA6 crystallization. In order to

  4. Eu2+ luminescence in strontium aluminates

    NARCIS (Netherlands)

    Dutczak, D.; Juestel, T.; Ronda, C.; Meijerink, A.

    2015-01-01

    The luminescence properties of Eu2+ doped strontium aluminates are reported and reviewed for a variety of aluminates, viz. SrAl12O19, SrAl4O7, Sr4Al14O25, SrAl2O4 and Sr3Al2O6. The aim of the research is to investigate the role of local coordination and covalency of the aluminate host lattice, relat

  5. Spectra of sodium aluminate solutions

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The UV spectra of sodium aluminate solutions were obtained in the sodium oxide concentration range from 59 to 409 g/L and the caustic ratio range from 1.5 to 4.0 to reveal the structure characteristics of them. It is found that a new peak appears at about 370 nm besides peaks at about 220 and 266 nm in all solutions. The new peak is strongly favored by high hydroxide concentration and high caustic ratio. And it only appears when the solutions are prepared by dissolving sodium hydroxide and aluminum hydroxide.In addition, the IR and Raman spectra of sodium aluminate solutions with high alkali concentration and high caustic ratio were measured, and the UV spectra of aqueous solutions of Al(H2O)63+ and AlF63- were measured as well. According to the crystal field theory in coordination chemistry as well as the above spectra characteristics, this new peak at about 370 nm is determined as the evidence of a new species of aluminate ion with a coordination number of 6.

  6. Aluminized alloy boosts turbine blade life

    Science.gov (United States)

    Gedwill, M. A.; Grisaffe, S. J.

    1974-01-01

    Description of an aluminized alloy coating technique that involves first the application of a ductile, oxidation-resistant overlay, such as NiCrAl, which is then partially aluminized. The duplex protective system has performance advantages over conventional aluminide coatings in that it provides higher-temperature hot corrosion resistance over a longer service life.

  7. Decomposition of supersaturated sodium aluminate solution

    Institute of Scientific and Technical Information of China (English)

    陈启元; 李洁; 尹周澜; 张平民

    2003-01-01

    The decomposition of supersaturated sodium aluminate solution in the process of alumina production was reviewed. Some fundamental problems, such as the structure of supersaturated sodium aluminate solution and the growth unit of gibbsite precipitation as well as the decomposition mechanism of sodium aluminate solution, were investigated by model analytic technique and theoretical calculation. It is found that the main Al-contained species is S4 symmetric [Al(OH)4(H2O)4]-. [Na+(H2O)4*Al(OH)-4] is found to form in intermediate concentrated solution while [Na+(H2O)2*Al(OH)-4] in highly concentrated solution. Meanwhile, it is proved that [(H2O)2Al(OH)4]- is the basic growth unit of gibbsite and [Al6(OH)18(H2O)6] is a favorable growth unit. Based on above results and ab initio quantum mechanical calculation and transition state theory, a reaction pathway of the decomposition of supersaturated sodium aluminate solution was put forward, in which the transformation of pentacoordinate aluminates ion to hexacoordinate basic growth unit as well as the formation of circled growth unit [Al6(OH)22(H2O)2]4- are the controlling steps.

  8. Structure of liquid tricalcium aluminate

    Science.gov (United States)

    Drewitt, James W. E.; Barnes, Adrian C.; Jahn, Sandro; Kohn, Simon C.; Walter, Michael J.; Novikov, Alexey N.; Neuville, Daniel R.; Fischer, Henry E.; Hennet, Louis

    2017-02-01

    The atomic-scale structure of aerodynamically levitated and laser-heated liquid tricalcium aluminate (Ca3Al2O6 ) was measured at 2073(30) K by using the method of neutron diffraction with Ca isotope substitution (NDIS). The results enable the detailed resolution of the local coordination environment around calcium and aluminum atoms, including the direct determination of the liquid partial structure factor, SCaCa(Q ) , and partial pair distribution function, gCaCa(r ) . Molecular dynamics (MD) simulation and reverse Monte Carlo (RMC) refinement methods were employed to obtain a detailed atomistic model of the liquid structure. The composition Ca3Al2O6 lies at the CaO-rich limit of the CaO:Al2O3 glass-forming system. Our results show that, although significantly depolymerized, liquid Ca3Al2O6 is largely composed of AlO4 tetrahedra forming an infinite network with a slightly higher fraction of bridging oxygen atoms than expected for the composition. Calcium-centered polyhedra exhibit a wide distribution of four- to sevenfold coordinated sites, with higher coordinated calcium preferentially bonding to bridging oxygens. Analysis of the MD configuration reveals the presence of ˜10 % unconnected AlO4 monomers and Al2O7 dimers in the liquid. As the CaO concentration increases, the number of these isolated units increases, such that the upper value for the glass-forming composition of CaO:Al2O3 liquids could be described in terms of a percolation threshold at which the glass can no longer support the formation of an infinitely connected AlO4 network.

  9. Aluminizing Low Carbon Steel at Lower Temperatures

    Institute of Scientific and Technical Information of China (English)

    Xiao Si; Bining Lu; Zhenbo Wang

    2009-01-01

    This study reports the significantly enhanced aluminizing behaviors of a low carbon steel at temperatures far below the austenitizing temperature, with a nanostructured surface layer produced by surface mechanical attrition treatment (SMAT). A much thicker iron aluminide compound layer with a much enhanced growth kinetics of η-Fe2Al5 in the SMAT sample has been observed relative to the coarse-grained steel sample. Compared to the coarse-grained sample, a weakened texture is formed in the aluminide layer in the SMAT sample. The aluminizing kinetics is analyzed in terms of promoted diffusivity and nucleation frequency in the nanostructured surface layer.

  10. A low temperature aluminizing treatment of hot work tool steel

    Energy Technology Data Exchange (ETDEWEB)

    Matijevic, B., E-mail: bozidar.matijevic@fsb.hr [University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Zagreb (Croatia)

    2010-07-01

    Conventional aluminizing processes by pack cementation are typically carried out at elevated temperatures. A low temperature powder aluminizing technology was applied to hot tool steel H13. The aluminizing treating temperature was from 550 to 620°C. Effects of temperature and time on the microstructure and phase evolution were investigated. Also, the intermetallic layer thickness was measured in the aluminized layer of a steel substrate. The cross-sectional microstructures, the aluminized layer thickness and the oxide layer were studied. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), glow discharge optical spectroscopy (GDOS) were applied to observe the cross-sections and the distribution of elements. (author)

  11. A Controlled New Process of Pack Aluminization

    Institute of Scientific and Technical Information of China (English)

    HUANG Zhi-rong; MA Liu-bao; LI Pei-ning; XU Hong

    2004-01-01

    Aluminum diffusion coatings are often prepared by a pack aluminization technique, which is a specific variety of chemical vapor deposition (CVD) method. The coating process takes place in a bed containing a mixed powder that serves as a source of the coatings forming element. The phase composition of the diffusion layer obtained depends on the activity of the Al during the pack aluminization processing. In this work, the proportion of Al to special additive powder in the pack and the treatment temperature are adjusted to achieve the desired surface composition of aluminized layer. The aluminized 20 plain carbon steel and HK40 austenitic steel were investigated by optical microscopy (OM) , X-ray diffraction (XRD)and microsclerometer. The results showed that the desired FeAl, Fe3Al and NiAl were respectively formed on the 20 plain carbon steel and HK40 austenitic steel, and the aluminides FeAl3, Fe2Al5 or Ni2Al3, NiAl3 could be inhibited.

  12. A Controlled New Process of Pack Aluminization

    Institute of Scientific and Technical Information of China (English)

    HUANGZhi-rong; MALiu-bao; LIPei-ning; XUHong

    2004-01-01

    Aluminum diffusion coatings are often prepared by a pack aluminization technique, which is a specific variety of chemical vapor deposition (CVD) method. The coating process takes place in a bed containing a mixed powder that serves as a source of the coatings forming element. The phase composition of the diffusion layer obtained depends on the activity of the Al during the pack aluminization processing. In this work, the proportion of Al to special additive powder in the pack and the treatment temperature are adjusted to achieve the desired surface composition of aluminized layer. The aluminized 20 plain carbon steel and HK40 austenitic steel were investigated by optical microscopy (OM) , X-ray diffraction (XRD) and microsclerometer. The results showed that the desired FeAl, Fe3Al and NiAl were respectively formed on the 20 plain carbon steel and HK40 austenitic steel, and the aluminides FeAl3, Fe2Al5 or Ni2Al3, NiAl3 could be inhibited.

  13. Eu(2+) luminescence in strontium aluminates.

    Science.gov (United States)

    Dutczak, D; Jüstel, T; Ronda, C; Meijerink, A

    2015-06-21

    The luminescence properties of Eu(2+) doped strontium aluminates are reported and reviewed for a variety of aluminates, viz. SrAl12O19, SrAl4O7, Sr4Al14O25, SrAl2O4 and Sr3Al2O6. The aim of the research is to investigate the role of local coordination and covalency of the aluminate host lattice, related to the Sr/Al ratio, on the optical properties of the Eu(2+) ion. The UV and VUV excited luminescence spectra as well as luminescence decay curves were recorded to characterize the luminescence properties of the investigated aluminates. The emission of Eu(2+) ions varies over a wide spectral range, from ultraviolet (UV) to red, for the series of aluminates. The variation in emission color can be related to the crystal-field splitting of the 5d levels and the covalent interaction with the surrounding oxygen anions. In the least covalent material, viz. SrAl12O19:Eu(2+), narrow line emission due to the (6)P7/2-(8)S7/2 transition occurs at 4 K, indicating that the 4f(6)5d excited state is situated above the (6)P7/2(4f(7)) excited state around 360 nm. The most alkaline material, viz. Sr3Al2O6:Eu(2+) is the most covalent host and exhibits several d-f emission bands in the yellow to red spectral range due to the Eu(2+) ions located on different crystallographic Sr(2+) sites. The Eu(2+) emission spectra in the other aluminates confirm the trend that with increasing Sr/Al ratio the Eu(2+) emission shifts to longer wavelengths. Interesting differences are observed for the Eu(2+) from different crystallographic sites which cannot always be related with apparent differences in the first oxygen coordination sphere. The discussion gives insight into how in a similar class of materials, strontium aluminates, the emission color of Eu(2+) can be tuned over a wide spectral region.

  14. The aluminizing in powder technology of AISI 304 steel

    Science.gov (United States)

    Băitanu, D. B.; Găluşcă, D. G.; Achiţei, D. C.; Minciună, M. G.; Bakri Abdullah, Mohd Mustafa Al

    2016-06-01

    The paper presents a study about the aluminizing treatments applied to AISI 304 stainless steel, with the purpose to improve the corrosion resistance. The aluminizing is realized in a powder medium, composed by aluminium powder (with 99.95% purity), aluminium oxide Al2O3 and ammonium chloride NH4Cl. The structural characterization was made by scanning electronic microscopy to highlight the structure of layer after aluminizing, at different magnitudes.

  15. Development of electrodialysis process for aluminous solutions

    Institute of Scientific and Technical Information of China (English)

    Todorov; S.; A.; Lainer; Y.; A.; Medvedev; A.; S.

    2005-01-01

    One of the mostly perspective method of scrapping industrial drains is electrodialysis, which is used by us for processing of low concentrated aluminous solutions (g/L: Na2Ototal - 23.2, Na2 O ic - 3.9, Al2O3 -2.7, SO3-5.8), arises by receipting of aluminum hydroxide, which goes to synthesis of aluminum hydroxochloride-high effective new generation coagulant.……

  16. Development of electrodialysis process for aluminous solutions

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ One of the mostly perspective method of scrapping industrial drains is electrodialysis, which is used by us for processing of low concentrated aluminous solutions (g/L: Na2Ototal - 23.2, Na2 O ic - 3.9, Al2O3 -2.7, SO3-5.8), arises by receipting of aluminum hydroxide, which goes to synthesis of aluminum hydroxochloride-high effective new generation coagulant.

  17. A LOW TEMPERATURE ALUMINIZING TREATMENT OF HOT WORK TOOL STEEL

    OpenAIRE

    Matijević, Božidar

    2013-01-01

    Conventional aluminizing processes by pack cementation are typically carried out at elevated temperatures. A low temperature powder aluminizing technology was applied to the X40CrMoV5-1 hot tool steel. The aluminizing temperature was from 550 °C to 620 °C. Effects of temperature and time on the microstructure and phase evolution were investigated. Also, the intermetallic layer thickness was measured in the aluminized layer of a steel substrate. The cross-sectional microstructures, the alumini...

  18. Aluminizing Coating and Aluminizing-Y2O3 Coating Deposited by Pulsed Spark

    Institute of Scientific and Technical Information of China (English)

    何业东; 黄祖芬; 王德仁; 齐惠滨; 高 高唯

    2001-01-01

    Aluminizing coating and aluminizing-dispersed Y2O3 composite coating were prepared on 20 steel specimens by pulsed spark technique, which exhibited a micro-crystallized structure with grain size in the range of several ten to several hundred nanometers. It is shown that, after oxidation at 600 ℃ in air for 100 h, these two kinds of coatings have excellent resistance to high temperature oxidation and scale spallation, and the aluminizing-dispersed Y2O3 composite coating has even better property than the aluminizing coating. AFM, SEM, EDS and XRD were applied to analyze the surface morphology, composition and phases structure of these coatings and the oxide scale formed in oxidation. The mechanism for these coatings that how to enhance the oxidation resistance and scale spallation resistance was discussed by considering the factors, such as Al concentration on the selective oxidation of Fe-Al alloy, the effect of micro-crystallization, reactive element effect (REE) caused by dispersed Y2O3, etc.

  19. Aluminate solution decomposition new technology development

    Energy Technology Data Exchange (ETDEWEB)

    Abramov, V.Ya.; Stelmakova, G.D. [Scientific Technical Centre Reactor, Moscow (Russian Federation)

    1996-10-01

    Scientific Technical Centre Reactor together with SC Aluminy carried out the number of investigations in the field of aluminum solution decomposition new technology development. It was based on large prime ratio on one hand, and liquid-solid countercurrent flow movement on the other hand. Practically the suggested technology was considered to be the result of unstationary, mass-transfer theory, which had been checked up at 100 m3 plot scale plant. Hydrate washing was accomplished at the first stage under the condition of countercurrent flow and less than 1 m3 water discharge. The experiments of 3.2--3.3 caustic module aluminate solution decomposition were carried out at the second stage. While full reactor 20 hour regime operation the caustic module increased till 4.1. Usually it accounts 3.7 under the analogous conditions and time.

  20. Military Specification, Mirror, Front Surfaced Aluminized: For Optical Elements

    Science.gov (United States)

    2007-11-02

    uniform magnesium fluoride or silicon monoxide or as otherwise specified on the applicable drawing. Tha film shall be free from holes, foreign...Mt] «. OATI Of IIMMIMION (YYMHDDt MIL-M-13508C AMENDMENT 1 27 May 1983 MILITARY SPECIFICATION MIRROR, FRONT SURFACED ALUMINIZED : FOR OPTICAL... ALUMINIZED : FOR OPTICAL ELEMENTS This notice should be filed in front of MIL-M-13508C, dated 19 March 1973 MIL-M-13508C dated 19 March 1973 with

  1. Optical properties of hollow calcium aluminate glass waveguides.

    Science.gov (United States)

    Abel, T; Harrington, J A; Foy, P R

    1994-06-20

    Calcium aluminate glass has a refractive index less than 1 at 10.6 µ, and therefore it is a good candidate for a hollow fiber for the transmission of CO(2) laser energy. We have drawn hollow calcium aluminate glass fibers with inner diameters ranging from 380 to 500 µ. The loss for our 500-µm inner-diameter hollow glass fibers measured at 10.6 µm is 8.6 dB/m.

  2. Structural, optical and photocatalytic activity of cerium doped zinc aluminate

    Science.gov (United States)

    Sumathi, Shanmugam; Kavipriya, A.

    2017-03-01

    Zinc aluminate and cerium-doped zinc aluminate nanoparticles are synthesised by co-precipitation method. Ammonium hydroxide is used as a precipitating agent. The synthesised compounds are characterised by powder X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FT-IR), Ultraviolet diffuse reflectance spectroscopy (UV-DRS), Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and Surface area measurements. The photocatalytic activity of zinc aluminate and cerium doped zinc aluminate nanoparticles are studied under the UV light and visible light taking methylene blue as a model pollutant. The amount of catalyst, concentration of dye solution and time are optimised under UV-light. Degradation of methylene blue under the UV-light is found to be 99% in 20 min with 10 mg of cerium doped catalyst. Compared to visible light degradation, the degradation of dye under UV-light is higher. Cerium doping in zinc aluminate (ZnAl2O4:Ce3+) increased the photocatalytic activity of zinc aluminate.

  3. Etude vibrationnelle d'aluminates et de gallates de terres rares—IV. Aluminates de samarium et d'europium

    Science.gov (United States)

    Saine, M. C.; Husson, E.

    In order to complete our studies on rare earth aluminates and gallates of perovskite structure, we have calculated a force field for orthorhombic SmAlO 3 and EuAlO 3. This force field is anisotropic with regard to the ab plane of the structure and is slightly weaker than the force field of the rhombohedral aluminates LaAlO 3 or NdAlO 3.

  4. Synthesis of magnesium aluminate spinel by periclase and alumina chlorination

    Energy Technology Data Exchange (ETDEWEB)

    Orosco, Pablo, E-mail: porosco@unsl.edu.ar [Instituto de Investigaciones en Tecnología Química (INTEQUI), Chacabuco y Pedernera, San Luis (Argentina); Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis Chacabuco y Pedernera, San Luis (Argentina); Barbosa, Lucía [Instituto de Investigaciones en Tecnología Química (INTEQUI), Chacabuco y Pedernera, San Luis (Argentina); Instituto de Ciencias Básicas (ICB), Universidad Nacional de Cuyo Parque General San Martín, Mendoza (Argentina); Ruiz, María del Carmen [Instituto de Investigaciones en Tecnología Química (INTEQUI), Chacabuco y Pedernera, San Luis (Argentina); Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis Chacabuco y Pedernera, San Luis (Argentina)

    2014-11-15

    Highlights: • Use of chlorination for the synthesis of magnesium aluminate spinel. • The reagents used were alumina, periclase and chlorine. • Isothermal and non-isothermal assays were performed in air and Cl{sub 2}–N{sub 2} flows. • The chlorination produced magnesium aluminate spinel at 700 °C. • Selectivity of the chlorination reaction to obtain spinel is very high. - Abstract: A pyrometallurgical route for the synthesis of magnesium aluminate spinel by thermal treatment of a mechanical mixture containing 29 wt% MgO (periclase) and 71 wt% Al{sub 2}O{sub 3} (alumina) in chlorine atmosphere was developed and the results were compared with those obtained by calcining the same mixture of oxides in air atmosphere. Isothermal and non-isothermal assays were performed in an experimental piece of equipment adapted to work in corrosive atmospheres. Both reagents and products were analyzed by differential thermal analysis (DTA), X-ray diffraction (XRD) and X-ray fluorescence (XRF). Thermal treatment in Cl{sub 2} atmosphere of the MgO–Al{sub 2}O{sub 3} mixture produces magnesium aluminate spinel at 700 °C, while in air, magnesium spinel is generated at 930 °C. The synthesis reaction of magnesium aluminate spinel was complete at 800 °C.

  5. Behavior of calcium silicate hydrate in aluminate solution

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-bin; ZHAO Zhuo; LIU Gui-hua; ZHOU Qiu-sheng; PENG Zhi-hong

    2005-01-01

    Using calcium hydroxide and sodium silicate as starting materials, two kinds of calcium silicate hydrates, CaO · SiO2 · H2O and 2CaO · SiO2 · 1.17H2O, were hydro-thermally synthesized at 120 ℃. The reaction rule of calcium silicate hydrate in aluminate solution was investigated. The result shows that CaO · SiO2 · H2O is more stable than 2CaO · SiO2 · 1.17H2 O in aluminate solution and its stability increases with the increase of reaction temperature but decreases with the increase of caustic concentration. The reaction between calcium silicate hydrate and aluminate solution is mainly through two routes. In the first case, Al replaces partial Si in calcium silicate hydrate, meanwhile 3CaO · Al2 O3 · xSiO2 · (6-2x) H2 O (hydro-garnet) is formed and some SiO2 enters the solution. In the second case, calcium silicate hydrate can react directly with aluminate solution, forming hydro-garnet and Na2O · Al2O3 · 2SiO2 · nH2O (DSP). The desilication reaction of aluminate solution containing silicate could contribute partially to forming DSP.

  6. Limestone reaction in calcium aluminate cement–calcium sulfate systems

    Energy Technology Data Exchange (ETDEWEB)

    Bizzozero, Julien, E-mail: julien.bizzozero@gmail.com; Scrivener, Karen L.

    2015-10-15

    This paper reports a study of ternary blends composed of calcium aluminate cement, calcium sulfate hemihydrate and limestone. Compressive strength tests and hydration kinetics were studied as a function of limestone and calcium sulfate content. The phase evolution and the total porosity were followed and compared to thermodynamic simulation to understand the reactions involved and the effect of limestone on these binders. The reaction of limestone leads to the formation of hemicarboaluminate and monocarboaluminate. Increasing the ratio between sulfate and aluminate decreases the extent of limestone reaction.

  7. Thermoluminescence dosimetry of rare earth doped calcium aluminate phosphors

    Indian Academy of Sciences (India)

    K Madhukumar; K Rajendra Babu; K C Ajith Prasad; J James; T S Elias; V Padmanabhan; C M K Nair

    2006-04-01

    The thermoluminescence (TL) properties of calcium aluminate (CaAl2O4) doped with different rare earth ions have been studied and their suitability for radiation dosimetry applications is discussed. It is observed that monocalcium aluminate doped with cerium is a good dosimeter having linear response up to about 4 kGy of radiation doses. Dopant concentration of 0.25 mol% cerium gives maximum TL emission. The well-defined single peak observed at 295°C can be advantageously used for high temperature dosimetry applications.

  8. IMPACT OF INCREASED ALUMINATE CONCENTRATIONS ON PROPERTIES OF SALTSTONE MIXES

    Energy Technology Data Exchange (ETDEWEB)

    Harbour, J; Tommy Edwards, T; Erich Hansen, E; Vickie Williams, V

    2007-10-12

    One of the goals of the Saltstone variability study is to identify the operational and compositional variables that control or influence the important processing and performance properties of Saltstone mixes. The protocols developed in this variability study are ideally suited as a tool to assess the impact of proposed changes to the processing flow sheet for Liquid Waste Operations (LWO). One such proposal that is currently under consideration is to introduce a leaching step in the treatment of the High Level Waste (HLW) sludge to remove aluminum prior to vitrification at the Defense Waste Processing Facility (DWPF). This leachate would significantly increase the soluble aluminate concentrations as well as the free hydroxide ion concentration in the salt feed that will be processed at the Saltstone Processing Facility (SPF). Consequently, an initial study of the impact of increased aluminate concentration on the Saltstone grout properties was performed. The projected compositions and ranges of the aluminate rich salt stream (which includes the blending strategy) are not yet available and consequently, in this initial report, two separate salt stream compositions were investigated. The first stream starts with the previously projected baseline composition of the salt solution that will be fed to SPF from the Salt Waste Processing Facility (SWPF). The second stream is the solution that results from washing of the current Tank 51 sludge and subsequent transfer of the salt solution to Tank 11. The SWPF simulant has higher nitrate and lower free hydroxide than the Tank 11 simulant. In both of these cases, the aluminate was varied up to a maximum of 0.40 to 0.45M aluminate in order to evaluate the impact of increasing aluminate ion concentration on the grout properties. In general, the fresh grout properties of mixes made with SWPF and Tank 11 simulants were relatively insensitive to an increase in aluminate concentration in the salt solutions. However, the overall

  9. Effect of Microwave Processing on Aluminate Cement Clinkering

    Institute of Scientific and Technical Information of China (English)

    DONG Jianmiao; LONG Shizong

    2005-01-01

    When raw materials were preheated to 1000-1300 ℃ by electricity and microwave was inputted for 1 min 5 s-4 mins, then alunminate clinkers were obtained. The f-CaO contents,XRD patterns and lithofacies analysis show that the microwave processing accelerates the clinkering reaction,and Fe2O3 is contributed to the aluminate cement clinkering. The appearance of liquid phase in process of microwave heating increases the microwave absorbability of materials greatly.

  10. Inhibited Aluminization of an ODS FeCr Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Vande Put Ep Rouaix, Aurelie [ORNL; Pint, Bruce A [ORNL

    2012-01-01

    Aluminide coatings are of interest for fusion energy applications both for compatibility with liquid Pb-Li and to form an alumina layer that acts as a tritium permeation barrier. Oxide dispersion strengthened (ODS) ferritic steels are a structural material candidate for commercial reactor concepts expected to operate above 600 C. Aluminizing was conducted in a laboratory scale chemical vapor deposition reactor using accepted conditions for coating Fe- and Ni-base alloys. However, the measured mass gains on the current batch of ODS Fe-14Cr were extremely low compared to other conventional and ODS alloys. After aluminizing at two different Al activities at 900 C and at 1100 C, characterization showed that the ODS Fe-14Cr specimens formed a dense, primarily AlN layer that prevented Al uptake. This alloy batch contained a higher (> 5000 ppma) N content than the other alloys coated and this is the most likely reason for the inhibited aluminization. Other factors such as the high O content, small ({approx} 140 nm) grain size and Y-Ti oxide nano-clusters in ODS Fe-14Cr also could have contributed to the observed behavior. Examples of typical aluminide coatings formed on conventional and ODS Fe- and Ni-base alloys are shown for comparison.

  11. Morphological and microstructural studies on aluminizing coating of carbon steel

    Energy Technology Data Exchange (ETDEWEB)

    Samsu, Zaifol; Othman, Norinsan Kamil; Daud, Abd Razak; Hussein, Hishammuddin [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia)

    2013-11-27

    Hot dip aluminizing is one of the most effective methods of surface protection for steels and is gradually gaining popularity. The morphology and microstructure of an inter-metallic layer form on the surface of low carbon steel by hot dip aluminization treatment had been studied in detail. This effect has been investigated using optical and scanning electron microscopy, and X-ray diffraction. The result shows that the reaction between the steel and the molten aluminium leads to the formation of Fe–Al inter-metallic compounds on the steel surface. X-ray diffraction and electron microscopic studies showed that a two layer coating was formed consisting of an external Al layer and a (Fe{sub 2}Al{sub 5}) inter metallic on top of the substrate after hot dip aluminizing process. The inter-metallic layer is ‘thick’ and exhibits a finger-like growth into the steel. Microhardness testing shown that the intermetallic layer has high hardness followed by steel substrate and the lowest hardness was Al layer.

  12. Effect of aluminizing treatment on the oxidation properties of 12Cr heat resisting steel

    Science.gov (United States)

    Kim, Jae-Hwan; Wang, Jei-Pil; Kang, Chang-Yong

    2011-12-01

    In order to investigate the effect of aluminization on the oxidation properties of 12Cr martensitic heat resisting steel, a specimen was prepared by forging after centrifugal casting. After aluminizing treatment under various conditions, scanning electron microscopy observation, and hardness, line profile and x-ray diffraction analysis of the alloy layer were performed. The results confirmed that the thickness of the layer of Al13Fe4, with a Vickers hardness of over 880, increased with increasing aluminizing temperature and time. Moreover, it was concluded from the results of the oxidation experiment that the oxidation properties of the aluminized specimen were improved by up to approximately 30 %.

  13. Crystal structure control of aluminized clay minerals on the mobility of caesium in contaminated soil environments

    Science.gov (United States)

    Dzene, Liva; Ferrage, Eric; Viennet, Jean-Christophe; Tertre, Emmanuel; Hubert, Fabien

    2017-01-01

    Radioactive caesium pollution resulting from Fukushima Dai-ichi and Chernobyl nuclear plant accidents involves strong interactions between Cs+ and clays, especially vermiculite-type minerals. In acidic soil environments, such as in Fukushima area, vermiculite is subjected to weathering processes, resulting in aluminization. The crystal structure of aluminized clays and its implications for Cs+ mobility in soils remain poorly understood due to the mixture of these minerals with other clays and organic matter. We performed acidic weathering of a vermiculite to mimic the aluminization process in soils. Combination of structure analysis and Cs+ extractability measurements show that the increase of aluminization is accompanied by an increase in Cs+ mobility. Crystal structure model for aluminized vermiculite is based on the interstratification of unaltered vermiculite layers and aluminized layers within the same particle. Cs+ in vermiculite layers is poorly mobile, while the extractability of Cs+ is greatly enhanced in aluminized layers. The overall reactivity of the weathered clay (cation exchange capacity, Cs+ mobility) is then governed by the relative abundance of the two types of layers. The proposed layer model for aluminized vermiculite with two coexisting populations of caesium is of prime importance for predicting the fate of caesium in contaminated soil environments. PMID:28233805

  14. Effect of rare earth (RE) on diffusion of aluminum atoms in aluminizing

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; YE Xiao-feng; PANG Bi-jun; ZHOU Si-kai

    2006-01-01

    The RE-aluminized coating and pure aluminized coating on 20 carbons steel were prepared by hot dip aluminizing method at 740 ℃. After diffusion treatment at 850 ℃ for 4 h, the distribution of aluminum and lanthanum elements in the coating was analyzed with energy disperse spectroscopy(EDS) and electron probe microanalyses(EPMA), and the lattice parameter of α-Fe in the matrix of the coating was measured precisely by X-ray diffractometer(XRD). The results show that RE permeates into the aluminized coating, leads to lattice disturbance and increases the depth of the aluminized coating. On the basis of the results, the expression of the diffusion coefficient of Al atoms is derived from the diffusion flow, and the effect of the high vacancy concentration and high concentration gradient of vacancies on the diffusion of Al atoms was analyzed by establishing the kinetics model of the vacancy mechanism of diffusion. The results show that the high vacancy concentration and high concentration gradient of vacancies in the RE-aluminized processes are the main reason why the diffusion coefficient of Al atoms in RE-aluminizing is bigger than that in pure aluminizing.

  15. Crystal structure control of aluminized clay minerals on the mobility of caesium in contaminated soil environments

    Science.gov (United States)

    Dzene, Liva; Ferrage, Eric; Viennet, Jean-Christophe; Tertre, Emmanuel; Hubert, Fabien

    2017-02-01

    Radioactive caesium pollution resulting from Fukushima Dai-ichi and Chernobyl nuclear plant accidents involves strong interactions between Cs+ and clays, especially vermiculite-type minerals. In acidic soil environments, such as in Fukushima area, vermiculite is subjected to weathering processes, resulting in aluminization. The crystal structure of aluminized clays and its implications for Cs+ mobility in soils remain poorly understood due to the mixture of these minerals with other clays and organic matter. We performed acidic weathering of a vermiculite to mimic the aluminization process in soils. Combination of structure analysis and Cs+ extractability measurements show that the increase of aluminization is accompanied by an increase in Cs+ mobility. Crystal structure model for aluminized vermiculite is based on the interstratification of unaltered vermiculite layers and aluminized layers within the same particle. Cs+ in vermiculite layers is poorly mobile, while the extractability of Cs+ is greatly enhanced in aluminized layers. The overall reactivity of the weathered clay (cation exchange capacity, Cs+ mobility) is then governed by the relative abundance of the two types of layers. The proposed layer model for aluminized vermiculite with two coexisting populations of caesium is of prime importance for predicting the fate of caesium in contaminated soil environments.

  16. Thermal Properties of Double-Aluminized Kapton at Low Temperatures

    Science.gov (United States)

    Tuttle, J.; DiPirro, M.; Canavan, E.; Hait, T.

    2008-03-01

    Double-aluminized kapton (DAK) is commonly used in multi-layer insulation blankets in cryogenic systems. NASA plans to use individual DAK sheets in lightweight deployable shields for satellites carrying instruments. A set of these shields will reflect away thermal radiation from the sun, the earth, and the instrument's warm side and allow the instrument's cold side to radiate its own heat to deep space. In order to optimally design such a shield system, it is important to understand the thermal characteristics of DAK down to low temperatures. We describe experiments which measured the thermal conductivity and electrical resistivity down to 4 Kelvin and the emissivity down to 10 Kelvin.

  17. Detonation of the aluminized explosives with sodium azide

    Energy Technology Data Exchange (ETDEWEB)

    Maranda, A.; Nowaczewski, J.; Trzcinski, W. [Military University of Technology Kaliskiego, Warsaw (Poland)

    1996-12-31

    The velocity of detonation in the aluminized explosives containing sodium azide was measured. he experimental results were compared with those of calculation. Two different explosive components were used in the tests: RDX and ammonium nitrate. The contents of constituents of explosive mixture varied within a wide range. The X-ray analysis of the solid detonation products was also made. The results enable us to predict a behaviour of sodium azide and aluminium during detonation process of the explosive tested and to verify the possibility of reaction between aluminium and nitrogen during that process. (authors) 12 refs.

  18. System and process for aluminization of metal-containing substrates

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Yeong-Shyung; Stevenson, Jeffry W

    2015-11-03

    A system and method are detailed for aluminizing surfaces of metallic substrates, parts, and components with a protective alumina layer in-situ. Aluminum (Al) foil sandwiched between the metallic components and a refractory material when heated in an oxidizing gas under a compression load at a selected temperature forms the protective alumina coating on the surface of the metallic components. The alumina coating minimizes evaporation of volatile metals from the metallic substrates, parts, and components in assembled devices during operation at high temperature that can degrade performance.

  19. Transformation of monomer aluminate ions from tetrahedron to octaheron

    Institute of Scientific and Technical Information of China (English)

    陈启元; 周俊; 李洁; 尹周澜

    2003-01-01

    During the precipitation of gibbsite from supersaturated sodium aluminate solution, the main aluminum containing species in solution will transform from tetrahedral [Al(OH)4]-to sixfold octahedral [(H2O)2Al-(OH)4]-. In order to elucidate the mechanisms responsible for above transformation, the formation Gibbs free energy as well as frontier orbits of a wide range of aluminum species are studied by ab initio method at B3LYP/6-31G** level. Based on theoretical calculation results, thermodynamic possibility and coordination possibility for aluminate ion transforming from [Al(OH)4]-to [(H2O)2Al(OH)4]-are analyzed and thermodynamic permitted reaction pathways are extracted. It is found that [Al(OH)4]-can not react directly with H2O to carry out the variation of coordination number. Transformation of tetrahedral [Al(OH)4]-to octahedral [(H2O)2Al(OH)4]-is involved in two reaction pathways, one is realized by neutral [Na(H2O)+4*Al(OH)-4] acting mediator, the other is carried by neutral [(H2O)Al(OH)3]. Though there is a strong thermodynamic trend for the transformation of [Al(OH)4]-to [(H2O)2Al(OH)4]-, the practical transformation is very slow. Thus, it can be concluded that there is a great kinetic resistance during the transformation from [Al(OH)4]-to [(H2O)2Al(OH)4]-.

  20. HOT DIPPING ALUMINIZED COATING AS HYDROGEN PERMEATION BARRIER

    Institute of Scientific and Technical Information of China (English)

    Z.Y. Yao; M. Chini; A. Aiello; Benamati

    2001-01-01

    The hydrogen permeation experiment of MANET II with hot dipping aluminized 1oat-ing was performed in temperature range of 573 to 623K, in gas phase and in liquiaPb-17Li phase. The hydrogen permeation reduction factor (PRF) evaluated in gasphase is 620 at 573K and 260 at 623K, and in liquid Pb-17Li phase is 24 45 at 573Kand 12-30 at 623K. The self-healing of coating is obvious and effective above 673K.The pressure dependence of permeation flux indicates strong surface contribution. Theway of filling hydrogen by continuous flow and/or bubble can increase permeation flux.The result of SEM-EDS shows that the microcrack is on the surface of the wetted part,but not on the not wetted part. The crack is superficial and affects only thin outsidelayer not penetrate aluminized layer. The surface elemental analysis shows that Al/Oatomic ratio changes from 2/3 of not wetted part to about 1 of wetted part. Thedamage of coating surface seems to be related to the interaction of outside layer withliquid Pb-17Li and thermal stress during heating sample.

  1. Sonochemical synthesis of cobalt aluminate nanoparticles under various preparation parameters.

    Science.gov (United States)

    Lv, Weizhong; Qiu, Qi; Wang, Fang; Wei, Shaohui; Liu, Bo; Luo, Zhongkuan

    2010-06-01

    Cobalt aluminate (CoAl(2)O(4)) nanoparticles were synthesized using a precursor method with the aid of ultrasound irradiation under various preparation parameters. The effects of the preparation parameters, such as the sonochemical reaction time and temperature, precipitation agents, calcination temperature and time on the formation of CoAl(2)O(4) were investigated. The precursor on heating yields nanosized CoAl(2)O(4) particles and both these nanoparticles and the precursor were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The use of ultrasound irradiation during the homogeneous precipitation of the precursor reduces the duration of the precipitation reaction. The mechanism of the formation of cobalt aluminate was investigated by means of Fourier transformation infrared spectroscopy (FT-IR) and EDX (energy dispersive X-ray). The thermal decomposition process and kinetics of the precursor of nanosized CoAl(2)O(4) were investigated by means of differential scanning calorimetry (DSC) and thermogravimetry (TG). The apparent activation energy (E) and the pre-exponential constant (A) were 304.26 kJ/mol and 6.441 x 10(14)s(-1), respectively. Specific surface area was investigated by means of Brunauer Emmett Teller (BET) surface area measurements.

  2. Improper Ferroelectricity in Stuffed Aluminate Sodalites for Pyroelectric Energy Harvesting

    Science.gov (United States)

    Maeda, Yusaku; Wakamatsu, Toru; Konishi, Ayako; Moriwake, Hiroki; Moriyoshi, Chikako; Kuroiwa, Yoshihiro; Tanabe, Kenji; Terasaki, Ichiro; Taniguchi, Hiroki

    2017-03-01

    In the present study, we demonstrate ferroelectricity in stuffed aluminate sodalites (Ca1 -xSrx)8[AlO2]12(WO4)2 (x ≤0.2 ) (C1 -xSxAW ). Pyroelectric measurements clarify switchable spontaneous polarization in polycrystalline C1 -xSxAW , whose polarization values are on the order of 10-2 μ C /cm2 at room temperature. A weak anomaly in the dielectric permittivity at temperatures near the ferroelectric transition temperature suggests improper ferroelectricity of C1 -xSxAW for all investigated values of x . A comprehensive study involving synchrotron x-ray powder diffraction measurements, molecular dynamics simulations, and first-principles calculations clarifies that the ferroelectric phase transition of C1 -xSxAW is driven by the freezing of the fluctuations of WO4 tetrahedra in the voids of an [AlO2]12 12 - framework. The voltage response and electromechanical coupling factor of C1 -xSxAW estimated from the present results indicate that this material exhibits excellent performance as a pyroelectric energy harvester, suggesting that aluminate sodalites exhibit great promise as a class of materials for highly efficient energy-harvesting devices.

  3. High temperature corrosion of hot-dip aluminized steel in Ar/1%SO2 gas

    Science.gov (United States)

    Abro, Muhammad Ali; Lee, Dong Bok

    2017-01-01

    Carbon steels were hot-dip aluminized in Al or Al-1at%Si baths, and corroded in Ar/1%SO2 gas at 700-800 °C for up to 50 h. The aluminized layers consisted of not only an outer Al(Fe) topcoat that had interdispersed needle-like Al3Fe particles but also an inner Al-Fe alloy layer that consisted of an outer Al3Fe layer and an inner Al5Fe2 layer. The Si addition in the bath made the Al(Fe) topcoat thin and nonuniform, smoothened the tongue-like interface between the Al-Fe alloy layer and the substrate, and increased the microhardness of the aluminized layer. The aluminized steels exhibited good corrosion resistance by forming thin α-Al2O3 scales, along with a minor amount of iron oxides on the surface. The interdiffusion that occurred during heating made the aluminized layer thick and diffuse, resulting in the formation of Al5Fe2, AlFe and AlFe3 layers. It also smoothened the tongue-like interface, and decreased the microhardness of the aluminized layer. The non-aluminized steel formed thick, nonadherent, nonprotective (Fe3O4, FeS)-mixed scales.

  4. Effect of Rare Earth on Void Band of Diffusion Layer and Properties of Aluminized Steel

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; FAN Zhi-kang; HU Peng-fei; LONG Yong-qiang; LIU Hua; WEN Jiu-ba

    2006-01-01

    The effects of the addition of rare earth (RE) elements on the void band in the diffusion layer, and the resistances to both oxidation and spalling of aluminized steel were investigated through high temperature oxidation and spalling tests. The results showed that RE had significant effects on the void band in the diffusion layer and the properties of aluminized steel. After diffusion treatment, a considerable number of the voids between the middle layer and transitional layer of pure aluminized coating, aggregated into wavy-line-shaped void bands parallel to the outer surface. For the RE-added aluminized coating, only a few voids aggregated into intermittent block shapes. During high temperature oxidation at 800 ℃ for 200 h, the wavy void band of pure aluminized coating aggregated further into a linear crack parallel to the outer surface, and the internal oxidation occurred within them; the open cracks perpendicular to the surface penetrated through the diffusion layer. For the RE-added aluminized coating, only a few voids aggregated into intermittent meniscus shapes. During cyclic spalling tests, the peeling, spallation, and pulverulent cracking occurred along the void band in the diffusion layer of pure aluminized coating, but only a little spallation occurred in the diffusion layer of the RE-added aluminized coating, in which cracks perpendicular to the surface were much smaller than those of pure aluminized coating and did not penetrate through the diffusion layer. It is evident that RE addition can restrain the formation and aggregation of voids and subsequently improve the resistances to oxidation and spalling. The mechanism of the RE effect on the void band in the diffusion layer is also discussed.

  5. Solubilities of sodium nitrate, sodium nitrite, and sodium aluminate in simulated nuclear waste

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, D.A.; Herting, D.L.

    1984-09-01

    Solubilities were determined for sodium nitrate, sodium nitrite, and sodium aluminate in synthetic nuclear waste liquor. Solubilities were determined as a function of temperature and solution composition (concentrations of sodium hydroxide, sodium nitrate, sodium nitrite, and sodium aluminate). Temperature had the greatest effect on the solubilities of sodium nitrate and sodium nitrite and a somewhat lesser effect on sodium aluminate solubility. Hydroxide had a great effect on the solubilities of all three salts. Other solution components had minor effects. 2 references, 8 figures, 11 tables.

  6. Calcium aluminate cement hydration in a high alkalinity environment

    Directory of Open Access Journals (Sweden)

    Palomo, Á.

    2009-03-01

    Full Text Available The present paper forms part of a broader research project that aims primarily to devise new cementitious products via the alkali activation of silico-aluminous materials. This work addresses the possibility of using small percentages of calcium aluminate cement (CAC as a source of reactive aluminium. For this reason, a preliminary review was needed of the behaviour of CACs in highly alkaline media (2, 8 and 12M NaOH solutions. Two, 28- and 180-day mechanical strength was determined and the reaction products were characterized with XRD and FTIR. The water-hydrated CAC was used as the control.The results obtained showed that CAC hardening took place much more slowly in highly alkaline media than in water. Nonetheless, the 28-day compressive strength obtained, ≥80MPa. As main reaction products, to ambient temperature and from the two days of cured, cubic aluminate C3AH6, and AH3 polymorphs are formed, instead of the usual hexagonal aluminatos (CAH10 and C2AH8 that are formed in the normal hydrate with water.El presente trabajo forma parte de una amplia investigación cuyo objetivo principal es el de elaborar nuevos materiales con propiedades cementantes mediante la activación alcalina de materiales de naturaleza silito-aluminosa. En estos estudios se contempla la posibilidad de utilizar pequeños porcentajes de cemento de aluminato de calcio (CAC como fuente de aluminio reactivo. Por ello inicialmente se ha estudiado el comportamiento de los CAC en medios fuertemente alcalinos (disoluciones de NaOH 2M, 8M y 12M. Se determinaron las resistencias mecánicas a 2, 28 y 180 días y se realizó una caracterización de los productos de reacción formados por DRX, FTIR. Como sistema de referencia se consideró la hidratación del CAC con agua.Los resultados obtenidos muestran que en medios fuertemente alcalinos se retrasan los procesos de rápido endurecimiento de CAC con agua. No obstante a 28 días se obtienen valores de resistencia a compresión

  7. Synthesis and optical study of barium magnesium aluminate blue phosphors

    Science.gov (United States)

    Jeet, Suninder; Sharma, Manoj; Pandey, O. P.

    2015-05-01

    Europium doped barium magnesium aluminate (BaMgAl10O17:Eu2+) phosphor was prepared via solution combustion method at 550°C using urea as a fuel. Morphological and optical properties of the prepared sample was studied by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Photoluminescence spectroscopy (PL). XRD result showed the formation of pure phase BaMgAl10O17(JCPDS 26-0163) along with an additional phase BaAl2O4(JCPDS 01-082-1350). TEM image indicated the formation of faceted particles with average particle size 40 nm. From PL spectra, a broad emission band obtained at about 450 nm attributes to 4f6 5d → 4f7 transition of Eu2+ which lies in the blue region of the visible spectrum.

  8. Synthesis and optical study of barium magnesium aluminate blue phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Jeet, Suninder, E-mail: suninder.jeet@thapar.edu; Pandey, O. P., E-mail: oppandey@thapar.edu [School of Physics and Materials Science, Thapar University, Patiala (147003), Punjab (India); Sharma, Manoj, E-mail: manojnarad@sggswu.org [Department of Nanotechnology, Sri Guru Granth Sahib World University, Fatehgarh Sahib(146406), Punjab (India)

    2015-05-15

    Europium doped barium magnesium aluminate (BaMgAl{sub 10}O{sub 17}:Eu{sup 2+}) phosphor was prepared via solution combustion method at 550°C using urea as a fuel. Morphological and optical properties of the prepared sample was studied by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Photoluminescence spectroscopy (PL). XRD result showed the formation of pure phase BaMgAl{sub 10}O{sub 17}(JCPDS 26-0163) along with an additional phase BaAl{sub 2}O{sub 4}(JCPDS 01-082-1350). TEM image indicated the formation of faceted particles with average particle size 40 nm. From PL spectra, a broad emission band obtained at about 450 nm attributes to 4f{sup 6} 5d → 4f{sup 7} transition of Eu{sup 2+} which lies in the blue region of the visible spectrum.

  9. On structural, optical and dielectric properties of zinc aluminate nanoparticles

    Indian Academy of Sciences (India)

    E Muhammad Abdul Jamal; D Sakthi Kumar; M R Anantharaman

    2011-04-01

    Zinc aluminate nanoparticles with average particle size of 40 nm were synthesized using a sol–gel combustion method. X-ray diffractometry result was analysed by Rietveld refinement method to establish the phase purity of the material. Different stages of phase formation of the material during the synthesis were investigated using differential scanning calorimetry and differential thermogravimetric analysis. Particle size was determined with transmission electron microscopy and the optical bandgap of the nanoparticles was determined by absorption spectroscopy in the ultraviolet-visible range. Dielectric permittivity and a.c. conductivity of the material were measured for frequencies from 100 kHz to 8 MHz in the temperature range of 30–120°C. The presence of Maxwell–Wagner type interfacial polarization was found to exist in the material and hopping of electron by means of quantum mechanical tunneling is attributed as the reason for the observed a.c. conductivity.

  10. Method of winning aluminum metal from aluminous ore

    Science.gov (United States)

    Loutfy, Raouf O.; Keller, Rudolf; Yao, Neng-Ping

    1981-01-01

    Aluminous ore such as bauxite containing alumina is blended with coke or other suitable form of carbon and reacted with sulfur gas at an elevated temperature. For handling, the ore and coke can be extruded into conveniently sized pellets. The reaction with sulfur gas produces molten aluminum sulfide which is separated from residual solid reactants and impurities. The aluminum sulfide is further increased in temperature to cause its decomposition or sublimation, yielding aluminum subsulfide liquid (AlS) and sulfur gas that is recycled. The aluminum monosulfide is then cooled to below its disproportionation temperature to again form molten aluminum sulfide and aluminum metal. A liquid-liquid or liquid-solid separation, depending on the separation temperature, provides product aluminum and aluminum sulfide for recycle to the disproportionation step.

  11. Ethylene glycol contamination effects on first surface aluminized mirrors

    Science.gov (United States)

    Dunlop, Patrick; Probst, Ronald G.; Evatt, Matthew; Reddell, Larry; Sprayberry, David

    2016-07-01

    The Dark Energy Spectroscopic Instrument (DESI) is under construction for installation on the Mayall 4 Meter telescope. The use of a liquid cooling system is proposed to maintain the DESI prime focus assembly temperature within ±1°C of ambient. Due to concerns of fluid deposition onto optical surfaces from possible leaks, systematic tests were performed of the effects on first surface aluminized mirrors of ethylene glycol and two other candidate coolants. Objective measurement of scattering and reflectivity was an important supplement to visual inspection. Rapid cleanup of a coolant spill followed by a hand wash of the mirror limited surface degradation to the equivalent of a few months of general environmental exposure. Prolonged exposure to corrosive coolants dissolved the aluminum, necesitating mirror recoating.

  12. Magnesium and Calcium Aluminate Liquids: In Situ High-Temperature 27Al NMR Spectroscopy.

    Science.gov (United States)

    Poe, B T; McMillan, P F; Coté, B; Massiot, D; Coutures, J P

    1993-02-05

    The use of high-temperature nuclear magnetic resonance (NMR) spectroscopy provides a means of investigating the structure of refractory aluminate liquids at temperatures up to 2500 K. Time-averaged structural information indicates that the average aluminum coordination for magnesium aluminate (MgAl(2)O(4)) liquid is slightly greater than for calcium aluminate (CaAl(2)O(4)) liquid and that in both liquids it is close to four. Ion dynamics simulations for these liquids suggest the presence of four-, five-, and six-coordinated aluminate species, in agreement with NMR experiments on fast-quenched glasses. These species undergo rapid chemical exchange in the high-temperature liquids, which is evidenced by a single Lorentzian NMR line.

  13. Development of Pack Cementation Aluminizing Process on Inner Surface of 316L Stainless Steel Tube

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>In order to form the FeAl coatings on the inner surface of the 316L stainless steel tube,the pack cementation aluminizing process is introduced in this paper. The outside diameter,wall thickness and

  14. Etude vibrationnelle d'aluminates et de gallates de terres rares—III. Aluminates et gallates de structure grenat

    Science.gov (United States)

    Saine, M. C.; Husson, E.; Brusset, H.; de, A. Cerez

    The i.r. absorption and Raman scattering spectra of some aluminium and gallium garnets have been studied. They show a stronger force field in the aluminates than in the gallates and the influence of the ionic radius of the Ln 3+ cation on the frequencies of the aluminium—oxygen or gallium—oxygen network. The study of the system Er 3Ga 5O 12-Er 3Al 5O 12 permitted us to propose an assignment of the different ranges of frequencies and to point out that the tetrahedra vibrations are higher than the octahedra ones. The i.r. spectrum of the perovskite NdGaO 3 is compared to the garnet Nd 3GasO 12 one.

  15. Nanocrystallization of aluminized surface of carbon steel for enhanced resistances to corrosion and corrosive wear

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C. [Dept. of Materials Physical and Chemical, University of Science and Technology Beijing, Beijing 100083 (China); Dept. of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, T6G 2V4 (Canada); Li, D.Y., E-mail: dongyang.li@ualberta.c [Dept. of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, T6G 2V4 (Canada); Shang, C.J. [Dept. of Materials Physical and Chemical, University of Science and Technology Beijing, Beijing 100083 (China)

    2009-12-15

    Aluminizing is often used to improve steel's resistances to corrosion, oxidation and wear. This article reports our recent attempts to further improve aluminized carbon steel through surface nanocrystallization for higher resistances to corrosion and corrosive wear. The surface nanocrystallization was achieved using a process combining sandblasting and recovery heat treatment. The entire surface modification process includes dipping carbon steel specimens into a molten Al pool to form an Al coat, subsequent diffusion treatment at elevated temperature to form an aluminized layer, sandblasting to generate dislocation network or cells, and recovery treatment to turn the dislocation cells into nano-sized grains. The grain size of the nanocrystallized aluminized surface layer was in the range of 20-100 nm. Electrochemical properties, electron work function (EWF), and corrosive wear of the nanocrystalline alloyed surfaces were investigated. It was demonstrated that the nanocrystalline aluminized surface of carbon steel exhibited improved resistances to corrosion, wear and corrosive wear. The passive film developed on the nanocrystallized aluminized surface was also evaluated in terms of its mechanical properties and adherence to the substrate.

  16. The Effect of Nano-Aluminumpowder on the Characteristic of RDX based Aluminized Explosives Underwater Close-Filed Explosion

    Directory of Open Access Journals (Sweden)

    Junting Yin

    2017-01-01

    Full Text Available In order to investigate the effect of nano-aluminum powder on the characteristic of RDX based aluminized explosives underwater closed-filed explosions, the scanning photographs along the radial of the charges were gained by a high speed scanning camera. The photographs of two different aluminized explosives underwater explosion have been analyzed, the shock wave curves and expand curves of detonation products were obtained, furthermore the change rules of shock waves propagation velocity, shock front pressure and expansion of detonation products of two aluminized explosives were investigated, and also the parameters of two aluminized explosives were contrasted. The results show that the aluminized explosive which with nano-aluminum whose initial shock waves pressure propagation velocity, shock front pressure are smaller than the aluminized explosive without nano-aluminum and has lower decrease rate attenuation of energy.

  17. Thermal desorption study of catalytic systems. Communication 20. Adsorption of water vapors on the calcium aluminate components of catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Nissenbaum, V.D.; Danyushevskii, V.Y.; Golosman, E.Z.; Rubinstein, A.M.; Yakerson, V.I.

    1985-05-01

    Ca aluminates are used as a component of catalysts of gas-phase processes, some of which take place with the participation of water. Nickel calcium aluminate catalysts are thus used for hydrogenation of CO and CO/sub 2/ to CH/sub 4/ and water; zinc calcium aluminate catalysts are used for sulfur purification of process gases, where water is liberated during sulfiding of ZnO; and copper zinc calcium aluminate catalysts are used in low-temperature conversion of CO with water vapor. It is also known that Ca aluminates undergo various transformations in aqueous media with the formation of Ca hydroaluminates. This paper discusses the adsorption of water from the gas phase on calcium aluminate systems, which was investigated by the thermal desorption method. Samples of varying phase composition, different CaO/Al/sub 2/O/sub 3/ ratios, and specific surface areas were also studied and are reported on here.

  18. Shock Wave Dynamics of Novel Aluminized Detonations and Empirical Model for Temperature Evolution from Post-Detonation Combustion Fireballs

    Science.gov (United States)

    2011-03-01

    to steel confinement, the presence of aluminum and wax in the HE as well as the presence of the 62   aluminized PE annulus surrounding the HE may...an aluminized plastic-bonded spin-cast liner all inside a steel munitions tube. The rate of change of temperature in the post- detonation combustion...0.18 m) inner diameter. The steel tubes are lined with an aluminized polyethylene (PE) annulus in the inner diameter and filled with melt-cast RDX

  19. Aluminizing of plain carbon steel: Effect of temperature on coating and alloy phase morphology at constant holding time

    OpenAIRE

    Isiko, Maureen Bangukira

    2012-01-01

    Aluminized steel possesses excellent physical, chemical and mechanical properties as compared to plain carbon steel. This type of steel has found application in high temperature, oxidizing and corrosive environments. In addition, aluminized steel is more cost effective than stainless steels. The objective of the current study is to study effect of temperature on the thicknesses and phase morphology of the coating and intermetallic layer that is formed during hot-dip aluminizing of steel at a ...

  20. Reducing DRIFT Backgrounds with a Submicron Aluminized-Mylar Cathode

    CERN Document Server

    Battat, James B R; Dorofeev, Alexei; Ezeribe, Anthony C; Fox, Jennifer R; Gauvreau, Jean-Luc; Gold, Michael; Harmon, Lydia; Harton, John; Lafler, Randy; Lauer, Robert J; Lee, Eric R; Loomba, Dinesh; Lumnah, Alexander; Matthews, John; Miller, Eric H; Mouton, Frederic; Murphy, Alexander St J; Phan, Nguyen; Sadler, Stephen W; Scarff, Andrew; Schuckman, Fred; Snowden-Ifft, Daniel; Spooner, Neil J C; Walker, Daniel

    2015-01-01

    Background events in the DRIFT-IId dark matter detector, mimicking potential WIMP signals, are predominantly caused by alpha decays on the central cathode in which the alpha particle is completely or partially absorbed by the cathode material. We installed a 0.9 micron thick aluminized-mylar cathode as a way to reduce the probability of producing these backgrounds. We study three generations of cathode (wire, thin-film, and radiologically clean thin-film) with a focus on the ratio of background events to alpha decays. Two independent methods of measuring the absolute alpha decay rate are used to ensure an accurate result, and agree to within $10\\%$. Using alpha range spectroscopy, we measure the radiologically cleanest cathode version to have a contamination of $3.3\\pm0.1$ ppt $^{234}$U and $73\\pm2$ ppb $^{238}$U. This cathode reduces the probability of producing an RPR from an alpha decay by a factor of $70\\pm20$ % while reducing the overall background rate by $96.5\\pm0.5\\%$ compared to the original stainles...

  1. Synthesis and optical property of zinc aluminate spinel cryogels

    Directory of Open Access Journals (Sweden)

    Lifen Su

    2016-06-01

    Full Text Available Zinc aluminate spinel cryogels with various molar ratio of Al/Zn are synthesized by sol–gel technology followed by vacuum freeze drying. The structures and optical properties are both found to be affected by the molar ratios of Al/Zn and annealed temperatures. The peaks of zinc oxide (ZnO and zinc dialuminum oxide (ZnAl2O4 are both obtained for the samples with more Zn content annealed at 750 °C or upward. The composites have a large surface area (137 m2/g with mesoporous structure after annealing at 750 °C. The SEM images reveal that the ZnAl2O4 crystals formed a multilayer structure with redundant ZnO particles which deposited on it. Furthermore, the maximum infrared reflectance is about 80% with an improvement of 35% in the infrared region after annealing at 950 °C compared with that of 450 °C, which indicates that these porous cryogels have a potential application as thermal insulating materials at a high temperature.

  2. Luminescent characteristics of praseodymium-doped zinc aluminate powders

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Perez, C.D.; Garcia-Hipolito, M.; Alvarez-Fregoso, O. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Coyoacan, DF (Mexico); Alvarez-Perez, M.A. [Facultad de Odontologia, Universidad Nacional Autonoma de Mexico, Coyoacan, DF (Mexico); Ramos-Brito, F. [Laboratorio de Materiales Optoelectronicos, DIDe, Centro de Ciencias de Sinaloa, Av. De las Americas No. 2771 Nte. Col. Villa Universidad, Culiacan, Sinaloa (Mexico); Falcony, C. [Centro de Investigaciones y Estudios Avanzados del IPN, Departamento de Fisica, Mexico, DF (Mexico)

    2010-02-15

    In this research, we report the cathodoluminescence (CL) and preliminary photoluminescence (PL) properties of praseodymium-doped zinc aluminate powders. ZnAl{sub 2}O{sub 4}:Pr powders were synthesized by a very simple chemical process. X-ray diffraction spectra indicated a cubic spinel crystalline structure with an average crystallite size of 15 nm. CL properties of the powders were studied as a function of the praseodymium concentration and electron-accelerating potential. In this case, all the cathodoluminescent emission spectra showed main peaks located at 494, 535, 611, 646, and 733 nm, which were associated to the electronic transitions {sup 3}P{sub 0}{yields}{sup 3}H{sub 4}, {sup 3}P{sub 0}{yields}{sup 3}H{sub 5}, {sup 3}P{sub 0}{yields}{sup 3}H{sub 6}, {sup 3}P{sub 0}{yields}{sup 3}F{sub 2}, and {sup 3}P{sub 0}{yields}{sup 3}F{sub 4} of the Pr{sup 3+} ions, respectively. A quenching of the CL, with increasing doping concentration, was observed. Also, an increment on cathodoluminescent emission intensity was observed as the accelerating voltage increased. The PL emission spectrum showed similar characteristics to those of the CL spectra. The chemical composition of the powders, as determined by energy dispersive spectroscopy, is also reported. In addition, the surface morphology characteristics of the powders are shown. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  3. Combustion synthesis, characterization and luminescence properties of barium aluminate phosphor

    Institute of Scientific and Technical Information of China (English)

    AH Wako; FB Dejene; HC Swart

    2014-01-01

    The blue-green emitting Eu2+and Nd3+ doped polycrystalline barium aluminate (BaAl2O4:Eu2+,Nd3+) phosphor, was pre-pared by a solution-combustion method at 500 ºC without a post-annealing process. The characteristic variation in the structural and luminescence properties of the as-prepared samples was evaluated with regards to a change in the Ba/Al molar ratio from 0.1:1 to 1.4:1. The morphologies and the phase structures of the products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), while the optical properties were investigated using ultra-violet (UV) and photoluminescence (PL) spectroscopy, respectively. The XRD and TEM results revealed that the average crystallite size of the BaAl2O4:Eu2+,Nd3+ phosphor was about 70 nm. The broad-band UV-excited luminescence of the phosphors was observed atλmax=500 nm due to transitions from the 4f65d1 to the 4f7 configuration of the Eu2+ ion. The PL results indi-cated that the main peaks in the emission and excitation spectrum of phosphor particles slightly shifted to the short wavelength due to the changes in the crystal field due to the structure changes caused by the variation in the quantity of the Ba ions in the host lattice.

  4. Improving electrochemical properties of AISI 1045 steels by duplex surface treatment of plasma nitriding and aluminizing

    Energy Technology Data Exchange (ETDEWEB)

    Haftlang, Farahnaz, E-mail: f.haftlang@students.semnan.ac.ir [Department of Metallurgy and Materials Engineering, Faculty of Engineering, Semnan University, Semnan (Iran, Islamic Republic of); Habibolahzadeh, Ali [Department of Metallurgy and Materials Engineering, Faculty of Engineering, Semnan University, Semnan (Iran, Islamic Republic of); Sohi, Mahmoud Heydarzadeh [School of Metallurgy and Materials, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2015-02-28

    Highlights: • AlN coating was applied on AISI 1045 steel via plasma nitriding and aluminizing. • Plasma nitriding and post-aluminizing result in AlN single phase layer on the steel. • PN–Al coated steel had better corrosion resistance than Al–PN one. • Formation of oxide layer provided protection of PN–Al coated steel against corrosion. • Pitting and surface defects was the dominant corrosion mechanism in Al–PN coated steel. - Abstract: Improvement in electrochemical behavior of AISI 1045 steel after applying aluminum nitride coating was investigated in 3.5% NaCl solution, using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) analyses. Aluminum nitride coating was applied on the steel surface by duplex treatment of pack aluminizing and plasma nitriding. Some specimens were plasma nitrided followed by aluminizing (PN–Al), while the others were pack aluminized followed by plasma nitriding (Al–PN). Topological and structural studies of the modified surfaces were conducted using scanning electron microscope (SEM) equipped by energy dispersive X-ray spectroscope (EDS), and X-ray diffractometer (XRD). The electrochemical measurements showed that the highest corrosion and polarization (R{sub p}) resistances were obtained in PN–Al specimens, having single phase superficial layer of AlN. Pitting mechanism was dominant reason of lower corrosion resistance in the Al–PN specimens.

  5. Complex Boronized Layer on the Hot-dip Aluminized Steels and Its Surface Performances

    Institute of Scientific and Technical Information of China (English)

    LUO Xin-min; LI Dian-kai; WANG Lan; CHEN Kang-min

    2004-01-01

    Plain carbon steels were dipped in molten aluminum bath at 720℃±5℃ and diffused for 1, 2.5 and 6 hours respectively and then boronized at 950℃ for 6 hours. The oxidation, hot-corrosion and abrasion resistance behavior were examined. The experimental results showed the compounds of the aluminized layer, from the surface to the matrix, were composed of Fe2Al5 ( η -phase )、 Fe3Al ( β 1-phase ) and α phase. The microstructure of aluminized plus complex boronized were similar to that simplex boronized. The XRD analysis results indicated that there existed Fe2B、 Fe2AlB2 and Fe2Al5 in this kind of layer. The simplex aluminized layers still remained bright gray appearance when oxidized at 950℃, but complex boronized layer was not able to resist oxidization at the temperature. Both the layers of complex boronized and aluminized had the same anti-oxidization level in the circulative oxidization tests, and also good anti-corrosion ability in molten salt medium. Under dry abrasive conditions, wear resistance of complex boronized layer was superior to the aluminized layer.

  6. Complex Boronized Layer on the Hot-dip Aluminized Steels and Its Surface Performances

    Institute of Scientific and Technical Information of China (English)

    LUOXin-min; LIDian-kai; WANGLan; CHENKang-min

    2004-01-01

    Plain carbon steels were dipped in molten aluminum bath at 720℃±5℃ and diffused for 1.2.5 and 6 hours respectively and then horonized at 950℃ for 6 hours. The oxidation, hot-corrosion and abrasion resistance behavior were examined. The experimental results showed the compounds of the aluminized layer, from the surface to the matrix, were composed of Fe2Al5(η-phase/.Fe3Al(β1-phase)and α phase. The microstructure of aluminized plus complex boronized were similar to that simplex boronized. The XRD analysis results indicated that there existed Fe.B. Fe2AlB2 and Fe2Al5 in this kind of layer, The simplex aluminized layers still remained bright gray appearance when oxidized at 950℃, but complex horonized layer was not able to resist oxidization at the temperature. Both the layers of complex botanized and aluminized had the same anti-oxidizatian level in the circulative oxidization tesfs, and also good anti-corrosion abilily in molten salt medium. Under dry abrasive conditions, wear resistance of complex botanized layer was superior to the aluminized layer.

  7. Structural Characterization of Spinel Zinc Aluminate Nanoparticles Prepared By Coprecipitation Method

    Science.gov (United States)

    Sunder, Shyam; Rohilla, Sunil; Kumar, Sushil; Aghamkar, Praveen

    2011-12-01

    Zinc aluminate is well known wide bandgap semiconductor with cubic spinel structure and transparent for wavelength greater than 320 nm. Therefore, ZnAl2O4 can be used for ultraviolet photoelectronic devices. Furthermore, spinel zinc aluminate is useful in many reactions as catalytic support. Moreover, zinc aluminate can be used as second phase in glaze layer of white ceramics to improve wear resistance and to preserve whiteness. In present study cubic spinel zinc aluminate nanoparticles have been synthesized from aqueous solution of Zn(NO3)2.6H2O (0.1 M) and Al(NO3)2.9H2O (0.2 M) using chemical coprecipitation technique. Ammonium hydroxide was used as precipitating agent and pH was maintained between 8 to 9. The precipitated slurry was filtered and washed several times with deionized double distilled water and dried at 110 °C. The fine powder was annealed at different temperatures from 600 °C to 900 °C for 4h in temperature controlled furnace. Structural characterization of annealed samples was carried out via X-ray Diffraction (XRD), and Fourier Transform Infrared spectroscopy (FTIR). XRD patterns reveal that zinc aluminate samples were cubic spinel nanoparticles and grain size determined by Debye-Scherrer formula is from 5 to 16 nm.

  8. MBE Growth of AlN Nanowires on Si Substrates by Aluminizing Nucleation.

    Science.gov (United States)

    E, Yanxiong; Hao, Zhibiao; Yu, Jiadong; Wu, Chao; Liu, Runze; Wang, Lai; Xiong, Bing; Wang, Jian; Han, Yanjun; Sun, Changzheng; Luo, Yi

    2015-12-01

    By introducing an aluminization process to achieve nucleation of nanowires (NWs), spontaneous growth of AlN NWs on Si substrates has been realized by plasma-assisted molecular beam epitaxy. The AlN NWs are grown from the nuclei formed by the aluminization process, and the NW density and diameter can be controlled by the aluminization parameters. The influence of growth conditions on the morphologies of AlN NWs is carefully investigated. Island-like films are found to grow between the NWs due to poor migration ability of Al adatoms. The films are proved to be Al-polar different from the N-polar AlN NWs, which can explain the absence of newly formed NWs. Increasing the V/III ratio can efficiently suppress the growth of Al-polar AlN films.

  9. Fine structures in Fe3Al alloy layer of a new hot dip aluminized steel

    Indian Academy of Sciences (India)

    Li Yajiang; Wang Juan; Zhang Yonglan; X Holly

    2002-12-01

    The fine structure in the Fe–Al alloy layer of a new hot dip aluminized steel (HDA) was examined by means of X-ray diffractometry (XRD), electron diffraction technique, etc. The test results indicated that the Fe–Al alloy layer of the new aluminized steel mainly composed of Fe3Al, FeAl and -Fe (Al) solid solution. There was no brittle phase containing higher aluminum content, such as FeAl3 (59.18% Al) and Fe2Al7 (62.93% Al). The tiny cracks and embrittlement, formerly caused by these brittle phases in the conventional aluminum-coated steel, were effectively eliminated. There was no microscopic defect (such as tiny cracks, pores or loose layer) in the coating. This is favourable to resist high temperature oxidation and corrosion of the aluminized steel.

  10. Rare earth activated yttrium aluminate phosphors with modulated luminescence.

    Science.gov (United States)

    Muresan, L E; Popovici, E J; Perhaita, I; Indrea, E; Oro, J; Casan Pastor, N

    2016-06-01

    Yttrium aluminate (Y3 A5 O12 ) was doped with different rare earth ions (i.e. Gd(3+) , Ce(3+) , Eu(3+) and/or Tb(3+) ) in order to obtain phosphors (YAG:RE) with general formula,Y3-x-a Gdx REa Al5 O12 (x = 0; 1.485; 2.97 and a = 0.03). The synthesis of the phosphor samples was done using the simultaneous addition of reagents technique. This study reveals new aspects regarding the influence of different activator ions on the morpho-structural and luminescent characteristics of garnet type phosphor. All YAG:RE phosphors are well crystallized powders containing a cubic-Y3 Al5 O12 phase as major component along with monoclinic-Y4 Al2 O9 and orthorhombic-YAlO3 phases as the impurity. The crystallites dimensions of YAG:RE phosphors vary between 38 nm and 88 nm, while the unit cell slowly increase as the ionic radius of the activator increases. Under UV excitation, YAG:Ce exhibits yellow emission due to electron transition in Ce(3+) from the 5d level to the ground state levels ((2) F5/2 , (2) F7/2 ). The emission intensity of Ce(3+) is enhanced in the presence of the Tb(3+) ions and is decreased in the presence of Eu(3+) ions due to some radiative or non-radiative processes that take place between activator ions. By varying the rare earth ions, the emission colour can be modulated from green to white and red. Copyright © 2015 John Wiley & Sons, Ltd.

  11. Long afterglow of trivalent dysprosium doped strontium aluminate

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yuan Ming, E-mail: dongshanisland@126.com [School of Mathematics and Physics, Changzhou University, Jiangsu 213164 (China); Ma, Qing-lan [School of Mathematics and Physics, Changzhou University, Jiangsu 213164 (China); School of Electronics and Information, Nantong University, Jiangsu 226019 (China)

    2015-04-15

    Trivalent dysprosium doped strontium aluminate (SrA1{sub 2}O{sub 4}:Dy{sup 3+}) was synthesized via the sol–gel combustion method to realize green afterglow in the absence of Eu{sup 2+} luminescent centers. The morphology, crystal structure, photoluminescence and long afterglow of the SrAl{sub 2}O{sub 4}:Dy{sup 3+} were characterized with scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and photoluminescence spectroscopy, respectively. The bluish-green photoluminescence of SrAl{sub 2}O{sub 4}:Dy{sup 3+} consists of a broad emission band centered at about 520 nm and two characteristic emissions of Dy{sup 3+} ions centered at 480 and 575 nm, respectively. The green afterglow of SrAl{sub 2}O{sub 4}:Dy{sup 3+} is a broad emission band centered at around 520 nm, and the lifetime extracted from afterglow decay is found to be 53 s. The mechanism on the green afterglow from SrAl{sub 2}O{sub 4}:Dy{sup 3+} is discussed in terms of the possible defect levels in the host. - Highlights: • Broad band long-lasting afterglow is observed in SrAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors. • Characteristic emissions of Dy{sup 3+} ions are superimposed on the broad PL of phosphors. • Dy{sup 3+} ions can also act as luminescent centers in addition to electron traps. • A mechanism on long afterglow of SrAl{sub 2}O{sub 4}:Dy{sup 3+} is proposed without Eu{sup 2+} activator.

  12. Influence of chemical bonding of chlorides with aluminates in cement hidratation process on corrosion steel bars in concrete

    Directory of Open Access Journals (Sweden)

    Bikić Farzet H.

    2010-01-01

    Full Text Available The presence of chlorides in concrete is a permanent subject of research because they cause corrosion of steel bars. Chlorides added to the concrete during preparation, as accelerators of the bonding of cement minerals process, enter into reaction with aluminates, creating a phase known as chloroaluminate hydrates. In everyday conditions the product of chemical bonding between chlorides and aluminates is usually monochloridealuminate C3A·CaCl2·Hx, better known as Friedel's salt. In this paper, the influence of chemical bonding of chlorides with aluminates during the process of cement hydration on corrosion of steel bars in concrete was investigated. The process of chlorides bonding with aluminates yielding monochloride aluminate is monitored by XRD analyses. It was found that the amount of chlorides bonding with aluminates increases with an increase of temperature, and as a result, reduces the amount of 'free' chlorides in concrete. Potentiodynamic measurements have shown that increase in temperature of the heat treatment of working electrodes by chlorides leads to a reduction of steel bars corrosion as a result of either the increase of the monochloride-aluminate content or the decrease of free chlorides amount. Chlorides bound in chloroaluminate hydrates do not cause activation of steel bars corrosion in concrete. It was also proven that the increase of free chlorides concentration in the concrete leads to intensification of steel bars corrosion. This additionally approves that free chlorides are only the activators of process of steel bars corrosion in the concrete.

  13. Wear Resistance and Wear Mechanism of a Hot Dip Aluminized Steel in Sliding Wear Test

    Science.gov (United States)

    Xue, Zhiyong; Hao, Xiaoyang; Huang, Yao; Gu, Lingyun; Ren, Yu; Zheng, Ruipeng

    2016-12-01

    Sliding wear experiments were conducted on a hot dip aluminized steel to investigate its wear resistance and wear mechanism. The wear tests were also carried out on a hot dip galvanized steel and the base material (steel Q345) as a comparison. Results show that the wear resistance and hardness of the hot dip aluminized steel are significantly higher than that of the hot dip galvanized steel and the steel Q345 at room temperature. The better wear resistance of the hot dip aluminized steel attributes mainly to the formation of a transition layer containing abundant Fe-Al intermetallic compounds and the transformation of wear-resisting oxides during the friction process. The main phase in the transition layer is Fe2Al5. The thickness of the transition layer is about 90-120 μm. When the wear load increases from 3 N to 19 N, the wear type of the aluminized layer transform from adhesive wear (3 N) into abrasive wear (7 N) and finally into slight wear mixed with oxidation (higher than 11 N).

  14. The Effect of (Ag, Ni, Zn)-Addition on the Thermoelectric Properties of Copper Aluminate

    DEFF Research Database (Denmark)

    Yanagiya, Shun-ichi; Van Nong, Ngo; Xu, Jianxiao Jackie;

    2010-01-01

    Polycrystalline bulk copper aluminate Cu1-x-yAgxByAlO2 with B = Ni or Zn were prepared by spark plasma sintering and subsequent thermal treatment. The influence of partial substitution of Ag, Ni and Zn for Cu-sites in CuAlO2 on the high temperature thermoelectric properties has been studied...

  15. [Study on the influence of mineralizer on the structures and spectral properties of calcium aluminates].

    Science.gov (United States)

    Zheng, Huai-Li; Liu, Jun-Yu; Li, Lin-Tao; Li, Fang

    2009-11-01

    The present paper investigated the effect of mineralizer on the structure and properties of calcium aluminates formation. Calcium aluminates powder was synthesized under high temperature calcination by mixing bauxite, limestone and a certain amount of mineralizer. The product structure, compositional information and spectral properties were carefully characterized by XRD, IR and DTA-TG, and the mineralization mechanism of mineralizer was studied during the process of calcium aluminates preparation. The results showed that calcium aluminates powder could be obtained under lower temperature calcination after adding mineralizer to the raw materials. The main products of the reaction were CaAl10 O18 and CaAl2 Si2 O8 without mineralizer, however, the main products of the reaction were CaAl3 BO7 and Ca3 Al10 O18 with mineralizer, in which Al2 O3s could be extracted easily, while CaAl2 Si2 O8 was reduced greatly in which Al2 O3 could not be extracted easily. At the same time, it is easy for calcspar to decompose after adding mineralizer. It is favorable to Al-Si bond break and Al stripping from bauxite. These facts could improve the extraction rate of Al2 O3 from raw materials. Also, in the case of adding mineralizer to the raw mixes, the crystal structure and composition are changed, which is beneficial to reducing calcination temperature.

  16. The Prospect of China’s Alumin-ium Extrusion Product Market

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>China’s aluminium extrusion industry can be dated back to the 1950s-70s,when the North- east 101 Plant was established in 1956,the Northwest Aluminium and Southwest Alumin- ium were completed and put into operation in 1968-1969.The three plants’ extrusion assem- bly lines were designed to produce aluminium

  17. Crystal growth and characterization of LaMAl 11O 19 lanthanum aluminates

    Science.gov (United States)

    Laville, F.; Lejus, A. M.

    1983-10-01

    New magnetoplumbite-type lanthanum aluminates with the formula LaMAl 11O 19 (M 2+ = Ni 2+, Co 2+, Fe 2+, Mg 1- xMn x, 0≤ x ≤1, have been grown as large single crystals using the Verneuil process or the floating zone method. Some characteristics of these crystals are given.

  18. Software framework for the upcoming MMT Observatory primary mirror re-aluminization

    Science.gov (United States)

    Gibson, J. Duane; Clark, Dusty; Porter, Dallan

    2014-07-01

    Details of the software framework for the upcoming in-situ re-aluminization of the 6.5m MMT Observatory (MMTO) primary mirror are presented. This framework includes: 1) a centralized key-value store and data structure server for data exchange between software modules, 2) a newly developed hardware-software interface for faster data sampling and better hardware control, 3) automated control algorithms that are based upon empirical testing, modeling, and simulation of the aluminization process, 4) re-engineered graphical user interfaces (GUI's) that use state-of-the-art web technologies, and 5) redundant relational databases for data logging. Redesign of the software framework has several objectives: 1) automated process control to provide more consistent and uniform mirror coatings, 2) optional manual control of the aluminization process, 3) modular design to allow flexibility in process control and software implementation, 4) faster data sampling and logging rates to better characterize the approximately 100-second aluminization event, and 5) synchronized "real-time" web application GUI's to provide all users with exactly the same data. The framework has been implemented as four modules interconnected by a data store/server. The four modules are integrated into two Linux system services that start automatically at boot-time and remain running at all times. Performance of the software framework is assessed through extensive testing within 2.0 meter and smaller coating chambers at the Sunnyside Test Facility. The redesigned software framework helps ensure that a better performing and longer lasting coating will be achieved during the re-aluminization of the MMTO primary mirror.

  19. Geomorfología de la región de los lagos Moquehue y Aluminé: consideraciones acerca de las propuestas Calderas Meseta del Arco y Nacimientos del Aluminé (Neuquén Geomorphology of the Moquehue and Aluminé Lakes: Considerations about the Meseta del Arco and Nacimientos del Aluminé calderas

    Directory of Open Access Journals (Sweden)

    Emilio F. González Díaz

    2010-05-01

    Full Text Available Se exponen elementos de juicio geomórficos y estructurales, que avalan la morfogénesis glaciaria de la depresión en artesa que aloja la cuenca lacustre Moquehue-Aluminé, ubicada en la cordillera neuquina (38°30´S, adyacente al límite internacional. Trabajos anteriores distinguen en la región dos calderas de un gran complejo volcánico plio-cuaternario, situado al este del frente volcánico actual e integrado por nueve depresiones caldéricas y cuerpos dómicos asociados. En el área de estudio sólo la caldera de Pino Hachado tiene la validez necesaria, cuestionándose el reconocimiento de las calderas denominadas Nacimientos del Aluminé y Meseta del Arco, al tiempo que se avala el origen erosivo de las abruptas escarpas orientales que marginan el plateau de Lonco Luan-Meseta del Arco, las que fueran interpretadas como márgenes de las sugeridas calderas. Se analizan las fases o tipología del englazamiento pleistoceno local, su extensión, las direcciones de los principales movimientos de su flujo y su más que probable aporte de hielo por difluencia, a un contemporáneo englazamiento en Chile (laguna Icalma. Se describen aspectos de la morfogenia volcánica cenozoica y otros más locales de la remoción en masa y el proceso eólico. Se incorporan breves comentarios acerca de un propuesto drenaje atlántico de un río Bío Bío preglaciario y se cuestiona aquellos antecedentes que avalan la extensión en la región de la fosa Bío Bío-Aluminé y la presencia de las citadas calderas. Una serie de perfiles esquemáticos topográfico-geológicos contribuyen a dicho cuestionamiento.The region is situated in the Neuquén Cordillera at 38° 30´S latitud close to the international border. Geomorphic and structural features are presented which indicated a glacial morphogenesis for the depression that contains the Moquehue- Aluminé lakes. Previous works have identified a large volcanic complex related to Plio-Quaternary volcanic activity

  20. Influence of chemical bonding of chlorides with aluminates in cement hidratation process on corrosion steel bars in concrete

    OpenAIRE

    2010-01-01

    The presence of chlorides in concrete is a permanent subject of research because they cause corrosion of steel bars. Chlorides added to the concrete during preparation, as accelerators of the bonding of cement minerals process, enter into reaction with aluminates, creating a phase known as chloroaluminate hydrates. In everyday conditions the product of chemical bonding between chlorides and aluminates is usually monochloridealuminate C3A·CaCl2·Hx, better known as Friedel's salt. In this paper...

  1. Combined effect of amino and carboxyl group in α-alanine on seeded precipitation of sodium aluminate solution

    Institute of Scientific and Technical Information of China (English)

    L(U) Bao-lin; CHEN Qi-yuan; YIN Zhou-lan; HU Hui-ping

    2009-01-01

    α-alanine was adopted as a new additive to elucidate the seeded precipitation mechanism of sodium aluminate solution. α-alanine has the inhibitory effect at the initial period of reaction, but the favorable effect in subsequent reaction. The combined effect of amino and carboxyl group in α-alanine was confirmed by investigating the effect of propionic acid, ethamine and the mixture of propionic acid and ethamine (mole ratio 1:1) on the precipitation of sodium aluminate solution, respectively. The inhibitory effect derives from the adsorption of amino or carboxyl group in α-alanine on the active surface sites of gibbsite, which was confirmed by the alleviating inhibitory effects of propionic acid, ethamine and α-alanine due to the double crystal seed mass. The semi-quantitative IR spectrum analysis of the relative concentrations of Al2O(OH)62- with the band at about 550 cm-1 and polynuclear aluminate ion with the bands at about 880 cm-1 and 635 cm-1, indicates that the dynamic balance among some aluminate species present in sodium aluminate solution is broken due to the addition of α-alanine, thus resulting in the change of the seeded precipitation ratio of sodium aluminate solution.

  2. Removal of methyl orange from aqueous solutions through adsorption by calcium aluminate hydrates.

    Science.gov (United States)

    Zhang, Ping; Wang, Tianqi; Qian, Guangren; Wu, Daishe; Frost, Ray L

    2014-07-15

    Methyl orange (MO) is a kind of anionic dye and widely used in industry. In this study, tricalcium aluminate hydrates (Ca-Al-LDHs) are used as an adsorbent to remove methyl orange (MO) from aqueous solutions. The resulting products were studied by X-ray diffraction (XRD), infrared spectroscopy (MIR), thermal analysis (TG-DTA) and scanning electron microscope (SEM). The XRD results indicated that the MO molecules were successfully intercalated into the tricalcium aluminate hydrates, with the basal spacing of Ca-Al-LDH expanding to 2.48 nm. The MIR spectrum for CaAl-MO-LDH shows obvious bands assigned to the N=N, N=H stretching vibrations and S=O, SO3(-) group respectively, which are considered as marks to assess MO(-) ion intercalation into the interlayers of LDH. The overall morphology of CaAl-MO-LDH displayed a "honey-comb" like structure, with the adjacent layers expanded.

  3. Fracture Toughness and Thermal Shock Properties of Calcium Aluminate Composite with Controlled Duplex Structure

    Institute of Scientific and Technical Information of China (English)

    W.J.Wei; H.J.Liaw

    2004-01-01

    This study used monocalcium aluminate (CaAl2O4,CA) for producing ceramic composites with duplex microstructures by hydration and gelation reactions of the aluminate, and compared the properties with those made by a die-pressing process of mixed powders. Densification of the composite was optimized. The microstructure of sintered bodies, the fracture strengths and toughness of the composites with and without thermal shocking was characterized by different techniques. Experimental results show that the green body with the addition of CA resulted glomerated platelets or uniform distribution of platy CA6 grains. The former, which appeared a duplex microstructure consisted of dense matrix and distributed clusters of CA6 platelets, performed an improvement on toughness and thermal shock resistance. Toughness mechanisms of samples with duplex microstructure are also investigated.

  4. Coating Prospects in Corrosion Prevention of Aluminized Steel and Its Coupling with Magnesium

    Science.gov (United States)

    Sun, Fuyan

    In this study, a plasma electrolytic oxidation (PEO) process was used to form oxide coating on aluminized steel, heated aluminized steel and magnesium. A potentiodynamic polarization corrosion test was employed to investigate the general corrosion properties. Galvanic corrosion of steel samples and magnesium samples was studied by zero resistance ammeter (ZRA) tests and boiling tests. Scanning electron microscopy (SEM) and EDS were used to investigate the coating microstructure and the coating/substrate interface. In general, the PEO coatings on all three substrate can help prevent general corrosion. 6-min coated magnesium with unipolar current mode performs best in most galvanic couplings for preventing both general corrosion and galvanic corrosion. Factors which could influence galvanic corrosion behaviors of tested samples were discussed based on area ratios of anode/cathode and cell potential driving force during the ZRA corrosion tests and boiling tests.

  5. Effect of Ultrasound Frequency on the Precipitation Process of Supersaturated Sodium Aluminate Solution

    Institute of Scientific and Technical Information of China (English)

    刘吉波; 陈金清; 尹周澜; 张平民; 陈启元

    2004-01-01

    The effects of frequency of ultrasound on the precipitation process of prepared supersaturatedsodium aluminate solutions of practical concentration were studied experimentally under seeded,isothermal, batch crystallization conditions at various temperatures and initial αk(mole ratio ofNa2O/Al2O3). The decomposition and the particle number percentage for size below 2 μm at time of 15 hwere compared, particle size distribution and SEM photos of the product aluminum hydroxide were alsoanalyzed. The results indicate that the ultrasonic treatment at 16 kHz can enhance the decomposition rateof sodium aluminate solutions, and also has effects on particle morphology and particle size distributionof aluminum hydroxide precipitated.

  6. Highly reflective and adhesive surface of aluminized polyvinyl chloride film by vacuum evaporation

    Science.gov (United States)

    Li, Denian; Tai, Qile; Feng, Qiang; Li, Qi; Xu, Xizhe; Li, Hairong; Huang, Jing; Dong, Lijie; Xie, Haian; Xiong, Chuanxi

    2014-08-01

    Aluminized poly(vinyl chloride) (PVC) film with high reflectivity and strong adhesion was facilely fabricated by vacuum evaporation. The technical study revealed that both alkali-pretreatment of the PVC matrix and thermal annealing after aluminization could greatly promote the peeling adhesion force of this metal/polymer composite by producing interfacial active chemical groups and removing the inner stress, respectively. Reflectivity test and AFM study indicated that the reflecting capacitance of the aluminum coating was closely related to the surface roughness, which can be easily controlled by modulating deposition of aluminum. Moreover, the formation of aluminum layer follows an island model process, and a continuous and smooth coating with highest reflectivity and lowest surface resistance was achieved at deposition time of 60 s. We anticipate that the cost-effective metallized PVC film by this strategy may find extensive applications in light harvesting, solar energy, and flexible mirrors, among others.

  7. The aluminization of 600k WLS fibers for the TileCal/ATLAS/LHC

    CERN Document Server

    Saraiva, J G; Maneira, M J P; Patriarca, J; Wemans, A

    2003-01-01

    The TILE CALorimeter, the hadronic sampling calorimeter of ATLAS/LHC /CERN, is made of iron and polystyrene scintillating tiles. The light produced in scintillating tiles is absorbed and guided to the photomultipliers (PMTs) through Wave Length Shifter (WLS) optical fibers. To optimize the detection of jets and muons, the top of the fibers away of the PMTs is coated with an aluminum mirror, that increases the light output in asymptotically equal to 75% and enhances the uniformity light output by asymptotically equal to 10%. The aluminum mirror is produced by Magnetron Sputtering, that adds to an excellent reproducibility a minimal thermal aggression important for proper film adhesion to the plastic surface. A dedicated machine for mass production of the ATLAS WLS aluminized fibers has been designed and constructed fulfilling the critical production optical and time requirements. The aluminization of the fibers and their quality control started in August 1999 and went on continuously until May 2002. The qualit...

  8. Relation between silico-aluminous fly ash and its coal of origin

    Institute of Scientific and Technical Information of China (English)

    Jean-Charles Benezet; Pierre Adamiec; Ali Benhassaine

    2008-01-01

    Fly ashes are typical complex solids which incorporate at the same time intrinsic properties derived from the layers (various mineralogical and dimensional spectra) and major transformations generated during prior processing. To use fly ashes in various applications, it is necessary to characterise them completely. The first research to date carried out on silico-aluminous fly ashes in order to characterise them physically,morphologically, chemically and mineralogically, resulted in the recognition that they are relatively simple materials. In the present study, a silico-aluminous fly ash coming from the power station of Albi (France) was selected. Heat treatment at 450 and 1200 ~C together with coal simulated the treatment undergone by coal in the power station in order to mimic real coal residue. In conclusion, the diversity of the particles contained in fly ash could only be explained by the relation existing between the fly ash and its coal of origin.

  9. Identification of the hydrate gel phases present in phosphate-modified calcium aluminate binders

    Energy Technology Data Exchange (ETDEWEB)

    Chavda, Mehul A.; Bernal, Susan A. [Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD (United Kingdom); Apperley, David C. [Solid-State NMR Group, Department of Chemistry, Durham University, Durham DH1 3LE (United Kingdom); Kinoshita, Hajime [Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD (United Kingdom); Provis, John L., E-mail: j.provis@sheffield.ac.uk [Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2015-04-15

    The conversion of hexagonal calcium aluminate hydrates to cubic phases in hydrated calcium aluminate cements (CAC) can involve undesirable porosity changes and loss of strength. Modification of CAC by phosphate addition avoids conversion, by altering the nature of the reaction products, yielding a stable amorphous gel instead of the usual crystalline hydrate products. Here, details of the environments of aluminium and phosphorus in this gel were elucidated using solid-state NMR and complementary techniques. Aluminium is identified in both octahedral and tetrahedral coordination states, and phosphorus is present in hydrous environments with varying, but mostly low, degrees of crosslinking. A {sup 31}P/{sup 27}Al rotational echo adiabatic passage double resonance (REAPDOR) experiment showed the existence of aluminium–phosphorus interactions, confirming the formation of a hydrated calcium aluminophosphate gel as a key component of the binding phase. This resolves previous disagreements in the literature regarding the nature of the disordered products forming in this system.

  10. The effect of Y2O3 addition on thermal shock behavior of magnesium aluminate spinel

    OpenAIRE

    Pošarac Milica; Devečerski A.; Volkov-Husović T.; Matović B.; Minić D.M.

    2009-01-01

    The effect of yttria additive on the thermal shock behavior of magnesium aluminate spinel has been investigated. As a starting material we used spinel (MgAl2O4) obtained by the modified glycine nitrate procedure (MGNP). Sintered products were characterized in terms of phase analysis, densities, thermal shock, monitoring the damaged surface area in the refractory specimen during thermal shock and ultrasonic determination of the Dynamic Young modulus of elasticity. It was found that a new phase...

  11. Aluminizing and subsequent nitriding of plain carbon low alloy steels for piston ring applications

    Energy Technology Data Exchange (ETDEWEB)

    Bindumadhavan, P.N.; Keng Wah, H.; Prabhakar, O. [Nanyang Technol. Univ., Singapore (Singapore). Div. of Mater. Eng.; Makesh, S. [Chemical and Nuclear Engineering Building, University of Maryland, 20783, College Park, MD (United States); Gowrishankar, N. [I P Rings Ltd., D 11/12, Industrial Estate, 603209, Maraimalainagar (India)

    2000-05-22

    Nitriding is a case hardening process that is commonly used for increasing the wear life of automotive piston rings. However, special alloy steels are required to achieve high surface hardness and nitrided case depth values required by the automotive industry. The cost of such alloy steels is one of the major components of the total cost of the nitrided piston ring. To address this issue, efforts have been directed towards development of cheaper raw materials as substitutes for nitridable steels. In this study, an attempt has been made to increase the surface hardness of two plain carbon low alloy steels by aluminizing and subsequent diffusion treatment and nitriding. The process parameters for the aluminizing operation are discussed. Results indicate that a near twofold increase in surface hardness is achievable by aluminizing followed by diffusion treatment and nitriding (580-1208 HV for EN32B steel and 650-1454 HV for 15CR3 steel). It has also been found that the nitrided case depth obtained (0.11-0.13 mm for EN32B steel and 0.10-0.14 mm for 15CR3 steel) matches well with the general requirements of the piston ring industry. The diffusion of aluminum into the alloy layer has also been discussed and the theoretical predictions were compared with actual values of Al concentration, as obtained by SEM-EDS system. It is found that Fick's law gives a fairly good prediction of the actual Al concentration profile, in spite of the complexity of the diffusion path. X-Ray diffraction studies have confirmed the presence of AlN in the alloy layer, which could be instrumental in the significant increase in surface hardness. It is proposed that aluminizing followed by diffusion treatment and nitriding of plain carbon low alloy steels could provide an alternative to the use of expensive nitridable steels for piston ring applications. (orig.)

  12. Production of Copper and Cobalt Aluminate Spinels and Their Application As Supports for Inulinase Immobilization

    OpenAIRE

    Abaide,Ederson Rossi; Anchieta,Chayene Gonçalves; Foletto,Vitória Segabinazzi; Reinehr,Beatriz; Nunes,Lucielle Ferreira; Kuhn,Raquel Cristine; Mazutti,Marcio Antonio; Foletto, Edson Luiz

    2015-01-01

    AbstractCopper and cobalt aluminates were obtained through the use of chitosan as template. In this synthesis route, chitosan is eliminated by heating, and a porous material is produced. These oxides were used as supports for inulinase immobilization by adsorption process. Physical properties of produced particles were analyzed by X-ray diffraction (XRD) and nitrogen adsorption-desorption isotherms. Both oxides presented particles containing mesoporous characteristics and high surface area, w...

  13. Microhardness Indentation Size Effect in Flux-grown Crystals of Rare Earth Aluminates

    Institute of Scientific and Technical Information of China (English)

    Jianghong GONG; Zhenduo GUAN

    2001-01-01

    The previously reported results of microhardness measurements on flux-grown crystals of rare earth aluminates were re-examined in this paper to explore the applicability of the proportional specimen resistance (PSR) model to describe the indentation size effect. It was found that the PSR model is insufficient for describing the experimental data and a modified form of this model was proposed based on the consideration of the effect of surface stress state on hardness testing.

  14. Lithium aluminates and tritium production; Aluminatos de litio y produccion de tritio

    Energy Technology Data Exchange (ETDEWEB)

    Carrera G, L.M.; Palacios G, O.; Bosch G, P. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1997-07-01

    In this work it is studied the crystalline structure of lithium aluminates prepared by three different methods, namely: solid state reaction, humid reaction and sol-gel reaction. The analysis methods are the X-ray diffractometry and the scanning and transmission electron microscopy. This study is realized as in original materials as in irradiated materials at the TRIGA Mark reactor, to correlate the synthesis method with response of these materials to the mixed irradiation of nuclear reactor. (Author)

  15. Effect of X-Rays on the Mechanical Properties of Aluminized FEP Teflon(trademark)

    Science.gov (United States)

    Gaier, James R.; Brinkmeier, Michael R.; Gaier, Elizabeth M.

    1999-01-01

    Pieces of the multilayer insulation (MLI) that is integral to the thermal control of the Hubble Space Telescope (HST) have been returned by two servicing missions after 3.6 and 6.8 years in orbit. They reveal that the outer layer, which is made from 5 mil (0.13 mm) thick aluminized fluorinated ethylenepropylene (FEP) Teflon. has become severely embrittled. Although possible agents of this embrittlement include electromagnetic radiation across the entire solar spectrum, trapped particle radiation, atomic oxygen, and thermal cycling, intensive investigations have not yielded unambiguous causes. Previous studies utilizing monoenergetic photons in the 69-1900 eV range did not cause significant embrittlement, even at much higher doses than were experienced by the HST MLI. Neither did x-rays in the 3 to 10 keV range generated in a modified electron bean evaporator. An antidotal aluminized FEP sample that was exposed to an intensive dose from unfiltered Mo x-ray radiation from a rotating anode generator, however, did show the requisite embrittlement. Thus, a study was undertaken to determine the effects of x-ray exposure on the embrittlement of aluminized FEP in hopes that it might elucidate the HST MLI degradation mechanism. Tensile specimens of aluminized 5 mil thick FEP were exposed to a constant fluence of unfiltered x-ray radiation from a Mo target whose maximum energy ranged from 20-60 kV. Other samples were annealed, thermally cycled (100x) between 77-333 K, or cycled and irradiated. Tensile tests and density measurements were then performed on the samples. Only the samples which had been irradiated had the drastically reduced elongation-to-break, characteristic of the HST samples. Thermal cycling may accelerate the embrittlement, but the effect was near the scatter in the measurements. Annealing and thermal cycling had no apparent effect. Only the samples which had been irradiated and annealed showed significant density increases, likely implicating polymer chain

  16. The Uses of Copper and Zinc Aluminates to Capture and Convert Carbon dioxide to Syn-gas at Higher Temperature

    Directory of Open Access Journals (Sweden)

    R.Y. Raskar

    2014-03-01

    Full Text Available The uses of copper and zinc aluminates to capture and convert the CO2 to syn-gas were studied at higher temperatures. The samples of copper and zinc aluminates were prepared by solid-solid fusion method by calcining in air at 900 oC for 3 h. Those samples were characterized by acidity/alkalinity, surface area, XRD pattern, IR, SEM images and screening to capture CO2 at the different temperatures. The phases Cu2O, CuO, ZnO, CuAl2O4 and ZnAl2O4 were found to be in the samples of zinc and copper aluminates. Acidity and surface area of the samples of copper and zinc aluminates were found to be in the ranges from 0.063 to 9.37 mmol g-1 and 3.04 to 11.8 m2 g-1, respectively. The captured CO2 by the samples of copper and zinc aluminates was found to be 19.92 to 31.52 wt% for the temperature range 40 to 850 oC. The captured CO2 at 550 oC by variable Zn/Al and Cu/Al mol ratio from 0.5 to 6 of the samples of copper and zinc aluminates was found to be 12.81 to 18.04 wt%. The reduction of carbon dioxide by zinc and copper aluminates was observed. The conversion of CO2 by methane over variable mol ratio of Cu/Al and Zn/Al in copper and zinc aluminates, respectively, at 500 oC showed the production of syn-gas by using the gas hourly space velocities (GHSV 12000, 12000 and 6000 ml. h-1. g-1 of helium, CO2 and methane. The conversions of CO2 by methane over the samples of zinc and copper aluminates were studied at different mol ratios of CO2 to methane.  © 2014 BCREC UNDIP. All rights reservedReceived: 13rd May 2013; Revised: 8th November 2013; Accepted: 8th November 2013[How to Cite: Raskar, R.Y., Gaikwad, A.G. (2014. The Uses of Copper and Zinc Aluminates to Cap-ture and Convert Carbon Dioxide to Syn-gas at Higher Temperature. Bulletin of Chemical Reaction Engineering & Catalysis, 9 (1: 1-15. (doi:10.9767/bcrec.9.1.4899.1-15[Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.1.4899.1-15

  17. The synthesis and spectroscopic characterisation of hydrotalcite formed from aluminate solutions.

    Science.gov (United States)

    Palmer, Sara J; Grand, Laure M; Frost, Ray L

    2011-06-01

    Raman spectroscopy has been used to characterise nine hydrotalcites prepared from aluminate and magnesium solutions (magnesium chloride and seawater). The aluminate hydrotalcites are proposed to have the following formula Mg(6)Al(2)(OH)(16)(CO(3)(2-))·xH(2)O, Mg(6)Al(2)(OH)(16)(CO(3)(2-),SO(4)(2-))·xH(2)O, and Mg(6)Al(2)(OH)(16)(SO(4)(2-))·xH(2)O. The synthesis of these hydrotalcites using seawater results in the intercalation of sulfate anions into the hydrotalcite interlayer. The spectra have been used to assess the molecular assembly of the cations and anions in the hydrotalcite structures. The spectra have been conveniently subdivided into spectral features based upon the carbonate anion, the hydroxyl units and water units. This investigation has shown the ideal conditions to form hydrotalcite from aluminate solutions is at pH 14 using a magnesium chloride solution at a volumetric ratio of 1:1. Changes in synthesis conditions resulted in the formation of impurity products aragonite, thenardite, and gypsum.

  18. The synthesis and spectroscopic characterisation of hydrotalcite formed from aluminate solutions

    Science.gov (United States)

    Palmer, Sara J.; Grand, Laure M.; Frost, Ray L.

    2011-06-01

    Raman spectroscopy has been used to characterise nine hydrotalcites prepared from aluminate and magnesium solutions (magnesium chloride and seawater). The aluminate hydrotalcites are proposed to have the following formula Mg 6Al 2(OH) 16(CO 32-)· xH 2O, Mg 6Al 2(OH) 16(CO 32-,SO 42-)· xH 2O, and Mg 6Al 2(OH) 16(SO 42-)· xH 2O. The synthesis of these hydrotalcites using seawater results in the intercalation of sulfate anions into the hydrotalcite interlayer. The spectra have been used to assess the molecular assembly of the cations and anions in the hydrotalcite structures. The spectra have been conveniently subdivided into spectral features based upon the carbonate anion, the hydroxyl units and water units. This investigation has shown the ideal conditions to form hydrotalcite from aluminate solutions is at pH 14 using a magnesium chloride solution at a volumetric ratio of 1:1. Changes in synthesis conditions resulted in the formation of impurity products aragonite, thenardite, and gypsum.

  19. Zinc-aluminates for an in situ sulfur reduction in cracked gasoline

    Energy Technology Data Exchange (ETDEWEB)

    Quintana-Solorzano, R.; Valente, J.S.; Hernandez-Beltran, F.J.; Castillo-Araiza, C.O. [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas Norte 152 C.P., 07730 Mexico, D.F. (Mexico)

    2008-05-30

    Using additives remains as an attractive alternative for an in situ sulfur reduction in cracked gasoline since it is a practical, flexible and economical option. Zinc-aluminates prepared by the sol-gel method are used as additives for reducing sulfur in gasoline from the cracking of a high-sulfur feed in a fixed-bed bench reactor. Products distribution and feed conversion are not dramatically altered after incorporating the additive to the base catalyst with some effect on gasoline and its octane number and coke. A decrease in the gasoline sulfur content of up to 35 wt% including benzothiophene, and up to 50% excluding benzothiophene, is observed when blending the zinc-aluminates to the base catalyst, which is caused by lowering the C{sub 1} to C{sub 4} alkyl-thiophenes content. The zinc content of the zinc-aluminates has a positive effect on the gasoline sulfur reduction. It is suggested that together with the direct cracking of adsorbed thiophenic species on the additive, a further gasoline sulfur decrease is possible through cracking of saturated thiophenic species formed by hydrogenation of adsorbed thiophenic species with hydrogen produced in situ in the additive. The obtained results also demonstrate that solids with higher Lewis acidity are not unfailingly the most effective for gasoline sulfur reduction. (author)

  20. Development of LiCl-containing calcium aluminate cement for bone repair and remodeling applications.

    Science.gov (United States)

    Acuña-Gutiérrez, I O; Escobedo-Bocardo, J C; Almanza-Robles, J M; Cortés-Hernández, D A; Saldívar-Ramírez, M M G; Reséndiz-Hernández, P J; Zugasti-Cruz, A

    2017-01-01

    The effect of LiCl additions on the in vitro bioactivity, hemolysis, cytotoxicity, compressive strength and setting time of calcium aluminate cements was studied. Calcium aluminate clinker (AC) was obtained via solid state reaction from reagent grade chemicals of CaCO3 and Al2O3. Calcium aluminate cements (CAC) were prepared by mixing the clinker with water or aqueous LiCl solutions (0.01, 0.0125 or 0.015M (M)) using a w/c ratio of 0.4. After 21days of immersion in a simulated body fluid (SBF) at physiological conditions of temperature and pH, a Ca-P rich layer, identified as hydroxyapatite (HA), was formed on the cement without LiCl and on the cement prepared with 0.01M of LiCl solution. This indicates the high bioactivity of these cements. The cements setting times were significantly reduced using LiCl. The measured hemolysis percentages, all of them lower than 5%, indicated that the cements were not hemolytic. The compressive strength of the cements was not negatively affected by the LiCl additions. The obtained cement when a solution of LiCl 0.010M was added, presented high compressive strength, appropriated bioactivity, no cytotoxicity and low setting time, making this material a potentially bone cement.

  1. Microstructure characterization of oxidation of aluminized coating prepared by a combined process

    Energy Technology Data Exchange (ETDEWEB)

    Liu, H.B. [College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016 (China); Tao, J. [College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016 (China)], E-mail: taojie@nuaa.edu.cn; Xu, J.; Chen, Z.F.; Sun, X.J.; Xu, Z. [College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016 (China)

    2008-08-31

    Alumina layer is a good candidate for the tritium penetration barrier that is important in the control of tritium losses due to permeation through structural materials used in high-temperature gas-cooled reactors and in fusion reactors. This paper describes the microstructure of the oxide film of the tritium penetration barrier formed on 316L stainless steel, which was prepared by a combined process, namely, aluminizing and oxidizing treatments using a double glow plasma technology. Microstructure and phase structure of the coatings investigated were examined by scanning electronic microscope (SEM), X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM), respectively. The chemical composition and the chemical states of Al, O elements in the oxidation film were identified by X-ray photoelectron spectroscopy (XPS). After aluminization, the typical microstructure of the coating mainly consisted of an outer high aluminum-containing intermetallic compound layer (Fe{sub 2}Al{sub 5} and FeAl) and intermediate ferritic stainless steel ({alpha} Fe(Al))layer followed by the austenitic substrate. After the combined process, an oxide layer that consisted of Al{sub 2}O{sub 3} and spinel FeAl{sub 2}O{sub 4} had been successfully formed on the aluminizing coating surface, with an amorphous outmost surface and an underlying subsurface nanocrystalline structure.

  2. Structure and mechanical properties of ceramic coatings fabricated by plasma electrolytic oxidation on aluminized steel

    Science.gov (United States)

    Wu, Zhenqiang; Xia, Yuan; Li, Guang; Xu, Fangtao

    2007-08-01

    Ceramic coatings were formed by plasma electrolytic oxidation (PEO) on aluminized steel. Characteristics of the average anodic voltages versus treatment time were observed during the PEO process. The micrographs, compositions and mechanical properties of ceramic coatings were investigated. The results show that the anodic voltage profile for processing of aluminized steel is similar to that for processing bulk Al alloy during early PEO stages and that the thickness of ceramic coating increases approximately linearly with the Al layer consumption. Once the Al layer is completely transformed, the FeAl intermetallic layer begins to participate in the PEO process. At this point, the anodic voltage of aluminized steel descends, and the thickness of ceramic coating grows more slowly. At the same time, some micro-cracks are observed at the Al 2O 3/FeAl interface. The final ceramic coating mainly consists of γ-Al 2O 3, mullite, and α-Al 2O 3 phases. PEO ceramic coatings have excellent elastic recovery and high load supporting performance. Nanohardness of ceramic coating reaches about 19.6 GPa.

  3. Effect of Ga2O3 on Structure and Properties of Calcium Aluminate Glasses

    Institute of Scientific and Technical Information of China (English)

    WANG Yanhang; ZU Chengkui; HE Kun; ZHAO Huifeng; LIU Yonghua

    2016-01-01

    The effect of Ga2O3 on the structure and properties of calcium aluminate glasses fabricated by vacuum melting process was investigated by Raman spectrum, differential scanning calorimeter (DSC), and infrared spectrum methods. The results show that calcium aluminate glass network only consists of [AlO4] tetrahedral units. With the gradual addition of Ga2O3, the quantity of [GaO4] tetrahedral units increases. Substitution of Ga2O3 for Al2O3 results in a decrease inTg,Tx, andTp, and an increase in the thermal stable indexΔT. Similarly, the absorption band around 3.0 μm obviously reduces and the transparency in 4.0-6.0 μm rapidly increases with increasing Ga2O3 content. However, the chemical stability of calcium aluminate glasses decreases if Ga2O3 is introduced due to the increasing of [GaO4] units in the glass network.

  4. IMPACT OF ALUMINATE IONS ON THE PROPERTIES OF SALTSTONE GROUT MIXES

    Energy Technology Data Exchange (ETDEWEB)

    Harbour, J; Tommy Edwards, T; Erich Hansen, E; Vickie Williams, V

    2008-02-21

    It is important to identify and control the operational and compositional variables that impact the important processing and performance properties of Saltstone grout mixes. The grout that is produced at the Saltstone Production Facility (SPF) is referred to as Saltstone and is a waste form that immobilizes low concentrations of radionuclides as well as certain toxic metals. The Saltstone will be disposed of in vaults at Savannah River Site (SRS). An effort referred to as the Saltstone Variability Study has been initiated to achieve this goal. The protocols developed in this variability study are also ideally suited as a tool to assess the impact of proposed changes to the processing flow sheet for Liquid Waste Operations at SRS. One such proposal that is currently under consideration is to introduce a leaching step in the treatment of the High Level Waste (HLW) sludge to remove aluminum prior to vitrification at the Defense Waste Processing Facility (DWPF). This leachate would significantly increase the soluble aluminate concentration in the salt feed that will be processed at the SPF. Consequently, an initial study of the impact of increased aluminate concentration on the Saltstone grout properties was performed. Prior work by Lukens (1) showed that aluminate in the salt solutions increases the amount of heat generation.

  5. High-resolution /sup 27/Al NMR study of calcium aluminate catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Yakerson, V.I.; Nissenbaum, V.D.; Golosman, E.Z.; Mastikhin, V.M.

    1987-06-01

    The high-resolution /sup 27/Al NMR spectra of calcium aluminates, calcium hydroaluminates, and calcium alumina supports and catalysts have been studied. The structures of the anhydrous calcium aluminates (CaAl/sub 2/O/sub 3/, CaAl/sub 4/O/sub 7/, 3CaO x Al/sub 2/O/sub 3/, 12CaO x 7Al/sub 2/O/sub 3/, talyum) consist of aluminum-oxygen tetrahedra and contain various types of aluminum atoms, the nonequivalence of which increases in going from strongly basic to weakly basic aluminates. In the NMR spectrum the signal of octahedrally coordinated aluminum is due to disordered aluminum-oxygen structures. During the forming of the calcium-alumina catalysts and supports the process (AlO/sub 4/) ..-->.. (AlO/sub 6/) takes place during hydration, and (AlO/sub 6/) ..-->.. (AlO/sub 4/) during thermolysis; the nonequivalence of the tetrahedrally coordinated aluminum atoms decreases, while the (AlO/sub 4/):(AlO/sub 6/) ratio decreases as the degree of hydration increases.

  6. The stabilities of gibbsite, boehmite, aluminous goethites and aluminous hematites in bauxites, ferricretes and laterites as a function of water activity, temperature and particle size

    Science.gov (United States)

    Trolard, Fabienne; Tardy, Yves

    1987-04-01

    Stability relationships between Al-goethite, Al-hematite, boehmite and gibbsite are presented in terms of water activity [H 2O], temperature ( T), grain size and bulk-composition in the system Fe 2O 3-Al 2O 3-H 2O at a total pressure of 1 bar. Al-goethite and Al-hematite are treated as ideal solid solutions, the former of the end-members FeOOH (goethite) and AlOOH (diaspore) and the latter of the end-members Fe 2O 3 (hematite) and Al 2O 3 (corundum). Using log K sp provided by the literature for the various phases involved, the common associations observed in laterites, bauxites and ferricretes do not have stability fields over geologically reasonable intervals of [H 2O] and T. Consequently a new internally consistent set of log Ksp values is proposed and used, and allows such associations to have actual stability fields in the appropriate diagrams. The new log Ksp values used in the calculations are such that the solubilities of the end members are greater than those commonly listed. This is in agreement with natural observations which show that such minerals, are generally poorly crystallized and of very small size. The assumption of an ideal solid solution in aluminous goethite and aluminous hematite combined with the new log Ksp values leads to prediction of composition limits for these two minerals which agree well with observed values. The fact that an ideal solid solution must extend continuously from one end-member to the other is masked by the appearance of other stability fields ( e.g. gibbsite or boehmite) which cross and overlap a part of the solid solution stability fields of AlOOH-FeOOH and Fe 2O 3-Al 2O 3.

  7. Development of an aluminized multi-phase steel with dual phase properties for high temperature corrosion resistance applications

    Energy Technology Data Exchange (ETDEWEB)

    Mahieu, J.; Cooman, B.C. de [Lab. for Iron and Steelmaking, Dept. of Metallurgy and Materials Science, Ghent Univ., Zwijnaarde (Belgium); Maki, J. [Yawata R and D Lab., Nippon Steel Corp. (Japan); Fiorucci, M. [Galvalange Sarl, Dudelange (Luxembourg); Claessens, S. [OCAS NV, Zelzate (Belgium)

    2003-04-01

    A high strength, high Mn, Cr-Mo containing multi-phase steel grade was aluminized with a 90 wt% Al-10 wt% Si alloy coating, using a laboratory hot-dip simulator. The adhesion of the coating to the steel strip was evaluated and the microstructure of the as deposited material was assessed. The coated sheet steel was tested at high temperatures by monitoring the weight gain of the samples and their mechanical properties as a function of time. It was found that the thermal properties of the aluminized sheet were excellent. The analysis of the coating/substrate interface revealed the dissolution of brittle intermetallic phases, explaining the excellent high temperature resistance performance of the Al-Si coating up to temperatures as high as 900 C. In addition, the use of a continuous annealing cycle common in current aluminizing lines, resulted in a dual phase microstructure. (orig.)

  8. Calcium aluminate coated and uncoated free form fabricated CoCr implants: a comparative study in rabbit.

    Science.gov (United States)

    Palmquist, A; Jarmar, T; Hermansson, L; Emanuelsson, L; Taylor, A; Taylor, M; Engqvist, H; Thomsen, P

    2009-10-01

    The purpose of this study was to compare the integration in bone of uncoated free form fabricated cobalt chromium (CoCr) implants to the same implant with a calcium aluminate coating. The implants of cylindrical design with a pyramidal surface structure were press-fit into the limbs of New Zealand white rabbits. After 6 weeks, the rabbits were sacrificed, and samples were retrieved and embedded. Ground sections were subjected to histological analysis and histomorphometry. The section counter part was used for preparing an electron transparent transmission electron microscopy sample by focused ion beam milling. Calcium aluminate dip coating provided a significantly greater degree of bone contact than that of the native CoCr. The gibbsite hydrate formed in the hardening reaction of the calcium aluminate was found to be the exclusive crystalline phase material in direct contact with bone.

  9. Methods of use of calcium hexa aluminate refractory linings and/or chemical barriers in high alkali or alkaline environments

    Science.gov (United States)

    McGowan, Kenneth A; Cullen, Robert M; Keiser, James R; Hemrick, James G; Meisner, Roberta A

    2013-10-22

    A method for improving the insulating character/and or penetration resistance of a liner in contact with at least one of an alkali and/or alkaline environments is provided. The method comprises lining a surface that is subject to wear by an alkali environment and/or an alkaline environment with a refractory composition comprising a refractory aggregate consisting essentially of a calcium hexa aluminate clinker having the formula CA.sub.6, wherein C is equal to calcium oxide, wherein A is equal to aluminum oxide, and wherein the hexa aluminate clinker has from zero to less than about fifty weight percent C.sub.12A.sub.7, and wherein greater than 98 weight percent of the calcium hexa aluminate clinker having a particle size ranging from -20 microns to +3 millimeters, for forming a liner of the surface. This method improves the insulating character/and or penetration resistance of the liner.

  10. Calcium Hex aluminate reaction sintering by Spark Plasma Sintering; Sinterizacion reactiva de Hexaluminato de Calcio mediante Spark Plasma Sintering

    Energy Technology Data Exchange (ETDEWEB)

    Iglesia, P. G. de la; Garcia-Moreno, O.; Torrecillas, R.; Menendez, J. L.

    2012-11-01

    Calcium hex aluminate (CaAl{sub 1}2O{sub 1}9) is the most alumina-rich intermediate compound of the CaO-Al{sub 2}O{sub 3} system. The formation of this aluminate is produced by the reaction between calcium oxide and alumina with the consequent formation of intermediates compounds with lower alumina content with increasing temperature (CaAl{sub 2}O{sub 4}, CaAl4O{sub 7}). In this study we studied the variation of sintering parameters for obtaining dense and pure calcium hex aluminate by reaction sintering by Spark Plasma Sintering (SPS). A mixing of Al{sub 2}O{sub 3} and CaCO{sub 3} were used as reactive. Final densities close to the theoretical and phase transformation over 93% were achieved by this method. (Author) 22 refs.

  11. SODIUM CITRATE INFLUENCE ON FORMATION OF CEMENT STONE IN THE ALUMINOUS BINDER

    Directory of Open Access Journals (Sweden)

    S. N. Leonovich

    2016-01-01

    Full Text Available The paper deals with the effect of sodium citrate on the formation of a cement stone in the aluminous binder. Formation of cement stone framework in cement hydraulic binder is accompanied with complicated physical and chemical processes of interphase interactions and dispersion, these processes are predicated on qualitative and quantitative composition of the cement mortar, continuous changes in its properties from preparation stage till curing. Addition of sodium citrate to tempering water enhances hydration of both Portland cement and calcium aluminate cement. Process pertaining to an increase of cement hydration rate is considered as a consequence of destruction in surface formations and exclusion of damping effect in respect of hydration rate and hydrolysis of products resulted from interaction of clinker material with tempering. It has been established that sodium citrate makes it possible to control processes of hydration, hydrolysis, binding and curing for cement mass. High degree of hydration of aluminous cement in the presence of sodium citrate provides fast binding and curing of binder, low porosity and rather high compression breaking strength of cement stone for all curing stages. An increase in concentration of sodium citrate in cement mixture up to 10 % of the cement mass exerts an influence not only on the process of cement mortar liquefaction, reduction of time for cement mass setting and hardening but also increases compression strength of cement stone. An analysis of the structure for cleavage surface of cement stone gives ground to declare that the addition of sodium citrate provides cement stone sealing and reduces its water absorption.

  12. The morphology of coating/substrate interface in hot-dip-aluminized steels

    Energy Technology Data Exchange (ETDEWEB)

    Awan, Gul Hameed [Metallurgical and Materials Engineering Department, University of Engineering and Technology, Lahore 54890 (Pakistan); Hasan, Faiz ul [Metallurgical and Materials Engineering Department, University of Engineering and Technology, Lahore 54890 (Pakistan)], E-mail: drfaiz@uet.edu.pk

    2008-01-15

    In hot-dip-aluminized (HAD) steels, the morphology and the profile of the interface between the aluminum coating and the substrate steel, are affected both by the composition of the molten aluminum as well as by the composition, and even the microstructure, of the substrate steel. This effect has been investigated using optical and scanning electron microscopy, and X-ray diffraction. The reaction between the steel and the molten aluminum leads to the formation of Fe-Al inter-metallic compounds on the steel surface. The thickness of the inter-metallic compound layer as well as the morphology of the interface between the steel and the interlayer varies with the silicon content of the molten aluminum. In hot-dip-aluminizing with pure aluminum, the interlayer is 'thick' and exhibits a finger-like growth into the steel. With a gradually increasing addition of silicon into the aluminum melt, the thickness of the interlayer decreases while the interface between the interlayer and the substrate gradually becomes 'smoother'. With an increase in the carbon content of the substrate steel the growth of the interlayer into the steel is impeded by the pearlite phase, whereas the ferrite phase appears to dissolve more readily. X-ray diffraction and electron microscopic studies showed that the interlayer formed in samples aluminized in pure aluminum, essentially consisted of orthorhombic Fe{sub 2}Al{sub 5}. It was further observed that the finger-like grains of Fe{sub 2}Al{sub 5} phase exhibited a preferred lattice orientation. With a gradual addition of silicon into the aluminum melt, a cubic phase based on Fe{sub 3}Al also started to form in the interlayer and replaced most of the Fe{sub 2}Al{sub 5}.

  13. The effect of Y2O3 addition on thermal shock behavior of magnesium aluminate spinel

    Directory of Open Access Journals (Sweden)

    Pošarac Milica

    2009-01-01

    Full Text Available The effect of yttria additive on the thermal shock behavior of magnesium aluminate spinel has been investigated. As a starting material we used spinel (MgAl2O4 obtained by the modified glycine nitrate procedure (MGNP. Sintered products were characterized in terms of phase analysis, densities, thermal shock, monitoring the damaged surface area in the refractory specimen during thermal shock and ultrasonic determination of the Dynamic Young modulus of elasticity. It was found that a new phase between yttria and alumina is formed, which improved thermal shock properties of the spinel refractories. Also densification of samples is enhanced by yttria addition.

  14. Water-sensitive positron trapping modes in nanoporous magnesium aluminate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Filipecki, J [Institute of Physics of Jan Dlugosz University, 13/15, al. Armii Krajowej, Czestochowa, PL 42201 (Poland); Ingram, A [Opole University of Technology, 75, Ozimska str., Opole, PL 45370 (Poland); Klym, H [Institute of Materials of SRC ' Carat' , 202, Stryjska str., Lviv, UA 79031 (Ukraine); Shpotyuk, O [Institute of Materials of SRC ' Carat' , 202, Stryjska str., Lviv, UA 79031 (Ukraine); Vakiv, M [Institute of Materials of SRC ' Carat' , 202, Stryjska str., Lviv, UA 79031 (Ukraine)

    2007-08-15

    The water-sensitive positron trapping modes in nanoporous MgAl{sub 2}O{sub 4} ceramics with a spinel structure are studied. It is shown that water-sorption processes in magnesium aluminate ceramics leads to corresponding increase in positron trapping rates of extended defects located near intergranual boundaries. This catalytic affect has reversible nature, being strongly dependent on sorption water fluxes in ceramics. The fixation of all water-dependent positron trapping inputs allow to refine the most significant changes in positron trapping rate of extended defects.

  15. Characterization of irregular seeds on gibbsites precipitated from caustic aluminate solutions

    Institute of Scientific and Technical Information of China (English)

    CHEN Guo-hui; CHEN Qi-yuan; YIN Zhou-lan; YIN Zhi-min

    2006-01-01

    The irregular surface of seeds on which gibbsites are precipitated from caustic aluminate solutions, was investigated according to the fractal theory. Two kinds of fractal dimensions were used to characterize these irregularity. Box-dimension and spectral dimension are based on the SEM images of seeds and diffusive dynamic equation ofthe precipitation respectively. Both these two dimensions are affected by the reaction temperature, evolved with different reaction conditions and can reflect the influence of irregularity of seeds on the precipitation rate. Box dimension is fit for the characterization of the irregular morphology of seeds, while spectral dimension can explain the fractal dynamic behavior.

  16. Nucleation during gibbsites precipitation with seeds from sodium aluminate solution processed under ultrasound

    Institute of Scientific and Technical Information of China (English)

    陈国辉; 陈启元; 尹周澜; 张斌

    2004-01-01

    The secondary nucleation during gibbsite precipitation with seeds from sodium aluminate solution processed by ultrasound was examined by particle size distribution(PSD) analyses. Experiments indicate that at low temperature(<65 ℃ ) and with low frequency ultrasound, the precipitation efficiency and also the secondary nucleation can be improved. Solution processed by low frequency ultrasound has more nuclei than common liquor does at low temperature. At 55 ℃, precipitation efficiency can he improved by 5.31 %, and the effect promoted by low frequency ultrasound decreases with the increase of temperature.

  17. Effect of X-Rays on the Mechanical Properties of Aluminized FEP Teflon(R)

    Science.gov (United States)

    Gaier, James R.; Brinkmeier, Michael R.; Gaier, Elizabeth M.

    1998-01-01

    Pieces of the multilayer insulation (MLI) that is integral to the thermal control of the Hubble Space Telescope (HST) have been returned by two servicing missions after 3.6 and 6.8 years in orbit. They reveal that the outer layer, which is made from 5 mil (0.13 mm)thick aluminized fluorinated ethylene propylene(FEP) Teflon(R), has become severely embrittled. Although possible agents of this embrittlement include electromagnetic radiation across the entire solar spectrum, trapped particle radiation, atomic oxygen, and thermal cycling, intensive investigations have not yielded unambiguous causes. Previous studies utilizing monoenergetic photons in the 69-1900 eV range did not cause significant embrittlement, even at much higher doses than were experienced by the HST MLI. Neither did x-rays in the 3 to 10 keV range generated in a modified electron beam evaporator. An antidotal aluminized FEP sample that was exposed to an intensive dose from unfiltered Mo x-ray radiation from a rotating anode generator, however, did show the requisite embrittlement. Thus, a study was undertaken to determine the effects of x-ray exposure on the embrittlement of aluminized FEP in hopes that it might elucidate the HST MLI degradation mechanism. Tensile specimens of aluminized 5 mil thick FEP were exposed to a constant fluence of unfiltered x-ray radiation from a Mo target whose maximum energy ranged from 20-60 kV. Other samples were annealed, thermally cycled (100x) between 77-333 K, or cycled and irradiated. Tensile tests and density measurements were then performed on the samples. Only the samples which had been irradiated had the drastically reduced elongation-to-break, characteristic of the HST samples. Thermal cycling may accelerate the embrittlement, but the effect was near the scatter in the measurements. Annealing and thermal cycling had no apparent effect. Only the samples which had been irradiated and annealed showed significant density increases, likely implicating polymer

  18. Conduction calorimetric studies of ternary binders based on Portland cement, calcium aluminate cement and calcium sulphate

    OpenAIRE

    Torrens Martín, David; Fernández Carrasco, Lucía; Blanco Varela, M.Teresa

    2013-01-01

    Different binders of Portland cement, calcium aluminate cement and calcium sulphate (PC/CAC/CS) have been investigated to determinate the in¿uence the CAC and CS amount in the reactions mechanism. Several mixtures were studied, ratios of 100, 85/15 and 75/25 of PC/CAC with 0, 3 and 5 % of CS. Conduction calorimetric technique was used to follow the hydration during 100 h. The XRD and FTIR techniques were used as support in the analysis of the hydration products. The results have shown tha...

  19. CORROSION RESISTANT CERAMIC COATING FOR X80 PIPELINE STEEL BY LOW-TEMPERATURE PACK ALUMINIZING AND OXIDATION TREATMENT

    OpenAIRE

    HUANG MIN; FU QIAN-GANG; WANG YU; ZHONG WEN-WU

    2013-01-01

    In this paper, we discuss the formation of ceramic coatings by a combined processing of low-temperature pack aluminizing and oxidation treatment on the surface of X80 pipeline steel substrates in order to improve the corrosion resistance ability of X80 pipeline steel. First, Fe-Al coating consisting of FeAl3 and Fe2Al5 was prepared by a low-temperature pack aluminizing at 803 K which was fulfilled by adding zinc in the pack powder. Pre-treatment of X80 pipeline steel was carried out through s...

  20. Criterion for selection the optimal physical and chemical properties of cobalt aluminate powder used in investment casting process

    OpenAIRE

    M. Zielińska; J. Sieniawski; B. Gajecka

    2009-01-01

    The aim of this work was to determine physical and chemical properties of cobalt aluminate (CoAl2O4) modifiers produced by different companies and the influence of different types of modifiers on the grain size of high temperature creep resisting superalloys: Inconel 713C, René 77 and MAR-M 509.The first stage of the research work took over the investigations of physical and chemical properties of cobalt aluminate manufactured by three different companies: Remet, Mason Color and Permedia Lubl...

  1. Synthesis and Characterization of Porous Magnesium Aluminate Spinel by Hydrothermal Process

    Institute of Scientific and Technical Information of China (English)

    WANG Xiuhui; DUAN Jinxia; LU Shengbo; YIN Jianlong; SU Zhenguo; GAO Hong; YANG Jinlong

    2015-01-01

    Magnesium aluminate spinel has a great prospect in catalyst supports due to the porousstructure, good cata-lytic activity, high thermal stability and the presence of two active centers as acid and alkaline. The magnesium alumi-nate spinel powders were synthesized by a hydrothermal process. The samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and N2adsorption-desorption isotherms, respectively. The particle surface with the laminated structure increases with the increase of hydrothermal temperature and hydro-thermal time. The spinel has a worm-like porous structure, and the pores become smaller and well-distributed under hexadecyl trimethyl ammonium bromide condition. The phase of the spinel appears at 450°C and the perfect crystalline structure emerges at 600°C. The percentage of MgAl2O4spinel increases with the increase of heat treatment temperature. The spinel has a great specific surface area (i.e., 245.68–58.65 m2/g) when the calcinating temperature increases from 500 to 1200°C. Moreover, the specific surface area is 195.11 m2/g 1 at.% hexadecyl trimethyl ammonium bromide.

  2. Synthesis and Characterization of Porous Magnesium Aluminate Spinel by Hydrothermal Process

    Institute of Scientific and Technical Information of China (English)

    WANG; Xiuhui; DUAN; Jinxia; LU; Shengbo; YIN; Jianlong; SU; Zhenguo; GAO; Hong; YANG; Jinlong

    2015-01-01

    Magnesium aluminate spinel has a great prospect in catalyst supports due to the porous structure, good catalytic activity, high thermal stability and the presence of two active centers as acid and alkaline. The magnesium aluminate spinel powders were synthesized by a hydrothermal process. The samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and N2 adsorption-desorption isotherms, respectively. The particle surface with the laminated structure increases with the increase of hydrothermal temperature and hydrothermal time. The spinel has a worm-like porous structure, and the pores become smaller and well-distributed under hexadecyl trimethyl ammonium bromide condition. The phase of the spinel appears at 450°C and the perfect crystalline structure emerges at 600°C. The percentage of Mg Al2O4 spinel increases with the increase of heat treatment temperature. The spinel has a great specific surface area(i.e., 245.68–58.65 m2/g) when the calcinating temperature increases from 500 to 1200°C. Moreover, the specific surface area is 195.11 m2/g 1 at.% hexadecyl trimethyl ammonium bromide.

  3. Growth and characterisation of epitaxially ordered zinc aluminate domains on c-sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Grabowska, J.; Rajendra Kumar, R.T. [School of Physical Sciences/National Centre for Plasma Science and Technology, Dublin City University (Ireland); McGlynn, E. [School of Physical Sciences/National Centre for Plasma Science and Technology, Dublin City University (Ireland)], E-mail: enda.mcglynn@dcu.ie; Nanda, K.K. [School of Physical Sciences/National Centre for Plasma Science and Technology, Dublin City University (Ireland); Newcomb, S.B. [Glebe Scientific Ltd., Newport, Co. Tipperary (Ireland); McNally, P.J.; O' Reilly, L. [School of Electronic Engineering/Research Institute for Networks and Communications Engineering, Dublin City University (Ireland); Mosnier, J.-P.; Henry, M.O. [School of Physical Sciences/National Centre for Plasma Science and Technology, Dublin City University (Ireland)

    2008-02-29

    Epitaxially ordered zinc aluminate domains with sub-micron dimensions are formed on bare c-sapphire substrates using a vapour phase method (with vapour generated by carbothermal reduction of ZnO) at various temperatures and growth durations. A zinc aluminate (ZnAl{sub 2}O{sub 4}) layer is formed by reaction of the source materials (Zn and O) with the substrate. We observe crystallites with a well-defined epitaxial relationship on the sapphire substrate in addition to polycrystalline material. The epitaxially oriented deposit displays the form of characteristically twinned (singly or multiply) grains of sub-micron dimensions with three variants, consistent with the c-sapphire substrate symmetry. Scanning electron microscopy and transmission electron microscopy studies show that the formation of these grains is associated with the presence of extended defects in the sapphire substrate. Epitaxially ordered grains formed at higher temperatures show a change in the nature of the twin boundaries and epitaxial relations as a function of growth time, attributed to the effects of annealing during growth.

  4. Dynamic Mechanical Properties and Constitutive Relation of an Aluminized Polymer Bonded Explosive at Low Temperatures

    Directory of Open Access Journals (Sweden)

    Yuliang Lin

    2014-01-01

    Full Text Available Polymer bonded explosives (PBXs are widely used as energetic fillings in various warheads, which maybe are utilized under extreme environments, such as low or high temperatures. In this paper, the dynamic response of an aluminized polymer bonded explosive was tested at a range of temperatures from −55°C to −2°C and a fixed loading strain rate (~700 s−1 with the split Hopkinson pressure bar (SHPB. The PBX tested is aluminized, which contains 76 wt% RDX, 20 wt% aluminum powder, and 4 wt% polymer binder, respectively. The results show that the effect of temperature on the strength of the PBX is obvious at the tested strain rates. Based on the experimental results and prophase studies, a constitutive model was obtained, in which the effect of temperature and strain rate were considered. The modeling curves fit well with the experimental results, not only at low temperature under 0°C, but also at room temperature (20°C. The model may be used to predict the dynamic performances of the PBXs in various environments.

  5. Effect of resorbable calcium aluminate ceramics on regulation of calcium and phosphorus in rats.

    Science.gov (United States)

    Carvalho, B A; Bajpai, P K; Graves, G A

    1976-06-01

    Ions released from resorbable ceramics could be toxic to the animal. Experiments were designed to study the effect of implanting three different weights of porous resorbable calcium aluminate ceramics (0.172, 0.332, and 0.504 g) in rats for a total duration of 300 days. Gross and microscopic examination of heart, liver, kidneys, trachea with thyroid, and muscle adjacent to the implant did not show any pathological changes. Calcium and inorganic phosphate content of bone, serum and urine were not affected by the implants. Urine hydroxyproline excretion did not change in the animals implanted with ceramics. Animals implanted with 0.332 g of ceramics had a significantly higher serum alkaline phosphatase activity than the control animals. Resorption of calcium and depositon of inorganic phosphates in the implanted ceramics suggested that ions were being exchanged with the body fluids. Implantation of 0.172 to 0.332 g porous resorbable calcium aluminate ceramic was not toxic to the animal.

  6. Synthesis and characterization of nickel/barium hexa-aluminate composite coatings

    Indian Academy of Sciences (India)

    Dinesh Kumar; Sampada Gurav; Vikram Jayaram; Sanjay Kumar Biswas

    2012-11-01

    Electrodeposition of nickel/barium hexa-aluminate (Ni/BHA) composite coatings has been carried out from a Watt’s bath on mild steel substrate. BHA powders with plate habit were synthesized by solution combustion synthesis followed by heat treatment to ensure complete conversion to the hexa-aluminate phase. Heat treated material was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) combined with X-ray analysis. The dispersion behaviour and stability of BHA suspensions with cationic and anionic surfactants at room temperature were studied by dynamic light scattering under different pH. The influence of BHA concentration in the electrolytic bath, deposition temperature, pH, current density and duty cycle on particle incorporation in the coatings were studied and conditions for maximum particle incorporation were established. Coatings with a roughness of about 0.4 m were produced by using this technique. Effect of BHA content on microhardness was also investigated. A reasonably good thickness of the coatings was achieved in a given set of conditions.

  7. Effect Of Heat Treatment On The Corrosion Resistance Of Aluminized Steel Strips

    Directory of Open Access Journals (Sweden)

    Żaba K.

    2015-09-01

    Full Text Available The paper presents the results of corrosion resistance of heat treated aluminized steel strips. Products coated by Al-10Si alloy are used among others in a manufacturing process of welded pipes as the elements of the car exhaust systems, working in high temperatures and different environments (eg. wet, salty. The strips and tubes high performance requirements are applied to stability, thickness and roughness of Al-Si coating, adhesion and corrosion resistance. Tubes working in elements of exhaust systems in a wide range of temperatures are exposed to the effects of many aggressive factors, such as salty snow mud. It was therefore decided to carry out research on the impact of corrosion on the environmental influence on heat treated aluminized steel strips. The heat treatment was carried out temperatures in the range 250-700°C for 30, 180, 1440 minutes. Then the coatings was subjected to cyclic impact of snow mud. Total duration of treatment was 12 months and it was divided into three stages of four months and at the end of each stage was made the assessment of factor of corrosion. The results are presented in the form of macroscopic, microscopic (using a scanning electron microscope observations and the degree and type of rusty coating.

  8. Reaction temperature variations on the crystallographic state of spinel cobalt aluminate.

    Science.gov (United States)

    Taguchi, Minori; Nakane, Takayuki; Hashi, Kenjiro; Ohki, Shinobu; Shimizu, Tadashi; Sakka, Yoshio; Matsushita, Akiyuki; Abe, Hiroya; Funazukuri, Toshitaka; Naka, Takashi

    2013-05-21

    In this study, we report a rapid and simple technique for obtaining cobalt aluminate having a spinel structure. The products were prepared from a hydroxide precursor synthesized by coprecipitation of cobalt (Co(2+)) and aluminum (Al(3+)) nitrates with an alkaline solution. The chosen precursor enabled low temperature fabrication of cobalt aluminate with a spinel structure by sintering it for 2 hours at low temperatures (>400 °C). Crystallographic and thermal analyses suggest that the low-temperature-sintered products contain Co(3+) ions stabilized by chemisorbed water and/or hydroxide groups, which was not observed for products sintered at temperatures higher than 1000 °C. The color of the products turned from clear blue (Thenard's blue) to dark green when sintering temperatures were below 1000 °C. Magnetic quantities, Curie constants, and Weiss temperatures show a strong dependence on the sintering temperature. These findings suggest that there are mixed valent states, i.e. Co(2+) and Co(3+), and unique cation distributions at the different crystallographic sites in the spinel structure, especially in the products sintered at lower temperatures.

  9. Influence of silicate anions structure on desilication in silicate-bearing sodium aluminate solution

    Institute of Scientific and Technical Information of China (English)

    刘桂华; 张闻; 齐天贵; 彭志宏; 周秋生; 李小斌

    2016-01-01

    The structural changes of silicate anions in the desilication process with the addition of calcium hydrate alumino-carbonate were studied by measuring Raman spectra, infrared spectra and corresponding second derivative spectra. The results show that the desilication ratio in the solution prepared by the addition of sodium silicate (solution-SS) is much greater than that in the solution by the addition of green liquor (solution-GL), and low alumina concentration in the sodium aluminate solutions facilitates the desilication process. It is also shown that alumino-silicate anions in the solution-GL, and Q3 polymeric silicate anions in solution-SS are predominant, respectively. In addition, increasing the concentration of silica favors respectively the formation of the alumino-silicate or the Q3 silicate anions in the solution-GL or the solution-SS. Therefore, it can be inferred that the low desilication ratio in the silicate-bearing aluminate solution is mainly attributed to the existence of alumino-silicate anions.

  10. Additives effects on crystallization and morphology in a novel caustic aluminate solution decomposition process

    Institute of Scientific and Technical Information of China (English)

    Ying ZHANG; Sbili ZHENG; Yifei ZHANG; Hongbin XU; Yi ZHANG

    2009-01-01

    A novel process of caustic aluminate solution decomposition by alcohol medium was developed by the Institute of Process Engineering, Chinese Academy of Sciences in order to solve the problem of low decomposi-tion ratio in the traditional Bayer seeded hydrolysis process. In this research, effects of additives on the crystallization ratio, secondary particle size and morphol-ogy of aluminum hydroxide in the new process were studied to obtain high-quality products. On the basis of primary selection of additives, an orthogonal design L9(34)was used as a chemometric method to investigate the effects of additives. The studied parameters include the reaction style, quantity of additives, caustic soda concen-tration, as well as the combination manner. The crystal-lization ratios of sodium aluminate solution and crystal size of aluminum hydroxide, determined by ICP-OES, SEM and MLPSA (Malvern Laser Particle Size Analyzer), were used to evaluate the effects of the additives. The results showed that different combination manners could promote agglomeration or dispersion. An additive composed by Tween 80 and PEG 200 could promote agglomeration,while a spot of PEG species had a relatively strong dispersion effect. However, the additives had little effects on the crystallization ratios. According to the Raman spectra result, the added alcohol medium might serve as a kind of solvent.

  11. Investigation of calcium aluminates by IR spectroscopy in diffusely scattered light

    Energy Technology Data Exchange (ETDEWEB)

    Medin, A.S.; Borovkov, V.Yu.; Nissenbaum, V.D.; Yakerson, V.I.; Kazanskii, V.B.

    1989-01-01

    The hydroxyl covering and the adsorption sites for CO and H/sub 2/O on aluminum-calcium catalysts and supports with developed surfaces have been studied by IR spectroscopy in diffusely scattered light. The presence of several types of surface OH groups, viz., terminal groups bonded to calcium ions with different types of coordination, bridging OH groups, and groups appearing in (CaOH)/sup +/ groupings, which perform the role of compensating cations in the zeolite-like structure of calcium aluminates, has been established. The shifts of the bands of the OH groups upon the adsorption of C/sub 6/H/sub 6/ and cyclo-C/sub 6/H/sub 12/ point out their weakly acidic or basic character. When calcium aluminates are dehydroxylated, aprotic sites appear on their surfaces, and the rehydration of such surfaces is accompanied by the formation of OH groups and the weakening of the Al-O-M bonds (M = Al, Ca) with the appearance of additional sites for the strong adsorption of water.

  12. Synchrontron VUV and Soft X-Ray Radiation Effects on Aluminized Teflon FEP

    Science.gov (United States)

    Dever, Joyce A.; Townsend, Jacqueline A.; Gaier, James R.; Jalics, Alice I.

    1998-01-01

    Surfaces of the aluminized Teflon FEP multi-layer thermal insulation on the Hubble Space Telescope (HST) were found to be cracked and curled in some areas at the time of the second servicing, mission in February 1997, 6.8 years after HST was deployed in low Earth orbit (LEO). As part of a test program to assess environmental conditions which would produce embrittlement sufficient to cause cracking of Teflon on HST, samples of Teflon FEP with a backside layer of vapor deposited aluminum were exposed to vacuum ultraviolet (VUV) and soft x-ray radiation of various energies using facilities at the National Synchrotron Light Source. Brookhaven National Laboratory. Samples were exposed to synchrotron radiation of narrow energy bands centered on energies between 69 eV and 1900 eV. Samples were analyzed for ultimate tensile strength and elongation. Results will be compared to those of aluminized Teflon FEP retrieved from HST after 3.6 years and 6.8 years on orbit and will he referenced to estimated HST mission doses of VUV and soft x-ray radiation.

  13. Evaluation of cytotoxicity, antimicrobial activity and physicochemical properties of a calcium aluminate-based endodontic material

    Directory of Open Access Journals (Sweden)

    Emmanuel Joao Nogueira Leal SILVA

    2014-01-01

    Full Text Available A calcium aluminate-based endodontic material, EndoBinder, has been developed in order to reduce MTA negative characteristics, preserving its biological properties and clinical applications. Objectives: The aim of this study was to evaluate the cytotoxicity, antimicrobial activity, pH, solubility and water sorption of EndoBinder and to compare them with those of white MTA (WMTA. Material and Methods: Cytotoxicity was assessed through a multiparametric analysis employing 3T3 cells. Antimicrobial activity against Enterococcus faecalis (ATCC 29212, Staphylococcus aureus. (ATCC 25923 and Candida albicans (ATCC 10556 was determined by the agar diffusion method. pH was measured at periods of 3, 24, 72 and 168 hours. Solubility and water sorption evaluation were performed following ISO requirements. Data were statistically analyzed by ANOVA and Tukey`s test with a significance level of 5%. Results: EndoBinder and WMTA were non-cytotoxic in all tested periods and with the different cell viability parameters. There was no statistical differences between both materials (P>.05. All tested materials were inhibitory by direct contact against all microbial strains tested. EndoBinder and WMTA presented alkaline pH in all tested times with higher values of pH for WMTA (P.05. Conclusion: Under these experimental conditions, we concluded that the calcium aluminate-based endodontic material EndoBinder demonstrated suitable biological and physicochemical properties, so it can be suggested as a material of choice in root resorption, perforations and root-end filling.

  14. IMPACT OF TIME / TEMPERATURE CURING CONDITIONS AND ALUMINATE CONCENTRATIONS ON SALTSTONE PROPERTIES

    Energy Technology Data Exchange (ETDEWEB)

    Harbour, J.; Edwards, T.; Williams, V.

    2009-05-05

    This report addresses the impact of (1) the time and temperature curing conditions (profile) and (2) the impact of higher aluminate concentrations in the decontaminated salt solution on Saltstone processing and performance properties. The results demonstrate that performance properties as well as some of the processing properties of Saltstone are highly sensitive to the conditions of time and temperature under which curing occurs. This sensitivity is in turn dependent on the concentration of aluminate in the salt feed solution. In general, the performance properties and indicators (Young's modulus, compressive strength and total porosity) are reduced when curing is initially carried out under high temperature. However, this reduction in performance properties is dependent on the sequence of temperatures (the time/temperature profile) experienced during the curing process. That is, samples that are subjected to a 1, 2, 3 or 4 day curing time at 60 C followed by final curing at 22 C lead to performance properties that are significantly different than the properties of grouts allowed to cure for 1, 2, 3 or 4 days at 22 C followed by a treatment at 60 C. The performance properties of Saltstone cured in the sequence of higher temperature first are generally less (and in some cases significantly less) than performance properties of Saltstone cured only at 22 C. This loss in performance was shown to be mitigated by increased slag content or cement content in the premix at the expense of fly ash. For the sequence in which the Saltstone is initially cured at 22 C followed by a higher temperature cure, the performance properties can be equal to or greater than the properties observed with curing only at 22 C curing. The results in this report indicate that in order to meaningfully measure and report the performance properties of Saltstone, one has to know the time/temperature profile conditions under which the Saltstone will be cured. This will require thermal modeling

  15. Stabilities of gibbsite, boehmite, aluminous goethites and aluminous hematites in bauxites, ferricretes and laterites as a function of water activity, temperature and particle size

    Energy Technology Data Exchange (ETDEWEB)

    Trolard, F.; Tardy, Y.

    1987-04-01

    Stability relationships between Al-goethite, Al-hematite, boehmite and gibbsite are presented in terms of water activity (H/sub 2/O), temperature (T), grain size and bulk-composition in the system Fe/sub 2/O/sub 3/-Al/sub 2/O/sub 3/-H/sub 2/O at a total pressure of 1 bar. Al-goethite and Al-hematite are treated as ideal solid solutions, the former of the end-members FeOOH and AlOOH and the latter of the end-members Fe/sub 2/O/sub 3/ (hematite) and Al/sub 2/O/sub 3/ (corundum). Using log K/sub sp/ provided by the literature for the various phases involved, the common associations observed in laterites, bauxites and ferricretes do not have stability fields over geologically reasonable intervals of (H/sub 2/O) and T. Consequently a new internally consistent set of log K/sub sp/ values is proposed and used, and allows such associations to have actual stability fields in the appropriate diagrams. The new log K/sub sp/ values used in the calculations are such that the solubilities of the end members are greater than those commonly listed. This is in agreement with natural observations which show that such minerals, are generally poorly crystallized and of very small size. The assumption of an ideal solid solution in aluminous goethite and aluminous hematite combined with the new log K/sub sp/ values leads to prediction of composition limits for these two minerals which agree well with observed values. The fact than an ideal solid solution must extend continuously from one end-member to the other is masked by the appearance of other stability fields which cross and overlap a part of the solid solution stability fields of AlOOH-FeOOH and Fe/sub 2/O/sub 3/-Al/sub 2/O/sub 3/.

  16. Thermochemical properties of gibbsite, bayerite, boehmite, diaspore, and the aluminate ion between 0 and 350/degree/C

    Energy Technology Data Exchange (ETDEWEB)

    Apps, J.A.; Neil, J.M.; Jun, C.H.

    1989-01-01

    A requirement for modelling the chemical behavior of groundwater in a nuclear waste repository is accurate thermodynamic data pertaining to the participating minerals and aqueous species. In particular, it is important that the thermodynamic properties of the aluminate ion be accurately determined, because most rock forming minerals in the earth's crust are aluminosilicates, and most groundwaters are neutral to slightly alkaline, where the aluminate ion is the predominant aluminum species in solution. Without a precise knowledge of the thermodynamic properties of the aluminate ion aluminosilicate mineral solubilities cannot be determined. The thermochemical properties of the aluminate ion have been determined from the solubilities of the aluminum hydroxides and oxyhydroxides in alkaline solutions between 20 and 350/degree/C. An internally consistent set of thermodynamic properties have been determined for gibbsite, boehmite, diaspore and corundum. The thermodynamic properties of bayerite have been provisionally estimated and a preliminary value for ..delta..G/sub f, 298//sup 0/ of nordstrandite has been determined. 205 refs., 17 figs., 25 tabs.

  17. Recovery of iron and calcium aluminate slag from high-ferrous bauxite by high-temperature reduction and smelting process

    Institute of Scientific and Technical Information of China (English)

    Ying-yi Zhang; Wei L; Yuan-hong Qi; Zong-shu Zou

    2016-01-01

    A high-temperature reduction and smelting process was used to recover iron and calcium aluminate slag from high-ferrous bauxite. The effects of w(CaO)/w(SiO2) ratio, anthracite ratio, and reduction temperature and time on the recovery and size of iron nuggets and on the Al2O3 grade of the calcium aluminate slag were investigated through thermodynamic calculations and experiments. The optimized process conditions were the bauxite/anthracite/slaked lime weight ratio of 100:16.17:59.37, reduction temperature of 1450°C and reduction time of 20 min. Under these conditions, high-quality iron nuggets and calcium aluminate slag were obtained. The largest size and the highest recov-ery rate of iron nuggets were 11.42 mm and 92.79wt%, respectively. The calcium aluminate slag mainly comprised Ca2SiO4 and Ca12Al14O33, with small amounts of FeAl2O4, CaAl2O4, and Ca2Al2SiO7.

  18. Etude vibrationnelle d'aluminates et de gallates de terres rares—I. Alluminates de structure pérovskite

    Science.gov (United States)

    Saine, M. C.; Husson, E.; Brusset, H.; Cerez, A.

    The i.r. spectra of some aluminates of rhomboedral and orthorhombic perovskite types are presented and analysed. The complete vibrational analysis of NdAlO 3 is presented and a force field is proposed for this type of compounds; the potential energy distribution is given and the normal modes are drawn using ORTEP program.

  19. Roles of Eu2+, Dy3+ Ions in Persistent Luminescence of Strontium Aluminates Phosphors

    Institute of Scientific and Technical Information of China (English)

    L(U) Xingdong; ZHONG Minjuan; WANG Renqin

    2008-01-01

    The polycrystalline Eu2+ and Dy3+ co-doped strontium aluminates SrAl2O4: Eu2+,Dy3+ with different compositions were prepared by solid state reactions. The UV-excited photoluminescence, persistent luminescence and thermo-luminescence were studied and compared. Results show that the doped Eu2+ ion in SrAl2O4: Eu2+, Dy3+phosphors works as not only the UV-excited luminescent center but also the persistent luminescent center. The doped Dy3+ ion can hardly yield any luminescence under UV-excitation, but effectively enhance the persistent luminescence and thermo-luminescence of SrAl2O4: Eu2+. Dy3+ co-doping can help form electron traps with appropriate depth due to its suitable electro-negativity, and increase the density and depth of electron traps. Based on above observations, a persistent luminescence mechanism, electron transfer model, is proposed and illustrated.

  20. Soft sensor for ratio of soda to aluminate based on PCA-RBF multiple network

    Institute of Scientific and Technical Information of China (English)

    GUI Wei-hua; LI Yong-gang; WANG Ya-lin

    2005-01-01

    Based on principal component analysis, a multiple neural network was proposed. The principal component analysis was firstly used to reorganize the input variables and eliminate the correlativity. Then the reorganized variables were divided into 2 groups according to the original information and 2 corresponding neural networks were established. A radial basis function network was used to depict the relationship between the output variables and the first group input variables which contain main original information. An other single-layer neural network model was used to compensate the error between the output of radial basis function network and the actual output variables. At last, The multiple network was used as soft sensor for the ratio of soda to aluminate in the process of high-pressure digestion of alumina. Simulation of industry application data shows that the prediction error of the model is less than 3%, and the model has good generalization ability.

  1. Exposing elusive cationic magnesium-chloro aggregates in aluminate complexes through donor control.

    Science.gov (United States)

    Brouillet, Etienne V; Kennedy, Alan R; Koszinowski, Konrad; McLellan, Ross; Mulvey, Robert E; Robertson, Stuart D

    2016-04-07

    The cationic magnesium moiety of magnesium organohaloaluminate complexes, relevant to rechargeable Mg battery electrolytes, typically takes the thermodynamically favourable dinuclear [Mg2Cl3](+) form in the solid-state. We now report that judicious choice of Lewis donor allows the deliberate synthesis and isolation of the hitherto only postulated mononuclear [MgCl](+) and trinuclear [Mg3Cl5](+) modifications, forming a comparable series with a common aluminate anion [(Dipp)(Me3Si)NAlCl3](-). By pre-forming the Al-N bond prior to introduction of the Mg source, a consistently reproducible protocol is reported. Usage of the green solvent 2-methyltetrahydrofuran in place of THF in the context of Mg/Al battery electrolyte type complexes is also promoted.

  2. Effect of LiF on the Optical Transmittance of Magnesium Aluminate Spinel

    Institute of Scientific and Technical Information of China (English)

    LI Fahui; LIN Hong; LI Jianbao; LEI Muyun; HUANG Cunxin; WEN Fang

    2012-01-01

    The effect of LiF as a sintering aid to the optical transparency of magnesium aluminate (MgAl2O4) spinel ceramics is studied.The spinel ceramics is prepared in a process proved to be suitable for commercial production.LiF,in different concentrations ranging from 0-2.5 wt%,is doped into MgAl2O4powders prepared by sol-gel method.Sample MgAl2O4 ceramic discs are fabricated by ball milling,cold pressing,and hot-pressing,or hot-isostatic-pressing of the powder mixtures.Optical transparency measurements show that,hot-pressed samples exhibit higher transparency when more LiF is added,While for hot-isostatic pressed samples,excessive LiF content leads to a decrease in optical transparency.The optimal LiF doping quantity is suggested for the present technique.

  3. Investigation of the reactions of chlorides binding to aluminates using XRD and DTA methods

    Directory of Open Access Journals (Sweden)

    Bikić Farzet H.

    2009-01-01

    Full Text Available The reactions of chlorides binding to aluminates were investigated by analyzing the monochloroaluminate hydrate, product of the reaction. The results show that the product is formed in the fresh concrete, after adding chloride within the stage of the preparation of concrete, as well as adding chlorides by penetration from the environment into the concrete. The obtained results are significant, considering the aspect of preventing corrosion of the steel reinforcement into the concrete. It is known that only free chlorides activate corrosion processes in the steel reinforcement in concrete. The process of chloride bonding is followed by X-ray diffraction (XRD and differential thermal (DTA analysis of samples of the cement paste, which is the process of preparation and care is described in detail in this work.

  4. Calibration of the BKW--EOS and application to aluminized composite explosives

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, M.L.; Baer, M.R.

    1993-01-01

    The Becker-Kistiakowsky-Wilson equation of state (BKW-EOS) has been calibrated over a wide initial density range near C-J states using measured detonation properties from 62 explosives at III total initial densities. Values for the empirical BKW constants [alpha], [beta], [kappa], and [theta] were 0.5, 0.298, 10.5, and 6620, respectively. Covolumes were assumed to be invariant. Model evaluation includes comparison to measurements from 91 explosives composed of combinations of Al, B, Ba, C, Ca, Cl, F, H, N, 0, P, Pb, and Si at 147 total initial densities. Adequate agreement between predictions and measurements were obtained with a few exceptions for nonideal explosives. However, detonation properties for the nonideal explosives can be predicted adequately by assuming partial equilibrium. The partial equilibrium assumption was applied to aluminized composites of RDX, HMX, TNETB, and TNT to predict detonation velocity and temperature.

  5. Calibration of the BKW--EOS and application to aluminized composite explosives

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, M.L.; Baer, M.R.

    1993-04-01

    The Becker-Kistiakowsky-Wilson equation of state (BKW-EOS) has been calibrated over a wide initial density range near C-J states using measured detonation properties from 62 explosives at III total initial densities. Values for the empirical BKW constants {alpha}, {beta}, {kappa}, and {theta} were 0.5, 0.298, 10.5, and 6620, respectively. Covolumes were assumed to be invariant. Model evaluation includes comparison to measurements from 91 explosives composed of combinations of Al, B, Ba, C, Ca, Cl, F, H, N, 0, P, Pb, and Si at 147 total initial densities. Adequate agreement between predictions and measurements were obtained with a few exceptions for nonideal explosives. However, detonation properties for the nonideal explosives can be predicted adequately by assuming partial equilibrium. The partial equilibrium assumption was applied to aluminized composites of RDX, HMX, TNETB, and TNT to predict detonation velocity and temperature.

  6. Effect of agglomeration during coprecipitation: Delayed spinellization of magnesium aluminate hydrate

    Indian Academy of Sciences (India)

    Soumen Pal; A K Bandyopadhyay; S Mukherjee; B N Samaddar; P G Pal

    2010-08-01

    Precipitation of magnesium aluminate hydrate with faster addition of ammonia at desired pH causes agglomeration. Agglomerated powder, without any further treatment, on calcination forms intermediate compounds at low temperatures (≤ 900°C). The intermediate compounds on further heat treatment (≥ 1000°C) decompose into MgO, MgAl2O4 and -Al2O3. Effect of agglomeration and absorption of foreign ions such as Cl–, SO$^{2-}_{4}$, and NH$^{+}_{4}$ in complex compounds probably cause loss of Al3+ and Mg2+ ions during heat treatment, and stoichiometry changes. Powders prepared by continuous method with better control of process parameters than batch process yields better spinellization.

  7. Phenomena in late period of seeded precipitation of sodium aluminate solution

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-bin; FENG Gang-tao; ZHOU Qiu-sheng; PENG Zhi-hong; LIU Gui-hua

    2006-01-01

    Aiming at seeded precipitation of aluminate solution with high caustic ratio(αk>2.4), corresponding to the late period of seeded precipitation, the influence of different types of seed on precipitation ratio was explained with respect to solution structure in the interface of seed and the evolution of Al(OH)3 growth units in this layer. The effects of solid content and seed size on agglomeration were determined by calculating the particle number of product. The results imply that the solution structure in the interface of seed imposes a notable significance on the process in the late period of seeded precipitation. Agglomeration still exists in this period. However, the agglomeration bodies break in the case of prolonging precipitation due to the mechanical effect, which results in the increase of particle number.

  8. Poly(carboxylate ether)-based superplasticizer achieves workability retention in calcium aluminate cement

    Science.gov (United States)

    Akhlaghi, Omid; Menceloglu, Yusuf Ziya; Akbulut, Ozge

    2017-01-01

    Calcium aluminate cement (CAC) suffers from loss of workability in less than an hour (~15 minutes) after first touch of water. Current superplasticizers that are utilized to modify the viscosity of cement admixtures are designed to target ordinary Portland cement (OPC). The high affinity between these superplasticizers and cement particles were found to be detrimental in CAC systems. Utilization of a monomer that, instead, facilitates gradual adsorption of a superplasticizer provides workability retention. For the first time in literature, we report a superplasticizer that caters to the properties of CAC such as high rate of surface development and surface charge. While neat CAC was almost unworkable after 1 hour, with the addition of only 0.4% of the optimized superplasticizer, 90% fluidity retention was achieved.

  9. Effect of 20kHz ultrasound on alumina hydrate precipitation from seeded sodium aluminate solution

    Institute of Scientific and Technical Information of China (English)

    赵继华; 陈启元

    2002-01-01

    The effect of 20kHz ultrasound on alumina hydrate precipitation from seeded sodium aluminate solution was studied. Compared with alumina hydrate precipitation without treatment of ultrasound, the precipitation time is reduced from 30h to 15h when the precipitation ratio is 45% under 20kHz ultrasound. Furthermore, agglomeration is increased and the growth rate of alumina hydrate is increased under 20kHz ultrasound by comparing the crystal size distribution and the SEM photographs. As a result, the average size of alumina hydrate is increased by 3.7μm. The structure of product is not changed according to the results of X-ray powder deflection.

  10. Hot-Dip Aluminizing of Low Carbon Steel Using Al-7Si-2Cu Alloy Baths

    OpenAIRE

    Prashanth Huilgol; Suma Bhat; K. Udaya Bhat

    2013-01-01

    Hot-dip aluminizing of low carbon steel was done in molten Al-7Si-2Cu bath at 690°C for dipping time ranging from 300 to 2400 seconds. Characterization of the intermetallics layer was done by using scanning electron microscope with energy dispersive spectroscopy. Four intermetallic phases, τ5-Al7Fe2Si, θ-FeAl3, η-Fe2Al5, and τ1-Al2Fe3Si3, were identified in the reaction layer. τ5- Al7Fe2Si phase was observed adjacent to aluminum-silicon topcoat, θ-FeAl3 between τ5 and η-Fe2Al5, η-Fe2Al5 adjac...

  11. Chemical synthesis of nanocrystalline magnesium aluminate spinel via nitrate-citrate combustion route

    Energy Technology Data Exchange (ETDEWEB)

    Saberi, Ali [Ceramic Division, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)], E-mail: ASaberi@IUST.ac.ir; Golestani-Fard, Farhad; Sarpoolaky, Hosein [Ceramic Division, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Willert-Porada, Monika; Gerdes, Thorsten [Chair of Materials Processing, University of Bayreuth, Bayreuth (Germany); Simon, Reinhard [Chair of Ceramic Materials Engineering, University of Bayreuth, Bayreuth (Germany)

    2008-08-25

    Nanocrystalline magnesium aluminate spinel (MgAl{sub 2}O{sub 4}) was synthesized using metal nitrates, citric acid and ammonium solutions. The precursor and the calcined powders at different temperatures were characterized by X-ray diffraction (XRD), simultaneous thermal analysis (STA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The combustion mechanism was also studied by a quadrupole mass spectrometer (QMS) which coupled to STA. The generated heat through the combustion of the mixture of ammonium nitrate and citrate based complexes decreased the synthesis temperature of MgAl{sub 2}O{sub 4} spinel. The synthesized MgAl{sub 2}O{sub 4} spinel at 900 deg. C has faced shape with crystallite size in the range of 18-24 nm.

  12. Research of High Temperature Crystalline Structure and Property Evolution of Magnesium Aluminate Spinel

    Institute of Scientific and Technical Information of China (English)

    YU Yan; RUAN Yu-Zhong; WU Ren-Ping; LIU Sheng; ZENG Hua-Rui

    2008-01-01

    Magnesium aluminate spinel (MgAl2O4) with high purity has been prepared by materials to discuss the change laws and characteristics of crystalline structure, microstructures and properties. X-ray diffraction (XRD) and scanning electron microscopy (SEM), together with relevant analysis software, were used to characterize the crystal phases and microstructures so as to get MgAl2O4. Results show that when increasing the holding time the amount of MgAl2O4 increases firstly and then keeps stable, but bulk density and bending strength increase firstly and then decrease.The best holding time is determined to be 3 h because at this time the corresponding MgAl2O4 content is up to 93%, bulk density 3.23 g.cm-3, apparent porosity 4.6% and bending strength 122.4 MPa.

  13. Solidification/stabilization of toxic metals in calcium aluminate cement matrices.

    Science.gov (United States)

    Navarro-Blasco, I; Duran, A; Sirera, R; Fernández, J M; Alvarez, J I

    2013-09-15

    The ability of calcium aluminate cement (CAC) to encapsulate toxic metals (Pb, Zn and Cu) was assessed under two curing conditions. Changes in the consistency and in the setting time were found upon the addition of the nitrates of the target metals. Both Pb and Cu caused a delay in CAC hydration, while Zn accelerated the stiffening of the mortar. Compressive strengths of the metal-doped mortars, when initially cured at 60 °C/100% RH, were comparable with that of the free-metal mortar. Three different pore size distribution patterns were identified and related to the compounds identified by XRD and SEM. Sorbent capacities of CAC for the toxic metals were excellent: a total uptake was achieved for up to 3 wt.% loading of the three metals. In this way, CAC mortars were perfectly able to encapsulate the toxic metals, allowing the use of CAC for waste management as proved by the leaching tests.

  14. The Effect of (Ag, Ni, Zn-Addition on the Thermoelectric Properties of Copper Aluminate

    Directory of Open Access Journals (Sweden)

    Jianxiao Xu

    2010-01-01

    Full Text Available Polycrystalline bulk copper aluminate Cu1-x-yAgxByAlO2 with B = Ni or Zn were prepared by spark plasma sintering and subsequent thermal treatment. The influence of partial substitution of Ag, Ni and Zn for Cu-sites in CuAlO2 on the high temperature thermoelectric properties has been studied. The addition of Ag and Zn was found to enhance the formation of CuAlO2 phase and to increase the electrical conductivity. The addition of Ag or Ag and Ni on the other hand decreases the electrical conductivity. The highest power factor of 1.26 × 10-4 W/mK2 was obtained for the addition of Ag and Zn at 1,060 K, indicating a significant improvement compared with the non-doped CuAlO2 sample.

  15. Structural simulation of superlattices in lithium aluminates; Simulacion estructural de superredes en aluminatos de litio

    Energy Technology Data Exchange (ETDEWEB)

    Carrera G, L.M.; Basurto S, R. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1997-07-01

    Among the materials to be used on the tritium generator cover of the future fusion reactors the lithium aluminate ({gamma} - LiAlO{sub 2}) is one of the more studied. In this work it is presented the superlattice structural simulation that presents to {gamma} - LiAlO{sub 2} as main phase and to {alpha} - LiAlO{sub 2} as the secondary phase. The simulation is developed considering that as the two phases present different symmetry ({gamma} - LiAlO{sub 2} is tetrahedral and {alpha} - LiAlO{sub 2} is hexahedral) it is had a superlattice LUCS type (Layered Ultrathin Coherent Structure) that is it presents an structure in coherent ultrathin layers since it is what implicates a lesser energy of formation. (Author)

  16. Pre-desilication and digestion of gibbsitic bauxite with lime in sodium aluminate liquor

    Science.gov (United States)

    Pan, Xiao-lin; Yu, Hai-yan; Dong, Kai-wei; Tu, Gan-feng; Bi, Shi-wen

    2012-11-01

    The effect of lime on the pre-desilication and digestion of gibbsitic bauxite in synthetic sodium aluminate liquor at different temperatures was investigated. The bauxite is comprised of gibbsite, aluminogoethite, hematite, kaolin, quartz, and minor boehmite. Lime increases the desilication efficiency of the bauxite during the pre-desilication process by promoting the conversion of sodalite and cancrinite to hydrogarnet. Desilication reactions during the digestion process promoted by lime result in the loss of Al2O3 entering the red mud, but the amount of aluminogoethite-to-hematite conversion promoted by lime leads to the increase of aluminogoethitic Al2O3 entering the digested liquor. The alumina digestion rate at 245°C is higher than that at 145°C due to the more pronounced conversion of aluminogoethite to hematite. The soda consumption during the digestion process decreases due to lime addition, especially at higher temperatures.

  17. Creep of Polycrystalline Magnesium Aluminate Spinel Studied by an SPS Apparatus

    Directory of Open Access Journals (Sweden)

    Barak Ratzker

    2016-06-01

    Full Text Available A spark plasma sintering (SPS apparatus was used for the first time as an analytical testing tool for studying creep in ceramics at elevated temperatures. Compression creep experiments on a fine-grained (250 nm polycrystalline magnesium aluminate spinel were successfully performed in the 1100–1200 °C temperature range, under an applied stress of 120–200 MPa. It was found that the stress exponent and activation energy depended on temperature and applied stress, respectively. The deformed samples were characterized by high resolution scanning electron microscope (HRSEM and high resolution transmission electron microscope (HRTEM. The results indicate that the creep mechanism was related to grain boundary sliding, accommodated by dislocation slip and climb. The experimental results, extrapolated to higher temperatures and lower stresses, were in good agreement with data reported in the literature.

  18. The aluminization of 600 k WLS fibers for the TileCal/ATLAS/LHC

    CERN Document Server

    Saraiva, J G; Maneira, M J P; Maio, A; Patriarca, J

    2004-01-01

    The TILE CALorimeter, the hadronic sampling calorimeter of ATLAS/LHC /CERN, is made of iron and polystyrene scintillating tiles. The light produced in scintillating tiles is absorbed and guided to the photomultipliers (PMTs) through wave length shifter (WLS) optical fibers. To optimize the detection of jets and muons, the top of the fibers away of the PMTs is coated with an aluminum mirror. This aluminum mirror is produced by planar magnetron sputtering. This process adds to an excellent reproducibility a minimal thermal aggression, important for a proper film adhesion to the plastic surface. To satisfy schedule and optical critical requirements, a dedicated mass production machine named SIDELO II was projected and constructed. A reflectivity of R similar to 75% is achieved and the light output uniformity improved by asymptotically equal to 10%. The aluminization of the fibers and their quality control started in August 1999 and went on continuously until May 2002. The quality control results showed a reprodu...

  19. Effect of Calcium Aluminate Cement Variety on the Hydration of Portland Cement in Blended System

    Institute of Scientific and Technical Information of China (English)

    XU Linglin; WANG Peiming; Geert DE SCHUTTER; WU Guangming

    2014-01-01

    Two kinds of CACs with different monocalcium aluminate (CA) contents were used in the PC/CAC (PAC) mixtures. Effects of CA and CACs on the properties of PAC were analyzed by setting times and the compressive strength tests, and also by means of calorimetry, XRD, DTA-TG and ESEM. The experimental results show that the compressive strength of the PAC mortars decreases with increasing content of CAC while it declines sharply with a higher content of CA in CAC. Compared with neat PC paste, the content of calcium hydroxide in hydrates of PAC paste decreases significantly, and the hydration time of PC is prominently prolonged. Additionally, the higher the content of CA in CAC, the more obviously the hydration of PC is delayed, confirming that the CA phase in CAC plays an important role in the delay of PC hydration.

  20. Optical properties of rare earth doped strontium aluminate (SAO) phosphors: A review

    Science.gov (United States)

    Kshatri, D. S.; Khare, A.

    2014-11-01

    After the first news on rare earth (RE) doped strontium aluminate (SAO) phosphors in late 1990s, researchers all over the world geared up to develop stable and efficient persistent phosphors. Scientists studied various features of long lasting phosphors (LLP) and tried to earmark appropriate mechanism. However, about two decades after the discovery of SrAl2O4: Eu2+, Dy3+, the number of persistent luminescent materials is not significant. In this review, we present an overview of the optical characteristics of RE doped SAO phosphors in terms of photoluminescence (PL), thermoluminescence (TL) and afterglow spectra. Also, we refresh the work undertaken to study diverse factors like dopant concentration, temperature, surface energy, role of activator, etc. Simultaneously, some of our important findings on SAO are reported and discussed in the end.

  1. Zircon saturation in silicate melts: a new and improved model for aluminous and alkaline melts

    Science.gov (United States)

    Gervasoni, Fernanda; Klemme, Stephan; Rocha-Júnior, Eduardo R. V.; Berndt, Jasper

    2016-03-01

    The importance of zircon in geochemical and geochronological studies, and its presence not only in aluminous but also in alkaline rocks, prompted us to think about a new zircon saturation model that can be applied in a wide range of compositions. Therefore, we performed zircon crystallization experiments in a range of compositions and at high temperatures, extending the original zircon saturation model proposed by Watson and Harrison (Earth Planet Sci Lett 64:295-304, 1983) and Boehnke et al. (Chem Geol 351:324-334, 2013). We used our new data and the data from previous studies in peraluminous melts, to describe the solubility of zircon in alkaline and aluminous melts. To this effect, we devised a new compositional parameter called G [ {( {3 \\cdot {{Al}}2 {{O}}3 + {{SiO}}2 )/({{Na}}2 {{O}} + {{K}}2 {{O}} + {{CaO}} + {{MgO}} + {{FeO}}} )} ] (molar proportions), which enables to describe the zircon saturation behaviour in a wide range of rock compositions. Furthermore, we propose a new zircon saturation model, which depends basically on temperature and melt composition, given by (with 1σ errors): ln [ {{Zr}} ] = ( {4.29 ± 0.34} ) - ( {1.35 ± 0.10} ) \\cdot ln G + ( {0.0056 ± 0.0002} ) \\cdot T( °C ) where [Zr] is the Zr concentration of the melt in µg/g, G is the new parameter representing melt composition and T is the temperature in degrees Celsius. The advantages of the new model are its straightforward use, with the G parameter being calculated directly from the molar proportions converted from electron microprobe measurements, the temperature calculated given in degrees Celsius and its applicability in a wider range of rocks compositions. Our results confirm the high zircon solubility in peralkaline rocks and its dependence on composition and temperature. Our new model may be applied in all intermediate to felsic melts from peraluminous to peralkaline compositions.

  2. CITRIC ACID AS A SET RETARDER FOR CALCIUM ALUMINATE PHOSPHATE CEMENTS.

    Energy Technology Data Exchange (ETDEWEB)

    SUGAMA,T.; BROTHERS, L.E.

    2005-01-01

    Citric acid added as set retarder significantly contributed to enhancing the setting temperature and to extending the thickening time of a calcium aluminate phosphate (CaP) geothermal cement slurry consisting of calcium aluminate cement (CAC) as the base reactant and sodium polyphosphate (NaP) solution as the acid reactant. The set-retarding activity of citric acid was due to the uptake of Ca{sup 2+} ions from the CAC by carboxylic acid groups within the citric acid. This uptake led to the precipitation of a Ca-complexed carboxylate compound as a set-retarding barrier layer on the CAC grains' surfaces. However, this barrier layer was vulnerable to disintegration by the attack of free Ca{sup 2+} ions from CAC, and also to degradation at elevated temperature, thereby promoting the generation of exothermic energy from acid-base reactions between the CAC and NaP after the barrier was broken. The exothermic reaction energy that was promoted in this way minimized the loss in strength of the citric acid-retarded cement. The phase composition assembled in both retarded and non-retarded cements after autoclaving at 180 C encompassed three reaction products, hydroxyapatite (HOAp), hydrogrossular and boehmite, which are responsible for strengthening the autoclaved cement. The first two reaction products were susceptible to reactions with sulfuric acid and sodium sulfate to form crystalline bassanite scale as the corrosion product. The boehmite phase possessed a great resistance to acid and sulfate. Although the bassanite scales clinging to the cement's surfaces were the major factor governing the loss in weight, they served in protecting the cement from further acid- and sulfate-corrosion until their spallation eventually occurred. Nevertheless, the repetitive processes of HOAp and hydrogrossular {yields} bassanite {yields} spallation played an important role in extending the useful lifetime of CaP cement in a low pH environment at 180 C.

  3. Criterion for selection the optimal physical and chemical properties of cobalt aluminate powder used in investment casting process

    Directory of Open Access Journals (Sweden)

    M. Zielińska

    2009-07-01

    Full Text Available The aim of this work was to determine physical and chemical properties of cobalt aluminate (CoAl2O4 modifiers produced by different companies and the influence of different types of modifiers on the grain size of high temperature creep resisting superalloys: Inconel 713C, René 77 and MAR-M 509.The first stage of the research work took over the investigations of physical and chemical properties of cobalt aluminate manufactured by three different companies: Remet, Mason Color and Permedia Lublin. There were determined the grain size distribution of cobalt aluminate powder, the average diameter and morphology of powder particles, phase composition, as well as sodium and cobalt content, pH value of water suspension and the bulk density. In the next step, the ceramic moulds were made with different kind of cobalt aluminate (Mason Color, Remet, Permedia Lublin and its concentration (0, 5% in the primary slurry. The samples of stepped shape were poured in the ceramic moulds prepared earlier. The average grain size of the γ phase was determined on the stepped samples.It was established that physical and chemical properties of cobalt aluminate modifier are different up to the manufacturer. For example the modifiers manufactured by Permedia; Mason Color and Remet companies have different the average diameter of particles- 68,050d; 49,6 i 36,7μm, and also cobalt content _CoC=32,53%; 39,43% i 34,79%mass, respectively. The grain size of γ matrix of superalloys depends on the kind of used inoculant. The best grain refinement of the matrix of superalloys: Inconel 713C, René 77 and MAR-M 509 was observed in the castings modified with the use of Mason Color modifier. On the grounds of literature data and obtained results it was established that the cobalt content of cobalt aluminate influences the intensity of nucleation process during the crystallization of superalloys: Inconel 713C, René 77 i MAR-M 509.

  4. Aluminizing and Aluminizing-Y2O3 Coatings Deposited by Pulse Spark%电脉冲沉积铝化物及铝化物-Y2O3涂层

    Institute of Scientific and Technical Information of China (English)

    黄祖芬; 何业东; 王德仁; 齐慧滨; 雷林海; 吴浩

    2001-01-01

    采用电脉冲沉积技术在20碳钢表面上获得了冶金结合的晶粒尺寸约为几十到几百纳米的铝化物和铝化物+弥散Y2O3复合微晶涂层。 600 ℃空气中氧化100 h的结果表明, 电脉冲沉积获得的两种涂层均可显著地降低20碳钢的氧化速率并提高氧化层的抗剥落性能。用AFM, SEM, EDS和XRD对铝化物涂层及氧化层进行了分析,并讨论了两种涂层提高抗氧化性能的作用机制。%Aluminizing and aluminizing-dispersed Y2O3 composite coatings were prepared on 20 steel specimens by pulse spark technique, which exhibited a micro-crystallized structure with grain size in the range of several tens to several hundred nanometers. It is shown that after oxidation at 600 ℃ in air for 100 h, these two kinds of coatings have excellent resistance to high temperature oxidation and scale spallation, and the aluminizing-dispersed Y2O3 composite coatings has even more better property than the aluminizing coatings. AFM, SEM, EDS and XRD were applied to analyze the surface morphology, composition and phase structure of these coatings and the oxide scale formed during oxidation. The mechanism for these coatings to enhance the oxidation resistance and scale spallation resistance was discussed by considering the factors such as Al concentration on the selective oxidation of Fe-Al alloy, the effect of dispersed Y2O3, etc.

  5. Simultaneous chromizing-aluminizing coating of low alloy steels by a halide-activated pack cementation process

    Energy Technology Data Exchange (ETDEWEB)

    Geib, F.D.; Rapp, R.A. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

    1992-11-01

    The simultaneous chromizing-aluminizing of low-alloy steels has achieved Kanthal-like surface compositions of 16--2lCr and 5--8 wt%Al by the use of cementation packs with a Cr-Al masteralloy and an NH{sub 4}Cl activator salt. An initial preferential deposition of Al into the alloy induces the phase transformation from austenite to ferrite at the 1150{degrees}C process temperature. The low solubility of carbon in ferrite results in the rejection of solute C into the core of the austenitic substrate, thereby preventing the formation of an external Cr-carbide layer, which would otherwise block aluminizing and chromizing. The deposition and rapid diffusion of Cr and Al into the external bcc ferrite layer follows. Parabolic cyclic oxidation kinetics for alumina growth in air were observed over a wide range of relatively low temperatures (637--923{degrees}C).

  6. Simultaneous chromizing-aluminizing coating of low alloy steels by a halide-activated pack cementation process

    Energy Technology Data Exchange (ETDEWEB)

    Geib, F.D.; Rapp, R.A. (Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering)

    1992-11-01

    The simultaneous chromizing-aluminizing of low-alloy steels has achieved Kanthal-like surface compositions of 16--2lCr and 5--8 wt%Al by the use of cementation packs with a Cr-Al masteralloy and an NH[sub 4]Cl activator salt. An initial preferential deposition of Al into the alloy induces the phase transformation from austenite to ferrite at the 1150[degrees]C process temperature. The low solubility of carbon in ferrite results in the rejection of solute C into the core of the austenitic substrate, thereby preventing the formation of an external Cr-carbide layer, which would otherwise block aluminizing and chromizing. The deposition and rapid diffusion of Cr and Al into the external bcc ferrite layer follows. Parabolic cyclic oxidation kinetics for alumina growth in air were observed over a wide range of relatively low temperatures (637--923[degrees]C).

  7. Performance and Application of Hot Dip Aluminized Steel%热浸镀铝钢的性能及用途

    Institute of Scientific and Technical Information of China (English)

    李华飞; 俞敦义; 等

    2001-01-01

    为了便于研究人员和用户了解、掌握热浸镀铝钢的性能及其用途,进一步推动我国在这方面的大力发展,作者综述了热浸镀铝钢镀层的机械性能、耐腐蚀性能、抗高温氧化性能和其他性能及其在各工程领域上的应用情况,列出了部分性能指标。%The mechanical performance,corrosion resistance and high temperature oxidation resistance of hot dip aluminized steel were summarized.The hot- dip aluminized steel could extensively be used in various engineering fields.

  8. The Effect of La on the Microstructure and Corrosion-resistance of Hot-dipped Aluminizing Steel

    Institute of Scientific and Technical Information of China (English)

    WENJiu-ba; ZHANGWei; LIXiao-yuan; LIQuan-an

    2004-01-01

    The effect of the content of rare-earth La on the microstructure and corrosion-resistance of hot-dipped aluminum was investigated in this paper. The results show that, under the same technology conditions, the thickness of hot-dipped aluminizing layer by adding the appropriate content of rare-earth La is about 2-3 times as much as that without rare-earth La, and the microstructure of hot-dipped aluminizing layer has also greatly changed ,and a great deal of phase Fe3A1 waspreci pitated along the boundary of a phase. The corrosion resistance of the hot-dipped layer with rare-earth is greatly increased.

  9. The Effect of La on the Microstructure and Corrosion-resistance of Hot-dipped Aluminizing Steel

    Institute of Scientific and Technical Information of China (English)

    WEN Jiu-ba; ZHANG Wei; LI Xiao-yuan; LI Quan-an

    2004-01-01

    The effect of the content of rare-earth La on the microstructure and corrosion-resistance of hot-dipped aluminum was investigated in this paper. The results show that, under the same technology conditions, the thickness of hot-dipped aluminizing layer by adding the appropriate content of rare-earth La is about 2~3 times as much as that without rare-earth La, and the microstructure of hot-dipped aluminizing layer has also greatly changed ,and a great deal of phase Fe3Al was precipitated along the boundary of α phase. The corrosion resistance of the hot-dipped layer with rare-earth is greatly increased.

  10. Phase transformations in lithium aluminates irradiated with neutrons; Transformaciones de fase en aluminatos de litio irradiados con neutrones

    Energy Technology Data Exchange (ETDEWEB)

    Carrera, L.M.; Delfin L, A.; Urena N, F.; Basurto, R. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Bosch, P. [UAM-I, 09340 Mexico D.F. (Mexico)

    2003-07-01

    The lithium aluminate like candidate to be used in the coverings producers of tritium in the fusion nuclear reactors, presents high resistance to the corrosion to the one to be stuck to structural materials as special steels. However, the crystallographic changes that take place in the cover that is continually subjected to irradiation with neutrons, can alter its resistance to the corrosion. In this work the changes of crystalline structure are shown that they present two types of nano structures of lithium aluminates, subjected to an average total dose 7.81 x 10{sup 8} Gy in the fixed irradiation system of capsules of the one TRIGA Mark lll nuclear reactor of the Nuclear Center of Mexico. The studied nano structures presented only phase transformations without formation of amorphous material. (Author)

  11. Preparation of Al(OH)3 by ion membrane electrolysis and precipitation of sodium aluminate solution with seeds

    Institute of Scientific and Technical Information of China (English)

    LI Yuan-gao; CHEN Qi-yuan; WANG Song-sen; YIN Zhou-lan; ZHANG Ping-min

    2008-01-01

    The preparation of Al(OH)3 by the ion exchange membrane electrolysis followed by the precipitation of sodium aluminate solution with seeds was made. During the process of ion membrane electrolysis, the sodium aluminate solution is rapidly acidified and the caustic ratio (aK) is decreased due to oxygen evolution in the anodic region. And the causticity of solution is increased due to hydrogen evolution in the cathode region, producing the high concentration of caustic soda solution. Regulating the acidity of the anodic solution by controlling the electric quantity in the electrolysis and subsequent decomposing the solution, Al(OH)3 could yield with very large rate and high efficiency. The experiments also indicate that the quality of aluminum hydroxide product is greatly affected by the impurity silicon.

  12. Fast in situ x-ray-diffraction studies of chemical reactions: A synchrotron view of the hydration of tricalcium aluminate

    Science.gov (United States)

    Jupe, A. C.; Turrillas, X.; Barnes, P.; Colston, S. L.; Hall, C.; Häusermann, D.; Hanfland, M.

    1996-06-01

    We report observations on the early hydration of tricalcium aluminate, the most reactive component of Portland cement, using rapid-energy dispersive diffraction on a high brilliance synchrotron source. In situ observations of the hydration process over short time scales, and through bulk samples, reveal an intermediate calcium aluminate hydrate appearing just prior to the formation of the final stable hydrate, demonstrating the nucleating role of this intermediate. The superior quality of the data is sufficient to yield concentration versus time plots for each phase over the whole hydration sequence. This improvement derives from being able to use smaller diffracting volumes and consequent removal of time smearing due to inhomogenetics, and thus now offers the possibility of extending the technique in terms of time resolution and diversity of system.

  13. Etude vibrationnelle d'aluminates et de gallates de terres rares—II. Gallates de structure pérovskite

    Science.gov (United States)

    Saine, M. C.; Husson, E.; Brusset, H.

    The i.r. spectra of some gallates LnGaO 3 (Ln = La, Pr, Nd) with perovskite structure and the Raman spectrum of NdGaO 3 are presented and analysed. The force field, calculated for the three compounds, is stronger than for homologous aluminates. The GaO bonds which are parallel to the C2 axis are stronger than the others, thus showing the existence of a privileged direction. This effect decreases from La to Nd compounds.

  14. BLENDED CALCIUM ALUMINATE-CALCIUM SULFATE CEMENT-BASED GROUT FOR P-REACTOR VESSEL IN-SITU DECOMMISSIONING

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C.; Stefanko, D.

    2011-03-10

    The objective of this report is to document laboratory testing of blended calcium aluminate - calcium hemihydrate grouts for P-Reactor vessel in-situ decommissioning. Blended calcium aluminate - calcium hemihydrate cement-based grout was identified as candidate material for filling (physically stabilizing) the 105-P Reactor vessel (RV) because it is less alkaline than portland cement-based grout which has a pH greater than 12.4. In addition, blended calcium aluminate - calcium hemihydrate cement compositions can be formulated such that the primary cementitious phase is a stable crystalline material. A less alkaline material (pH {<=} 10.5) was desired to address a potential materials compatibility issue caused by corrosion of aluminum metal in highly alkaline environments such as that encountered in portland cement grouts [Wiersma, 2009a and b, Wiersma, 2010, and Serrato and Langton, 2010]. Information concerning access points into the P-Reactor vessel and amount of aluminum metal in the vessel is provided elsewhere [Griffin, 2010, Stefanko, 2009 and Wiersma, 2009 and 2010, Bobbitt, 2010, respectively]. Radiolysis calculations are also provided in a separate document [Reyes-Jimenez, 2010].

  15. Approach for determination of detonation performance and aluminum percentage of aluminized-based explosives by laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Rezaei, Amir Hossein; Keshavarz, Mohammad Hossein; Tehrani, Masoud Kavosh; Reza Darbani, Seyyed Mohammad; Farhadian, Amir Hossein; Mousavi, Seyyed Jabbar; Mousaviazar, Ali

    2016-04-20

    Energetic materials containing aluminum powder are hazardous compounds, which have wide applications as propellants, explosives, and pyrotechnics. This work introduces a new method on the basis of the laser-induced breakdown spectroscopy technique in air and argon atmospheres to investigate determination of aluminum content and detonation performance of 1,3,5-trinitro-1,3,5-triazine (RDX)-based aluminized explosives. Plasma emission of aluminized RDX explosives are recorded where atomic lines of Al, C, H, N, and O, as well as molecular bands of AlO and CN are identified. The formation mechanism of AlO and CN molecular bands is affected by the aluminum percentage and oxygen content present in the composition and plasma. Relative intensity of the Al/O is used to determine detonation velocity and pressure of the RDX/Al samples. The released energy in the laser-induced plasma of aluminized RDX composition is related to the heat of explosion and percentage of aluminum.

  16. Influence of supersaturation on structure of sodium aluminate solutions with medium concentration: a solution X-ray diffraction study

    Institute of Scientific and Technical Information of China (English)

    李洁; 陈启元; 尹周澜; 张平民; 李元高

    2002-01-01

    Influence of supersaturation on the structure of a series of freshly prepared supersaturated sodium aluminate solutions with medium concentration was investigated by solution X-ray diffraction. Experimental results show that the basic Al-containing species in all kinds of supersaturated solution is four-coordinated ions. Opposite to Al-O distance contracted in highly concentrated solution, a little expand of the Al-O distance from 1.75 to 1.85 occurs with increasing supersaturation, which is consistent with the occurrence of oligomeric aluminate species. Meanwhile, O-O distance in the first shell of H2O-H2O(OH) in supersaturated sodium aluminate solution is obviously longer than in hydroxide sodium solution and becomes longer and longer with increasing supersaturation. Na-O bond length is about 2.4 and changes little with supersaturation. The reason for Al-O bond expanding with supersaturation and its influence on the stability of solution was discussed.

  17. Formation of calcium aluminates in the lime sinter process. [Extraction of alumina from fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Chou, K.S.

    1980-03-01

    A study of the formation of several calcium aluminates from pure components in the lime sinter process was undertaken to determine the kinetics of formation and subsequent leaching using a dilute sodium carbonate solution. The composition CaO 61.98%, SiO/sub 2/ 26.67%, and Al/sub 2/O/sub 3/ 11.53% was used. Isothermal sintering runs of 0.2 to 10.0 h were carried out at 1200, 1250, 1300, and 1350/sup 0/C. When the sintering temperature was below the eutectic temperature (1335/sup 0/C), the ternary mixture behaved like two binary systems, i.e. CaO-Al/sub 2/O/sub 3/ and CaO-SiO/sub 2/. Only one compound, 3CaO.SiO/sub 2/, was formed between CaO and SiO/sub 2/. With lower sintering temperature and shorter sintering time, the ..beta..-phase was dominant. However, when both temperature and time increased, more and more of the ..beta..-C/sub 2/S was transformed into the ..gamma..-phase. Several different aluminates were formed during the sintering of CaO and Al/sub 2/O/sub 3/. The compounds CaO.Al/sub 2/O/sub 3/ and 3CaO.Al/sub 2/O/sub 3/ were observed at all tested sintering temperatures, while the 5CaO.3Al/sub 2/O/sub 3/ phase was found only at 1200/sup 0/C and 12CaO.7Al/sub 2/O/sub 3/ at 1250/sup 0/C or higher. The first compound formed between CaO and Al/sub 2/O/sub 3/ was probably 12CaO.7Al/sub 2/O/sub 3/, but the amount did not increase immediately with time. The first dominant compound between CaO and Al/sub 2/O/sub 3/ was CaO.3Al/sub 2/O/sub 3/. When the calcium ion diffused through the product layer of CaO.Al/sub 2/O/sub 3/, 3CaO.Al/sub 2/O/sub 3/ was formed. If unreacted Al/sub 2/O/sub 3/ were present after the formation of CaO.Al/sub 2/O/sub 3/, CaO.2Al/sub 2/O/sub 3/ would form. Subsequent leaching of the sinters showed that the extractable alumina in the products increased with both sintering temperature and time, reaching a max of about 90%. These extraction data corresponded very well to the quantities of aluminates in the sinters. 59 figures, 13 tables.

  18. Analyses of Hubble Space Telescope Aluminized-Teflon Insulation Retrieved After 19 Years of Space Exposure

    Science.gov (United States)

    deGroh, Kim K.; Waters, Deborah L.; Mohammed, Jelila S.; Perry, Bruce A.; Banks, Bruce A.

    2012-01-01

    Since its launch in April 1990, the Hubble Space Telescope (HST) has made many important observations from its vantage point in low Earth orbit (LEO). However, as seen during five servicing missions, the outer layer of multilayer insulation (MLI) has become successively more embrittled and has cracked in many areas. In May 2009, during the 5th servicing mission (called SM4), two MLI blankets were replaced with new insulation pieces and the space-exposed MLI blankets were retrieved for degradation analyses by teams at NASA Glenn Research Center (GRC) and NASA Goddard Space Flight Center (GSFC). The MLI blankets were from Equipment Bay 8, which received direct sunlight, and Equipment Bay 5, which received grazing sunlight. Each blanket contained a range of unique regions based on environmental exposure and/or physical appearance. The retrieved MLI blanket s aluminized-Teflon (DuPont) fluorinated ethylene propylene (Al-FEP) outer layers have been analyzed for changes in optical, physical, and mechanical properties, along with space induced chemical and morphological changes. When compared to pristine material, the analyses have shown how the Al-FEP was severely affected by the space environment. This paper reviews tensile properties, solar absorptance, thermal emittance, x-ray photoelectron spectroscopy (XPS) data and atomic oxygen erosion values of the retrieved HST blankets after 19 years of space exposure.

  19. Influence of mechanical activation of AL2O3 on synthesis of magnesium aluminate spinel

    Directory of Open Access Journals (Sweden)

    Zhihui Zhang

    2004-01-01

    Full Text Available Magnesium aluminate (MA spinel is synthesized by reaction sintering from alumina and magnesia. The effects of mechanical activation of Al2O3 on reaction sintering were investigated. Non-milled a - Al2O3 and a - Al2O3 high-energy ball milled for 12h, 24h and 36h were mixed with a MgO analytical reagent according to the stoichiometric MA ratio, respectively and pressed into billets with diameters of 20mm and height of 15mm. The green-body billets were then sintered at high temperature in an air atmosphere. The results show that bulk density, relative content of MA and grain size of MA increase with increasing high-energy ball milling time of Al2O3. However prolonged milling time over 24h has a small beneficial effect on the densification of MA. Bulk density and grain size of a sample of a- Al2O3 milled for 24h are 3.30g/cm3 and 4-5 mm, respectively.

  20. Investigation Into Gas-Sensing Mechanism of Nanostructured Magnesium Aluminate as a Function of Temperature.

    Science.gov (United States)

    Nithyavathy, N; Arunmetha, S; Dhineshbabu, N R; Rajendran, V

    2015-07-01

    In this study, we used a new simple chemical method to synthesise nanostructured magnesium aluminate (NMA) powder. Sol-gel technique followed by sonication was used to develop different sensor samples namely NMA573, NMA873, and NMA1 073 by calcination at temperatures of 573, 873, and 1073 K respectively. Average crystallite size of 18-27 nm and specific surface area of 68.09 to 61.84 m2 g(-1) was obtained for the sensor samples. The existence of functional groups at 800 and 550 cm-1 corresponding respectively to AIO6 group and the lattice vibration of MgO4 stretching were confirmed through FTIR studies; SEM/EDX confirm the spherical morphology with elemental composition Mg, Al and O at different calcination temperatures. UV-Vis absorption spectra show band gap energy as 3.50, 3.48, and 3.44 eV for the sensor samples NMA573, NMA873, and NMA1 073 respectively. The effect of polyethylene glycol on the gas-sensing behaviour was studied in all the sensor samples. In particular, NMA1073 was found to have better resistance and sensor response for CO gas than NMA573 and NMA873. The effect of increase in calcination temperature of the sensor samples on the structural, morphological, optical, and gas response properties were carried out extensively to explore its gas sensing applications.

  1. Minimising reversion, using seawater and magnesium chloride, caused by the dissolution of tricalcium aluminate hexahydrate.

    Science.gov (United States)

    Palmer, Sara J; Frost, Ray L; Smith, Matthew K

    2011-01-15

    The increase in pH and aluminium concentration after the neutralisation of bauxite refinery residues is commonly known as reversion. This investigation reports the extent of reversion in synthetic supernatant liquor and possible methods to reduce reversion. This work is based on bauxite refinery residues produced from alumina refineries, where reversion is a real life situation in neutralised refinery residues. Tricalcium aluminate hexahydrate, a common phase in bauxite refinery residues, has been found to cause reversion. It has been established that reductions in both pH and aluminium from the seawater neutralisation process are due to the formation of 'Bayer' hydrotalcite Mg(7)Al(2)(OH)(18)(CO(3)(2-),SO(4)(2-))·xH(2)O. This is the primary mechanism involved in the removal of aluminium from solution. Increasing the volume of seawater used for the neutralisation process minimises the extent of reversion for both synthetic supernatant liquor and red mud slurry. The addition of MgCl(2)·6H(2)O also showed a reduction in reversion and confirmed that the decrease in aluminium and hydroxyl ions is due to the formation of Bayer hydrotalcite and not simply a dilution effect.

  2. Transparent magnesium aluminate spinel: a prospective biomaterial for esthetic orthodontic brackets.

    Science.gov (United States)

    Krishnan, Manu; Tiwari, Brijesh; Seema, Saraswathy; Kalra, Namitha; Biswas, Papiya; Rajeswari, Kotikalapudi; Suresh, Madireddy Buchi; Johnson, Roy; Gokhale, Nitin M; Iyer, Satish R; Londhe, Sanjay; Arora, Vimal; Tripathi, Rajendra P

    2014-11-01

    Adult orthodontics is recently gaining popularity due to its importance in esthetics, oral and general health. However, none of the currently available alumina or zirconia based ceramic orthodontic brackets meet the esthetic demands of adult patients. Inherent hexagonal lattice structure and associated birefringence limits the visible light transmission in polycrystalline alumina and make them appear white and non transparent. Hence focus of the present study was to assess the feasibility of using magnesium aluminate (MgAl2O4) spinel; a member of the transparent ceramic family for esthetic orthodontic brackets. Transparent spinel specimens were developed from commercially available white spinel powder through colloidal shaping followed by pressureless sintering and hot isostatic pressing at optimum conditions of temperature and pressure. Samples were characterized for chemical composition, phases, density, hardness, flexural strength, fracture toughness and optical transmission. Biocompatibility was evaluated with in-vitro cell line experiments for cytotoxicity, apoptosis and genotoxicity. Results showed that transparent spinel samples had requisite physico-chemical, mechanical, optical and excellent biocompatibility for fabricating orthodontic brackets. Transparent spinel developed through this method demonstrated its possibility as a prospective biomaterial for developing esthetic orthodontic brackets.

  3. Thermal neutron response and theoretical comparison of LiF coated aluminized Mylar

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Kyle A., E-mail: knelson1@ksu.edu; Bellinger, Steven L.; Edwards, Nathaniel S.; Montag, Benjamin W.; Schmidt, Aaron J.; Wayant, Clayton; McGregor, Douglas S.

    2014-10-21

    Thin layers of LiF were deposited on a 2.0 µm thick aluminized BoPET (i.e. Mylar) in thicknesses of 4.5, 9.9, and 14.0 µm using an electron beam evaporator. These coatings were thinner than the summed triton and alpha particle range from the {sup 6}Li(n,t){sup 4}He reaction, which allows both particles to escape a suspended absorber sheet simultaneously and measured in a proportional gas region concurrently. Each thickness of the LiF coated Mylar sheets were positioned separately in a test chamber that had a single anode wire positioned on each side of the absorber sheets. The thermal neutron response pulse-height spectra were collected for each LiF thickness and are presented and discussed. The coatings became fragile at thicknesses greater than 5.0 µm and would flake off of the Mylar sheets. Additionally, the ideal LiF coating thickness that maximizes the intrinsic thermal neutron detection efficiency is greater than 5.0 µm, which is discussed in a greater detail in the text. Overall, the detectors are capable of achieving thermal-neutron detection efficiencies greater than 30% for a 5 layer device and 60 % for 20 layers, but these devices are complex to fabricate due to flaking of the LiF coatings. Additional research is required to eliminate flaking by possibly using additional mechanical structures or adhesive materials.

  4. The Hydration and Carbonation of Tricalcium Aluminate (C3A) in the Presence of Heavy Metals

    Institute of Scientific and Technical Information of China (English)

    CHEN Quanyuan; C. D. Hills; M. Tyrer; I. Slipper

    2005-01-01

    The hydration of tricalcium aluminate (C3A) has a significant effect on the effectiveness of cement-based systems. In addition, the carbonation of hydration products of C3A is particularly important in respect of durability performance. The present work investigates the hydration and carbonation reactions of C3A and the changes induced by the presence of the heavy metal ions such as Zn2+, Pb2+, Cu2+ and Cr3+ by X-ray diffractometry (XRD). During hydration of C3A, gehlenite hydrate, hydrogarnet, calcium monoaluminate (C4AHx) and calcium carboaluminate were detected in C3A pastes except the Zn2+doped paste, where hydrogarnet did not form. The examinations revealed that heavy metals coexisted with gehlenite hydrate, calcium monoaluminate (C4AHx) and calcium carboaluminate, inhibiting the formation of hydrogarnet. Hydrating C3A was liable to be carbonated on exposure to air and carbon dioxide, especially in the presence of heavy metals, resulting in the formation of carboaluminate and/or calcium carbonate. The presence of heavy metals in-fluenced the polymorphism of calcium carbonate,ndicating that heavy metals could co-precipitate with calcium to form a carbonate solid solution.

  5. Effective fingerprint recognition technique using doped yttrium aluminate nano phosphor material.

    Science.gov (United States)

    Darshan, G P; Premkumar, H B; Nagabhushana, H; Sharma, S C; Prashanth, S C; Prasad, B Daruka

    2016-02-15

    First time the yttrium aluminate nanoparticles are used to improve the fingerprint quality. Eco-friendly green combustion process is used to synthesize YAlO3:Sm(3+) (0.5-11mol%) nanophosphor using green tea leaf extract as non-toxic and eco-friendly fuel. Powder X-ray diffraction study confirms the orthorhombic phase. The average sizes of the crystallites were found to be in the range 20-35nm. The emission peaks centered at 564, 601 and 647nm is attributed to 4f-4f (4)G5/2→(6)HJ=5/2,7/2,9/2 forbidden transitions of Sm(3+) ions. Judd-Ofelt theory is applied to experimental data for providing qualitative support by determining J-O intensity parameters. The Commission International De I-Eclairage chromaticity co-ordinates are very close to National Television System Committee standard value of white emission (x=0.296, y=0.237). Further, correlated color temperature is found to be ∼11,900K. A simple, fast, highly sensitive and low-cost method for the detection and enhancement of fingermarks in a broad range of surfaces is developed and constitutes an alternative to traditional luminescent powders.

  6. OXIDATION RESISTANCE OF NANOCRYSTAL ODS ALUMINIDE COATINGS PRODUCED BY PACK ALUMINIZING PROCESS ASSISTED BY BALL PEENING

    Institute of Scientific and Technical Information of China (English)

    Z.L. Zhan; Y.D. He; W. Gao

    2006-01-01

    Nanocrystal ODS (oxide dispersion strengthening) aluminide coatings were produced on a stainless steel and nickel-based superalloy by the pack aluminizing process assisted by ball peening. Pure Al powders and 1% of ultra-fine Y2O3 powders were mixed by ball milling. The ultra-fine Y2O3powders were dispersed in Al particles. Ball peening welded the Al particles onto the substrate and accelerated the formation of aluminide coating. Nanocrystal ODS aluminide coatings were produced by the outward growth at a much low temperature (below 600℃) in a short treatment time.The effects of the operation temperature and treatment time on the formation of the coatings were analyzed. SEM (scanning electron microscope), AFM (atomic force microscope), EDS (energy dispersive X-ray spectroscopy), XRF (X-ray fluorescence spectrometer) and XRD (X-ray diffraction )methods were applied to investigate the microstructure of the coatings. High-temperature oxidation tests were carried out to evaluate the oxidation resistance of the ODS aluminide coatings.

  7. Hot-Dip Aluminizing of Low Carbon Steel Using Al-7Si-2Cu Alloy Baths

    Directory of Open Access Journals (Sweden)

    Prashanth Huilgol

    2013-01-01

    Full Text Available Hot-dip aluminizing of low carbon steel was done in molten Al-7Si-2Cu bath at 690°C for dipping time ranging from 300 to 2400 seconds. Characterization of the intermetallics layer was done by using scanning electron microscope with energy dispersive spectroscopy. Four intermetallic phases, τ5-Al7Fe2Si, θ-FeAl3, η-Fe2Al5, and τ1-Al2Fe3Si3, were identified in the reaction layer. τ5- Al7Fe2Si phase was observed adjacent to aluminum-silicon topcoat, θ-FeAl3 between τ5 and η-Fe2Al5, η-Fe2Al5 adjacent to base material, and τ1-Al2Fe3Si3 precipitates within Fe2Al5 layer. The average thickness of Fe2Al5 layer increased linearly with square root of dipping time, while for the rest of the layers such relationship was not observed. The tongue-like morphology of Fe2Al5 layer was more pronounced at higher dipping time. Overall intermetallic layer thickness was following parabolic relationship with dipping time.

  8. Solidification/stabilization of toxic metals in calcium aluminate cement matrices

    Energy Technology Data Exchange (ETDEWEB)

    Navarro-Blasco, I.; Duran, A.; Sirera, R.; Fernández, J.M.; Alvarez, J.I., E-mail: jalvarez@unav.es

    2013-09-15

    Highlights: • Reliable encapsulation and effective sorption of Pb, Zn and Cu on CAC was proved. • Cu and Pb were fully retained in the CAC mortar, while Zn was retained in 99.99%. •A maximum sorption capacity ca. 60 mg/g CAC was attained for Cu. • Three different PSD patterns were established as a function of XRD phase assemblage. • Some metal-loaded mortars achieved suitable mechanical strengths for landfilling. -- Abstract: The ability of calcium aluminate cement (CAC) to encapsulate toxic metals (Pb, Zn and Cu) was assessed under two curing conditions. Changes in the consistency and in the setting time were found upon the addition of the nitrates of the target metals. Both Pb and Cu caused a delay in CAC hydration, while Zn accelerated the stiffening of the mortar. Compressive strengths of the metal-doped mortars, when initially cured at 60 °C/100% RH, were comparable with that of the free-metal mortar. Three different pore size distribution patterns were identified and related to the compounds identified by XRD and SEM. Sorbent capacities of CAC for the toxic metals were excellent: a total uptake was achieved for up to 3 wt.% loading of the three metals. In this way, CAC mortars were perfectly able to encapsulate the toxic metals, allowing the use of CAC for waste management as proved by the leaching tests.

  9. Comprehensive Study of Lanthanum Aluminate High-Dielectric-Constant Gate Oxides for Advanced CMOS Devices

    Directory of Open Access Journals (Sweden)

    Masamichi Suzuki

    2012-03-01

    Full Text Available A comprehensive study of the electrical and physical characteristics of Lanthanum Aluminate (LaAlO3 high-dielectric-constant gate oxides for advanced CMOS devices was performed. The most distinctive feature of LaAlO3 as compared with Hf-based high-k materials is the thermal stability at the interface with Si, which suppresses the formation of a low-permittivity Si oxide interfacial layer. Careful selection of the film deposition conditions has enabled successful deposition of an LaAlO3 gate dielectric film with an equivalent oxide thickness (EOT of 0.31 nm. Direct contact with Si has been revealed to cause significant tensile strain to the Si in the interface region. The high stability of the effective work function with respect to the annealing conditions has been demonstrated through comparison with Hf-based dielectrics. It has also been shown that the effective work function can be tuned over a wide range by controlling the La/(La + Al atomic ratio. In addition, gate-first n-MOSFETs with ultrathin EOT that use sulfur-implanted Schottky source/drain technology have been fabricated using a low-temperature process.

  10. Tritium release from lithium silicate and lithium aluminate, in-reactor and out-of-reactor

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, A.B. Jr.

    1965-11-03

    Considerable technology has developed for production of tritium in metallic target systems. At normal N-Reactor temperatures ({approximately} 300{degrees}C), aluminum-lithium alloys appear to offer a satisfactory system for tritium production. However, reactor safety requirements have generated interest in a target system which will hold the lithium in place at temperatures to 1200{degrees}C. At the same time, gas retention at irradiation temperatures ({approximately}300{degrees}C) must be acceptable, and extraction of the product must be practical. To determine in-reactor gas release characteristics of the silicate and aluminate materials, targets were irradiated in quartz and aluminum capsules. Following irradiation, the gas (condensible and noncondensible fractions) released in-reactor was recovered by drilling the capsules. Subsequently, the targets were recovered and heated in a laboratory vacuum system to investigate characteristics of tritium and helium evolution as a function of temperature. The experimental procedures are discussed briefly, with details in the Appendix. The results of the study are discussed in terms of in-reactor release and later in terms of laboratory extractions.

  11. Cation disordering in magnesium aluminate spinel crystals induced by electron or ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Soeda, Takeshi E-mail: soeda@regroup5.nucl.kyushu-u.ac.jp; Matsumura, Syo; Kinoshita, Chiken; Zaluzec, Nestor J

    2000-12-01

    Structural changes in magnesium aluminate spinel (MgO {center_dot} nAl{sub 2}O{sub 3}) single crystals, which were irradiated with 900 keV electrons or 1 MeV Ne{sup +} ions at 873 K, were examined by electron channeling enhanced X-ray microanalysis. Unirradiated MgO {center_dot} Al{sub 2}O{sub 3} has a tendency to form the normal spinel configuration, where Mg{sup 2+} ions and Al{sup 3+} ions occupy mainly the tetrahedral and the octahedral sites, respectively. Electron irradiation induces simple cation disordering between the tetrahedral sites and the octahedral sites in MgO {center_dot} Al{sub 2}O{sub 3}. In addition to cation disordering, slight evacuation of cations from the tetrahedral sites to the octahedral sites occurs in a peak-damaged area in MgO {center_dot} Al{sub 2}O{sub 3} irradiated with Ne{sup +} ions. In contrast, cation disordering is suppressed in MgO {center_dot} 2.4Al{sub 2}O{sub 3} irradiated with electrons. The structural vacancies, present in the non-stoichiometric compound, appear to be effective in promoting irradiation damage recovery through interstitial-vacancy recombination.

  12. Elastic Properties of Tricalcium Aluminate from High-Pressure Experiments and First-Principles Calculations

    KAUST Repository

    Moon, Juhyuk

    2012-06-04

    The structure and elasticity of tricalcium aluminate (C 3A) have been experimentally and theoretically studied. From high-pressure X-ray diffraction experiments, the bulk modulus of 102(6) and 110(3) GPa were obtained by fitting second- and third-order finite strain equation of state, respectively. First-principles calculations with a generalized gradient approximation gave an isotropic bulk modulus of 102.1 GPa and an isothermal bulk modulus of 106.0 GPa. The static calculations using the exchange-correlation functional show an excellent agreement with the experimental measurements. Based on the agreement, accurate elastic constants and other elastic moduli were computed. The slight difference of behavior at high pressure can be explained by the infiltration of pressure-transmitting silicone oil into structural holes in C 3A. The computed elastic and mechanical properties will be useful in understanding structural and mechanical properties of cementitious materials, particularly with the increasing interest in the advanced applications at the nanoscale. © 2012 The American Ceramic Society.

  13. Novel porous calcium aluminate/phosphate nanocomposites: in situ synthesis, microstructure and permeability

    Science.gov (United States)

    Yang, Jingzhou; Hu, Xiaozhi; Huang, Juntong; Chen, Kai; Huang, Zhaohui; Liu, Yangai; Fang, Minghao; Sun, Xudong

    2016-02-01

    Permeable porous nanomaterials have extensive applications in engineering fields. Here, we report a novel system of porous calcium aluminate/phosphate (CaAl-CaP) nanocomposites fabricated by pore generator free processing. The CaAl rich samples have close micropores and are not permeable. Interestingly, the CaP rich composites have a unique three-dimensional nanosieve structure with interconnected nanopores and exhibit excellent liquid permeability and adsorbability. The pore size has a narrow distribution of 200-500 nm. The CaAl nanoplatelets in the CaP rich composite have a thickness of 202 nm, a diameter of 1600 nm and an aspect ratio of 8. The porosity is from 19% to 40%. The bending strength and compressive strength are 40.3 MPa and 195 MPa, respectively. The CaP rich nanocomposite is highly permeable so that a water droplet can completely penetrate in 10 seconds (1 mm thick disk). The blue dye can be desorbed in 45 min by ultrasonic vibration. Given the nanosieve porous structure, good permeability/adsorbability and high mechanical properties, the CaP rich nanocomposite has big potential in applications for chemical engineering, biomedical engineering and energy/environmental engineering.

  14. A theoretical study of intrinsic point defects and defect clusters in magnesium aluminate spinel.

    Science.gov (United States)

    Gilbert, C A; Smith, R; Kenny, S D; Murphy, S T; Grimes, R W; Ball, J A

    2009-07-08

    Point and small cluster defects in magnesium aluminate spinel have been studied from a first principles viewpoint. Typical point defects that occur during collision cascade simulations are cation anti-site defects, which have a small formation energy and are very stable, O and Mg split interstitials and vacancies. Isolated Al interstitials were found to be energetically unfavourable but could occur as part of a split Mg-Al pair or as a three atom-three vacancy Al 'ring' defect, previously observed in collision cascades using empirical potentials. The structure and energetics of the defects were investigated using density functional theory (DFT) and the results compared to simulations using empirical fixed charge potentials. Each point defect was studied in a variety of supercell sizes in order to ensure convergence. It was found that empirical potential simulations significantly overestimate formation energies, but that the type and relative stability of the defects are well predicted by the empirical potentials both for point defects and small defect clusters.

  15. Research on surface aluminizing process and properties of hot working die steel%热作模具钢的表面渗铝工艺及性能研究

    Institute of Scientific and Technical Information of China (English)

    赵宏宇

    2014-01-01

    The surface aluminizing process of 4CrSMoSiV1 hot working die steel was studied,and the microstructures of aluminizing layer with different NH4Cl content,aluminizing temperature and aluminizing time were observed.The phases and hardness of the aluminizing layer with optimized surface aluminizing process were analyzed by XRD and micro-hardness.The results show that the thickness of aluminizing layer increases gradually with the rising of aluminizing temperature,and the thickness increases obviously when the aluminizing temperature rises from 850 ℃ to 950 ℃.The thickness of aluminizing layer increases gradually with prolonging temperature holding time,during which the thickness increases most obviously when the aluminizing holding time is within 3-5 h.The optimal surface aluminizing process for hot working die steel is 1% NH4 Cl catalyst,the aluminizing temperature of 950 ℃ with holding time of 5 h.For the aluminizing layer obtained with optimized aluminizing process,the Fe3 Al and FeAl phases are formed in its surface layer and FeAl phase is formed in its inner layer.%研究了4Cr5 MoSiV1热作模具钢的表面渗铝工艺,对不同NH4Cl含量、不同渗铝温度和渗铝时间的渗层微观组织进行了观察,并采用XRD和显微硬度对最优渗铝工艺的渗层物相和硬度进行了检测和分析.研究结果表明:随着渗铝温度的升高,渗层厚度逐渐加大,当渗铝温度从850 ℃上升至950℃时,渗层厚度增加较为明显;渗层厚度随着渗铝保温时间的延长而逐渐增加,其中渗铝保温时间在3~5h间渗层厚度增加最为明显;热作模具钢的最佳渗铝工艺为:采用1%催渗剂NH4Cl,渗铝温度为950℃,保温时间为5h;优化工艺下的渗铝层中的表层形成了Fe3Al和FeAl相,内层形成了FeAl相.

  16. 575 nm laser oscillation in Dy3+-doped waterproof fluoro-aluminate glass fiber pumped by violet GaN laser diodes

    Science.gov (United States)

    Fujimoto, Yasushi; Ishii, Osamu; Yamazaki, Masaaki

    2011-02-01

    We successfully drew a low-loss Dy-doped optical fiber (0.3dB/m at 532nm) of a waterproof fluoro-aluminate glass system and demonstrated yellow laser oscillation in the Dy3+-doped fluoride fiber pumped by a 398.8-nm GaN laser diode. The maximum output power was 10.3 mW and the slope efficiency was 17.1% at 575 nm. Since the fluoro-aluminate- glass system has a remarkable water resistance advantage compared to ZBLAN glass, Dy-doped fluoro-aluminate glass fiber is expected to contribute to making a solid-state yellow fiber laser with high chemical durability without a frequency doubling technique.

  17. Study of damages by neutron irradiation in lithium aluminates; Estudio de danos por irradiacion neutronica en aluminatos de litio

    Energy Technology Data Exchange (ETDEWEB)

    Palacios G, O

    1999-06-01

    Lithium aluminates proposed to the production of tritium in fusion nuclear reactors, due to the thermal stability that they present as well as the behavior of the aluminium to the irradiation. As a neutron flux with profile ({approx_equal} 14 Mev) of a fusion reactor is not available. A irradiation experiment was designed in order to know the micro and nano structure damages produced by fast and thermal neutrons in two irradiation positions of the fusion nuclear reactor Triga Mark III: CT (Thermal Column) and SIFCA (System of Irradiation Fixed of Capsules). In this work samples of lithium aluminate were characterized by XRD (X-Ray Diffraction), TEM (Transmission Electron Microscopy) and SEM (Scanning Electron Microscopy). Two samples were prepared by two methods: a) coalition method and b) peroxide method. This characterization comprised original and irradiated samples. The irradiated sample amounted to 4 in total: one for each preparation method and one for each irradiation position. The object of this analysis was to correlate with the received neutron dose the damages suffered by the samples with the neutron irradiation during long periods (440 H), in their micro and nano structure aspects; in order to understand the changes as a function of the irradiation zone (with thermal and fast neutron flux) and the preparation methods of the samples and having as an antecedent the irradiation in SIFCA position by short times (2h). The obtained results are referred to the stability of {gamma} -aluminate phase, under given conditions of irradiation and defined nano structure arrangement. They also refer to the proposals of growth mechanism and nucleation of new phases. The error associated with the measurement of neutron dose is also discussed. (Author)

  18. Color-center production and recovery in electron-irradiated magnesium aluminate spinel and ceria.

    Science.gov (United States)

    Costantini, Jean-Marc; Lelong, Gérald; Guillaumet, Maxime; Weber, William J; Takaki, Seiya; Yasuda, Kazuhiro

    2016-08-17

    Single crystals of magnesium aluminate spinel (MgAl2O4) with (1 0 0) or (1 1 0) orientations and cerium dioxide or ceria (CeO2) were irradiated by 1.0 MeV and 2.5 MeV electrons in a high-fluence range. Point-defect production was studied by off-line UV-visible optical spectroscopy after irradiation. For spinel, regardless of both crystal orientation and electron energy, two characteristic broad bands centered at photon energies of 5.4 eV and 4.9 eV were assigned to F and F(+) centers (neutral and singly ionized oxygen vacancies), respectively, on the basis of available literature data. No clear differences in color-center formation were observed for the two crystal orientations. Using calculations from displacement cross sections by elastic collisions, these results are consistent with a very large threshold displacement energy (200 eV) for oxygen atoms at room temperature. A third very broad band centered at 3.7 eV might be attributed either to an oxygen hole center (V-type center) or an F2 dimer center (oxygen di-vacancy). The onset of recovery of these color centers took place at 200 °C with almost full bleaching at 600 °C. Activation energies (~0.3-0.4 eV) for defect recovery were deduced from the isochronal annealing data by using a first-order kinetics analysis. For ceria, a sub-band-gap absorption feature, which peaked at ~3.1 eV, was recorded for 2.5 MeV electron irradiation only. Assuming a ballistic process, we suggest that the latter defect might result from cerium atom displacement on the basis of computed cross sections.

  19. Transition of Blast Furnace Slag from Silicates-Based to Aluminates-Based: Viscosity

    Science.gov (United States)

    Yan, Zhiming; Lv, Xuewei; Liang, Dong; Zhang, Jie; Bai, Chenguang

    2016-05-01

    The effect of Al2O3 and the Al2O3/SiO2(A/S) ratio on the viscosity of the CaO-SiO2-Al2O3-MgO-TiO2 slag system was studied in the present work. At a fixed CaO/SiO2(C/S) ratio of 1.20, 9 mass pct MgO, and 1 mass pct TiO2, the viscosity increases with an increase in Al2O3 content at a range of 16 to 24 mass pct due to the polymerization of the aluminosilicate structures, while it decreases when the Al2O3 is higher than 24 mass pct, which means that Al2O3 acts as a network modifier at higher content. Increasing A/S from 0.47 to 0.92 causes a slight decrease in viscosity of the slags and has an opposite effect when A/S is more than 0.92. The free running temperature increases with the Al2O3 content and appears to show a peak at an A/S ratio of 0.92. The change of the apparent activation energy is in accordance with the change of viscosity. When Al2O3 content is more than 24 mass pct with low SiO2, CaO content ranges from 35 to 45 mass pct, and the slag transform from silicates-based to aluminates-based can still get a good operation region. Four different viscosity models were employed to predict the viscosity and RIBOUD's model was found to be the best in predicting the viscosity by comparing the estimated viscosity with the measured viscosity.

  20. Optical properties of Sm{sup 3+} doped strontium hexa-aluminate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Gheorghe, C., E-mail: cristina_gheorghe2002@yahoo.com; Gheorghe, L.; Achim, A.; Hau, S.; Avram, R.D.; Stanciu, G.

    2015-02-15

    Highlights: • Investigation of Sm{sup 3+} doped Sr{sub 1-x}Sm{sub y}La{sub x-y}Mg{sub x}Al{sub 12-x}O{sub 19} - Sm: ASL as laser material. • Polarized absorption and emission spectra of Sm: ASL were performed. • The spectroscopic properties of Sm{sup 3+} doped ASL single crystal were evaluated. • Sm: ASL exhibit favorable conditions for laser action in yellow-orange range. - Abstract: Sm{sup 3+} doped disordered strontium hexa-aluminate crystals Sr{sub 1-x}Sm{sub y}La{sub x-y}Mg{sub x}Al{sub 12-x}O{sub 19} (x = 0.2, y = 0.05, 0.1, 0.15) were grown by Czochralski method. Polarized absorption spectra, as well as emission and lifetime measurements were performed. Strong absorption line located at 404 nm, could be utilized for efficient excitation of material by InGaN/GaN laser diodes. The Judd-Ofelt theory, extended to anisotropic system, has been applied to evaluate the Ω{sub t} (t = 2, 4, 6) intensity parameters, radiative transition rates A{sub r}, branching ratios β, and radiative lifetime τ{sub r} of the fluorescent {sup 4}G{sub 5/2} level. The emission cross-section for the {sup 4}G{sub 5/2} → {sup 6}H{sub 7/2} transition at about 593 nm with the highest value of 1.6 × 10{sup -21} cm{sup 2} nm for σ-polarization and an experimental branching ratio β = 49.43%, gives high chance for obtaining laser action in four level operation scheme.

  1. Stabilizing cadmium into aluminate and ferrite structures: Effectiveness and leaching behavior.

    Science.gov (United States)

    Su, Minhua; Shih, Kaimin; Kong, Lingjun

    2017-02-01

    The inappropriate disposal of sludge, particularly for those enriched in heavy metals, is highly hazardous to the environment. Thermally converting sludge into useful products is a highly promising technique as heavy metals are immobilized and organic substances are mineralized. This work investigated the feasibility of stabilizing simulated cadmium-laden sludge by sintering with Al-and Fe-rich precursors. To simulate the process, cadmium oxide was alternatively mixed and sintered with γ-Al2O3 and α-Fe2O3. Cadmium was crystallographically incorporated into aluminate (CdAl4O7) monoclinic structure and ferrite (CdFe2O4) spinel, dependent on the type of precursor used. The CdFe2O4 formation was initialed at about 150-300 °C lower than that of CdAl4O7. With Rietveld refinement analysis of the collated XRD data, the weight percentages of crystalline phases in the fired samples were quantified. To evaluate the cadmium incorporation efficiency, a transformation ratio (TR) index was devised. The TR values revealed that, to effectively incorporate cadmium, 950 °C was favored by γ-Al2O3 and 850 °C was for α-Fe2O3 within a 3-h sintering treatment. Constant pH leaching test (CPLT) was used to assess the metal stabilization effects, revealing a remarkable reduction of cadmium by transformation into CdAl4O7 and CdFe2O4. Both CdAl4O7 and CdFe2O4 were incongruently dissolved in an acid solution. The overall finding indicated a potentially feasible technology in cadmium-laden sludge stabilization.

  2. Formation of lead-aluminate ceramics: Reaction mechanisms in immobilizing the simulated lead sludge.

    Science.gov (United States)

    Lu, Xingwen; Shih, Kaimin

    2015-11-01

    We investigated a strategy of blending lead-laden sludge and an aluminum-rich precursor to reduce the release of hazardous lead from the stabilized end products. To quantify lead transformation and determine its incorporation behavior, PbO was used to simulate the lead-laden sludge fired with γ-Al2O3 by Pb/Al molar ratios of 1/2 and 1/12 at 600-1000 °C for 0.25-10 h. The sintered products were identified and quantified using Rietveld refinement analysis of X-ray diffraction data from the products generated under different conditions. The results indicated that the different crystallochemical incorporations of hazardous lead occurred through the formation of PbAl2O4 and PbAl12O19 in systems with Pb/Al ratios of 1/2 and 1/12, respectively. PbAl2O4 was observed as the only product phase at temperature of 950 °C for 3h heating in Pb/Al of 1/2 system. For Pb/Al of 1/12 system, significant growth of the PbAl12O19 phase clearly occurred at 1000 °C for 3 h sintering. Different product microstructures were found in the sintered products between the systems with the Pb/Al ratios 1/2 and 1/12. The leaching performances of the PbO, Pb9Al8O21, PbAl2O4 and PbAl12O19 phases were compared using a constant pH 4.9 leaching test over 92 h. The leachability data indicated that the incorporation of lead into PbAl12O19 crystal is a preferred stabilization mechanism in aluminate-ceramics.

  3. X-AFm stabilization as a mechanism of bypassing conversion phenomena in calcium aluminate cements

    Energy Technology Data Exchange (ETDEWEB)

    Falzone, Gabriel, E-mail: gabefalzone@gmail.com [Laboratory for the Chemistry of Construction Materials LC" 2, Department of Civil and Environmental Engineering, University of California, Los Angeles, CA (United States); Department of Materials Science and Engineering, University of California, Los Angeles, CA (United States); Balonis, Magdalena, E-mail: mbalonis@ucla.edu [Department of Materials Science and Engineering, University of California, Los Angeles, CA (United States); Institute for Technology Advancement, University of California, Los Angeles, CA (United States); Sant, Gaurav, E-mail: gsant@ucla.edu [Laboratory for the Chemistry of Construction Materials LC" 2, Department of Civil and Environmental Engineering, University of California, Los Angeles, CA (United States); California Nanosystems Institute (CNSI), University of California, Los Angeles, CA (United States)

    2015-06-15

    Phase conversion phenomena are often observed in calcium aluminate cements (CACs), when the water-rich hydrates (e.g., CAH{sub 10}, C{sub 2}AH{sub 8}) formed at early ages, at temperatures ≤ 30 °C, expel water in time to form more compact, less water-rich structures (C{sub 3}AH{sub 6}). The phase conversions follow a path regulated by the thermodynamic stabilities (solubilities) of phases. Based on this premise, it is proposed that conversion phenomena in CACs can be bypassed by provoking the precipitation of phases more preferred than those typically encountered along the conversion pathway. Therefore, X-AFm formation (where in this case, X = NO{sub 3}{sup −}) triggered by the sequential addition of calcium nitrate (Ca(NO{sub 3}){sub 2} = CN) additives is identified as a new means of bypassing conversion. A multi-method approach comprising X-ray diffraction (XRD), thermal analytics, and evaluations of the compressive strength is applied to correlate phase balances and properties of CAC systems cured at 25 °C and 45 °C. The results highlight the absence of the C{sub 3}AH{sub 6} phase across all systems and the curing conditions considered, with enhanced strengths being noted, when sufficient quantities of CN are added. The experimental outcomes are supported by insights gained from thermodynamic calculations which highlight thermodynamic selectivity as a means of regulating and controlling the evolutions of solid phase balances using inorganic salts in CACs, and more generally in cementing material systems.

  4. ALUMINIZING OIL CASING STEEL N80 BY A LOW-TEMPERATURE PACK PROCESSING MODIFIED WITH ZINC ADDITION

    OpenAIRE

    MIN HUANG; YU WANG; XIAO YONG ZHANG

    2011-01-01

    Different aluminide coatings were prepared on oil casing steel N80 at a relatively lower temperature of 530°C for 2 h by pack powder modified with different content of zinc (Zn). The cross-sectional microstructure, element distribution and properties of as-aluminized oil casing steel N80 were investigated by SEM, EDS, micro-hardness test and electrochemical corrosion measurement. Results show that aluminide coating with around 50 μm in thickness can be successfully achieved by a low-temperatu...

  5. 含镁铝尖晶石的铝酸盐水泥的制备及其抗侵蚀性%PREPARATION AND CORROSION RESISTANCE OF ALUMINOUS CEMENT CONTAINING MAGNESIUM ALUMINATE SPINEL

    Institute of Scientific and Technical Information of China (English)

    肖国庆; 高云琴; 段锋

    2008-01-01

    以白云石和工业Al2O3为原料,采用烧结法制备了含镁铝尖晶石的铝酸盐新型水泥,利用X射线衍射检测了合成产物的物相组成,采用扫描电子显微镜观察了新型铝酸盐水泥中各物相的形貌和能谱分析了成分分布,测量了这种铝酸盐水泥的凝结时间、耐火度以及其所结合的高铝矾土制成的耐火浇注料的早期强度.选择静态坩埚法进行抗渣性实验,对比了新型铝酸盐水泥和纯铝酸钙水泥结合刚玉浇注料的抗渣性差异.结果表明:这种水泥的物相组成为镁铝尖晶石、一铝酸钙和二铝酸钙;物相分布较为均匀.与纯铝酸钙水泥比较,凝结时间正常,新型铝酸盐水泥结合刚玉浇注料与纯铝酸钙水泥结合刚玉浇注料的抗弯强度相当,耐火度较高和抗侵蚀性较好,其原因在于水泥中存在镁铝尖晶石相,而镁铝尖晶石有较高的熔点和抗熔渣侵蚀能力.%A new type of aluminous cement containing magnesium aluminate (MA) spinel was prepared from mixtures of dolomite and alumina by a sintering process. The microstructures and phase constituents of the synthesized product were inspected by X-ray diffraction and scanning electron microscope with energy dispersive X-ray spectrometry. The setting time, refractoriness and bonding strength of the new type of aluminous cement were measured by means of standard methods. The corrosion resistance property was also investigated by static crucible method. The experimental results show that the new type of aluminous cement consists of MA spinel, calcium monoaluminate and calcium dialuminate phases. Compared with aluminous cement, the prepared cement with more uniform phase distribution has a reasonable setting time, and the cement containing MA spinel bonded castables with bauxite as an aggregate have considerable bonding strength, higher refractoriness and better corrosion resistance. This is due to the introduction of MA spinel, which has a high

  6. Effect of polymorphism of Al2O3 on sintering and grain growth of magnesia aluminate spinel

    Directory of Open Access Journals (Sweden)

    Zhihui Z.

    2007-01-01

    Full Text Available The effect of polymorphism of Al2O3 on sintering and grain growth of magnesia aluminate spinel was studied. γ - Al2O3 and α - Al2O3 were mixed with MgO according to the stoichiometric MA ratio, respectively, and pressed into billets with a 20mm diameter and 15mm height, and then were sintered at temperature from 1250ºC to 1400ºC in air atmosphere. Bulk density, apparent porosity and grain size were measured. The results indicated that the grain size of MA with γ-Al2O3 is larger than the grain size of MA with α - Al2O3. This is because the activation energy of grain growth of magnesia aluminate spinel prepared by γ-Al2O3 is lower than that by α -Al2O3, the former is 159KJ/mol and the latter is 217KJ/mol.

  7. Effect of B2O3 content on structure and spectroscopic properties of neodymium-doped calcium aluminate glasses

    Science.gov (United States)

    Kang, Shuai; Wang, Xue; Xu, Wenbin; Wang, Xin; He, Dongbing; Hu, Lili

    2017-04-01

    Nd2O3-doped calcium aluminate glasses was synthesized with the following compositions: (100-x)(33Al2O3-62CaO-2MgO-3BaO)-xB2O3-0.5Nd2O3 (x = 0, 2.5, 5, 7.5, 10). The Raman, absorption, and emission spectra were measured to characterize the structure and spectroscopic properties of these glasses. The glass thermal stability was studied using differential scanning calorimetry (DSC) tests. Both the Raman spectra and DSC results indicated a decrease in the non-bridging oxygens (NBOs) in the [AlO4]- network with an increase in the B2O3 content. The J-O intensity parameter Ω2, covalency degree of the Nd-O bond, and emission bandwidth of the Nd3+ ions decreased with the B2O3 content. The stimulated emission cross-section and optical gain property increased with an increase in the B2O3 content. The tunable gain property and broadband emission feature of the Nd3+-doped CaO-Al2O3-B2O3-MgO-BaO calcium aluminate glass suggested a potential application to a high-energy ultra-short-pulse laser.

  8. Influence of silicon on hot-dip aluminizing process and subsequent oxidation for preparing hydrogen/tritium permeation barrier

    Energy Technology Data Exchange (ETDEWEB)

    Han, Shilei; Li, Hualing; Wang, Shumao; Jiang, Lijun; Liu, Xiaopeng [Energy Materials and Technology Research Institute, General Research Institute for Nonferrous Metals, Beijing 100088 (China)

    2010-04-15

    The development of the International Thermonuclear Experimental Reactor (ITER) requires the production of a material capable of acting as a hydrogen/tritium permeation barrier on low activation steel. It is well known that thin alumina layer can reduce the hydrogen permeation rate by several orders of magnitude. A technology is introduced here to form a ductile Fe/Al intermetallic layer on the steel with an alumina over-layer. This technology, consisting of two main steps, hot-dip aluminizing (HDA) and subsequent oxidation behavior, seems to be a promising coating method to fulfill the required goals. According to the experiments that have been done in pure Al, the coatings were inhomogeneous and too thick. Additionally, a large number of cracks and porous band could be observed. In order to solve these problems, the element silicon was added to the aluminum melt with a nominal composition. The influence of silicon on the aluminizing and following oxidation process was investigated. With the addition of silicon into the aluminum melt, the coating became thinner and more homogeneous. The effort of the silicon on the oxidation behavior was observed as well concerning the suppression of porous band and cracks. (author)

  9. Synthesis of zinc aluminate with high surface area by microwave hydrothermal method applied in the transesterification of soybean oil (biodiesel)

    Energy Technology Data Exchange (ETDEWEB)

    Quirino, M.R. [Chemistry Laboratory of Federal University of Paraiba (LABQUIM), Campus III, 58200-000 Bananeiras, PB (Brazil); Oliveira, M.J.C. [Academic Unit of Materials Engineering, UFCG, Campina Grande Campus I, 58429-900 Campina Grande, PB (Brazil); Keyson, D. [Laboratory of study in Science, DME, Federal University of Paraíba, Campus I, 58051-900 João Pessoa, PB (Brazil); Lucena, G.L., E-mail: guilherme_leo1@yahoo.com.br [Chemistry Laboratory of Federal University of Paraiba (LABQUIM), Campus III, 58200-000 Bananeiras, PB (Brazil); Oliveira, J.B.L. [Federal University of Rio Grande do Norte, UFRN, Campus I, 59078-970 Natal, RN (Brazil); Gama, L. [Academic Unit of Materials Engineering, UFCG, Campina Grande Campus I, 58429-900 Campina Grande, PB (Brazil)

    2016-02-15

    Highlights: • ZnAl{sub 2}O{sub 4} spinel was synthesized by the microwave hydrothermal method in only 15 or 30 min. • The powders show high specific surface area. • ZAT{sub b}15 showed activity of 52.22% for the conversion of soybean oil into biodiesel. - Abstract: Zinc aluminate is a material with high thermal stability and high mechanical strength that, owing to these properties, is used as a catalyst or support. In this work, zinc aluminate spinel was synthesized by the microwave hydrothermal method in only 15 or 30 min at a low temperature (150 °C) without templates, using only Al(NO{sub 3}){sub 3}·9H{sub 2}O, Zn(NO{sub 3}){sub 2}·6H{sub 2}O, and urea as precursors and applied in the transesterification of soybean oil. X-ray diffraction analysis showed that ZnAl{sub 2}O{sub 4} had a cubic structure without secondary phases. The nitrogen adsorption measurements (BET) revealed a high surface area (266.57 m{sup 2} g{sup −1}) for the nanopowder synthesized in 15 min. This powder showed activity of 52.22% for the catalytic conversion of soybean oil into biodiesel by transesterification.

  10. Effects of aluminizing temperature on the growth kinetics of voids along interface between aluminized layer and steel substrate%镀铝温度对渗铝层/基体界面空洞生长动力学的影响

    Institute of Scientific and Technical Information of China (English)

    张伟; 刘爱萍; 文九巴

    2012-01-01

    采用不同的镀铝温度在20碳钢上制备了不同厚度的热浸镀铝层,通过测量热浸镀铝层厚度以及高温氧化后渗铝层/基体界面空洞平均直径和形核数量随氧化时间的变化,研究了镀铝温度对渗铝层/基体界面空洞生长的影响。结果表明:随镀铝温度升高,镀铝后的表面层厚度减小,合金层厚度增加;在高温氧化期间,渗铝层/基体界面空洞的生长速度随镀铝温度的升高而减小,其变化规律与热浸镀铝后表面层厚度随镀铝温度的变化规律相一致;界面空洞平均深度随镀铝温度升高而增加,其变化规律与热浸镀铝后合金层厚度随镀铝温度的变化规律相一致;界面空洞增量随氧化时间的延长先增加而后逐步减少,且镀铝温度越高,空洞形核速度越小。分析了镀铝温度对界面空洞生长的影响机制。%Aluminized layer with different thickness on a low carbon steel was prepared by hot tip aluminizing process at different temperatures.The effects of aluminizing temperature on formation and growth of voids along interface between aluminized layer and steel substrate were investigated by cyclic oxidation test and measuring of variations of the average size and number of the voids with oxidation time.The results show that the aluminized layer consists of surface layer and alloy layer,and the thickness of surface layer decreases gradually and thickness of alloy layer increases gradually with increasing aluminizing temperature.The growth speed of the voids decreases gradually with increasing aluminizing temperature during high temperature oxidation and its variations regulation are in accord with the variations regulation of the thickness of the surface layer with aluminizing temperature.However the average depth of the voids in the aluminized layer increases gradually with increasing aluminizing temperature and its variations are in accord with the variations of the thickness of the alloy layer

  11. Processing method and process modeling of large aperture transparent magnesium aluminate spinel domes

    Science.gov (United States)

    Yu, Jian; McWilliams, Brandon; Kilczewski, Steven; Gilde, Gary; Lidie, Ashley; Sands, James

    2009-05-01

    Polycrystalline spinel serves as an alternative to materials such as sapphire and magnesium fluoride that are currently being used in electromagnetic window applications such as missile domes, where high strength, high hardness and high transmittance in the visible and infrared spectra are required. The cubic crystal lattice of spinel imparts an isotropy to the bulk optical property, which eliminates optical distortion due to birefringence that occurs in sapphire and other non-cubic materials. The current study is to find a reliable manufacturing process to produce large magnesium aluminate spinel domes from powder consolidation efficiently. A binder-less dry ball milling process was used to deflocculate the spinel powder to increase its fluidity in an effort to ease the shape-forming. Dry ball milling time trials were conducted at several intervals to determine the appropriate level of time required to break up both the hard and soft agglomerates associated with the virgin spinel powder. The common problems encountered in dry powder shape-forming are crack growth and delamination of the green body during cold isostatic pressing (CIPing). The cracking and the delamination are due to the buildup of stress gradients on the green body that are created by the frictional force between the powder and the die wall or mold wall. To understand the stresses during the CIPing process, a finite element analysis of stresses on the green body was conducted. The simulation was used to evaluate the effect of die tooling and process characteristics on the development of stress gradients in the green body dome. Additionally, the effect of friction between the die wall and powder was examined by the simulation. It was found that by mitigating the frictional forces, cracking and delamination on the green body could be eliminated. A stepped-pressure CIPing technique was developed to reduce stress gradient build-up during CIPing. Also, oleic acid lubricant was applied to the die wall to

  12. Quantitative determination of tricalcicum aluminate in portland cement by X-ray diffraction

    Directory of Open Access Journals (Sweden)

    Sagrera Moreno, José Luis

    1989-06-01

    Full Text Available Tricalcium aluminate (C3A is one of the constitutive phase of the cement-clinker. Its concentration influences the cement behaviour in sulphate aggressive soils. Therefore its quantification is very convenient and International standards fix its content when the concrete is used in contact with soils or liquids containing sulphate compounds. There are two possibilities in order to calculate the amount of C3A in clinker phases: one consist in a mathematical calculation from the results of the chemical analysis (Bogue formulae and the order is based in X-ray diffraction, using the height of the representative peak of the C3A phase. In the present note, the experimental procedure in order to determine the C3A content from X-ray test is presented.

    El aluminato tricáicico es una de las fases constitutivas del clinker de cemento portland. Su concentración en el cemento influye en el comportamiento de éste, en las obras sometidas a la posible agresividad de diferentes sulfatos cuando entran en contacto con las estructuras que se fabrican con él. Por ello la determinación de su concentración es un dato que puede invalidar su uso en una obra. De ahí que las normas internacionales fijen la cantidad de aluminato tricáicico según se clasifique la agresividad del entorno en el que una estructura será colocada. Existen fórmulas matemáticas para calcular la concentración de cada una de las fases del clinker a partir de las concentraciones de los elementos químicos de clinker expresados en forma de óxidos. Los posibles errores en los análisis químicos producen errores en los cálculos de las concentraciones de cada fase. Para determinar la concentración de dichas fases se puede emplear también la técnica de difracción de rayos X, basándose en la medida de la altura del pico representativo de la fase que se quiere determinar.

  13. Kinetics of calcium sulfoaluminate formation from tricalcium aluminate, calcium sulfate and calcium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xuerun, E-mail: xuerunli@163.com; Zhang, Yu; Shen, Xiaodong, E-mail: xdshen@njut.edu.cn; Wang, Qianqian; Pan, Zhigang

    2014-01-15

    The formation kinetics of tricalcium aluminate (C{sub 3}A) and calcium sulfate yielding calcium sulfoaluminate (C{sub 4}A{sub 3}$) and the decomposition kinetics of calcium sulfoaluminate were investigated by sintering a mixture of synthetic C{sub 3}A and gypsum. The quantitative analysis of the phase composition was performed by X-ray powder diffraction analysis using the Rietveld method. The results showed that the formation reaction 3Ca{sub 3}Al{sub 2}O{sub 6} + CaSO{sub 4} → Ca{sub 4}Al{sub 6}O{sub 12}(SO{sub 4}) + 6CaO was the primary reaction < 1350 °C with and activation energy of 231 ± 42 kJ/mol; while the decomposition reaction 2Ca{sub 4}Al{sub 6}O{sub 12}(SO{sub 4}) + 10CaO → 6Ca{sub 3}Al{sub 2}O{sub 6} + 2SO{sub 2} ↑ + O{sub 2} ↑ primarily occurred beyond 1350 °C with an activation energy of 792 ± 64 kJ/mol. The optimal formation region for C{sub 4}A{sub 3}$ was from 1150 °C to 1350 °C and from 6 h to 1 h, which could provide useful information on the formation of C{sub 4}A{sub 3}$ containing clinkers. The Jander diffusion model was feasible for the formation and decomposition of calcium sulfoaluminate. Ca{sup 2+} and SO{sub 4}{sup 2−} were the diffusive species in both the formation and decomposition reactions. -- Highlights: •Formation and decomposition of calcium sulphoaluminate were studied. •Decomposition of calcium sulphoaluminate combined CaO and yielded C{sub 3}A. •Activation energy for formation was 231 ± 42 kJ/mol. •Activation energy for decomposition was 792 ± 64 kJ/mol. •Both the formation and decomposition were controlled by diffusion.

  14. PROCESSING OF ZIRCONIA AND CALCIUM ALUMINATE CEMENT MIXTURES BY SPARK PLASMA SINTERING

    Directory of Open Access Journals (Sweden)

    Y. L. Bruni

    2015-12-01

    Full Text Available Spark Plasma sintering (SPS was applied for the densification of Calcia stabilized ZrO2 based composites obtained from mixtures of pure zirconia (m-ZrO2 and calcium aluminate cement (HAC. Two commercial powders of pure zirconia were employed as reactants. One of these powders had a coarse mean particle size (d50 = 8 μm and the other was a submicrometer sized power (d50 = 0.44 μm. Several compositions containing different proportions of HAC (5 to 30 mol. % CaO in ZrO2 were sintered by SPS at temperatures between 1200 and 1400ºC under a pressure of 100 MPa during 10 min. The effect of processing conditions on phase composition, densification, microstructure and Vickers hardness of the obtained composites was examined. SPS significantly enhanced the densification in both type of composites (relative density > 93 % as compared to those previously produced by conventional sintering. Composites with low CaO content consisted of mixtures of c-ZrO2, (Ca0.15Zr0.85O1.85, unreacted m-ZrO2 and calcium dialuminate (CaAl4O7 or CA2. The highest hardness was determined for composites sintered at 1400ºC being related to the maximum relative density (~ 99 %. High densification of composites with 30 mol. % CaO composed by similar proportions of CaAl4O7 and c-ZrO2 were obtained even at 1200ºC but led to a slightly lower hardness. In general, the use of the finer m-ZrO2 powder contributed to increase both the c-ZrO2 content and densification of composite sintered at a relatively lower temperature. For these composites, best hardness (Hv near to 10 GPa resulted when the microstructure consisted of a fine grained ZrO2 matrix surrounding the dispersed CaAl4O7 grains instead of large interconnection between grains of both phases existed.

  15. 铝酸钡与氢氧化钡脱硫过程比较%Comparison of Barium Aluminate and Barium Hydroxide Desulfurization Process

    Institute of Scientific and Technical Information of China (English)

    张念炳; 黎志英; 丁彤

    2012-01-01

    The seed precipitation liquor was desulfurized with barium aluminate and barium hydroxide respectively. The desulfurization slag was characterized by XRD analysis, and the desulfurization process was compared. The results show that barium hydroxide exceeds barium aluminate with better desulfurization in terms of effect, speed and duration. In the desulfurization process with barium aluminate, 2BaO · Al2O3 · 5H2O is firstly produced in the reaction of barium aluminate with alkali, and then it reacts with sodium sulfate and sodium carbonate. To compare, Ba(OH)2 · 8H2O directly reacts with sodium sulfate and sodium carbonate in the desulfurization process with barium hydroxide. Both of desulfurization reaction processes can be described with "shrinking core model".%用铝酸钡和氢氧化钡对种分母液进行脱硫试验,对脱硫渣进行XRD分析,并比较脱硫过程.结果表明,氢氧化钡的脱硫效果更好,脱硫完成时间更短,速率更快;铝酸钡先与碱液反应生成2BaO·Al2O3·5H2O,再与硫碱和碳碱反应,而氢氧化钡直接与硫碱和碳碱反应,脱硫过程均可用未反应核模型描述.

  16. Effect of aluminizing of Cr-containing ferritic alloys on the seal strength of a novel high-temperature solid oxide fuel cell sealing glass

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Y. S.; Stevenson, Jeffry W.; Singh, Prabhakar

    2008-12-01

    A novel high-temperature alkaline-earth silicate sealing glass was developed for solid oxide fuel cell (SOFC) applications. The glass was used to join two metallic coupons of Cr-containing ferritic stainless steel for seal strength evaluation. In previous work, SrCrO4 was found to form along the glass/steel interface, which led to severe strength degradation. In the present study, aluminization of the steel surface was investigated as a remedy to minimize or prevent the strontium chromate formation. Three different processes for aluminization were evaluated with Crofer22APU stainless steel: pack cementation, vapor phase deposition, and aerosol spraying. It was found that pack cementation resulted in a rough surface with occasional cracks in the Al-diffused region. Vapor phase deposition yielded a smoother surface, but the resulting high Al content increased the coefficient of thermal expansion (CTE), resulting in failure of joined coupons. Aerosol spraying of an Al-containing salt resulted in formation of a thin aluminum oxide layer without any surface damage. The room temperature seal strength was evaluated in the as-fired state and in environmentally aged conditions. In contrast to earlier results with uncoated Crofer22APU, the aluminized samples showed no strength degradation even for samples aged in air. Interfacial and chemical compatibility was also investigated. The results showed aluminization to be a viable candidate approach to minimize undesirable chromate formation between alkaline earth silicate sealing glass and Cr-containing interconnect alloys for SOFC applications.

  17. Aluminizing and boroaluminizing treatments of Mar-M247 and their effect on hot corrosion resistance in Na2SO4-NaCl molten salt

    Science.gov (United States)

    Cho, J. H.; Kim, T. W.; Son, K. S.; Yoon, J. H.; Kim, H. S.; Leisk, G. G.; Mitton, D. B.; Latanision, R. M.

    2003-06-01

    The effect of surface modifications of Mar-M247 superalloy on hot corrosion resistance was examined in Na2SO4-NaCl molten salt. The Mar-M247 was aluminized and boroaluminized by pack cementation in Ar and underwent a cyclic hot corrosion test in Na2SO4-NaCl molten salt. The XRD results showed that a Ni2Al3 phase was formed between the aluminized layer and the substrate when the surface modification temperature was below 1273 K. However, a NiAl phase formed when the temperature was above 1273 K. The intensity of the XRD peak in the NiAl phase increased after post heat treatment. Hot corrosion resistance increased for the specimens containing NiAl rather than Ni2Al3 phase. The ductile NiAl phase suppressed the potential for crack initiation during thermal cycling. Post heat treatment increased the corrosion resistance of the aluminized layer for Mar-M247, which underwent surface modification at 1273 K and above. In the boroaluminized Mar-M247 specimens, corrosion resistance decreased as a result of the blocking of outward diffusion of Cr by boron and decreased cohesion between the oxide scale and the aluminized layer during thermal cycling.

  18. 高含铝炸药爆炸过程中的能量分析%Energy Analysis in the Explosion Process of High Aluminized Explosive

    Institute of Scientific and Technical Information of China (English)

    李静; 王伯良; 赵新颖; 滕婉婷

    2013-01-01

    在野外静爆实验中,利用高分辨率、高精度冲击波超压系统分别测试了高含铝炸药和TNT的爆炸场冲击波超压,根据试验数据,计算该含铝炸药的爆炸场冲击波超压的TNT当量,利用TNT当量评价该高含铝炸药的威力,用能量反演方法分析该含铝炸药中可燃组分的反应程度和可能的反应模式,计算可得该含铝炸药爆炸反应释放能量的有效利用率为65.41%,为高含铝炸药配方优化设计提供新的研究方法.%The shock wave overpressures were measured in explosion field tests for high aluminized explosive and TNT with high resolution and precision. Based on the experimental data and explosion law, the TNT equivalence of shock wave overpressure in explosion field for high aluminized explosive was calculated. The power of aluminized explosive was estimated by TNT equivalence, and the energy inversion principle was applied to assess the reaction extent of combustible components and possible reaction patterns of metal component. It is obtained by calculation that the effective utilization of energy in the aluminized explosive is 65. 41% , which provides a new approach for aluminized explosive optimization design.

  19. Preparation and investigation of aluminized coating and subsequent heat treatment on 9Cr–1Mo Grade 91 steel

    Energy Technology Data Exchange (ETDEWEB)

    Singh, K., E-mail: singhkw@barc.gov.in [Materials Group, BARC, Trombay, Mumbai 400085 (India); Fernandes, A. [Department of Mechanical Engineering, Manipal University, Jaipur (India); Paul, B.; Gonal, M.R.; Abraham, G.; Krishnamurthy, N. [Materials Group, BARC, Trombay, Mumbai 400085 (India)

    2014-11-15

    Highlights: • Hot dip aluminizing and heat treatment was carried out on 9Cr–1Mo Grade 91 steel. • Sample heat treated at 650 °C showed Fe{sub 2}Al{sub 5} phase and at 750 °C showed Fe{sub 2}Al{sub 5}/FeAl. • Samples heat treated at 950 °C showed FeAl/α-Fe(Al). • The scratch test showed the best result with 950 °C/5 h + 750 °C/2 h sample. • α-Al{sub 2}O{sub 3} and γ-Al{sub 2}O{sub 3} were present on the surface of the samples treated at 950 °C. - Abstract: Iron aluminide inner coating with alumina top layer is being considered as a potential solution for tritium permeation barrier and mitigating MHD pressure drop for liquid metal blanket concepts in the fusion reactor systems. Hot-dip aluminizing with subsequent heat treatment seems to offer a good possibility to produce aluminized coating with alumina top layer. 9Cr–1Mo Grade 91 steel samples were hot dipped in Al melt containing 2.25 wt% of Si at 750 °C for 3 min. Heat treatment was performed at 650, 750 and 950 °C for 5 h; samples were either air cooled or furnace cooled. Coatings have been evaluated by SEM, EDX, X-ray diffraction, microhardness, scratch adhesion and Raman spectroscopy. The thickness of the layers and phases formed were influenced by the heat treatment adopted. Fe{sub 2}Al{sub 5} was the major phase present in the samples heat treated at 650/750 °C, whereas FeAl and α-Fe(Al) primarily made up the outer and inner layers respectively in the samples heat treated at 950 °C. Cooling method deployed affected the hardness. Air cooled samples had comparatively higher hardness than furnace cooled samples. The scratch test showed the adhesion for the samples heat treated at 950 °C was much better as compared to the samples heat treated at 650/750 °C. Raman spectroscopy analysis showed the presence of both α-Al{sub 2}O{sub 3} and γ-Al{sub 2}O{sub 3} on the surface of the samples heat treated at 950 °C, while Fe{sub 3}O{sub 4} was present in the furnace cooled sample only.

  20. Effect of Air and Vacuum Storage on the Degradation of X-Ray-Exposed Aluminized-Teflon Investigated

    Science.gov (United States)

    deGroh, Kim K.; Gummow, Jonathan D.

    2001-01-01

    Metalized Teflon FEP (fluorinated ethylene propylene, DuPont), a common thermal control material, has been found to degrade in the low-Earth-orbit space environment. The aluminized-FEP (Al-FEP) exterior layer on the Hubble Space Telescope has become extremely embrittled, with extensive cracking occurring on all sides of the telescope. This embrittlement has been primarily attributed to radiation exposure (x-rays from solar flares, electron/proton radiation, and possibly near-ultraviolet radiation) combined with thermal cycling. Limited samples of FEP tested after long-term exposure to low Earth orbit on the Hubble Space Telescope and on the Long Duration Exposure Facility indicated that there might be continued degradation in tensile properties over time. An investigation was conducted at the NASA Glenn Research Center to evaluate the effect of air and vacuum storage on the mechanical properties of x-ray-exposed FEP. Aluminized-FEP (5-mil-thick) tensile samples were x-ray exposed with 15.3-kV copper xrays for 2 hr, reducing the percent elongation to failure by approximately 50 percent in comparison to that for pristine Al-FEP. X-ray-exposed samples were stored in air or under vacuum for various time periods to see the effect of storage on tensile properties. Tensile results indicated that samples stored in air had larger decreases in tensile properties than samples stored under vacuum had, as seen in the graph. Samples stored under vacuum (for up to 400 hr) showed no further decrease in tensile properties over time, whereas samples stored in air (for up to 900 hr) appeared to show decreases in tensile properties over time. X-ray-exposed samples stored in air developed a hazy appearance in the exposed area, as seen in the photographs. When the source of the haziness was evaluated using scanning electron microscopy and atomic force microscopy, it was found to reside at the Al/FEP interface as witnessed by an increased surface roughness of the aluminized side of the

  1. High-T sub c thin films on low microwave loss alkaline-rare-earth-aluminate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sobolewski, R.; Gierlowski, P.; Kula, W.; Zarembinski, S.; Lewandowski, S.J.; Berkowski, M.; Pajaczkowska, A. (Instytut Fizyki, Polska Akatlemia Nauk, Al. Lotnikow 32/46, PL-02668 Warszawa (PL)); Gorshunov, B.P.; Lyudmirsky, D.B.; Sirotinsky, O.I. (Institute of General Physics, USSR Academy of Sciences, 38 Vavilova Street, SU-117924 Moscow (SU))

    1991-03-01

    This paper reports on the alkaline-rare-earth aluminates (K{sub 2}NiF{sub 4}-type perovskites) which are an excellent choice as the substrate material for the growth of high-T{sub c} thin films suitable for microwave and far-infrared applications. The CaNdAlO{sub 4}, and SrLaAlO{sub 4} single crystals have been grown by Czochralski pulling and fabricated into the form of (001) oriented wafers. The Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O films deposited on these substrates by a single-target magnetron sputtering exhibited very good superconducting and structural properties.

  2. Surface studies on aluminized and thermally oxidized superalloy 690 substrates interacted with simulated nuclear waste and sodium borosilicate melt

    Science.gov (United States)

    Yusufali, C.; Kshirsagar, R. J.; Mishra, R. K.; Kaushik, C. P.; Sengupta, P.; Dutta, R. S.; Dey, G. K.

    2014-04-01

    Aluminized and thermally oxidized Ni-Cr-Fe based superalloy 690 substrates with Al2O3 layer on top have been exposed in nitrate based environment (simulated high level nuclear liquid waste) at 373 K for 216 hours and sodium borosilicate melt at 1248 K for 192 hours. The surfaces of exposed samples have been characterized by using Electron probe micro-analyzer (EPMA). Elemental X-ray mapping on coated specimen that exposed in simulated nuclear waste solution revealed that the surface is enriched with Ni, Cr and Al. X-ray mapping on surface of the specimen that interacted with sodium borosilicate melt indicated that the surface is composed of Al, Fe, Ni and Cr.

  3. Surface studies on aluminized and thermally oxidized superalloy 690 substrates interacted with simulated nuclear waste and sodium borosilicate melt

    Energy Technology Data Exchange (ETDEWEB)

    Yusufali, C., E-mail: yusuf@barc.gov.in; Sengupta, P.; Dutta, R. S.; Dey, G. K. [Materials Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085 (India); Kshirsagar, R. J. [High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085 (India); Mishra, R. K.; Kaushik, C. P. [Waste Management Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085 (India)

    2014-04-24

    Aluminized and thermally oxidized Ni-Cr-Fe based superalloy 690 substrates with Al{sub 2}O{sub 3} layer on top have been exposed in nitrate based environment (simulated high level nuclear liquid waste) at 373 K for 216 hours and sodium borosilicate melt at 1248 K for 192 hours. The surfaces of exposed samples have been characterized by using Electron probe micro-analyzer (EPMA). Elemental X-ray mapping on coated specimen that exposed in simulated nuclear waste solution revealed that the surface is enriched with Ni, Cr and Al. X-ray mapping on surface of the specimen that interacted with sodium borosilicate melt indicated that the surface is composed of Al, Fe, Ni and Cr.

  4. Lanthanum aluminate synthesis by reverse precipitation starting from pseudoboehmite; Sintesis de aluminato de lantano mediante precipitacion inversa partiendo de pseudoboehmita

    Energy Technology Data Exchange (ETDEWEB)

    Portilla Z, K. G.; Zarate M, J.; Tapia O, J. P.; Hernandez M, W., E-mail: whernandezmu@gmail.com [Universidad Michoacana de San Nicolas de Hidalgo, Instituto de Investigacion en Metalurgia y Materiales, Ciudad Universitaria, Edif. U, 58060 Morelia (Mexico)

    2015-10-15

    Full text: The lanthanum aluminate (Lao) shows a thermoluminescence response thus has been proposed as a material for dosimetry; this has made have been proposed various methods for their synthesis (hydrothermal, sol-gel, combustion, precipitation, etc.) These methods are complex or expensive if part of reagent grade materials which limits its application to larger scales. Therefore is proposed to use the pseudoboehmite as a precursor of alumina for the Lao phase. Pseudoboehmite was synthesized by reverse precipitation starting from aluminum sulfate and as precipitating agent the ammonium hydroxide. Lao perovskite phase was obtained at 1500 degrees C and 10 h of calcination s, at lower temperatures the presence of other phases as lanthanum oxide was detected. Also the morphology of the powders were characterized by scanning electron microscopy, finding clusters whose sizes are in the range of ∼0.25 and 1 μm. The measurement of the density by the Archimedes method reached 94% of the theoretical. (Author)

  5. Slow crack growth resistance and bridging stress determination in alumina-rich magnesium aluminate spinel/tungsten composites

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Suarez, T.; Lopez-Esteban, S.; Pecharroman, C. [Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Cientificas (CSIC), C/ Sor Juana Ines de la Cruz, 3, 28049 Cantoblanco, Madrid (Spain); Moya, J.S. [Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Cientificas (CSIC), C/ Sor Juana Ines de la Cruz, 3, 28049 Cantoblanco, Madrid (Spain)], E-mail: jsmoya@icmm.csic.es; El Attaoui, H.; Benaqqa, C.; Chevalier, J. [Universite de Lyon, INSA-Lyon, MATEIS, UMR CNRS 5510, 20 avenue Albert Einstein, Villeurbanne F-69621 (France)

    2009-04-15

    The slow crack growth (SCG) resistance (V-K{sub I} diagrams) of magnesium aluminate spinel and its tungsten composites with different metallic content (7, 10, 14 and 22 vol.%) is reported. It is found that tungsten plays a crucial role in the composite by increasing crack resistance: the higher the W content, the higher the stress intensity factor needed for crack extension at a given rate. The reinforcement is due to the bridging mechanism performed by metal particles, as it strongly affects the compliance of cracked specimens. Its magnitude is estimated by a compliance function {phi}(a) from a double torsion test. From the compliance function, R-curve behaviour is predicted for the composite with highest tungsten content. It explains the effect of metal particles on SCG curves. The W-MgAl{sub 2}O{sub 4} interface is believed to influence the reinforcement mechanism.

  6. The (oxalato)aluminate complex as an antimicrobial substance protecting the "shiro" of Tricholoma matsutake from soil micro-organisms.

    Science.gov (United States)

    Nishino, Katsutoshi; Shiro, Misao; Okura, Ryuki; Oizumi, Kazuya; Fujita, Toru; Sasamori, Takahiro; Tokitoh, Norihiro; Yamada, Akiyoshi; Tanaka, Chihiro; Yamaguchi, Muneyoshi; Hiradate, Syuntaro; Hirai, Nobuhiro

    2017-01-01

    Tricholoma matsutake, a basidiomycete, forms ectomycorrhizas with Pinus densiflora as the host tree. Its fruiting body, "matsutake" in Japanese, is an edible and highly prized mushroom, and it grows in a circle called a fairy ring. Beneath the fairy ring of T. matsutake, a whitish mycelium-soil aggregated zone, called "shiro" in Japanese, develops. The front of the shiro, an active mycorrhizal zone, functions to gather nutrients from the soil and roots to nourish the fairy ring. Bacteria and sporulating fungi decrease from the shiro front, whereas they increase inside and outside the shiro front. Ohara demonstrated that the shiro front exhibited antimicrobial activity, but the antimicrobial substance has remained unidentified for 50 years. We have identified the antimicrobial substance as the (oxalato)aluminate complex, known as a reaction product of oxalic acid and aluminum phosphate to release soluble phosphorus. The complex protects the shiro from micro-organisms, and contributes to its development.

  7. Oxidation of Uncoated and Aluminized 9-12% Cr Boiler Steels at 550-650 °C

    Science.gov (United States)

    Metsäjoki, J.; Huttunen-Saarivirta, E.; Lepistö, T.

    2011-03-01

    In this paper, oxidation behavior of 9-12% Cr steels P91 and HCM12A is studied in air and in a mixture of air and water vapor. Comparison is made between these steels in uncoated condition and coated with aluminum diffusion coating by a slurry method. Oxidation tests were carried out at 550, 600, and 650 °C for a discontinued duration of 1000 h; every 250 h the specimens were slowly cooled to room temperature and weighed. SEM + EDS and XRD characterization were performed after 500 and 1000 h. The results showed that oxidation rate of uncoated P91 and HCM12A was significantly higher in the mixture of air and water vapor than in air. Oxidation resistance of the studied materials improved substantially when they were aluminized.

  8. Recent progress in advanced optical materials based on gadolinium aluminate garnet (Gd3Al5O12).

    Science.gov (United States)

    Li, Ji-Guang; Sakka, Yoshio

    2015-02-01

    This review article summarizes the recent achievements in stabilization of the metastable lattice of gadolinium aluminate garnet (Gd3Al5O12, GAG) and the related developments of advanced optical materials, including down-conversion phosphors, up-conversion phosphors, transparent ceramics, and single crystals. Whenever possible, the materials are compared with their better known YAG and LuAG counterparts to demonstrate the merits of the GAG host. It is shown that novel emission features and significantly improved luminescence can be attained for a number of phosphor systems with the more covalent GAG lattice and the efficient energy transfer from Gd(3+) to the activator. Ce(3+) doped GAG-based single crystals and transparent ceramics are also shown to simultaneously possess the advantages of high theoretical density, fast scintillation decay, and high light yields, and hold great potential as scintillators for a wide range of applications. The unresolved issues are also pointed out.

  9. Experimental Research on Calcium Aluminate Desulphurizer Slags%铝酸钙脱硫渣系的实验研究

    Institute of Scientific and Technical Information of China (English)

    袁守谦; 郭强; 王伟; 梁德安

    2011-01-01

    The desulphurizer of CaO-Al2O3-CaF2 was researched in laboratory. The results show that increasing the contents of pre-melted desulphurizer can increase the velocity and ratio of desulfurization. In the meanwhile, elevating temperature of liquid steel can increase desulfurization degree; the S-content can decrease to a relative low level (0.026wt) in 10 minutes at 1620℃. The desulphurization effect using calcium aluminate desulphurizer slags with CaO is superior to that using pure 12CaO. 7Al2O3 slag, while the additive amount of CaO is 10wt , the desulphurizatien effect is best. Therefore the calcium aluminate desulphurizer slags with CaO can be used as a high efficient, high speed and an environmental friendly desulphurizer.%在实验室的条件下,对用CaO、Al2O3、CaF2为原料配制的钢水脱硫剂进行了实验研究.研究发现,增加预熔脱硫剂量,可提高脱硫速度,增大脱硫率.提高钢水温度可以增大脱硫效率,在1620℃下,10min就可将钢液中的硫降低到0.026wt%的较低水平.添加CaO的铝酸钙预熔渣的脱硫效果明显优于纯12CaO·7Al2O3渣系,加氧化钙含量为10wt%时,整体脱硫效果最好.此预熔合成渣原料将可能成为一种高效、快速、环保的脱硫剂.

  10. Determinación de la resistencia del hornnigón en viguetas fabricadas con cemento aluminóso

    Directory of Open Access Journals (Sweden)

    de la Fuente Sánchez, Antonio

    1993-03-01

    Full Text Available Not Available.

    La resistencia de los hormigones en viguetas de cemento aluminóso es uno de los parámetros más solicitados a los laboratorios de control. La dificultad de su determinación estriba en la gran cantidad de armaduras que suelen llevar las alas de la vigueta, siendo el alma la única zona de la que pueden extraerse muestras de hormigón.

  11. Effect of aluminizing of Cr-containing ferritic alloys on the seal strength of a novel high-temperature solid oxide fuel cell sealing glass

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Yeong-Shyung; Stevenson, Jeffry W.; Singh, Prabhakar [K2-44, Energy Materials Department, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99354 (United States)

    2008-12-01

    A novel high-temperature alkaline earth silicate sealing glass was developed for solid oxide fuel cell (SOFC) applications. The glass was used to join two metallic coupons of Cr-containing ferritic stainless steel for seal strength evaluation. In previous work, SrCrO{sub 4} was found to form along the glass/steel interface, which led to severe strength degradation. In the present study, aluminization of the steel surface was investigated as a remedy to minimize or prevent the strontium chromate formation. Three different processes for aluminization were evaluated with Crofer22APU stainless steel: pack cementation, vapor-phase deposition, and aerosol spraying. It was found that pack cementation resulted in a rough surface with occasional cracks in the Al-diffused region. Vapor-phase deposition yielded a smoother surface, but the resulting high Al content increased the coefficient of thermal expansion (CTE), resulting in the failure of joined coupons. Aerosol spraying of an Al-containing salt resulted in the formation of a thin aluminum oxide layer without any surface damage. The room temperature seal strength was evaluated in the as-fired state and in environmentally aged conditions. In contrast to earlier results with uncoated Crofer22APU, the aluminized samples showed no strength degradation even for samples aged in air. Interfacial and chemical compatibility was also investigated. The results showed aluminization to be a viable candidate approach to minimize undesirable chromate formation between alkaline earth silicate sealing glass and Cr-containing interconnect alloys for SOFC applications. (author)

  12. Luminescence centers and spectrum characteristics of a novel Eu{sup 2+}-activated hexa-aluminate CaZrBAl{sub 9}O{sub 18}

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Ruijin; Li, Hongjuan; Ma, Hailong; Wang, Caifeng; Wang, Huan [College of Science, Northwest A and F University, Yangling, Shaanxi (China)

    2014-04-15

    A new blue-emitting phosphor of Eu{sup 2+}-activated hexa-aluminate CaZrBAl{sub 9}O{sub 18} was synthesized by a conventional solid-state reaction method. The crystalline phase formation was confirmed by X-ray powder diffraction (XRD) measurements. The photoluminescence excitation and emission spectra, the luminescence decay curves and the time-resolved spectra of CaZrBAl{sub 9}O{sub 18}:Eu{sup 2+} were taken to investigate the luminescence characteristics. The dependence of CaZrBAl{sub 9}O{sub 18}:Eu{sup 2+} luminescence intensity on the Eu{sup 2+} doping concentrations was investigated. This phosphor can be efficiently excited by UV light and presents blue luminescence. There is one kind of Eu{sup 2+} luminescence center in the lattices, which was confirmed by the time-resolved luminescence spectra. The temperature-dependent luminescence intensity was measured and the activation energy (ΔE) for thermal quenching was reported. The phosphor shows high luminescence intensity and an excellent thermal stability on temperature quenching. Eu{sup 2+}-doped hexa-aluminate CaZrBAl{sub 9}O{sub 18} presents bright blue-emitting luminescence with high thermal quenching; only one Eu{sup 2+} center was confirmed in this hexa-aluminate lattices. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. A convenient alumination of functionalized aromatics by using the frustrated Lewis pair Et3 Al and TMPMgCl⋅LiCl.

    Science.gov (United States)

    Unsinn, Andreas; Wunderlich, Stefan H; Jana, Anukul; Karaghiosoff, Konstantin; Knochel, Paul

    2013-10-18

    A straightforward and efficient alumination of functionalized arenes by using the frustrated Lewis pair Et3 Al and TMPMgCl⋅LiCl (TMP=2,2,6,6-tetramethylpiperidyl) has been developed. In particular, halogenated electron-rich aromatics can be smoothly functionalized by using the frustrated Lewis pair Et3 Al and TMPMgCl⋅LiCl. Compared with previously described alumination methods, this procedure avoids extensive cooling and the need for an excess of base. This in situ procedure has proven to be most practical and allows for regio- and chemoselective metalation of a wide range of aromatics with sensitive functional groups (CONEt2 , CO2 Me, CN, OCONMe2 ) or halogens (F, Cl, Br, I). The resulting aromatic aluminates, which were characterized by using NMR spectroscopy, were subjected to allylations, acylations, and palladium-catalyzed cross-coupling reactions after transmetalation to zinc. It was shown that the nature of the Zn salt used for transmetalation is crucial. Thus, compared with ZnCl2 (2 equiv), the use of Zn(OPiv)2 (2 equiv; OPiv=pivalate) allows the subsequent quenching reactions to be performed with only a slight excess of electrophile (1.2 equiv) and provides interesting functionalized aromatics in good yields.

  14. Relation between microstructure and dielectric breakdown in the case of aluminous ceramics (SEMM method); Comportement d'alumines face a l'injection de charges. Relation microstructure - claquage dielectrique - mesure des charges d'influence (methode SEMM)

    Energy Technology Data Exchange (ETDEWEB)

    Liebault, J.

    1999-02-01

    The dielectric breakdown is strongly linked to the injection and the accumulation of charges in a non-conducting material. The physics of charged insulators proposes mechanisms of trapping and transport of charges in aluminium oxides by considering defects as localization sources of charges and of energy. In order to measure the influence of defects on dielectric breakdown, various aluminous ceramics have been elaborated. The nature and the quantity of defects have been characterized by the nature and the rate of impurities, by porosity, by the quantity of grain boundaries and by the presence and distribution of secondary phases. These materials have undergone breakdown tests. The dielectric rigidity depends strongly on the nature and the distribution of crystallographic defects (vacancy, interstitial ions and dislocation), on the other hand porosity below 5% has no influence. The doping of an alumina ceramic containing less than 100 ppm of impurities implies a diminution of its dielectric rigidity. The measurement of the SEMM (scanning electron microscopy mirror) effect allows the characterization of insulating materials. This method permits the evaluation of the ability for materials to trap charges, it gives information about the charge kinetic of trapping, charge localization and the energy levels of traps. (A.C.)

  15. CORROSION RESISTANCE OF PACK ALUMINIZED SUS304 STAINLESS STEEL%SUS304ss包埋粉末渗铝的耐蚀性能

    Institute of Scientific and Technical Information of China (English)

    罗宏

    2009-01-01

    In order to research the corrosion resistance of SUS304 stainless steels with pack aluminized process,the corrosion resistance tests in 0.33 mol/L FeCl_3+0.05 mol/L HCl,the oxidation tests at 1000℃, and the corrosion resistance tests in deposition of alkali-chloride and sulphate at 500℃were conducted.The corrosion resistance was comprehensively evaluated by weight loss method and electrochemical tests etc.The experimental results indicated that aluminized layer of SUS304ss was dense,and the thickness was 50μm;the pitting corrosion resistance of almuinized SUS304ss was better than that of unaluminized one;the oxidation properties of aluminized SUS304ss increased 5 times at 1000℃;the corrosion resistance of aluminized SUS304 in deposition of alkali-chloride and sulphate increased about 20 times at 500℃;the corrosion potential of aluminized SUS304 was higher than that of unaluminized one,which had better corrosion resistance.%展开了SUS304ss及其渗铝后在0.33 mol/L FeCl_3+0.05 mol/L HCl溶液中的耐蚀性实验、1000℃下的抗高温氧化实验及表面沉积碱金属氯化物和硫酸盐在500℃下的耐蚀性实验,用失重法和电化学方法等综合评定了SUS304ss渗铝后的耐蚀性.研究表明:渗铝SUS304ss表面渗铝层结构致密,厚度为50 μm;在0.33mol/L FeCl3+0.05 mol/L HCl溶液中SUS304ss发生了严重孔蚀,渗铝后表而发生轻微孔蚀;渗铝SUS304ss在1000℃下加热,表面和截面形貌完好,耐高温氧化性提高了约5倍;在500℃下表面沉积盐碱混合物,渗铝SUS304ss耐腐蚀性约提高20倍;渗铝后SUS304ss的腐蚀电位大于未渗铝钢,耐蚀性提高.

  16. Effect of Pack Temperature on Microstructure and Properties of Aluminized N80 Oil Casing Steel%包埋温度对N80套管钢渗铝层微观结构及性能的影响

    Institute of Scientific and Technical Information of China (English)

    黄敏; 王宇

    2011-01-01

    The aluminizing layer was prepared on the surface of N80 oil easing steel by pack aluminizing processing at 950 ℃ and 1050 ℃. The effects of pack temperature on the microstructure, microhardness and electrochemical corrosion resistance of as-aluminized N80 oil casing steel were studied. The results show that the as-prepared aluminizing layer with thickness over 200μ m at 950℃ and 1050 ℃ exhibit higher microhardness and better corrosion resistance thanthat of non-aluminizing N80 oil casing steel. Although the thickness of aluminizing layer and microhardness of aluminized N80 oil casing steel can be obviously improved by increasing the pack temperature, the property of N80 oil casing steel substrate decreases at a very high pack temperature.%采用固体粉末包埋法对N80套管钢进行渗铝,形成富铝表层.研究了包埋温度为950、1050℃时所得渗铝N80套管钢的微观结构、硬度及电化学腐蚀特性.结果表明:不同包埋温度所得渗铝层厚度均超过200μm;渗铝N80套管钢在渗层深度范围内的硬度高于基体;渗铝后N80套管钢的耐腐蚀性得以提高.升高包埋温度可以显著提高所得渗铝层的厚度和硬度,但过高的包埋温度会同时造成基体性能更严重地下降.

  17. Calcium aluminates potential for endodontics and orthopedics applications; Aluminatos de calcio e seu potencial para aplicacao em endodontia e ortopedia

    Energy Technology Data Exchange (ETDEWEB)

    Santos, G.L. dos; Andrade, T.L.; Oliveira, I.R., E-mail: ivonero@univap.br [Universidade do Vale do Paraiba (UNIVAP), Sao Jose dos Campos, SP (Brazil); Pandolfelli, V.C. [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil)

    2011-07-01

    The mostly used material in the areas of endodontics (MTA, mineral trioxide aggregate) and bone reconstruction (PMMA, polymethyl methacrylate) present some limiting properties requiring thus changes in their compositions as well as the development of alternative materials. In this context, a novel biomaterial-based calcium aluminate cement (CAC) has been studied in order to keep the positive properties and clinical applications of MTA and PMMA, overcoming some their disadvantages. Recent studies involving the use of CAC are based on commercial products consisting of a mixture of phases. Improvements can be attained by searching the synthesis routes of CAC aiming the proper balance between the phases and the control of impurities that may impair its performance in applications in the areas of health. By the optimization of the CAC phases production, this article aims to present their characterization based on hydration temperature; working time and setting time; pH, ions solubilization and dissolution in contact with water and different solutions of simulated body fluid. The results indicated the CA phase as the most suitable for application in the areas of health. (author)

  18. Effect of substitution of Co{sup 2+} ions on the structural and electrical properties of nanosized magnesium aluminate

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Javed, E-mail: dr.j.ahmad@gmail.co [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Awan, Muhammad Qadeer; Mazhar, Muhammad Ehsan [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Ashiq, Muhammad Naeem [Department of Chemistry, Bahauddin Zakariya University, Multan 60800 (Pakistan)

    2011-01-15

    Cobalt substituted nanosized magnesium aluminates having a nominal composition MgAl{sub 2-x}Co{sub x}O{sub 4} where x = 0.0, 0.5, 1.0, 1.5, 2.0 were synthesized by the chemical co-precipitation method. Aluminium (Al{sup 3+}) ions were completely and successfully substituted by Co{sup 2+} ions, which yielded an electron rich terminal compound MgCo{sub 2}O{sub 4}. All the samples were characterized by means of X-ray diffraction (XRD), thermogravimetry and differential thermal analysis (TG/DTA) and dc electrical resistivity measurements. The investigated samples were found to be spinel single phase cubic close packed crystalline materials as demonstrated by XRD data. Using the Debye Scherer formula, the calculated crystallite size was found Co{sup 2+} concentration dependent and varied between 7 and 19 nm. The lattice constant, X-ray density and bulk density were found to increase while percentage porosity decreases on increasing the Co{sup 2+} concentration. The dc electrical resistivity was found to decrease as a function of temperature as expected for a typical semiconductor. The doped Co{sup 2+} ions are believed to form small polarons and hopping of these small polarons between the adjacent sites seems to be partially responsible for conduction in the system. The activation energy of hopping of small polarons was also calculated.

  19. Ion beam damage assessment and waveguide formation induced by energetic Si-ion irradiation in lanthanum aluminate crystal

    Science.gov (United States)

    Liu, Y.; Huang, Q.; Crespillo, M. L.; Qiao, M.; Liu, P.; Wang, X. L.

    2017-02-01

    Lanthanum aluminate (LaAlO3) crystal has emerged as one of the most valuable functional-materials, and its physical, electronic and optical properties strongly depend on the crystal structure, which can be easily altered in an irradiation environment and therefore affect the performance of LaAlO3-based devices. On the other hand, the preparation of LaAlO3 waveguide is also a scientific challenge for its potential application prospects in optoelectronics field. In this work, the damage evolution behavior of LaAlO3 crystal under Si-ion irradiation has been discussed in detail utilizing complementary characterization techniques, and then, single-mode waveguide of LaAlO3 crystal in the visible band can be obtained based on ion-irradiation-induced lattice damage behavior. Waveguide optical-coupling techniques are used to show its competitive features. Thus, novel optical waveguides with optimized features in LaAlO3 crystals can be tailored by a proper selection of ion mass, energy and fluence using the modification of the target material during ion irradiation process.

  20. Tailoring the photoluminescence properties of lanthanum strontium aluminate phosphors by controlling crystal field environment with fluorine ions

    Institute of Scientific and Technical Information of China (English)

    顾席光; 傅仁利; 杨芳; 汤晔; 方军

    2016-01-01

    A series of novel lanthanum strontium aluminate phosphors, Ce3+-doped LaSr2AlO(5–0.5x)Fx(LSAF) phosphors were success-fully synthesized using the high-temperature solid state synthesis procedure under reducing atmosphere (H2/N2=1/4). The X-ray diffrac-tion pattern revealed that LSAF sample was a pure LaSr2AlO5 phase with a sintering temperature of 1250 °C. With the increasing amount of SrF2, the particle size of powders increased and the shape of particles changed more regularly. Being an orange/red emitting phosphors for orange and white light emitting diodes, LSAF:Ce3+ could be effectively excited by blue lights with typical 4f→5d transitions of Ce3+ ions. PL and PLE spectra showed inhomogeneous enlargement effects with the increase of F/O ratios, which suggested that electronega-tivity effect was promoted when F/O ratio increased. This was further confirmed by a red shift of PL spectra peak when F/O was in-creased. It can be concluded that the LSAF:Ce phosphors have the potential to meet the development of white light-emitting diodes.

  1. Corrosion of Aluminized and Uncoated 9-12% Cr Boiler Steels in Simulated Biomass andWaste Combustion Conditions

    Science.gov (United States)

    Metsäjoki, Jarkko; Huttunen-Saarivirta, Elina; Lepistö, T.

    2011-04-01

    Coatings are seen a promising way to improve the corrosion resistance of relatively cheap power plant steels to enable higher steam temperatures than currently in use. In this research, 9-12% Cr steels P91 and HCM12A are coated with aluminium diffusion coating by a slurry method and exposed for 336 hours at 833 K and 883 K to atmospheres containing varying amounts of O2, H2O, HCl and SO2. Corrosion behaviour of the coated steels is compared to that of those steels in an uncoated condition. Characterization is performed by weighing, SEM + EDS and XRD. The results show that corrosion resistance of P91 and HCM12A is significantly improved by the aluminium diffusion coating at high temperatures in atmospheres containing HCl and SO2. The corrosion rate of the aluminized specimens slightly increases with increase in test temperature but remains virtually the same irrespective of the composition of the atmosphere. On the other hand, the corrosion rate of the uncoated specimens is dependent on both the atmosphere and the temperature. The steels undergo active oxidation that results in formation of non-protective, thick and layered scales in HCl containing atmospheres. SO2 addition slightly decreases the corrosion rate although it is anyway higher than that in SO2 containing atmosphere without HCl.

  2. The effect of the host composition on the lifetime decay properties of barium/strontium aluminates compounds

    Energy Technology Data Exchange (ETDEWEB)

    Rezende, Marcos V. dos S., E-mail: mvsrezende@gmail.com [Departamento de Física, Universidade Federal de Sergipe, 49500-000 Itabaiana, SE (Brazil); Andrade, A. B.; Valerio, Mário E. G. [Departamento de Física, Universidade Federal de Sergipe, 49100-000 São Cristóvão, SE (Brazil); Montes, Paulo J. R [Instituto Federal de Sergipe, 49400-000 Lagarto, SE (Brazil)

    2014-03-14

    This paper reports the influence of the structural change on the luminescence of Eu-doped barium/strontium aluminates when excited with monochromatic X-rays (also known as X-ray excited optical luminescence—XEOL). Ba{sub 1−x}Sr{sub x}Al{sub 2}O{sub 4} samples, with 0 < x < 1, were produced via proteic sol-gel route and it was observed that the XEOL emission spectra are composed by the Eu{sup 2+} and Eu{sup 3+} transitions, although no Eu{sup 2+} was observed in the X-ray absorption spectra. The XEOL intensities while the sample is under irradiation decreased as a function of the irradiation time, indicating the buildup of radiation damage. The saturation level of the XEOL is directly correlated to the amount of damages induced by the irradiation and the sample composition. The Ba-rich samples are the ones with higher XEOL yield. X-ray induced long lasting phosphorescence (LLP) was also observed for all samples and it was found that the duration of the phosphorescence emission also depends on the sample composition. In Sr-rich samples, the LLP has a slower decay time constant than in Ba-rich samples. A model of the radiation induced luminescence is presented and all these features are discussed in terms of the energetic costs and the type of defects generated in the sample.

  3. Vibrational spectroscopy of aluminate spinels at 1 atm and of MgAl2O4 to over 200 kbar

    Science.gov (United States)

    Chopelas, A.; Hofmeister, A. M.

    1991-12-01

    Single-crystal Raman and infrared reflectivity data including high pressure results to over 200 kbar on a natural, probably fully ordered MgAl2O4 spinel reveal that many of the reported frequencies from spectra of synthetic spinels are affected by disorder at the cation sites. The spectra are interpreted in terms of factor group analysis and show that the high energy modes are due to the octahedral internal modes, in contrast to the behavior of silicate spinels, but in agreement with previous data based on isotopic and chemical cation substitutions and with new Raman data on gahnite (˜ ZnAl2O4) and new IR reflectivity data on both gahnite and hercynite (˜Fe0.58Mg0.42Al2O4). Therefore, aluminate spinels are inappropriate as elastic or thermodynamic analogs for silicate spinels. Fluorescence sideband spectra yield complementary information on the vibrational modes and provide valuable information on the acoustic modes at high pressure. The transverse acoustic modes are nearly pressure independent, which is similar to the behavior of the shear modes previously measured by ultrasonic techniques. The pressure derivative of all acoustic modes become negative above 110 kbar, indicating a lattice instability, in agreement with previous predictions. This lattice instability lies at approximately the same pressure as the disproportionation of spinel to MgO and Al2O3 reported in high temperature, high pressure work.

  4. 用正交实验法优化N80套管钢包埋渗铝的工艺参数%Optimization for Pack Aluminizing Process Parameters of N80 Oil Casing Steel by Orthogonal Experiment

    Institute of Scientific and Technical Information of China (English)

    叶晶; 王宇; 史新勃; 郭钊

    2013-01-01

    The thickness of aluminizing layer was studied by taking aluminizing temperature,time,the ratio of Al and NH4Cl content of pack powder as aluminizing process parameters.Proper orthogonal experiment array was designed.That includes 3 orthogonal factors,9 groups of test.The aluminizing layer thickness was analyzed by energy dispersive spectrometer (EDS) to optimize the aluminizing process parameters.%采用正交实验的方法在不需进行重复试验的情况下,把渗铝工艺中的渗铝温度、保温时间、渗剂中铝粉含量和氯化铵含量的比值3种参数作为3个正交因素,分别进行9组试验.借助能谱仪(EDS)分析每一组试样的渗铝层厚度,以优化渗铝工艺参数.

  5. Study on Process of Mechanical Energy Aided Aluminizing for Precipitation Hardening Stainless Steel%沉淀硬化不锈钢机械能助渗铝工艺研究

    Institute of Scientific and Technical Information of China (English)

    朱望伟; 王向东; 陈小平; 米丰毅

    2011-01-01

    通过机械能助渗铝工艺,实现了对沉淀硬化不锈钢的低温渗铝.在500℃渗铝 10h,得到厚约11μm的均一渗铝层.通过力学性能检测及显微硬度分析对渗铝层进行研究,发现可以在保证基体材料的力学性能基本无损耗的情况下,渗层硬度是基体材料的2倍以上.%The aluminizing of precipitation hardening stainless steel at low temperature was carried out by the process of mechanical energy aided aluminizing. The uniformity layer with thickness of 11 μm can be obtained after aluminizing at 500 ℃ for 10 h. The aluminized layer is researched by mechanical performance testing and micro-hardness analysis, the micro-hardness of aluminized layer is two times higher than that of matrix material, base on keeping the mechanical properties of matrix material isn't changed.

  6. 温度对合成含镁铝尖晶石铝酸盐水泥的影响%Effect of temperature on synthesis of magnesium aluminate spinel containing aluminate cement

    Institute of Scientific and Technical Information of China (English)

    宋雅楠; 朱伯铨; 李享成

    2014-01-01

    The magnesium aluminate spinel containing aluminate cement was prepared with starting mate-rials of industrial alumina,light burned magnesia and heavy weight calcium carbonate.The starting mate-rials were batched according to the Al2O3 MgO CaO mass ratio of 71 16 13,ball milled,and fired at 900,1 000,1 100,1 300 and 1 500 ℃ for 3 h,respectively.Phase compositions,microstructure and setting time of the prepared cement were investigated.The results indicate that:(1 )CA,MA and CA2 form at about 900,1 000 and 1 100 ℃,respectively;CA,CA2,and MA are detected in the specimen treated at 1 300 ℃ for 3 h,indicating a complete reaction of the starting materials;(2)SEM analysis indicates that in the cement fired at 1 300 or 1 500 ℃ for 3 h,CA and CA2 are tabular,MA is granular or octahedral,and MA well distributes around CA and CA2 particles;comparatively,CA,CA2,MA particles of the cement fired at 1 500 ℃ for 3 h develop better with larger crystal size;(3 )the initial setting times of the cement fired at 1 300 and 1 500 ℃ for 3 h are 37 min and 43 min,respectively,and the final setting times are 1 15 min and 163 min,respectively.%以工业氧化铝、轻烧氧化镁及重质碳酸钙为原料,按Al2O3、MgO、CaO质量比为711613配料,球磨混合后,分别在900、1000、1100、1300和1500℃保温3 h合成含镁铝尖晶石的铝酸盐水泥,然后分析了合成试样的物相组成、显微结构和凝结时间。结果表明:1)在900℃保温3 h后合成试样中已有CA生成,1000℃保温3 h后已有MA生成,1100℃保温3 h后已有CA2生成;1300℃保温3 h后,原料已完全反应,产物全部由CA、CA2、MA组成。2)在1300和1500℃保温3 h合成的水泥中,CA和CA2呈板状,MA呈粒状或八面体状, MA均匀分布在CA和CA2周围;在1500℃保温3 h合成的水泥中,CA、CA2、MA的晶粒比1300℃保温3 h合成的发育更完整,晶粒尺寸也更大。3)1300和1500℃保温3 h合成的水

  7. 放电等离子烧结制备刚玉-铝酸钙-镁铝尖晶石复相材料%Preparation of corundum-calcium aluminate-magnesium aluminate spinel composites by spark plasma sin-tering

    Institute of Scientific and Technical Information of China (English)

    唐海; 员文杰; 商恒; 樊希安; 邓承继; 祝洪喜

    2016-01-01

    In order to reduce the synthesis temperature of the composite material and maintain its physical properties,corundum-calcium aluminate-magnesium aluminate spinel composites were prepared using 35.16 mass% underburnt dolomite and 64.84 mass% flake alumina as raw materials by spark plasma sin-tering at different temperatures (1 050,1 100,and 1 150 ℃).The effects of the firing temperature on phase composition and strength of corundum-calcium aluminate-magnesium aluminate spinel composites were investigated.The results show that with the temperature increasing the corundum content decreases gradu-ally,while the contents of calcium aluminate and magnesium aluminate spinel gradually increase,the ap-parent porosity of composites slightly increases while the splitting tensile strength improves;flake corun-dum,formed calcium aluminate and magnesium aluminate spinel bond together at high temperatures by spark plasma sintering.The composites with the apparent porosity of 23.2% fired at 1 150 ℃ achieve the splitting tensile strength of 20 MPa.%为了降低复相材料的合成温度并保证其相应的物理性能,以质量分数分别为35.16%的欠烧白云石和64.84%的片状氧化铝为原料,在1050、1100和1150℃下利用放电等离子烧结法(SPS)制备了刚玉-铝酸钙-镁铝尖晶石复相材料,并研究了烧成温度对复相材料的物相组成及强度的影响。结果表明:随着温度的升高,复相材料中刚玉相的含量逐渐降低,而铝酸钙和镁铝尖晶石的含量逐渐上升,材料的显气孔率略有增大,但是其劈裂抗拉强度逐渐增大。放电等离子烧结使复相材料中片状刚玉、生成的铝酸钙和镁铝尖晶石在高温下相互结合。当烧成温度为1150℃时,所制备的复相材料显气孔率为23.2%,劈裂抗拉强度达到20 MPa。

  8. The effect of annealing temperature on the structure and optical properties of sol-gel derived nanocrystalline cobalt aluminate spinel

    Energy Technology Data Exchange (ETDEWEB)

    Kurajica, S., E-mail: stankok@fkit.hr [University of Zagreb, Faculty of Chemical Engineering and Technology, 19 Marulic Square, HR-10000 Zagreb (Croatia); Popovic, J. [Division of Materials Physics, Ruder Boskovic Institute, Bijenicka 54, Zagreb (Croatia); Tkalcec, E. [University of Zagreb, Faculty of Chemical Engineering and Technology, 19 Marulic Square, HR-10000 Zagreb (Croatia); Grzeta, B. [Division of Materials Physics, Ruder Boskovic Institute, Bijenicka 54, Zagreb (Croatia); Mandic, V. [University of Zagreb, Faculty of Chemical Engineering and Technology, 19 Marulic Square, HR-10000 Zagreb (Croatia)

    2012-08-15

    The thermal evolution of a sol-gel derived cobalt aluminate (CoAl{sub 2}O{sub 4}) of a spinel-type structure was studied. The samples were prepared by the sol-gel technique using aluminum-sec-butoxide [Al(O{sup s}Bu){sub 3}] and cobalt nitrate hexahydrate Co(NO{sub 3}){sub 2} Multiplication-Sign 6H{sub 2}O as starting materials and ethyl-acetoacetate (C{sub 6}H{sub 10}O{sub 3}) as a chelating agent. The powder precursors were annealed at various temperatures ranging from 200 to 900 Degree-Sign C. The properties of products were characterized using differential thermal analysis and thermo-gravimetric analysis (DTA/TGA), UV-vis diffuse reflectance spectroscopy (DRS) and X-ray diffraction (XRD). The UV-vis DRS spectra revealed that in samples annealed at temperatures below 700 Degree-Sign C a part of Co existed in a 3 + oxidation state. The accommodation of Co{sup 3+} in octahedral cation sites yields with a green color. Thermal treatment at higher temperatures promote the reduction of Co{sup 3+} ions to Co{sup 2+} and a change of color from green to blue, later being characteristic of Co{sup 2+} ions in tetrahedral coordination. The XRD revealed that annealing of the precursor powder at a lower temperature (500 and 600 Degree-Sign C) resulted in a crystal spinel-type phase Co{sub 2}AlO{sub 4.} Annealing at higher temperatures (700-900 Degree-Sign C) induces a reaction of Co{sub 2}AlO{sub 4} with amorphous alumina producing a phase CoAl{sub 2}O{sub 4} having a partially inverse spinel structure, with {delta} in the range of 0.198-0.260. The spinel powders obtained at all annealing temperatures were in the nanosize range. -- Graphical abstract: UV-vis DRS spectra of cobalt aluminate powders heat treated at various temperatures. Highlights: Black-Right-Pointing-Pointer Sol-gel derived spinel-type CoAl{sub 2}O{sub 4} thermal evolution was monitored. Black-Right-Pointing-Pointer Below 700 Degree-Sign C part of Co exists in 3{sup +} state (octahedral sites), yielding green

  9. Reaction of aluminous perovskite and water at high pressure and temperature and water transport into the lower mantle

    Science.gov (United States)

    Ohira, I.; Ohtani, E.; Sakai, T.; Miyahara, M.; Hirao, N.; Ohishi, Y.; Nishijima, M.

    2012-12-01

    Water cycle is an important issue in earth science, because water can affect rheological properties and melting temperature of the mantle. It has been clarified that water can be transported to at least deep upper mantle and the transition zone (e.g., Ono, 1998). The transition zone is believed to be a water reservoir in the earth, because wadsleyite and ringwoodite which compose the transition zone can contain 1 to 3 wt.% water (Inoue et al., 1995; Kohlstedt et al., 1996). However, it has been a debated matter whether water can be transported into the lower mantle and the core. Here we report the phase relation and mineral chemistry of MgSiO3-perovskite and delta-AlOOH obtained from a combination of in-situ X-ray diffraction measurements at high-pressure and high-temperature, and chemical analyses using scanning transmission electron microscope with an EDS detector (STEM-EDS). We used MgSiO3-Al2O3-H2O gel-samples for high-temperature and high-pressure experiments at the SPring-8 BL10XU. The bulk composition of the starting gel sample was 70 mol% MgSiO3 - 30 mol% Al2O3. H2O contents of the starting gel samples were 1.5 wt.%, 6.0wt.% and 7.0 wt.%. A double sided laser heating diamond anvil cell was used for generation of high pressure and temperature. The YAG (Nd) or fiber laser was used for heating the sample. A Pt foil or powder was mixed with the sample for the absorber of the laser. In situ X-ray diffraction was conducted in the pressure and temperature ranges of 55~87 GPa and 1700~2400 K. We observed a clear coexistence of perovskite and delta-AlOOH at 68 GPa and 2000 K. The chemical analysis of the recovered sample revealed that MgSiO3-perovskite coexisting with delta-AlOOH contains 6.6±2.2 mol.% Al2O3 and delta-AlOOH phase contains about 50 mol.% MgSiO3. Our results revealed a new reaction of aluminous perovskite and water to form a mixture of alumina-depleted perovskite and Mg, Si-bearing delta-AlOOH along the mantle geotherm under the lower mantle

  10. Analyses of Hubble Space Telescope Aluminized-Teflon Multilayer Insulation Blankets Retrieved After 19 Years of Space Exposure

    Science.gov (United States)

    de Groh, Kim K.; Perry, Bruce A.; Mohammed, Jelila S.; Banks, Bruce

    2015-01-01

    Since its launch in April 1990, the Hubble Space Telescope (HST) has made many important observations from its vantage point in low Earth orbit (LEO). However, as seen during five servicing missions, the outer layer of multilayer insulation (MLI) has become increasingly embrittled and has cracked in many areas. In May 2009, during the 5th servicing mission (called SM4), two MLI blankets were replaced with new insulation and the space-exposed MLI blankets were retrieved for degradation analyses by teams at NASA Glenn Research Center (GRC) and NASA Goddard Space Flight Center (GSFC). The retrieved MLI blankets were from Equipment Bay 8, which received direct sunlight, and Equipment Bay 5, which received grazing sunlight. Each blanket was divided into several regions based on environmental exposure and/or physical appearance. The aluminized-Teflon (DuPont, Wilmington, DE) fluorinated ethylene propylene (Al-FEP) outer layers of the retrieved MLI blankets have been analyzed for changes in optical, physical, and mechanical properties, along with chemical and morphological changes. Pristine and as-retrieved samples (materials) were heat treated to help understand degradation mechanisms. When compared to pristine material, the analyses have shown how the Al-FEP was severely affected by the space environment. Most notably, the Al-FEP was highly embrittled, fracturing like glass at strains of 1 to 8 percent. Across all measured properties, more significant degradation was observed for Bay 8 material as compared to Bay 5 material. This paper reviews the tensile and bend-test properties, density, thickness, solar absorptance, thermal emittance, x-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS) elemental composition measurements, surface and crack morphologies, and atomic oxygen erosion yields of the Al-FEP outer layer of the retrieved HST blankets after 19 years of space exposure.

  11. Effect of Solar Exposure on the Atomic Oxygen Erosion of Hubble Space Telescope Aluminized-Teflon Thermal Shields

    Science.gov (United States)

    Guo, Aobo; Ashmead, Claire C.; deGroh, Kim K.

    2012-01-01

    When exposed to low Earth orbital (LEO) environment, external spacecraft materials degrade due to radiation, thermal cycling, micrometeoroid and debris impacts, and atomic oxygen (AO) interaction. Collisions between AO and spacecraft can result in oxidation of external spacecraft surface materials, which can lead to erosion and severe structural and/or optical property deterioration. It is therefore essential to understand the AO erosion yield (Ey), the volume loss per incident oxygen atom (cu cm/atom), of polymers to assure durability of spacecraft materials. The objective of this study was to determine whether solar radiation exposure can increase the rate of AO erosion of polymers in LEO. The material studied was a section of aluminized-Teflon (DuPont) fluorinated ethylene propylene (Al-FEP) thermal shield exposed to space on the Hubble Space Telescope (HST) for 8.25 years. Retrieved samples were sectioned from the circular thermal shield and exposed to ground laboratory thermal energy AO. The results indicate that the average Ey of the solar facing HST Al-FEP was 1.9 10(exp -24)cu cm/atom, while the average Ey of the anti-solar HST Al-FEP was 1.5 10(exp -24)cu cm/atom. The Ey of the pristine samples was 1.6- 1.7 10(exp -24)cu cm/atom. These results indicate that solar exposure affects the post-flight erosion rate of FEP in a plasma asher. Therefore, it likely affects the erosion rate while in LEO.

  12. Growth of epitaxial films of sodium potassium tantalate and niobate on single-crystal lanthanum aluminate [100] substrates

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, George H. [University of Tennessee, Knoxville (UTK); Specht, Eliot D [ORNL; Larese, John Z [ORNL; Xue, Ziling [University of Tennessee, Knoxville (UTK); Beach, David B [ORNL

    2008-01-01

    Epitaxial films of sodium potassium tantalate (Na{sub 0.5}K{sub 0.5}TaO{sub 3}, NKT) and sodium potassium niobate (Na{sub 0.5}K{sub 0.5}NbO{sub 3}, NKN) were grown on single-crystal lanthanum aluminate (LAO) (100) (indexed as a pseudo-cubic unit cell) substrates via an all-alkoxide solution (methoxyethoxide complexes in 2-methoxyethanol) deposition route for the first time. X-ray diffraction studies indicated that the onset of crystallization in powders formed from hydrolyzed gel samples was 550 C. {sup 13}C nuclear magnetic resonance studies of solutions of methoxyethoxide complexes indicated that mixed-metal species were formed, consistent with the low crystallization temperatures observed. Thermal gravimetric analysis with simultaneous mass spectrometry showed the facile loss of the ligand (methoxyethoxide) at temperatures below 400 C. Crystalline films were obtained at temperatures as low as 650 C when annealed in air. {theta}-2{theta} x-ray diffraction patterns revealed that the films possessed c-axis alignment in that only (h00) reflections were observed. Pole-figures about the NKT or NKN (220) reflection indicated a single in-plane, cube-on-cube epitaxy. The quality of the films was estimated via {omega} (out-of-plane) and {psi} (in-plane) scans and full-widths at half-maximum (FWHMs) were found to be reasonably narrow ({approx}1{sup o}), considering the lattice mismatch between the films and the substrate.

  13. Host-mediated synthesis of cobalt aluminate/γ-alumina nanoflakes: a dispersible composite pigment with high catalytic activities.

    Science.gov (United States)

    Dandapat, Anirban; De, Goutam

    2012-01-01

    Cobalt aluminate/γ-alumina (CoAl(2)O(4)/γ-Al(2)O(3)) nanocomposite pigment with mesoporous structure has been synthesized. The method simply involves adsorption of Co(2+) ion on the surface of a commercially available boehmite (AlOOH) powder followed by the reaction of Co(2+) and AlOOH at relatively low temperature (500 °C) to obtain CoAl(2)O(4)/γ-Al(2)O(3) composite nanopowders. The formation of γ-Al(2)O(3) from boehmite induces the in situ generation of isostructural CoAl(2)O(4) (both crystallize as cubic spinel) at such a low temperature. The obtained intense blue powder of optimal composition (53.6 wt % CoAl(2)O(4) in γ-Al(2)O(3)) can be dispersed in glycerol and characterized by UV-visible, X-ray diffraction, Raman spectroscopy, TEM, and nitrogen sorption analyses. Raman studies confirm the formation of CoAl(2)O(4) phase in γ-Al(2)O(3). TEM studies reveal the formation of flake shaped (5-10 nm in width and 10-25 nm in length) nanopowders, and these flakes are assembled to form mesoporous structure. The specific surface area, total pore volume and average pore diameter of this powder are estimated to be ~118 m(2) g(-1), 0.1375 cm(3) g(-1), and 4.65 nm, respectively. This composite nanopowder has been used as an active catalyst for the decomposition of H(2)O(2) at room temperature and the decomposition follows the first order kinetics with rate constant value close to 2.3 × 10(-2) min(-1). This pigment nanopowder can be reused for several cycles without noticeable degradation of its original catalytic activity.

  14. Investigations into thermoluminescence and afterglow characterization of strontium aluminates with boron-modification and reductions via sol-gel route

    Institute of Scientific and Technical Information of China (English)

    Ⅰ-Cherng Chen; Ker-Kong Chen; Hong-Sen Chen; Je-kang Du; Tsao-Jen Lin; Shiu-Shiung Lin; Teng-Ming Chen; Tien-Yu Shieh

    2012-01-01

    The effects of strontium aluminates of SrAl2O4:Eu2+,Dy3+ (SAED) and boron-modified SAED (BSAED) phases synthesized from a sol-gel process on thermoluminescence (TL) along with their afterglow properties were systematically investigated with thermal activation in the different atmospheres.The result showed that the addition of boron and the reduction routes of Eu3+ to Eu2+ in SrAl2O4:Dy3+ were related to the phosphorescent decay properties.The aid of Dy3+ to induce the hole-trapping effect required both SAED and BSAED to be heated at 1300 ℃ under the H2/N2 (5%:95%) atmosphere.However,the trapping behavior of the reductions of SAED in nitrogen was similar to the compound without Dy3+ co-doping SrAl2O4:Eu2+ (SAE) in H2/N2 (5%:95%).BSAED showed deeper traps in situ compared to SAED which contained no boron,and this led to the better afterglow properties of BSAED than those of SAED.The afterglow spectrum of BSAED showed two peaks at 400+1 nm and 4854±1 nm,which were two individuals composed and contributed from different depths of traps at 0.57 and 0.76 eV,accordingly.The depth of the traps was calculated from the Hoogenstraaten's plot of glow curves.The calculations for SAED and SAE were at around 0.43 and 0.18 eV,respectively.

  15. Study on Mechanical Energy Aided Aluminizing of Precipitation Hardening Stainless Steel%沉淀硬化不锈钢机械能助渗铝的试验研究

    Institute of Scientific and Technical Information of China (English)

    朱望伟; 殷铁志; 王向东; 李坚; 陈小平; 米丰毅; 朱志兵

    2011-01-01

    通过机械能助渗铝工艺,实现对沉淀硬化不锈钢的低温渗铝.500℃渗铝10 h,可以在保证基体材料的力学性能基本无损耗的情况下,得到厚度约为11μm的均一渗铝层.采用SEM、EDS、显微硬度分析以及盐雾试验等测试手段对渗铝层进行研究,发现通过机械能助渗铝得到的为富铝相渗层,渗层硬度是基体材料的两倍以上,且具有良好的耐腐蚀及抗中温氧化性能.从渗铝反应机理的角度对机械能助渗铝工艺进行了分析.%Precipitation hardening stainless steel has been aluminized in the low temperature by the process of mechanical energy aided aluminizing. This technique produce layers with thickness of 11 μm and appear to be homogeneous for 10 h treatment at 500 ℃, base on keeping the mechanical properties of matrix material unchanged. The aluminized layer is researched by using SEM、EDS、micro-hardness anal ysis and salt spray . The layers appear to be aluminum-rich phase, and have excellent resistance to corro sion and middle temperature oxidation, also, the micro-hardness of aluminized layer is more than two times than that of matrix material. The process of mechanical energy aided aluminizing is deep discussed from aluminizing reaction mechanism.

  16. EFFECT OF MAGNETRON-SPUTTERED Al FILM ON LOW-TEMPERATURE PACK-ALUMINIZING COATING FOR OIL CASING STEEL N80

    OpenAIRE

    MIN HUANG; YU WANG; MENG-XIAN ZHANG; YAN-QIU HUO; PENG-JIN GAO

    2014-01-01

    Low-temperature aluminizing coating was prepared onto the surface of oil casing steel N80 with a magnetron-sputtered Al film to improve its corrosion resistance. Results show that magnetron-sputtered Al film is able to form gradient aluminide coating, composed of iron aluminide FeAl3, Fe2Al5 and Fe3Al with different contents of aluminum. Both the density and continuity of iron aluminide layer for oil casing steel N80 with magnetron-sputtered Al film can be improved. Under the same corrosion c...

  17. Emergence of electrophilic alumination as the counterpart of established nucleophilic lithiation: an academic sojourn in organometallics with William Kaska as fellow traveler.

    Science.gov (United States)

    Eisch, John J

    2015-04-21

    William Kaska pursued doctoral studies with John Eisch in mechanistic organometallic chemistry, first with organolithium reactions at St. Louis University and then at the University of Michigan with organoaluminum reactions. Thereby he revealed the change in mechanism from nucleophilic lithiation and carbolithiation to that of electrophilic alumination, carboalumination and hydroalumination of organic substrates, which reactions were previously observed by Karl Ziegler in his empirical studies of organoaluminum reactions. Our findings were the first mechanistic studies attempting to set such Ziegler chemistry on a modern theoretical basis.

  18. A study on new type aluminous cements containing magnesium aluminate spinel%新型含镁铝尖晶石的铝酸盐水泥的研究

    Institute of Scientific and Technical Information of China (English)

    肖国庆; 高志鹏; 荆桂花; 庞锐

    2005-01-01

    A new type of calcium aluminate cement containing MA spinel was produced by sintering the raw materials of dolomite and alumina mixture. The effects of raw materials and sintering temperature and additives on the properties of cements was were investigated. X-ray diffraction (XRD) results indicate that the final products consisted of CA, CA2and MA. The microstructure of product was analyzed by means of scanning electron microscope (SEM)and energy dispersive spectrometry (EDS). The experiments results showed that the cement had the satisfied cold bonding strength and sintering properties when the light-burned dolomite and alumina were employed and fired at 1600C. The new type cements has relatively uniform microstructure The early stage strength of the refractory castables bodies was greatly improved by adding 2wt. % of CaCl2 as a strength modifier.%以白云石和工业三氧化二铝为原料,采用反应烧结技术制得了含镁铝尖晶石的铝酸盐水泥,探讨了原料及烧结温度和添加剂对含镁铝尖晶石的铝酸盐水泥性能的影响,XRD结果表明产物的物相组成为MA,CA,CA2;采用扫描电镜(SEM)及能谱(EDS)对产物的显微结构进行了观察与分析.结果表明:以轻烧白云石和工业Al2O3为原料制得的水泥具有较高的结合强度;所制得的含镁铝尖晶石的铝酸盐水泥的显微结构较为均匀,外加剂CaCl2具有明显的早强效果.

  19. A novel synthetic route for magnesium aluminate (MgAl2O4) nanoparticles using sol-gel auto combustion method and their photocatalytic properties

    Science.gov (United States)

    Nassar, Mostafa Y.; Ahmed, Ibrahim S.; Samir, Ihab

    2014-10-01

    In this paper a novel and inexpensive route for the preparation of spinel magnesium aluminate nanoparticles (MgAl2O4) is proposed. Magnesium aluminate photocatalyst was synthesized via sol-gel auto combustion method using oxalic acid, urea, and citric acid fuels at 350 °C. Subsequently, the burnt samples were calcined at different temperatures. The pure spinel MgAl2O4 with average crystallite size 27.7, 14.6 and 15.65 nm was obtained at 800 °C calcinations using the aforementioned fuels, respectively. The obtained samples were characterized by powder X-ray diffraction, Fourier transform infrared, UV-Vis spectroscopy, transmission electron microscope, scanning electron microscope. The photo catalytic activity of MgAl2O4 product was studied by performing the decomposition of Reactive Red Me 4BL dye under UV illumination or sunlight irradiation. The dye considerably photocatalytically degraded by 90.0% and 95.45% under UV and sunlight irradiation, respectively, within ca. 5 h with pseudo first order rate constants of 5.85 × 10-3 and 8.38 × 10-3 min-1, respectively.

  20. Studies on densification, mechanical, micro-structural and structure–properties relationship of magnesium aluminate spinel refractory aggregates prepared from Indian magnesite

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Chandrima; Ghosh, Arup; Haldar, Manas Kamal, E-mail: manashaldar@cgcri.res.in

    2015-01-15

    The present work intends to study the development of magnesium aluminate spinel aggregates from Indian magnesite in a single firing stage. The raw magnesite has been evaluated in terms of chemical analysis, differential thermal analysis, thermogravimetric analysis, infrared spectroscopy, and X-ray diffraction. The experimental batch containing Indian magnesite and calcined alumina has been sintered in the temperature range of 1550 °C–1700 °C. The sintered material has been characterized in terms of physico-chemical properties like bulk density, apparent porosity, true density, relative density and thermo-mechanical/mechanical properties like hot modulus of rupture, thermal shock resistance, cold modulus of rupture and structural properties by X-ray diffraction in terms of phase identification and evaluation of crystal structure parameters of corresponding phases by Rietveld analysis. The microstructures developed at different temperatures have been analyzed by field emission scanning electron microscope study and compositional analysis of the developed phase has been carried out by energy dispersive X-ray study. - Highlights: • The studies have been done to characterize the developed magnesium aluminate spinel. • The studies reveal correlation between refractory behavior of spinel and developed microstructures. • The studies show the values of lattice parameters of developed phases.

  1. A novel synthetic route for magnesium aluminate (MgAl2O4) nanoparticles using sol-gel auto combustion method and their photocatalytic properties.

    Science.gov (United States)

    Nassar, Mostafa Y; Ahmed, Ibrahim S; Samir, Ihab

    2014-10-15

    In this paper a novel and inexpensive route for the preparation of spinel magnesium aluminate nanoparticles (MgAl2O4) is proposed. Magnesium aluminate photocatalyst was synthesized via sol-gel auto combustion method using oxalic acid, urea, and citric acid fuels at 350°C. Subsequently, the burnt samples were calcined at different temperatures. The pure spinel MgAl2O4 with average crystallite size 27.7, 14.6 and 15.65nm was obtained at 800°C calcinations using the aforementioned fuels, respectively. The obtained samples were characterized by powder X-ray diffraction, Fourier transform infrared, UV-Vis spectroscopy, transmission electron microscope, scanning electron microscope. The photo catalytic activity of MgAl2O4 product was studied by performing the decomposition of Reactive Red Me 4BL dye under UV illumination or sunlight irradiation. The dye considerably photocatalytically degraded by 90.0% and 95.45% under UV and sunlight irradiation, respectively, within ca. 5h with pseudo first order rate constants of 5.85×10(-3) and 8.38×10(-3)min(-1), respectively.

  2. DIRECT PREPARATION OF HIGH PURE γ-ALUMINA FROM SODIUM ALUMINATE%由偏铝酸钠直接制取高纯γ-Al2O3

    Institute of Scientific and Technical Information of China (English)

    高建峰; 徐春彦; 王建中; 王久芬; 庄源益

    2003-01-01

    The purification of mother liquor containing sodium aluminate by using desilication agent and the preparation of high pure pseudo-boehmite and gamma alumina are reported. The sodium aluminate in the mother liquor coming from Shanxi Aluminium Plant is treated with home-made desilication agent, the ratios of SiO2/Al2O3 and Fe2Oa/Al2O3 in treated-solution are below 0.01%. The pseudo-boehmite is obtained with buffer solution deposition in which ammonia gas acts as a circulating medium. The specific surface area of pseudo-boehime powder reaches up to 300m2·g-1 and pore volume reaches about 0.7 ml·g-1. The content of sodium in pseudo-boehime is below 0. 005% after treating the pseudo-boehime with a sodium removal agent. The quality of this product is comparable to the SB powder made in Germany.Gamma alumina with a larger specific surface area and pore volume is obtained by temperature programmed calcination of pseudo-boehmite.

  3. The influence of starch oxidization and aluminate coupling agent on interfacial interaction, rheological behavior, mechanical and thermal properties of poly(propylene carbonate)/starch blends

    Science.gov (United States)

    Jiang, Guo; Zhang, Shui-Dong; Huang, Han-Xiong; The Key Laboratory of Polymer Processing Engineering of the Ministry of Education Team

    Poly(propylene carbonate) (PPC) is a kind of new biodegradable polymer that is synthesized by copolymerization of propylene oxide and carbon dioxide. In this work, PPC end-capped with maleic anhydride (PPCMA)/thermoplastic starch (TPS), PPCMA/thermoplastic oxidized starch (TPOS) and PPCMA/AL-TPOS (TPOS modified by aluminate coupling agent) blends were prepared by melt blending to improve its thermal and mechanical properties. FTIR results showed that there existed hydrogen-bonding interaction between PPCMA and starch. SEM observation revealed that the compatibility between PPCMA and TPOS was improved by the oxidation of starch. The enhanced interfacial interactions between PPCMA and TPOS led to a better performance of PPC blends such as storage modulus (G'), loss modulus (G''), complex viscosity (η*), tensile strength and thermal properties. Furthermore, the modification of TPOS by aluminate coupling agent (AL) facilitated the dispersion of oxidized starch in PPC matrix, and resulted in increasing the tensile strength and thermal stability. National Natural Science Foundation of China, National Science Fund of Guangdong Province.

  4. Effects of SrO/Al2O3 Molar Ratio on the Luminescent Characteristics of Rare—Earth Strontium Aluminate Phosphors

    Institute of Scientific and Technical Information of China (English)

    张玉军; 谭砂砾; 等

    2002-01-01

    The study on the effects of SrO/Al2O3molar ratio on the crystalline phases and photoluminescence characteistics of strontium aluminate phosphors co-activated with Eu2+andDy3+ were conductde by X-ray powder diffractometry ,fluorescence spectrometer and photometer.The strontium aluminate luminescent materials with different Sro/Al2O3molar ratio emit the visible lights with different color tone after removal of excitation.The peak wavelengths of the emission spectra drift in the direction of short wave,the quantity of Sr4A114O25crystalline phase molar ratio is near 1,the photoluminescence materials have high luminescent intensity,and when it is near0.75,they have long afterglow time.However,when SrO/Al2O3molar ratio is more than1,the luminescent materials appear strong alkaline in water solution;when SrO/Al2O3molar ratio is much less than 0.75,the samples need a higher temperature to be sintered.

  5. Effects of SrO/Al2O3 Molar Ratio on the Luminescent Characteristics of Rare-Earth Strontium Aluminate Phosphors

    Institute of Scientific and Technical Information of China (English)

    张玉军; 尹衍升; 谭砂砾

    2002-01-01

    The study on the effects of SrO/Al2O3 molar ratio on the crystalline phases and photoluminescence characteristics of strontium aluminate phosphors co-activ ated with Eu2+ and Dy3+ were conducted by X-ray powder diffractomet ry, fluorescence spectrometer and photometer. The strontium aluminate luminescen t materials with different SrO/Al2O3 molar ratio emit the visible lights wit h different color tone after removal of excitation. The peak wavelengths of the emission spectra drift in the direction of short wave, the quantity of Sr4Al 14O25 crystalline phase increases and the afterglow time lengthens wit h the SrO/Al2O3 reduction. The results show that when the SrO/Al2O3 mola r ratio is near 1, the photoluminescence materials have high luminescent intensi ty, and when it is near 0.75, they have long afterglow time. However, when SrO/ Al2O3 molar ratio is more than 1, the luminescent materials appear strong al k aline in water solution; when SrO/Al2O3 molar ratio is much less than 0.75, the samples need a higher temperature to be sintered.

  6. Photocatalytic NO{sub x} abatement by calcium aluminate cements modified with TiO{sub 2}: Improved NO{sub 2} conversion

    Energy Technology Data Exchange (ETDEWEB)

    Pérez-Nicolás, M. [MIMED Research Group, Department of Chemistry and Soil Sciences, School of Sciences, University of Navarra, c/Irunlarrea, 1, 31008 Pamplona (Spain); Balbuena, J.; Cruz-Yusta, M.; Sánchez, L. [Department of Inorganic Chemistry, School of Sciences, University of Córdoba, Campus de Rabanales, Edificio Marie Curie, 14071 Córdoba (Spain); Navarro-Blasco, I.; Fernández, J.M. [MIMED Research Group, Department of Chemistry and Soil Sciences, School of Sciences, University of Navarra, c/Irunlarrea, 1, 31008 Pamplona (Spain); Alvarez, J.I., E-mail: jalvarez@unav.es [MIMED Research Group, Department of Chemistry and Soil Sciences, School of Sciences, University of Navarra, c/Irunlarrea, 1, 31008 Pamplona (Spain)

    2015-04-15

    Photocatalytic activity of TiO{sub 2} was studied in two types of calcium aluminate cement (CAC) under two different curing regimes. The effect of the TiO{sub 2} addition on the setting time, consistency and mechanical properties of the CACs was evaluated. The abatement of gaseous pollutants (NO{sub x}) under UV irradiation was also assessed. These cementitious matrices were found to successfully retain NO{sub 2}: more abundant presence of aluminates in white cement (w-CAC, iron-lean) helped to better adsorb NO{sub 2}, thus improving the conversion performance of the catalyst resulting in a larger NO{sub x} removal under UV irradiation. As evidenced by XRD, SEM, EDAX and zeta potential analyses, the presence of ferrite in dark cement (d-CAC, iron-reach) induced a certain chemical interaction with TiO{sub 2}. The experimental findings suggest the formation of new iron titanate phases, namely pseudobrookite. The reduced band-gap energy of these compounds compared with that of TiO{sub 2} accounts for the photocatalytic activity of these samples.

  7. Simultaneous determination of NaOH, Na2CO3 and Al2O3 in sodium aluminate solutions by flow injection titration

    Institute of Scientific and Technical Information of China (English)

    陈晓青; 方彩云; 张心英; 张磊

    2001-01-01

    A flow injection titration method for simultaneous determination of hydroxide, carbonate and alumina in sodium aluminate solutions was proposed. 150μL sample was injected and firstly reacted with a mixture of methyl orange, phenolphthalein and sulfosalicylic acid, and secondly, a mixture of chlorhydric acid, ammonium fluoride and phenolphthalein. Methyl orange and phenolphthalein in the first are the corresponding indicators for the determination of hydroxide and carbonate; sulfosalicylic acid is both the titrant and masking agent for aluminum. Ammonium fluoride in the second is complexing agent for alumina and makes it release corresponding amounts of hydroxide ion to aluminum; phenolphthalein is the corresponding indicator for the determination of hydroxide, carbonate and alumina. Chlorhydric acid is the titrant agent for the three. The proposed method can be employed to analyze aluminate solutions containing hydroxide 3.1~15.5g/L-1, carbonate 3.1~15.5g/L-1 and alumina 0.51~1.02g/L-1 with a sampling frequency of 30 samples per hour. 0.54% and 0.89% are the RSD of sodium oxide and of alumina respectively (n=11).

  8. Luminescence behaviors of Eu- and Dy-codoped alkaline earth metal aluminate phosphors through potassium carbonate coprecipitation

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Chen-Jui, E-mail: cjliang@fcu.edu.tw; Siao, Hao-Yi

    2016-07-01

    An electronic energy mechanism of activator and sensitizer was established to describe the luminescence behaviors of Eu- and Dy-codoped M(II)Al{sub 2}O{sub 4} (M(II) = Ba, Sr, Ca, Mg) phosphors through potassium carbonate coprecipitation. Experimental results demonstrated that the prepared phosphors exhibited superior crystallinity at a temperature lower than 950 °C. The phosphors are ordered according to emission intensity as follows Ca- > Ba- > Sr- > Mg-containing phosphors. The energy level for Eu{sup 2+} 4f{sup 6}5d{sup 1} → 4f{sup 7}, Eu{sup 3+4}D{sub 0} → {sup 7}F, and Dy{sup 3+4}F{sub 9/2} → {sup 6}H transitions and the effects of nephelauxetic and crystal field in Ba-, Sr-, and Ca-containing phosphors were discussed. The energy gap, (hv){sub em}, between 5d and 4f of Eu{sup 2+} ion is strongly affected by host composition, crystal field strength, and nephelauxetic effect. The infrared emission of 4f{sub 9/2} → 6h for Dy{sup 3+} is merely depend on the transfer of energy from Eu{sup 2+} upon excited. Ca-containing phosphor with maximum (hv){sub em} is attributed to the lowest bond length of Ca−O and highest ionization potential of Ca{sup 2+} ion, which leads to the effects of crystal field and nephelauxetic greater than that in the other phosphors. - Highlights: • The list of the collected figure captions: • Develop a new coprecipitation method to prepare high efficiency phosphors. • Obtain superior crystallinity with lower calcination temperature. • Luminescence behavior of Eu- and Dy-codoped on aluminate phosphors is discussed. • Investigate the effects of alkaline earth metal containing on crystal field and nephelauxetic.

  9. Agglomerates, smoke oxide particles, and carbon inclusions in condensed combustion products of an aluminized GAP-based propellant

    Science.gov (United States)

    Ao, Wen; Liu, Peijin; Yang, Wenjing

    2016-12-01

    In solid propellants, aluminum is widely used to improve the performance, however the condensed combustion products especially the large agglomerates generated from aluminum combustion significantly affect the combustion and internal flow inside the solid rocket motor. To clarify the properties of the condensed combustion products of aluminized propellants, a constant-pressure quench vessel was adopted to collect the combustion products. The morphology and chemical compositions of the collected products, were then studied by using scanning electron microscopy coupled with energy dispersive (SEM-EDS) method. Various structures have been observed in the condensed combustion products. Apart from the typical agglomerates or smoke oxide particles observed before, new structures including the smoke oxide clusters, irregular agglomerates and carbon-inclusions are discovered and investigated. Smoke oxide particles have the highest amount in the products. The highly dispersed oxide particle is spherical with very smooth surface and is on the order of 1-2 μm, but due to the high temperature and long residence time, these small particles will aggregate into smoke oxide clusters which are much larger than the initial particles. Three types of spherical agglomerates have been found. As the ambient gas temperature is much higher than the boiling point of Al2O3, the condensation layer inside which the aluminum drop is burning would evaporate quickly, which result in the fact that few "hollow agglomerates" has been found compared to "cap agglomerates" and "solid agglomerates". Irregular agglomerates usually larger than spherical agglomerates. The formation of irregular agglomerates likely happens by three stages: deformation of spherical aluminum drops; combination of particles with various shape; finally production of irregular agglomerates. EDS results show the ratio of O to Al on the surface of agglomerates is lower in comparison to smoke oxide particles. C and O account for

  10. Determination of trace rare earth elements in gadolinium aluminate by inductively coupled plasma time of flight mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Abhijit; Deb, S.B.; Nagar, B.K.; Saxena, M.K., E-mail: saxenamk@barc.gov.in

    2014-04-01

    An analytical methodology was developed for the precise quantification of ten trace rare earth elements (REEs), namely, La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, and Tm, in gadolinium aluminate (GdAlO{sub 3}) employing an ultrasonic nebulizer (USN)-desolvating device based inductively coupled plasma mass spectrometry (ICP-MS). A microwave digestion procedure was optimized for digesting 100 mg of the refractory oxide using a mixture of sulphuric acid (H{sub 2}SO{sub 4}), phosphoric acid (H{sub 3}PO{sub 4}) and water (H{sub 2}O) with 1400 W power, 10 min ramp and 60 min hold time. An USN-desolvating sample introduction system was employed to enhance analyte sensitivities by minimizing their oxide ion formation in the plasma. Studies on the effect of various matrix concentrations on the analyte intensities revealed that precise quantification of the analytes was possible with matrix level of 250 mg L{sup −1}. The possibility of using indium as an internal standard was explored and applied to correct for matrix effect and variation in analyte sensitivity under plasma operating conditions. Individual oxide ion formation yields were determined in matrix matched solution and employed for correcting polyatomic interferences of light REE (LREE) oxide ions on the intensities of middle and heavy rare earth elements (MREEs and HREEs). Recoveries of ≥ 90% were achieved for the analytes employing standard addition technique. Three real samples were analyzed for traces of REEs by the proposed method and cross validated for Eu and Nd by isotope dilution mass spectrometry (IDMS). The results show no significant difference in the values at 95% confidence level. The expanded uncertainty (coverage factor 1σ) in the determination of trace REEs in the samples were found to be between 3 and 8%. The instrument detection limits (IDLs) and the method detection limits (MDLs) for the ten REEs lie in the ranges 1–5 ng L{sup −1} and 7–64 μg kg{sup −1} respectively. - Highlights: • A

  11. 铝酸钙粉矿物相红外光谱及铝溶出率分析%Analysis on infra-red spectrum of mineral phase of calcium aluminate powder and Al2O3 dissolution rate

    Institute of Scientific and Technical Information of China (English)

    黄志刚; 章兴华; 陆洋; 胡智; 杨鸿波; 舒海霞; 朱守平

    2012-01-01

    铝酸钙粉的结构会受到原料变化的强烈影响.对加入活化剂与未加入活化剂生产的铝酸钙粉进行了相关的结构鉴定与溶出率测定.X射线衍射及热重分析证实,加入活化剂的铝酸钙粉矿物相中含有卤化物,其中矿物相CaAl3XO7可能部分水解形成类弗雷德盐的双羟合结构体,这种铝酸钙粉存在2 116 cm-1及1 981 cm-1两个红外光谱特征峰.矿物相不同,铝酸钙粉的三氧化二铝溶出率有较大差异.%The structure of calcium aluminate powder will be strongly affected by the changes of raw materials.The structure and dissolution rate of calcium aluminates, which were produced with activator and without activator, were identified and measured.XRD and TGA analysis showed that after adding activator, the mineral phase of calcium aluminate powder contained halide,in which the mineral phase CaAl3XO7 may be partially hydrolyzed to form Friedel's salt double hydroxide phases.Furthermore,this calcium aluminate powder had two IR spectral feature peaks at 2 116 cm-1 and 1 981 cm-1'.Different mineral phases, dissolution rates of A12O3 in the calcium aluminate powder were quite different.

  12. 钢板连续热浸镀铝生产工艺技术%Production technology for continuous hot-dip aluminized steel sheet

    Institute of Scientific and Technical Information of China (English)

    刘灿楼; 李远鹏; 俞钢强; 张启富

    2016-01-01

    Hot-dip aluminized steel sheets are widely used for automotives,appliances and new-energy fields due to its excellent corrosion resistance,high temperature heat resistance,and light and heat reflectivity.The production flow of continuous hot-dip aluminized steel sheet is similar with CGL,but its continuous and stable industrialized production face challenges from the higher bath temperature,poor coating active and strong corrosivity on steel plate and immersion pieces of Al melt.Furnace atmosphere,Aluminum pool management,coating control and cooling af-ter coating are the key techniques for the production of hot dip aluminized steel sheet.Technical difficulties and countermeasures of those key techniques were discussed in detail.%镀铝钢板以其优异的耐蚀性、良好的耐热性(耐高温氧化性)和对光、热的反射性,被广泛应用于汽车、家电和新能源等各个领域。钢板连续热镀铝的生产工艺流程与传统的连续热镀锌基本一样。但由于铝的熔点高、可镀性差以及对钢板和浸入件腐蚀性强等特点,使得钢板连续热镀铝的连续稳定生产面临诸多挑战。还原退火炉气氛控制、镀锅管理技术、镀层控制以及镀后冷却控制技术等是钢板连续热镀铝的关键生产工艺技术,对上述各关键工艺点的技术难点和对策进行详细分析。

  13. Propriedades e bioatividade de um cimento endodôntico à base de aluminato de cálcio Properties and bioactivity of endodontic calcium aluminate cement

    Directory of Open Access Journals (Sweden)

    I. R. Oliveira

    2011-09-01

    Full Text Available Desde sua introdução na endodontia como um material retro-obturador e selador de defeitos da raiz dental, o agregado de trióxido mineral (MTA tem sido considerado como um material endodôntico revolucionário. Apesar disso, este material apresenta algumas propriedades limitantes, necessitando alterações em sua composição bem como desenvolvimento de novos materiais. Assim, o objetivo desse trabalho foi mostrar a influência de aditivos no desenvolvimento de um cimento endodôntico à base de cimento de aluminato de cálcio (ECAC. Além disso, foram avaliadas as propriedades do ECAC em comparação com o MTA, quando em contato com solução de fluido corporal simulado (SBF. Testes de manipulação e medidas de resistência à compressão, porosidade aparente, tempo de endurecimento, pH e condutividade iônica, foram realizados para os materiais MTA puro e ECAC contendo aditivos. Considerando as propriedades apresentadas pelo ECAC, este material alternativo pode ser indicado para múltiplas aplicações em endodontia.The mineral trioxide aggregate (MTA, a material primarily developed as a root-end filling has been extensively investigated as an innovative product for endodontic applications. However, changes in its formulation/composition involving its mineral aggregates and the development of alternatives of materials have been proposed in an attempt to overcome its negative physical-chemical characteristics. In this work, the influence of additives addition on the development of a novel endodontic cement based on calcium aluminate, has been evaluated. In addition, the properties of endodontic calcium aluminate cement (ECAC were compared with the gold standard mineral-trioxide-aggregate in contact with simulated body fluid (SBF. Manipulation tests and measurements of compressive strength, apparent porosity, setting time, pH and ionic conductivity were carried out on plain MTA and calcium aluminate cement with and without various additives

  14. Calcium aluminate cement concrete: durablllty and conversión. A fresh look at an old subject

    Directory of Open Access Journals (Sweden)

    George, C. M.

    1992-12-01

    Full Text Available This paper re-examines the relationship between durability and conversion of calcium aluminate cement concretes, CACC. Conversion is a natural and inevitable process whereby these materials reach a stable mature condition. Numerous structures built more than half a century ago remain serviceable and in service today. Some of these are illustrated. They are the best testament to the durability of converted concrete having survived far longer in the converted than the unconverted condition. The unique rapid hardening characteristics of CACC offer a valuable selfheating capability. Conversión is immediate and this leads to better long term strengths because more cement is hydrated. Moreover, recent work has shown that the thermodynamically stable hydrates of converted CAC are intrinsically more resistant to attack from such aggressive agents as sulphuric acid. This provides an explanation of the excellent long term performance of Fondu concretes, for example in many saewer applications. Our knowledge and understanding today of the durability of calcium alumínate bonded materials has been built on close to 100 years of accumulated experience and laboratory studies. We know how to use these materials and we know what to expect from them. We can be confident that they will serve us well in the century ahead.

    Este trabajo examina de nuevo la relación entre durabilidad y conversión de hormigones de cemento aluminoso, HAC (High Alumina Cement. La conversión es un proceso natural e inevitable a través del cual este material consigue una condición definitiva y estable. Numerosas estructuras que se edificaron hace más de medio siglo siguen utilizables y utilizadas hoy en día. Algunas de estas estructuras vienen ilustradas en este trabajo. Ellas sirven como mejor ejemplo de la durabilidad del hormigón convertido, ya que han sobrevivido mucho más tiempo en el estado convertido que en el no convertido. Las singulares caracter

  15. Effect of the strontium aluminate and hemihydrate contents on the properties of a calcium sulphoaluminate based cement

    Directory of Open Access Journals (Sweden)

    Velazco, G.

    2014-09-01

    Full Text Available The effect of strontium aluminate (SrAl2O4 on the hydration process of a calcium sulphoaluminate (C4A3Ŝ cement was investigated. Cement pastes were prepared by mixing C4A3Ŝ , hemihydrate (CaSO4· ½H2O, CŜH0.5 and 0, 10 or 20wt% of SrAl2O4 (SrA. The amount of CŜH0.5 was 15, 20 or 25wt% based on the C4A3Ŝ quantity. The cement pastes were hydrated using water to cement ratios (w/c of 0.4 and 0.5. Samples were cured from 1 to 28 d. The compressive strength and setting time were evaluated and the hydration products were characterized. It was found that the setting time was delayed up to 42 min for the samples containing SrAl2O4 compared to samples without addition. The samples with 25wt% hemihydrate containing 20wt% SrAl2O4 developed the highest compressive strength (60 MPa after 28 d of curing. The main product after hydration was ettringite (C6AŜ3H32. The morphology of this phase consisted of thin needle-shaped crystals.Se investigó el efecto de la adición de aluminato de estroncio (SrAl2O4 sobre las propiedades de un cemento de sulfoaluminato de calcio (C4A3Ŝ. Se prepararon muestras mezclando C4A3Ŝ, hemihidrato (CaSO4· ½H2O, CŜH0.5 y 0, 10 o 20% e.p de SrAl2O4 (SrA. La cantidad de CŜH0.5 fue de 15, 20 o 25% e.p. basado en la cantidad de C4A3Ŝ. Las relaciones agua/cemento utilizadas fueron 0.4 y 0.5. Las muestras fueron curadas hasta 28 d. Se evaluó el tiempo de fraguado y la resistencia a la compresión. Los productos de hidratación se caracterizaron mediante DRX y MEB. El tiempo de fraguado se retardó hasta 42 minutos con la adición del SrAl2O4 comparado con las muestras sin adiciones. Las muestras con 25% e.p. de yeso y 20% e.p. de SrAl2O4 desarrollaron la mayor resistencia a la compresión alcanzando 60 MPa a 28 d de curado. Los análisis por MEB y DRX muestran como principal producto de hidratación a la etringita (C6AŜ3H32, cuya morfología se observa como cristales aciculares.

  16. Dry reforming reaction over nickel catalysts supported on nanocrystalline calcium aluminates with different CaO/Al2O3 ratios

    Institute of Scientific and Technical Information of China (English)

    Atiyeh Ranjbar; Mehran Rezaei

    2012-01-01

    Nanocrystalline calcium aluminates with different CaO/Al2O3 ratios were prepared by a facile co-precipitation method using Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEG-PPG-PEG,MW:5800) as a surfactant.They were employed as catalyst support for nickel catalysts in methane reforming with carbon dioxide.The prepared samples were characterized by X-ray diffraction (XRD),N2 adsorption (BET),temperature-programmed reduction and oxidation (TPR-TPO),and scanning electron microscopy (SEM) techniques.Catalysts showed a relatively high catalytic activity and stability.TPR analysis revealed that the catalysts with higher CaO content are more difficult to be reduced.TPO analysis showed that the 5 wt%Ni/CA and 5 wt%Ni/C 12A7 catalysts with higher CaO amount were effective against coke deposition.

  17. The Effect of the Thickness of Fe2 Al5 Phase Layer at Fe/Al Interface on the Mechanics Behavior of Hot Dip Aluminizing Coating

    Institute of Scientific and Technical Information of China (English)

    XIA Yuan; YU Sheng-xue; CHEN Ling; CUI Rui-yi; YAO Mei

    2004-01-01

    Hot Dip Aluminized Coatings with different thickness were prepared on Q235 steel in aluminum solutions with different temperature for certain time. Through tensile tests and in-situ SEM observations, the effect of the coating's microstructure on the tensile strength of the samples was studied. It was disclosed at certain aluminum solution temperature,transaction layers mainly composed of Fe2 Al5 phase got thicker with time prolonging, and this changed initial crack's extending direction from parallel with to vertical with stretching direction. The change in crack direction decreased tensile strength of samples, thus made the coating easy to break. It was concluded that the existence of thick Fe2 Al5 phase layer was the basic reason for the lowering of tensile strength of the coating.

  18. Study of the ultrasonic waves action on the preparation of calcium aluminates cements; Estudo da acao das ondas ultrasonicas na sintese de cimentos de aluminatos de calcio

    Energy Technology Data Exchange (ETDEWEB)

    Lourenco, R.R.; Exposito, C.C.D.; Rodrigues, J.A., E-mail: josear@ufscar.b [Universidade Federal de Sao Carlos (DEMa/GEMM/UFScar), SP (Brazil). Dept. de Engenharia de Materiais. Grupo de Engenharia de Microestrutura de Materiais

    2009-07-01

    Calcium aluminates cements were prepared through a route that uses the sonochemical process. In this process, calcia and alumina in an aqueous suspension are put under an ultrasonic bath during some time. After that, the water is evaporated and the material is heat treated. In this work, the action of ultrasonic waves were studied on initials molar compositions calcia:alumina of 1:1. It was also verified the influence of the water on the reactivity of initial solids. SEM and X-ray diffraction were used to characterize the obtained materials. In addition, mechanical strength of the products was evaluated through splitting tensile tests. The X-ray diffractograms showed that the presence of the water was enough to form hydrated compounds. However the material subjected to the sonochemical process presented the highest mechanical strength, indicating the potential of this route of synthesis. (author)

  19. Function of magnesium aluminate hydrate and magnesium nitrate as MgO addition in crystal structure and grain size control of -Al2O3 during sintering

    Indian Academy of Sciences (India)

    Soumen Pal; A K Bandyopadhyay; S Mukherjee; B N Samaddar; P G Pal

    2010-02-01

    Chemically pure reactive alumina (-Al2O3) which is commercially available was used for densification study in presence of widely accepted dopant MgO as additive. MgO was added both as spinel (MgAl2O4) forming precursor i.e. magnesium aluminate hydrate, and magnesium nitrate. Sintering investigations were conducted in the temperature range 1500–1600°C with 2 h soaking. Structural study of sintered pellets was carried out by extensive XRD analysis. Scanning electron mode SEM images of the specimens were considered to understand the effect of both types of additions. Addition of MgO within and beyond optimum amount had some effect on development of microstructure of sintered bodies. Densification, around 99% ρth, with fine grain microstructure was achieved. These different types of additions caused two distinct changes in crystal structure of alumina-one small contraction and the other expansion of unit cell parameters.

  20. Y{sub 3-x}Er{sub x}Al{sub 5}O{sub 12} aluminate ceramics: preparation, thermal properties and theoretical model of thermal conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yan-Gai; Peng, Peng; Fang, Minghao; Huang, Zhaohui [School of Materials Science and Technology, China University of Geosciences, Beijing (China)

    2012-03-15

    Rare-earth aluminate ceramics for thermal-barrier coatings (TBCs) are synthesized. The Young's modulus and thermal properties decrease with erbium additive increasing. The Y{sub 3-x}Er{sub x}Al{sub 5}O{sub 12} ceramics (x=1,3) possess a much-lower thermal conductivity compared with 8YSZ. The lower Young's modulus and thermal-expansion coefficient are due to the larger atomic weight of the Er substitutional atom. Additional phonon-scattering effects also contribute to the lower thermal conductivity. The results indicate that Y{sub 3-x}Er{sub x}Al{sub 5}O{sub 12} can be explored as a candidate material for TBC systems. A theoretical model that describes the influence of point defects on the thermal conductivity is discussed. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. The Influence of Al on the Detonation Parameters of Aluminized Explosives%Al粉对含铝炸药爆轰性能的影响

    Institute of Scientific and Technical Information of China (English)

    冯晓军; 黄亚峰; 徐洪涛

    2012-01-01

    In order to research the influence of Al on the detonation parameters of aluminized explosives, the detonation velocity, detonation pressure and explosion heat of aluminized explosives of TNT-based and RDX-based were measured, and the detonation energy transform scale was calculated, then the influence rules of Al/O mole scale on the detonation parameters and the detonation energy transform scale were analyzed. The results showed that the detonation pressure, detonation velocity and the detonation energy transform scale decreased with the increase of Al/O mole scale, while the explosion heat increased firstly, when Al/O mole scale was 1, the value achieved maximum, then decreased with the increase of Al/O mole scale.%为了研究A1粉对含铝炸药爆轰性能的影响,选择以TNT和RDX为基的含铝炸药进行了爆速、爆压和爆热的测量,通过计算得到了含铝炸药的爆轰能量转化率,分析了Al/O摩尔比对爆轰参数及爆轰能量转化率的影响规律.结果表明:随着Al/O摩尔比的增大,含铝炸药的爆压、爆速和爆轰能量转化率均降低,而爆热呈先增大后减小趋势,当Al/O摩尔比为1时,爆热值达到最大.

  2. 45钢表面交流电场增强粉末法铝氮复合渗研究%Study on Alternating Current Field Enhanced Pack Aluminizing Plus Nitriding of 4 5 Carbon Steel Surface

    Institute of Scientific and Technical Information of China (English)

    张格; 谢飞; 潘建伟

    2016-01-01

    Alternating current field enhanced pack aluminizing plus nitriding (ACFEPAN)was carried out on 45 steel surface by applying ACF to the sample and treating agents with a pair of electrodes for overco-ming shortcomings of thin cases and long treating time in conventional pack aluminizing plus nitriding process.By investigating cases�structures,phases and hardness distributions of differently treated sam-ples,a preliminary study was made on characterizations of ACFEPAN on the surface of 45 steel.The re-sults show that the alternating current field (ACF)not only speed up aluminizing but also can avoid the formation of aluminium-rich phases during the alternating current field enhanced pack aluminizing.The a-luminium-rich phases formed by conventional pack aluminizing prevent the diffusion of N into the alumini-zing case during the later nitriding.By applying ACF to nitriding,the infiltration of nitrogen into the alu-minizing case is promoted,and N reacts with the aluminizing case to form AlN and Fe3 N.A case with an effective thickness of more than 150μm can be obtained by alternating current field enhanced 4h pack alu-minizing plus 4h nitriding.%针对现有铝氮复合渗工艺存在的渗层薄、渗扩时间长等问题,对置于两电极间的45钢试样与渗剂施加交流电场,进行交流电场增强粉末法铝氮复合渗。通过观察分析不同工艺所得试样的渗层组织、相结构与硬度分布,初步研究了交流电场增强45钢表面粉末法铝氮复合渗特性。结果表明:在复合渗的渗铝阶段施加交流电场不仅加快渗铝速度,还能够避免常规粉末法渗铝在表面形成富铝相对后续渗氮的阻碍;在后续渗氮中施加交流电场可促进氮渗入与渗铝层反应,在共渗层表层形成 AlN和 Fe3 N;通过将4 h 的交流电场增强渗铝与4 h 电场渗氮复合,能够获得有效厚度在150μm以上的复合渗层。

  3. 高铁水兑入比电炉炉盖用镁铝尖晶石浇注料的研制%Development of magnesium aluminate spinel castable for cover of EAF with high molten iron adding ratio

    Institute of Scientific and Technical Information of China (English)

    陈杨; 吴洪平; 朱冬冬; 张行

    2012-01-01

    Specimens of magnesium aluminate spinel castable and calcium aluminate cement bonded bauxite based castable were prepared using special bauxite (particle size ≤8 mm) and sintered magnesia as aggregates,SiO2 micropowder.cc-alumina micropowder and calcium aluminate cement as binders,drying, firing at 1 350 ℃ and 1 500 ℃ for 3 h,respectively. The bulk density,modulus of rupture,cold crushing strength, permanent change in dimensions on heating, thermal shock resistance and slag resistance were determined. The result shows that compared with calcium aluminate cement bonded bauxite based castable,the magnesium aluminate spinel castable has higher cold crushing strength after drying, better slag resistance but worse thermal shock resistance. Magnesium aluminate spinel based lid of EAF with high molten iron adding ratio has longer service life.%以粒度≤8 mm特级高铝矾土颗粒和烧结镁砂为骨料,SiO2微粉、α-Al2O3微粉、铝酸钙水泥作结合剂,分别制得镁铝尖晶石质浇注料和铝酸钙水泥结合高铝质浇注料.对试样分别进行烘干、1 350℃3 h和1 500℃3 h热处理并检测其体积密度、抗折强度、耐压强度、加热永久线变化、抗热震性和抗渣性.结果表明:与铝酸钙水泥结合高铝质浇注料相比,镁铝尖晶石质浇注料具有较高的烘干耐压强度,优良的抗渣性,但抗热震性较差.因此,在高铁水兑入比的电炉中,镁铝尖晶石质电炉盖表现出了更长的使用寿命.

  4. 不锈钢表面振动冲击加速渗铝工艺研究%Study on low-temperature aluminizing on a stainless steel assisted by ball milling

    Institute of Scientific and Technical Information of China (English)

    王德仁; 陈亮; 何业东

    2012-01-01

    In order to accelerate the formation process of aluminide coating on 1Cr18Ni9Ti stainless steel substrate at relatively low temperature,mechanical vibration and impact were applied to 1Cr18Ni9Ti sample during aluminizing by a similar ball peening process.The coating was obtained by aluminizing at 600 ℃ for 4 h,6 h and 8 h,and the aluminizing coating weight gain,coating thickness,alloying element distribution across aluminizing coating were investigated.High temperature oxidation kinetics of coatings and bare sample were measured at 900 ℃ for 100 h.The results show that a dence layer of aluminizing coating can formed on 1Cr18Ni9Ti steel substrate and the coating thickness can reach 35 μm after vibration aluminization at 600 ℃ for 4 h.Oxidation resistance performance measurement reveals that the optimal duration time is 6 h because the weight gain for 6 h is less than 4 h and 8 h.%研究了利用喷丸加速制备涂层技术,对1Cr18Ni9Ti不锈钢分别进行600℃×4、6和8 h渗铝处理,研究了1Cr18Ni9Ti试样的单位面积增重、Al涂层厚度、主要元素沿涂层截面的分布;并将不同温度下获得的铝化物涂层与空白试样一起进行了高温氧化测试实验(900℃×100 h)。结果表明,在较低的温度600℃和较短的时间4 h,可以在1Cr18Ni9Ti钢基体上形成35μm厚的铝化物涂层;但抗氧化性能测试结果却表明,振动渗制处理6 h获得的铝化物涂层性能优于处理4 h和8 h的涂层。

  5. Effect of heat treatment on mechanical properties and wear resistance of Q345 aluminized steel%热处理工艺对Q345渗铝钢力学性能及耐磨性的影响

    Institute of Scientific and Technical Information of China (English)

    黄耀; 王旭明; 牛海军; 林德源; 赵金飞; 陈云祥; 刘蔚宁

    2016-01-01

    研究了不同渗铝温度及冷却方式对渗铝钢力学性能的影响,对比研究了渗铝钢、镀锌钢和原材料的耐磨特性,采用SEM及能谱仪对磨损后的物相进行了分析。力学性能结果表明:当渗铝温度降低至715~735℃时,采用空冷,可保持原材料的力学性能;耐磨失重试验表明渗铝钢的质量损失明显低于镀锌钢,其质量损失随着加载力增加而缓慢增加,当加载力从3 N增加至19 N时,渗铝钢质量损失从0.87 mg增加至2.15 mg,其最大质量损失仅为Q345的19.8%,镀锌钢的28.1%。对渗铝钢、镀锌钢和原材料磨损后的物相分析表明:渗铝钢的耐磨相为Fe-Al-O化合物,镀锌钢耐磨相为Fe-Zn合金氧化物;磨损机理分析表明,Q345的磨损主要为粘着磨损,而渗铝钢则为磨粒磨损。%Effect of different aluminizing temperature and cooling method on mechanical properties of aluminized steel were investigated, then a comparative study of wear characteristics between aluminized steel, galvanized steel and Q345 was conducted by using scanning electron microscopy (SEM) and energy dispersive spectrometer. The mechanical properties results show that when the aluminizing temperature is reduced to 715-735 ℃, mechanical properties of the raw materials can maintain by using air cooling heat-treatment. Wear weight loss test demonstrates that weight loss of aluminized steel is significantly lower than that of galvanized steel, and the weight loss increases slowly with the loading force. When the loading force increases from 3 N to 19 N, weight loss value is enhanced from 0. 87 mg to 2. 15 mg, and the maximum value is only 19. 8% of Q345 steel, 28. 1% of galvanized steel. Phase analysis of the wear of aluminized steel, galvanized steel and Q345 show that wear-resistant phase of aluminized steel is Fe-Al-O compounds, and wear-resistant phase of galvanized steel is Fe-Zn alloy oxide. Wear mechanism analysis shows that the Q345 wear mechanism is

  6. Laser shock processing and aluminizing compound technology used on steel blade%钢制叶片激光冲击强化与渗铝的组合应用

    Institute of Scientific and Technical Information of China (English)

    李应红; 李伟; 何卫锋; 李玉琴; 李启鹏

    2011-01-01

    采用扫描电子显微镜(SEM),X射线衍射(XRD)等手段研究了激光冲击强化(LSP)对钢制叶片渗铝层的影响,结果表明渗铝后进行激光冲击强化会对渗铝层造成破环,而在渗铝之前进行激光冲击强化则能提高渗层质量.从残余应力和显微组织变化两方面分析了渗铝高温作用对不锈钢材料激光冲击强化效果的影响,激光冲击强化产生的残余压应力在510℃渗铝温度环境下保温150min仍有-295MPa稳定存在,晶粒细化组织也没有明显长大,激光冲击不锈钢材料的残余应力和微观组织具有良好的热稳定性.振动疲劳对比试验结果验证了"LSP+渗铝"组合工艺对不锈钢材料的强化效果,在660MPa应力水平下,采用该组合工艺试片的疲劳寿命为3.98×10^6,为原渗铝试片疲劳寿命的14倍左右.%Scanning electron microscopy (SEM), X-ray diffraction (XRD) and other techniques were used to detect the influence of laser shock processing (LSP) on aluminizing layer, which is infiltrated into the stainless steel blade for antisepticising. The results show that the aluminizing layer will be destroyed when LSP is implemented after aluminizing. And the quality of aluminizing layer will be improved while LSP is implemented before aluminizing. The influence on the LSP by the high temperature in the course of aluminizing was studied through residual stress test and metallographic analysis. After 150 minutes in the condition of aluminizing temperature 510℃, the residual compressive stress in the LSP zone was still -295MPa and the refined grain did not grow up remarkably. The residual compressive stress and grain refinement layer induced by LSP had good thermo stability. Finally, the vibration fatigue performance of different states stainless steels was tested. When the maximum stress is 660MPa, the fatigue life of "LSP before aluminizing" is about 3.98×10^6 , which is about fourteen times than that

  7. 热浸渗铝X70管线钢扩渗工艺研究%Research on Hot Diffusion Aluminizing Process of X70 Pipe Line Steel

    Institute of Scientific and Technical Information of China (English)

    黄敦伟; 胡爱萍; 张宏伟; 孔德军

    2013-01-01

    The relationship between hot diffusion aluminizing temperature,infiltration time and thickness of aluminized coating of X70 pipe line steel was researched by quadratic orthogonal regression testing method.The regression equation of the alloying layer thickness was established.The optimum process for hot diffusion aluminizing treatment was gotten.The surface and interface morphologies of X70 pipeline steel after the aluminizing treatment were observed,and Fe and Al content change by the carbonitride layer were analyzed.The element diffusion mechanism of hot dipping alumetizing process was discussed.The results show that alloying layer thickness is increased with the rising of insulation temperture and the extending of diffusion time.The ideal inoulation temperature is 950 ℃ and time is insulation 6 h.%采用二次正交回归试验方法,研究了X70管线钢热扩渗铝保温温度、扩渗时间与渗铝层厚度的关系,建立了渗层回归方程,得到X70管线钢最优的热扩渗铝工艺参数.观察了X70管线钢热浸渗铝处理后的表面、界面微观形貌,分析了Fe和Al的含量沿渗层的变化情况,并对热浸渗铝过程中的元素扩散机理进行了探讨.结果表明:渗铝层厚度随保温温度的升高和扩渗时间的延长而增大,适宜的保温温度为950℃,扩渗时间为6h.

  8. Computer fitting of growth kinetics of diffusion layer in aluminized steel%渗铝钢扩散层生长动力学的计算机拟合

    Institute of Scientific and Technical Information of China (English)

    刘爱萍; 张伟

    2011-01-01

    The pure aluminized layer and RE-aluminized layer on 20 steel were prepared by hot dip aluminizing method,respectively.After diffusion treatment at different temperature,the distributions of rare earth elements in diffusion layer and the thickness increment of diffusion layer were measured,the effect of rare earths on the growth kinetics of diffusion layer at different temperature was investigated,and its growth kinetic curves were given with computer fitting.The results show that rare earth elements permeate diffusion layer and there is partial cluster.The RE permeating into steel can enhance the thickness of diffusion layer,the effects of RE are stronger at 750 ℃ and 850 ℃,the diffusion coefficient has been increased by a factor of 1.8~2.3 and the diffusion activation energy is decreased 4500~7800 J.mol-1 compared with pure aluminizing.%在20钢上分别制备了热浸镀纯铝和稀土铝层。通过不同温度的扩散处理后,测定了扩散层的稀土分布和扩散层厚度增量,考察了在不同温度下稀土对扩散层生长动力学的影响,并通过计算机拟合给出了扩散层生长动力学曲线。结果表明,热浸镀稀土铝钢在扩散处理时,稀土渗入了扩散层,且存在偏聚;稀土可增加扩散层厚度,在750、850℃作用较明显;扩散系数增加1.8-2.3倍,扩散激活能降低4500-7800 J.mol-1。

  9. 重结晶对DNTF形貌和含铝炸药爆轰性能的影响%Influences of Recrystallization on the Morphology of DNTF and Detonation Performance of Aluminized Explosive

    Institute of Scientific and Technical Information of China (English)

    姚李娜; 王彩玲; 赵省向; 戴致鑫; 王海清

    2015-01-01

    DNTF explosive was pretreated by solvent-anti-solvent recrystallizing method. Crystal shape and DNTF granularity of pre-treatment were analyzed by SEM and laser particle size analyzer. Meanwhile, impact sensitivity, form-ability, detonation heat and detonation velocity of aluminized explosive were discussed. The experimental results show that:recrystallized DNTF, pretreated by ethyl-acetate as solvent and H2 O as anti-solvent, is of little granularity and has narrow particle size distribution, regular crystal shape, and low impact sensitivity. The formation density, detonation heat and det-onation velocity of aluminized explosive contained pretreated DNTF are obviously higher than aluminized explosive contai-ning DNTF, and pretreated DNTF improves the detonation characteristics of aluminized explosives to some extent.%采用溶剂-非溶剂法重结晶预处理3,4-二硝基呋咱基氧化呋咱(DNTF),通过SEM及激光粒度仪分析了预处理工艺对DNTF形貌和粒度的影响,并研究了含铝炸药的撞击感度、成型性、爆热和爆速性能。结果表明,以乙酸乙酯为溶剂,水为非溶剂,DNTF经重结晶预处理后,其晶体粒度变小,粒度分布变窄,晶体外形稍好,形状规则,撞击感度降低;含重结晶DNTF的含铝炸药成型密度、爆热和爆速均高于含粗品DNTF的含铝炸药,在一定程度上提高了DNTF含铝炸药的爆轰性能。

  10. Research on Aluminized Steel for Resisting Stress Corrosion Cracking and Hydrogen Embrittlement%渗铝钢抗应力腐蚀开裂及抗氢脆性能研究

    Institute of Scientific and Technical Information of China (English)

    吴昊; 李华飞

    2016-01-01

    以30CrMo钢为母体,对30CrMo钢及其渗铝钢分别进行抗硫化氢应力腐蚀开裂实验、抗氯离子应力腐蚀开裂实验,采用Devanathan双电池技术测量氢的扩散系数。实验结果表明:30CrMo钢渗铝后比渗铝前具有更好的抗硫化氢应力腐蚀开裂、抗氢脆性能;单一氯离子对30CrMo钢及其渗铝钢应力腐蚀开裂性能影响较小。%Using 30CrMo steel as the matrix, resistance to hydrogen sulfide stress corrosion cracking test and resistance to chloride ion stress corrosion cracking test were carried out respectively for 30CrMo steel and its aluminized steel.Using Devanathan double cell technology, and we measured hydrogen diffusion coefficient.Experimental results show that, aluminized steel of 30CrMo has better resistance to hydrogen sulfide stress corrosion cracking and hy-drogen embrittlement, and single chloride ion has little influence on the stress corrosion cracking for 30CrMo steel and its aluminized steel.

  11. 渗铝钢焊接工艺及焊接接头性能研究%Study on Welding Technology and Properties of Welded Joint for Aluminized Steel

    Institute of Scientific and Technical Information of China (English)

    熊从贵

    2013-01-01

    Four different electrode was applied on aluminized steel welding process test ,and the welding test pieces were used for mechanical properties testing .Based on the experiments ,four of the welding specimen mechanical properties data were obtained ,the aluminized steel manual arc welding process was summarizes ,which can be used as the aluminized steel welding process‐ing to provide specific reference data .%  采用4种不同焊条进行渗铝钢焊接工艺试验,并对焊接试件进行了力学性能检测。通过试验研究,得到了4种焊条的焊接试件力学性能数据,总结出了渗铝钢焊条电弧焊的焊接工艺方法,可为渗铝钢的焊接加工提供具体的参考数据。

  12. 渗铝钢合金层/基体界面的生长模型研究%Interfacial growing model between alloy layer and matrix of aluminized steel

    Institute of Scientific and Technical Information of China (English)

    韩存仓; 刘爱萍; 张伟

    2011-01-01

    Starting from the diffusion characteristic of the aluminized layer in the diffusion process of hot dip aluminized steel, in accordance with the crystal nucleus forming theory of intermetallic compound new phase, the growing model of the interfacial intermetallic compounds between alloy layer and steel matrix of hot dip aluminized steel was established. The experimental results show that the growing model can comparatively accurately calculate the intermetallic compound growth thickness of the interface between allov laver and steel matrix.%从钢的热浸镀铝钢扩散特点出发,根据金属间化合物新相晶核形成理论,建立了界面金属间化合物的生长行为模型.经试验验证,该模型能比较准确地计算扩散过程中界面金属间化合物相的生长厚度.

  13. Microstructural and compositional change of NaOH-activated high calcium fly ash by incorporating Na-aluminate and co-existence of geopolymeric gel and C–S–H(I)

    KAUST Repository

    Oh, Jae Eun

    2012-05-01

    This study explores the reaction products of alkali-activated Class C fly ash-based aluminosilicate samples by means of high-resolution synchrotron X-ray diffraction (HSXRD), scanning electron microscope (SEM), and compressive strength tests to investigate how the readily available aluminum affects the reaction. Class C fly ash-based aluminosilicate raw materials were prepared by incorporating Na-aluminate into the original fly ashes, then alkali-activated by 10 M NaOH solution. Incorporating Na-aluminate reduced the compressive strength of samples, with the reduction magnitude relatively constant regardless of length of curing period. The HSXRD provides evidence of the co-existence of C-S-H with geopolymeric gels and strongly suggests that the C-S-H formed in the current system is C-S-H(I). The back-scattered electron images suggest that the C-S-H(I) phase exists as small grains in a finely intermixed form with geopolymeric gels. Despite providing extra source of aluminum, adding Na-aluminate to the mixes did not decrease the Si/Al ratio of the geopolymeric gel. © 2012 Elsevier Ltd.

  14. 两种镁源反应烧结合成镁铝尖晶石%Synthesis of magnesium aluminate spinel by reaction sintering with different magnesia sources

    Institute of Scientific and Technical Information of China (English)

    曹晓炜; 易帅; 曾春燕; 刘艳改; 房明浩; 黄朝晖

    2013-01-01

    分别以轻烧菱镁矿粉和分析纯MgO粉为镁源,以工业α-Al2O3粉为铝源,按n(MgO)∶n(Al2O3)=1∶1的比例配料,经球磨混合、机压成型后,分别在1 550、1 600和1 650℃保温3h合成了两种不同镁源的镁铝尖晶石试样,对比检测了两种试样的致密度、强度、物相组成和显微结构的差异.结果表明:1)利用两种不同镁源合成试样的致密度和强度均随合成温度的升高而增大,在合成温度相同时,以轻烧菱镁矿为镁源的试样的致密度和强度较高.2)以轻烧菱镁矿为镁源、1 650℃合成的试样的主晶相为尖晶石,还有少量CA2和CaSiO3,其尖晶石晶体发育较好,八面体形态可辨;以分析纯MgO为镁源、1 650℃合成的试样中只有单相镁铝尖晶石,但尖晶石晶体发育较差,只有少数形成较完整的八面体形态.3)轻烧菱镁矿中SiO2、CaO杂质的存在有利于试样中形成CaO-Al2O3-MgO-SiO2系低熔点相,促进镁铝尖晶石晶体的发育及试样的烧结.%Two magnesium aluminate spinel specimens were prepared using light-burnt magnesite powder and analytically pure MgO powder as magnesia sources,respectively,industrial α-AI203 powder as alumina source,batching with n(MgO): n(AI2O3) =1:1,ball milling,shaping,then firing at 1 550 ℃,1 600 ℃ and 1 650 ℃ for 3 h,respectively. The densities,strengths,phase compositions and microstructures of the two specimens were compared. The results show that: (l)the densities and strengths of the two specimens increase with synthesis temperature rising;at the same synthesis temperature,the specimen using light-burned magnesite ass magnesia source has higher density and strength;(2) for the specimens synthesized at 1 650 ℃:using light-burnt magnesite as magnesia source,the phases are mainly spinel with a little CA2 and CaSiO3,and the spinel crystals grow well with octahedron morphology;using analytically pure MgO as magnesia source,the main phase is single-phase magnesium

  15. Nickel-doped zinc aluminate oxides: starch-assisted synthesis, structural, optical properties, and their catalytic activity in oxidative coupling of methane

    Science.gov (United States)

    Visinescu, Diana; Papa, Florica; Ianculescu, Adelina C.; Balint, Ioan; Carp, Oana

    2013-03-01

    Nanosized nickel-substituted zinc aluminate oxides were obtained by the gradual insertion of nickel cations within the zinc aluminate lattice, using starch as active ingredient. The obtained (Ni x Zn1- x Al2)-starch ( x = 0.1, 0.2, 0.4, 0.6, 0.8, 1) gel precursors were characterized through infrared spectroscopy and thermal analysis. The thermal behavior of the precursors are influenced by the nickel content, the DTA curves for the richer nickel samples revealing stronger, faster and overlapping exothermic reactions, that can be completed at lower temperatures. The corresponding spinelic oxides were obtained after calcination treatments at 800 °C and analyzed by means of NIR-UV-Vis spectroscopy, XRD measurements, SEM, TEM, and HRTEM investigations. The spinelic structure for all oxide samples is confirmed by XRD analysis, although small amounts of NiO cannot be neglected. TEM/HRTEM analysis revealed mesopores embedded in plate-like large (68.8 nm) particles of Ni0.2Zn0.8Al2O4 sample and smaller (15.7 nm) uniform equiaxial particles, with a more pronounced tendency of agglomeration for Ni0.8Zn0.2Al2O4 oxide. A formation mechanism for Ni0.2Zn0.8Al2O4 oxides was proposed based on DTA/TG, XRD, and SEM analyses. NIR-UV-Vis spectra for Ni x Zn1- x Al2O4 showed a significant presence of tetrahedral nickel cations that augments with nickel concentration increase. CIE- L * a * b * color parameters shown a variation of the lightness and also of the green and blue color components with x, the best color characteristics being obtained for x = 0.6. The oxides with a substitution degree x = 0.2 and 0.8 tested in the oxidative coupled of methane reaction (OCM) showed positive catalytic activity and selectivity due to an interesting synergetic effect of Zn(II) and Ni(II) ions.

  16. 地质聚合物合成中铝酸盐组分的作用机制%HYDROLYSIS KINETICS OF ALUMINATES IN GEOPOLYMERS SYNTHESIS

    Institute of Scientific and Technical Information of China (English)

    翁履谦; SAGOE-CRENTSIL Kwesi; 宋申华; 张化宇

    2005-01-01

    The mechanisms of A1 speciation and hydrolysis in geopolymers were investigated based on the partial charge model together with preliminary experimental validation. The study essentially concludes that aluminate species generally promote the condensation reactions in aluminosilicate systems owing to such factors as their partial charge, atomic size and the number of hydroxyl groups. Consequently, the solubility of aluminate sources, like metakaolin, has important influence on the properties of geopolymers. Experimental resultsfurther show that the duration of milling metakaolin, which results in different particle sizes and different dissolution rates of metakaolin, has an important effect on geopolymer properties such as setting time, microstructure and compressive strength. The samples from the larger specific surface area of metakaolin give quicker setting time, higher compressive strength, and a more homogeneous microstructure. The compressive strength is 54 MPa for the samples produced from coarse metakaolin, up to 74 MPa for those from fine metakaolin.%在对铝、硅酸盐离子团中离子的部分电荷计算的基础上,研究了铝组分在地质聚合物合成中的作用机制,并通过实验进行了初步验证.研究表明:铝组分对地质聚合物的合成中缩聚反应有显著的促进作用,因而在合成地质聚合物时原料中铝组分的溶解性至关重要.实验结果表明:由具有较小颗粒度的煅烧高岭土为原料合成的地质聚合物具有较短的固化时间,更均匀的显微结构和更高的机械强度.如由较粗的煅烧高岭土为原料合成的地质聚合物的抗压强度为54 MPa,而由较细的煅烧高岭土为原料合成的地质聚合物的抗压强度则能达到74 MPa.

  17. Research on the One-stage Desilication Process for the Mid-high Concentration of Sodium Aluminate Solution%中高浓度铝酸钠溶液一段脱硅工艺研究

    Institute of Scientific and Technical Information of China (English)

    王雅静; 王立思; 庞常健; 翟玉春

    2013-01-01

    硅是铝酸钠溶液中最难除去的杂质,若硅含量过高会造成氧化铝产品的损失.通过改变脱硅温度、脱硅时间、铝酸钠溶液浓度及脱硅剂用量来确定铝酸钠溶液一段脱硅的较优条件.试验表明最优条件是脱硅温度为100℃,时间为100 min,脱硅剂用量为27g/L,搅拌速度为300r/min,铝酸钠溶液浓度从140 ~ 200g/L,脱硅指数可达1000以上.并通过测定表面张力随脱硅时间、脱硅温度变化,及通过钙硅渣XRD衍射试验,分析了铝酸钠溶液一段脱硅机理.铝酸钠溶液一段脱硅后能够基本达到铝酸钠溶液二段脱硅的工艺要求.%The removal of silicon in the sodium aluminate solution is the most difficult among all the impurities.Alumina products will be lost if the content of silicon is too high.In this paper,the one-stage desilication optimal condition was obtained by changing the desilication temperature,desilication time,sodium aluminate solution concentration and calcium silicon slag content.The results showed when the desilication temperature is 100℃,the time is 100min,the dosage of the agent is 27g/L,the stirring speed is 300r/min and the concentration of the sodium aluminate solution is from 140g/L to 200g/L,the desilication index is more than 1000.The first-stage desilication mechanism of sodium aluminate solution was obtained by measuring surface tension with desilication time,temperature;and by analyzing the XRD of calcium silicon slag.The sodium aluminate solution after the first-stage desilication can almost meet the requirement of the deep desilication process.

  18. EDS analysis of aluminized coatings on X70 pipeline steel after salt spray corrosion%X70管线钢渗铝层盐雾腐蚀后能谱面扫描分析

    Institute of Scientific and Technical Information of China (English)

    孔德军; 吴永忠; 付贵忠; 龙丹

    2013-01-01

    利用激光热效应对X70管线钢进行渗铝处理,研究了其在5%盐雾试验中的腐蚀行为,通过SEM、EDS和XRD等手段对腐蚀产物表面-界面形貌、化学元素面扫描和物相组成进行了分析,探讨了渗铝层耐盐雾腐蚀机理.结果表明,渗铝层界面由渗铝层、扩散层和基体组成,Al和Fe原子在扩散层相互扩散,形成了FeAl2金属化合物相,是界面冶金结合的主要机制;盐雾腐蚀以点蚀为主,表面出现裂纹是热扩散过程中热应力作用的结果;腐蚀后渗铝层界面中存在Al和O元素的分层富集现象,形成的Al2O3氧化膜有效地阻止Cl-对基体金属的腐蚀,Al在渗铝层的局部富集是保护基体的主要因素,提高了X70管线钢的耐盐雾腐蚀性能.%Aluminizing treatment was conducted on surface of a X70 pipeline steel with laser thermal effect,and corrosion behavior of the aluminized coatings in 5% salt spray test was investigated.The surface-interface morphology,microstructure and phase component of the coatings were analyzed by means of SEM,EDS and XRD.The mechanism of salt spray corrosion of the aluminized coatings was discussed.The results show that the aluminized coatings are composed of aluminized layer,diffusion layer and substrate.The elements of Al and Fe are diffused each other in the diffusion layer,forming a intermetallic compound phase of FeAl2,that is the main mechanism of the metallurgical binding of the interface.The pitting corrosion in the aluminized coatings is the main mode for salt spray corrosion.The surface cracking is a result of thermal stress.There is a stratified enrichment of Al and O elements in the aluminized coating interface,forming a layer of Al2O3 film to effectively prevent Cl-from eroding the substrate metals,and the Al enrichment is a main factor of protecting the substrate,improving the properties of salt spray corrosion for X70 pipeline steel.

  19. a New Red Phosphor of the Mn Activated Non-Stoichiometric Strontium Aluminate 3SrO•5Al2O3 for High Color Rendering White Leds

    Science.gov (United States)

    Chen, Lei; Zhang, Yao; Liu, Fayong; Deng, Xiaorong; Xue, Shaochan; Luo, Anqi; Jiang, Yang; Chen, Shifu; Zhang, Wenhua

    2013-05-01

    A new red phosphor of strontium aluminate activated by Mn4+ was developed for high color rendering and warm white light-emitting diodes. The phosphor composition and conditions for synthesis were optimized through solid-state reaction. Meanwhile, the structure and morphology were investigated with XRD and SEM analysis. The results show that the 3SrO•5Al2O3 activated by 0.0005 M Mn fired at 1300°C in air ambient by adopting 2.5 wt.% AlF3 as flux exhibits most efficient luminescence. A white LED device prototype with CIE (0.3291, 0.3571), CCT 5639 K, CRI Ra 92.6, and efficacy 63 lm/W driven at 20 mA has been packaged by pre-coating the red phosphor combined with a yellow one Y3Al5O12:Ce3+ on a blue InGaN chip. The analysis of critical distance and luminescence quench reveal that the mechanism of energy transfer for luminescence is through dipole-dipole interaction.

  20. Highly efficient, 0.84 slope efficiency, 901 nm, quasi-two-level laser emission of Nd in strontium lanthanum aluminate.

    Science.gov (United States)

    Lupei, Voicu; Aka, Gerard; Vivien, Daniel

    2006-04-15

    The possibility of using direct pumping into the emitting level of the Nd3+ ion in magnesium-compensated strontium lanthanum aluminate (Sr(1-x)La(x-y)Nd(y)Mg(x)Al(12-x)O19) to improve 900 nm 4F(3/2) --> 4I(9/2) laser emission is discussed. Selection of the composition parameters x and y for optimization of laser emission and reduction of heat generation is based on the spectroscopic and crystal growth characteristics. Pumping in the 865.5 nm absorption band 4I(9/2)(Z1) --> 4F(3/2)(R1) transforms the laser process into a quasi-two-level scheme of very low (below 4%) quantum defects. A very high slope efficiency (over 84%) for 901 nm continuous-wave laser emission is demonstrated with Ti:sapphire laser pumping in this band for a crystal with x = 0.4 and y = 0.05.

  1. The Effect of Lithium Doping on the Sintering and Grain Growth of SPS-Processed, Non-Stoichiometric Magnesium Aluminate Spinel

    Directory of Open Access Journals (Sweden)

    Yuval Mordekovitz

    2016-06-01

    Full Text Available The effects of lithium doping on the sintering and grain growth of non-stoichiometric nano-sized magnesium aluminate spinel were studied using a spark plasma sintering (SPS apparatus. Li-doped nano-MgO·nAl2O3 spinel (n = 1.06 and 1.21 powders containing 0, 0.20, 0.50 or 1.00 at. % Li were synthesized by the solution combustion method and dense specimens were processed using a SPS apparatus at 1200 °C and under an applied pressure of 150 MPa. The SPS-processed samples showed mutual dependency on the lithium concentration and the alumina-to-magnesia ratio. For example, the density and hardness values of near-stoichiometry samples (n = 1.06 showed an incline up to 0.51 at. % Li, while in the alumina rich samples (n = 1.21, these values remained constant up to 0.53 at. % Li. Studying grain growth revealed that in the Li-MgO·nAl2O3 system, grain growth is limited by Zener pining. The activation energies of undoped, 0.2 and 0.53 at. % Li-MgO·1.21Al2O3 samples were 288 ± 40, 670 ± 45 and 543 ± 40 kJ·mol−1, respectively.

  2. Synthesis and hydration behavior of calcium zirconium aluminate (Ca{sub 7}ZrAl{sub 6}O{sub 18}) cement

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Eun-Hee [Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 151-744 (Korea, Republic of); Yoo, Jun-Sang [Department of Oral and Maxillofacial Surgery, School of Dentistry, Seoul National University, Seoul 110-749 (Korea, Republic of); Kim, Bo-Hye; Choi, Sung-Woo [Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 151-744 (Korea, Republic of); Hong, Seong-Hyeon, E-mail: shhong@snu.ac.kr [Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 151-744 (Korea, Republic of)

    2014-02-15

    Calcium zirconium aluminate (Ca{sub 7}ZrAl{sub 6}O{sub 18}) cements were prepared by solid state reaction and polymeric precursor methods, and their phase evolution, morphology, and hydration behavior were investigated. In polymeric precursor method, a nearly single phase Ca{sub 7}ZrAl{sub 6}O{sub 18} was obtained at relatively lower temperature (1200 °C) whereas in solid state reaction, a small amount of CaZrO{sub 3} coexisted with Ca{sub 7}ZrAl{sub 6}O{sub 18} even at higher temperature (1400 °C). Unexpectedly, Ca{sub 7}ZrAl{sub 6}O{sub 18} synthesized by polymeric precursor process was the large-sized and rough-shaped powder. The planetary ball milling was employed to control the particle size and shape. The hydration behavior of Ca{sub 7}ZrAl{sub 6}O{sub 18} was similar to that of Ca{sub 3}Al{sub 2}O{sub 6} (C3A), but the hydration products were Ca{sub 3}Al{sub 2}O{sub 6}·6H{sub 2}O (C3AH6) and several intermediate products. Thus, Zr (or ZrO{sub 2}) stabilized the intermediate hydration products of C3A.

  3. Synthesis optimization of calcium aluminate cement phases for biomedical applications; Avaliacao da sintese das fases de cimento de aluminato de calcio

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, T.L.; Santos, G.L.; Oliveira, I.R. [Universidade do Vale do Paraiba (UNIVAP), Sao Jose dos Campos, SP (Brazil); Pandolfelli, V.C. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil)

    2011-07-01

    Calcium aluminate cement (CAC) has been studied as a potential material for applications in the areas of health such as, endodontics and bone reconstruction. These studies have been based on commercial products consisting of a mixture of phases. Improvements can be attained by investigating the synthesis routes of CAC aiming the proper balance between the phases and the control of impurities that may impair its performance for biomedical applications. Thus, the aim of this work was to study the CAC synthesis routes in the Al{sub 2}O{sub 3}-CaCO{sub 3} and Al{sub 2}O{sub 3}-CaO systems, as well as the phase characterization attained by means of X ray analysis. The Al{sub 2}O{sub 3}-CaO route enabled the production of the target phases (CA, CA{sub 2}, C{sub 3}A and C{sub 12}A{sub 7}) with a higher purity compared to the Al2O3-CaCO3 one. As a result the particular properties of these phases can be evaluated to define a more suitable composition that results in better properties for an endodontic cement and other applications. (author)

  4. 含铝炸药中铝粉活性的光谱法测试研究%Determination of Aluminium Powder Activation in Aluminized Explosives by Spectrometry

    Institute of Scientific and Technical Information of China (English)

    胡岚; 王婧娜; 熊贤锋; 严蕊; 张婷; 高朗华; 李晓宇

    2012-01-01

    In order to evaluate the activation of aluminium powder in aluminized explosives,the activity of aluminium powder in military FLX and FLU series was measured by X-ray fluorescence (XRF) spectrometry and X-ray diffraction (XRD) spectrometry. The results show that only XRF method can be used to analyze activity of aluminium powder. A correction factor of aluminium activity is obtained by fitting results of XRF method and standardization method (chemical analysis method) GJB1738 -1993. The relative deviation obtained by XRF method and chemical analysis method for detecting activity of aluminium powder in A-Ⅸ-Ⅱ explosives is less than 4%.%为评价含铝炸药中铝粉的活性,用X荧光(XRF)光谱法、X衍射(XRD)光谱法测定了FLX、FLU系列中铝粉的活性.结果表明,仅XRF可以用于铝粉活性的分析.铝粉活性测试校正系数由拟合XRF法与标准方法GJB1738 - 1993的结果得到.XRF法和标准方法GJB1738 - 1993所得A-Ⅸ-Ⅱ炸药中铝粉活性结果的相对测量误差≤4%.

  5. Viscous properties of new mould flux based on aluminate systemwith CeO2 for continuous casting of RE alloyed heat resistant steel

    Institute of Scientific and Technical Information of China (English)

    QI Jie; LIU Chengjun; LI Chunlong; JIANG Maofa

    2016-01-01

    The conventional mould fluxes can not be applied to the continuous casting of RE alloyed heat resistant steel, because se-vere slag-metal interface reactions occur generally in the mold. To restrain the interface reaction and improve conditions for continu-ous casting, a new mould flux based on aluminate system was devised. The viscous properties were investigated. Scanning electron microscopy and X-ray diffraction were applied to detect and characterize the crystalline phases in the continuous cooling process. The results showed that appropriate addition of CeO2 could avoid the precipitation of CaO and decrease the viscosity of the mould flux. Increasing the mass ratio of CaO/Al2O3, especially to a value exceeding 1, could worsen the stability of the mould flux. With a con-tent of less than 14 wt.%, Li2O could reduce the viscosity and breaking temperature, but its effect could be weakened for the pro-moted precipitation of LiAlO2. To obtain a mould flux with stable viscous properties, such as viscosity and breaking temperature, ap-propriate contents of CeO2 and Li2O should be controlled to around 10 wt.% and 14 wt.%, while the mass ratio of CaO/Al2O3 should not be more than 1.

  6. 45钢稀土硼铝共渗的扫描电镜观察%SEM Observation of Steel 45 RE-boron-Aluminized

    Institute of Scientific and Technical Information of China (English)

    吉泽升; 赵密; 郭宗文

    2000-01-01

    The layers of steel 45 RE-boron-Aluminized were observed by SEM,and the surface scanning of Al,Ce and the depth profiles of B,C,Al,Fe were analyzed.The results show that the permeating amount of Al that mainly exists in subsurface layers in creases because of the adding of rare earth and the distribution of Al is changed as well.So Al atoms are permeated before Fe2B has covered the surface of specimen and beacuse Fe2B continously covering surface,Al atoms stop diffusing and gather at subsurface layers.%通过扫描电镜观察了45钢稀土硼铝共渗的渗层形貌,并进行了铝和铈的面扫描分以及硼、碳、铝、铁的线扫描分析。结果表明:铝存在于渗层的次表层中,稀土的加入增加了铝的渗入量并改变了铝的分布状况。由此认为,铝是先于硼化物覆盖表面之前渗入的,当硼化物覆盖表面后,铝则停止迁移而富集于次表层中。

  7. 合理利用资源生产铝酸钙精炼渣的研究%Study on Producing Calcium Aluminate by Optimal Use of Resources

    Institute of Scientific and Technical Information of China (English)

    张延大

    2012-01-01

    钢铁冶炼会消耗大量的优质矿产资源,本文通过分析石灰岩、矾土矿等相关资源储量形势,指出了利用工业废渣作为原材料生产铝酸钙精炼渣的可行性,并在轴承钢生产中得到了理想的应用效果,脱硫率最高达到了83.5%,钛显微夹杂物显著降低.这对合理利用资源,实现可持续发展具有重要意义.%It consumes a lot of premium resources to make iron and steel. This paper dwells on the reserve situation of limestone and bauxite, indicating the feasibility of producing calcium aluminate refining slag by taking use of industrial offscum and it has been effectively used in bearing steel with desulfurization rate reaching 83.5% and micro-titanium impurity decreasing remarkably, which has important influence on the rational use of recourses and sustainable development.

  8. Effect of Tartaric Acid on Hydration of a Sodium-Metasilicate-Activated Blend of Calcium Aluminate Cement and Fly Ash F

    Directory of Open Access Journals (Sweden)

    Tatiana Pyatina

    2016-05-01

    Full Text Available An alkali-activated blend of aluminum cement and class F fly ash is an attractive solution for geothermal wells where cement is exposed to significant thermal shocks and aggressive environments. Set-control additives enable the safe cement placement in a well but may compromise its mechanical properties. This work evaluates the effect of a tartaric-acid set retarder on phase composition, microstructure, and strength development of a sodium-metasilicate-activated calcium aluminate/fly ash class F blend after curing at 85 °C, 200 °C or 300 °C. The hardened materials were characterized with X-ray diffraction, thermogravimetric analysis, X-ray computed tomography, and combined scanning electron microscopy/energy-dispersive X-ray spectroscopy and tested for mechanical strength. With increasing temperature, a higher number of phase transitions in non-retarded specimens was found as a result of fast cement hydration. The differences in the phase compositions were also attributed to tartaric acid interactions with metal ions released by the blend in retarded samples. The retarded samples showed higher total porosity but reduced percentage of large pores (above 500 µm and greater compressive strength after 300 °C curing. Mechanical properties of the set cements were not compromised by the retarder.

  9. 不同气氛对TATB基含铝炸药爆热的影响%Detonation Heat of TATB-based Aluminized Explosive in Different Atmospheres

    Institute of Scientific and Technical Information of China (English)

    曹威; 郭向利; 段英良; 昝继超; 韩勇; 刘世俊

    2016-01-01

    [ ABSTRACT] To measure the heat generation of triaminotrinitrobenzene( TATB)-based aluminized explosive in different atmospheres, the exotherm of pressed charge in vacuum, 0. 1 MPa nitrogen, 0. 1 MPa air, 0. 1 MPa oxygen and 1. 5 MPa oxygen were measured by adiabatic calorimetric bomb and the energy release rule was studied. Then the solid explosion products were detected by X-ray diffraction ( XRD) . Results show that the heat output of TATB-based aluminized explosive increased gradually in the sequence of vacuum, 0. 1 MPa nitrogen, 0. 1 MPa air, 0. 1 MPa oxygen and 1. 5 MPa oxygen;the increase of atmospheric pressure results in the increase of heat output, which is shown that the heat output in 0. 1 MPa nitrogen increased by 15. 7% than that in vacuum; and the heat output increases with the increase of oxygen amount in atmosphere, which is verified by the conclusion that the heat output in 0. 1 MPa air was 7. 8% larger than that in 0. 1 MPa nitrogen, the heat output in 0. 1 MPa oxygen was 49. 7% higher than that in 0. 1 MPa nitrogen, and the heat output in 1. 5 MPa oxygen was 146. 1% higher than that in 0. 1 MPa nitrogen. In the case that the heat output of TATB-based aluminized explosive was measured in oxygen-rich atmosphere, the measured heat output was close to the combustion heat, and the XRD of the explosion products verified that the aluminum powders were almost completely oxidized. Meanwhile, AlN was not detected in 0. 1MPa nitrogen. It provides a method to measure the heat output of aluminized explosives and analyze the existing form of aluminum element in explosion products.%为了测定三氨基三硝基苯( TATB)基含铝炸药在不同气氛中的爆热,使用绝热式量热弹对其压装药在真空、0.1 MPa氮气、0.1 MPa空气、0.1 MPa氧气和1.5 MPa氧气条件下的爆热进行了测量,研究了其能量释放规律,并使用X射线衍射(XRD)对固相产物成分进行了分析。结果表明:TATB基含铝炸药在真空、0.1 MPa

  10. Preparation of iron aluminate (FeAl2O4) nanoparticles from FeAl2O4 hollow particles fabricated by using a spray pyrolysis process

    Science.gov (United States)

    Yun, Jaecheol; Kim, Yangdo; Park, Dahee; Yun, Jung-Yeul

    2015-05-01

    Iron aluminate (FeAl2O4) hollow particles with a spinel structure were synthesized by using a spray pyrolysis process. FeAl2O4 hollow particles were formed at a reaction temperature of 900 °C at a flow rate of 40 L/min as a result of the rapid solvent evaporation and decomposition gases from the droplets in the spray solution prepared from metal salts and organic reagents. FeAl2O4 hollow particles were fabricated at a reaction temperature of 900 °C with a flow rate of 40 L/min. The FeAl2O4 hollow particles were heat treated for 3 hours at 600 °C in a 5% H2/Ar atmosphere to form the crystal particles. Subsequently, FeAl2O4 nanoparticles were fabricated from the FeAl2O4 hollow particles by using the wet milling process. After milling for 60 minutes, transmission electron microscopy revealed the FeAl2O4 particles to have a mean size of approximately 50 nm. The FeAl2O4 nanoparticles were fabricated successfully by using a two-step process, spray pyrolysis and wet milling.

  11. Andean evolution of the Aluminé fold and thrust belt, Northern Patagonian Andes (38°30‧-40°30‧S)

    Science.gov (United States)

    García Morabito, Ezequiel; Ramos, Víctor A.

    2012-10-01

    The Aluminé fold and thrust belt between 38°30' and 40°30'S is the result of two periods of progression of deformation toward the foreland. The chronology of deformation and its relationship with magmatism through time show spatially and temporally separated magmatic events closely linked to distinct deformational stages. Data presented here confirms a Late Cretaceous mountain-building phase that coexisted in space and time with an eastward arc-migration. During this stage, a belt of deformation expanded through the foreland where it produced the Southern Neuquen Precordillera. This eastern independent mountain grew separately from the main Andean axis through a combination of inversion of the old rift systems and interaction with a pre-Andean belt which acted as a foreland obstacle. On the basis of tectonostratigraphic controls we define the last Andean contractional phase between the Late Miocene and the Pliocene. This event induced the reactivation of both sectors of the fold and thrust belt with minor propagation toward the foreland, leading to the uplift of the Patagonian Andes and reshaping the Southern Neuquén Precordillera. Both intervals of shortening are separated by a period of localized extension that resulted in the development of the Collón Cura basin within this Andean segment. Here, large thicknesses of volcanosedimentary sequences accumulated contemporaneously with the extensional activity between the earliest Oligocene and the Early Miocene.

  12. 硫铝酸盐-铝酸盐水泥体系高水充填材料的研制试验%Experimental study on high-moisture filling material prepared with sulphoaluminate-aluminate cement

    Institute of Scientific and Technical Information of China (English)

    李建杰; 丁全录; 佘海龙

    2012-01-01

    The properties of the high-moisture filling material prepared with sulphoaluminate-aluminate cement were studied by determing the setting time of every single slurry,setting time of the filling material,and the compressive strength of cement pastes.The results show that subsituting 5%~30% sulphoaluminate cement clinker(42.5 MPa)with the coarser aluminate cementclinker has effect on setting time of the filling material,and subtly decreases the early age(2 h) strength,and the late age strength will be largely increased,the late age(28 d) strength even exceeds that of the filling material without substitution of sulphoaluminate cement clinker to 48.9%.The high-moisture filling material prepared with subsituting 5%~30% sulphoaluminate cement clinker(42.5 MPa) with the coarser aluminate cement clinker can meet with the requirements of the standard of MT/T 420—1995.%研究了用硫铝酸盐-铝酸盐水泥体系制备高水充填材料的方法,进行了单浆凝结时间、胶凝时间、抗压强度的测试。结果表明,用细度较粗的铝酸盐水泥熟料替代5%~30%的强度级别42.5 MPa硫铝酸盐水泥的熟料制备高水充填材料,对材料的胶凝时间有所影响,使材料的2 h强度稍有降低,但可大幅度提高材料的后期强度,28 d抗压强度最大可提高48.9%,可以制备出满足MT/T 420—1995标准要求的高水充填材料。

  13. Carbon doped lanthanum aluminate (LaAlO{sub 3}:C) synthesized by solid state reaction for application in UV thermoluminescent dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Alves, N., E-mail: neire.radiologia@yahoo.com.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Ferraz, W.B.; Faria, L.O., E-mail: farialo@cdtn.br, E-mail: ferrazw@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    In this work we discuss the TL output for LaAlO{sub 3}:C crystals grown by using three different combinations of Al{sub 2}O{sub 3}, La{sub 2}O{sub 3} and carbon atoms during the synthesis process. Recently, LaAlO{sub 3} single crystals, co-doped with Ce{sup 3+} and Dy{sup 3+} rare earth trivalent ions and grown under hydrothermal conditions, have been reported to show high thermoluminescent response (TL) when exposed to low levels of ultraviolet radiation (UVR). However, undoped LaAlO{sub 3} synthesized by solid state reaction method from the 1:1 mixture of aluminum and lanthanum oxide under reducing atmosphere revealed to have still higher thermoluminescent sensitivity to UV photon fields than the co-doped with Ce{sup 3+} and Dy{sup 3+}. It is well known that carbon doped aluminum oxide monocrystals have excellent TL and photoluminescent response properties for X-rays, UV and gamma radiation fields. Thus, we conducted three different syntheses of LaAlO{sub 3} by this solid state reaction method, doping the mixture with carbon. The lanthanum aluminate polycrystals were synthesized from the 1:1 mixture of aluminum and lanthanum oxide, adding 0.1wt.% carbon and annealed at 1700°C for two hours in hydrogen atmosphere. The X-ray diffraction analysis revealed the formation of rhombohedral LaAlO{sub 3} crystallographic phase, however a small percentage (15%) of Al{sub 2}O{sub 3} has been also identified. The UV-Vis absorbance spectra were obtained and F and F {sup +}- center were ascribed. The UV irradiations were carried out using a commercial 8W UV lamp. Thermoluminescence measurements were performed at a Harshaw 4500 TL reader. All compositions investigated have shown high TL sensitivity to UVR. (author)

  14. 合成温度对含镁铝尖晶石的铝酸盐水泥晶粒尺寸及凝结性能的影响%Influence of synthesis temperature on crystal size and setting properties of calcium aluminate cement with magnesium aluminate spinel

    Institute of Scientific and Technical Information of China (English)

    陈平安; 李享成; 朱伯铨

    2016-01-01

    Dolomite,industrial alumina and caustic magnesite were used as starting materials to study the in-fluence of temperature on the crystal size and setting properties of aluminate cement with magnesium alu-minate spinel.The starting materials were mixed homogeneously according to the mass ratio of 71 9 20 of Al2 O3 MgO CaO,heated to 1 100,1 200,1 300,1 400,1 500 ℃,respectively,in a high temperature furnace and soaked for 3 h.After that,the cement bulk was crushed to below 50 μm.The MA bearing aluminate ce-ment was characterized by XRD and SEM,and the setting time was tested.The results show that the phases of CA,MA and CA2 can be formed at 900,1 100 and 1 200 ℃,respectively.The crystal size of spinel could be controlled from nanometer to micrometer as the synthesis temperature rises from 1 100 to 1 500 ℃,and CA as well as CA2 grows from 2 -3 μm to 5 μm,and then sinter together forming skeleton,CA and CA2 crystals are surrounded by MA crystals.Meanwhile,the setting time delays with the synthesis temperature rising due to the growth of CA or CA2 crystals,decreasing the hydration activity;and the growth of MA crystals,hindering the reactions between water and CA or CA2 ,thus obviously hindering the hydration of the cement.%为了研究合成温度对含镁铝尖晶石的铝酸盐水泥晶粒尺寸和凝结性能的影响,以白云石、工业氧化铝和轻烧镁砂为原料,按 Al2 O3、MgO、CaO 质量比为71920配料后混合均匀,并在高温炉中分别经1100、1200、1300、1400和1500℃保温3 h 煅烧并破粉碎至50μm 以下,制备了含 MA 的铝酸盐水泥,对水泥试样进行了XRD 和 SEM分析,并检测了凝结时间。研究结果表明:含 MA 的铝酸盐水泥中的 CA、MA 和 CA2相分别在900、1100和1200℃生成。当合成温度从1100℃升高至1500℃时,水泥中 MA 的晶粒尺寸从纳米到微米级可控,CA 或 CA2的粒径从2~3μm 逐渐长大至5μm 以上,并烧结在一起形成骨架,MA

  15. 熔焊对碳钢渗铝层组织和抗氧化性能的影响%Influence of Fusion Welding on Microstructure and Oxidation Resistance of Aluminized Layer on Carbon Steel

    Institute of Scientific and Technical Information of China (English)

    丛伟; 姚正军; 包卫军

    2011-01-01

    Vacuum diffusion Q235 steel after hop dip aluminizing was welded by tungsten gas arc welding.The effect of fusion welding on microstructure and high-temperature (800℃ ) oxidation resistance of the aluminized layer was investigated by means of optical microscopy, scanning electron microscopy, energy dispersive spectra and X-ray diffraction. The results show that the interface between aluminized layer and welding seam was metallurgical bonding. The elements of Cr, Ni and Al near fusion line gradiently distributed. The main phases near fusion line were Al2Cr, AlCrFe2 and (Fe, Cr) solid solution. The oxidation-mass gain curves of the post-weld sample were nearly parabolic. The main phases of the oxidation film in fusion zone were Al2O3, Cr2O3 and Fe2O3. Comparing with the high-temperature oxidation resistance of the aluminized sample before welding , the one of the sample after welding only decreased by 22. 8%.%采用钨极氩弧焊焊接了热浸镀铝后真空扩散的Q235钢板,采用光学显微镜、SEM、EDS、XRD等研究了熔焊对渗铝层组织及高温(800℃)抗氧化性能的影响.结果表明:渗铝层与焊缝之间实现冶金结合,铬、镍、铝元素在熔合线附近呈现梯度分布,熔合线附近的主要物相为Al2Cr、AlCrFe2以及(Fe,Cr)固溶体;焊后试样的氧化-增重曲线近似抛物线,熔合区氧化膜的主要物相为Al2O3、Cr2O3和Fe2O3,焊后渗铝试样的高温抗氧化性能比焊接前仅下降了22.8%.

  16. Research on High Temperature Oxidation Resistance of Hot-dip Aluminized Steel%热浸镀铝钢抗高温氧化腐蚀性能研究

    Institute of Scientific and Technical Information of China (English)

    吴笛

    2012-01-01

    Considering high temperature oxidation resistance of hot-dip aluminized steel, the experimental study on it at 900℃ and for 100h and through weight gain was discontinuously implemented. The results show that the oxidation by weight per unit area of hot-dip aluminized steel is a quarter of general carbon steel, and the oxide film which making up this deposit together with matrix and diffusion zone has excellent high temperature oxidation resistance.%在实验室条件下通过900C、100h的不连续氧化增重试验研究了热浸镀铝钢的抗高温氧化腐蚀性能,结果表明,热浸镀铝钢单位面积氧化增重量为普通碳钢的1/4,其中浸镀层由表面的氧化膜、母体和扩散区组成,氧化膜具有优良的抗高温氧化性能.

  17. The Corrosion Rules Study of Aluminizing and Sherardized Carbon-Steel in Oilfield Wastewater%渗铝和渗锌碳钢在油田采出水中腐蚀规律研究

    Institute of Scientific and Technical Information of China (English)

    张凤华; 徐艳飞; 李飞; 赵杉林

    2012-01-01

    以模拟的油田采出水和海水作为腐蚀介质,采用静态挂片腐蚀失重法对20#碳钢、渗铝碳钢和渗锌碳钢进行腐蚀实验,初步研究了Cl-,Ca2+,HCO3-和温度对20 #碳钢、渗铝碳钢和渗锌碳钢的腐蚀规律.腐蚀评价的结果表明,在模拟的油田采出水和海水的腐蚀介质中,渗锌碳钢的耐蚀性能明显好于20#碳钢和渗铝碳钢.%Simulated oilfield wastewater and seawater were used as corrosive mediums, corrosion tests of 20# carbon steel, aluminizing carbon steel and sherardized carbon steel were evaluated via static corrosion weight loss method. The impact factors containing concentration of Cl- ,Ca2+ , HCOr and temperature were investigated. The research results show chat the corrosion resistance performance of sherardized carbon steel is superior to 20" carbon steel and aluminizing carbon steel in the corrosion mediums.

  18. STUDY ON THE WELDING TECHNOLOGY AND PROPERTIES OF WELDED JOINT FOR ALUMINIZED STEEL%渗铝钢焊接工艺及焊接接头力学性能研究

    Institute of Scientific and Technical Information of China (English)

    熊从贵

    2012-01-01

    Four different welding rods are applied to carry out welding process test of the alumi- nized steel and mechanical properties examination is done on the welding test pieces. Based on plentiful experiments, mechanical property data of the welding test pieces of the four different welding rods are obtained and the welding technology for the manual arc welding used for alu-minized steel is summarized. And this provides specific data for reference in welding process of aluminized steel.%应用4种不同的焊条进行渗铝钢焊接工艺试验,并对焊接试件进行力学性能检测.通过大量的试验研究,得到4种焊条的焊接试件力学性能数据,总结出渗铝钢手工电弧焊的焊接工艺方法,为渗铝钢的焊接加工提供具体的参考数据.

  19. Composition coatings on the surface of carbon steel crucible by aluminizing%碳钢坩埚表面渗铝复合涂层

    Institute of Scientific and Technical Information of China (English)

    刘建睿; 王栓强; 黄卫东

    2011-01-01

    以碳钢板为基板材料,通过表面渗铝和高温化学反应在其表面形成复合保护涂层。研究了反应层厚度与反应温度、时间之间的关系,并用光学显微镜、XRD对涂层形貌、相组成进行了表征。实验结果表明:反应产物层厚度随反应温度、时间的增加而增加;复合涂层由过渡层和反应产物层组成,过渡层组成为Fe3Al及少量Fe2Al5、Fe14Al86、Al2O3,反应产物层组成为TiB2、MgO和少量的Mg2TiO4、Mg2B2O5、Fe3Al、FeAl、Ti285。%The composition protective coatings on the surfaee of carbon steel crucible were prepared by aluminizing and high temperature chemical reaction. The relations between the thickness of reaction product layer and reaction temperature and time were investigated. The microstructures and phase composition of the coating layer were investigated by means of optics microscope and XRD. The experimental results show that the thicknesses of reaction product layers increase with the reaction temperature and time increasing. The composition coatings are composed of transition layer and reaction product layer. The constitution of transition layer are Fe3Al and small amount of Fe2Al5, Fe14Al86 and Al2O3. The reaction product layer are consisted of TiB2 , MgO and small amount of Mg2 TiO4 , Mg2 B2O5 , Fe3Al, FeAl and Ti2B5.

  20. Effect of Sodium Carbonate on Deep Desiliconization of Sodium Aluminate Solution%碳酸钠对铝酸钠溶液深度脱硅的影响

    Institute of Scientific and Technical Information of China (English)

    王雅静; 李宏亮; 翟玉春; 张征

    2011-01-01

    During the course of producing aluminum oxide,as accumulation of sodium carbonate in circulation mother liquor,the flow rate increases and also the solution viscosity,which has influences on crystallization and growth of A1(OH)3. The experiment was performed by using calcium oxide as desiliconization reagents to study the effects of sodium carbonate on the condition and result of deep desiliconization of sodium aluminate solution. Finally, the optimal reaction condition of temperature as 90℃, time as ll0min, stirring speed as 867r/min and dosage of sodium carbonate as 30g/L was determined and the silicon index of refine liquor reached 3642. Meanwhile, Silicon residue of deep desiliconization was analyzed by XRD and found when the sodium carbonate concentration is 0 ~30g/L,it can promote disiliconization but when the concentration is more than 30g/L,it inhibits.%在氧化铝的生产过程中,随着循环母液里碳酸钠的积累使物料流量增加,溶液的粘度增大,并影响分解过程Al(OH)3的结晶及生长.试验采用氧化钙为脱硅剂,研究了碳酸钠对铝酸钠溶液深度脱硅条件和结果的影响,确定出较佳反应条件:在脱硅温度90℃、时间110min、搅拌速度867r/min,碳酸钠用量30g/L时,精制液的硅量指数达到3642.硅渣的XRD光谱分析表明,碳酸钠浓度在0~30g/L之间时,促进铝酸钠溶液脱硅;碳酸钠浓度高于30g/L时,抑制溶液脱硅.

  1. Characterization and origin of the Taishanmiao aluminous A-type granites: implications for Early Cretaceous lithospheric thinning at the southern margin of the North China Craton

    Science.gov (United States)

    Wang, Changming; Chen, Liang; Bagas, Leon; Lu, Yongjun; He, Xinyu; Lai, Xiangru

    2016-07-01

    Late Mesozoic magmatic rocks from the Taishanmiao Batholith were collected for LA-ICP-MS dating, Sr-Nd-Hf isotope systematics, and whole-rock major and trace element geochemistry to help understand the nature of collisional and extensional events along the southern margin of the North China Craton. The batholith consists of three texturally distinguishable phases of a 125 ± 1 Ma medium- to coarse-grained syenogranite, a 121 ± 1 Ma fine- to medium-grained syenogranite, and a 113 ± 1 Ma porphyritic monzogranite. Most of the units in the batholith are syenogranitic in composition with high levels of silica (70-78 wt% SiO2), alkalis (8.0-8.6 wt% Na2O + K2O), Fe* (FeOT/(FeOT + MgO) = 0.76-0.90), and depletion in CaO (0.34-1.37 wt%), MgO (0.12-0.52 wt%), TiO2 (0.09-0.40 wt%), and A/CNK (Al2O3/(Na2O + K2O + CaO)) molar ratios of 1.00-1.11. All samples have high proportions of Ga, Nb, Zr, Ga/Al, and REE, and depletions in Ba, Sr, Eu, and compatible elements, indicating that the batholith consists of A-type granites. The zircon saturation temperature for these units yields a mean value of 890 °C, and zircons with Early Cretaceous magmatic ages have ɛNd( t) values of -14.0 to -12.0, ɛHf( t) values ranging from -18.7 to -2.1, and corresponding Hf model ages of 2339-1282 Ma. These geochemical and isotopic characteristics allowed us to conclude that the primary magma for the Taishanmiao Batholith originated from partial melting of Precambrian crustal rocks in the medium-lower crust. However, the high Nb and Ta contents and low normalized Nb/Ta values for the Taishanmiao granites are due to fractionation in Nb- and Ta-rich amphibole (or biotite). It is further proposed that these aluminous A-type granites were generated in an extensional tectonic setting during the Early Cretaceous, which was induced by lithospheric thinning and asthenospheric upwelling beneath eastern China toward the Paleo-Pacific Plate.

  2. Investigation of barium-calcium aluminate process to manufacture and characterize impregnated thermionic cathode for power microwave devices; Investigacao do processo de obtencao de aluminatos de bario e calcio para construcao e caracterizacao de catodos termionicos impregnados para aplicacao em dispositivos de microondas de potencia

    Energy Technology Data Exchange (ETDEWEB)

    Higashi, Cristiane

    2006-07-01

    In the present work it is described the barium calcium aluminate manufacture processes employed to produce impregnated cathodes to be used in a traveling-wave tube (TWT). The cathodes were developed using a tungsten body impregnated with barium and calcium aluminate with a 5:3:2 proportion (molar). Three different processes were investigated to obtain this material: solid-state reaction, precipitation and crystallization. Thermal analysis, thermogravimetry specifically, supported to determine an adequate preparation procedure (taking into account temperature, time and pyrolysis atmosphere). It was verified that the crystallization showed a better result when compared to those investigated (solid-state reaction and precipitation techniques - formation temperature is about 1000 deg C in hydrogen atmosphere), whereas it presented the lower formation temperature (800 deg C) in oxidizing atmosphere (O{sub 2}). It was used the practical work function distribution theory (PWFD) of Miram to characterize thermionic impregnated cathode. The PWFD curves were used to characterize the barium-calcium aluminate cathode. PWFD curves shown that the aluminate cathode work function is about 2,00 eV. (author)

  3. 低温包埋渗铝及其在石油管材防腐蚀应用中的研究进展%Research Progress of Low-temperature Pack Aluminizing and Its Potential Application on Oil-casing Steel and Pipeline Steel

    Institute of Scientific and Technical Information of China (English)

    黄敏; 王宇

    2012-01-01

    慨述了钢基表面低温包埋渗铝的原理,分析了通过添加稀土元素、调整活性剂种类、在渗剂中添加合金、表面机械能助渗、基材表面自身纳米化预处理等实现低温渗铝的研究现状和优缺点.同时,针对高力学性能石油管材,提出了将表面自身纳米化技术与含锌的低温渗剂相结合的石油管材表面低温复合包埋渗铝技术,并对该技术在石油管材耐腐蚀保护方面的应用进行了展望,认为复合低温包埋渗铝技术在石油管材耐腐蚀处理中的应用具有广阔前景.%The main principle of low-temperature pack aluminizing of carbon steel was described. The present research situation and different characteristics of low-temperature pack aluminizing processing were analyzed by the addition of rare earth element, the adjustment of active agent type, the addition of alloy dement, the assistance of surface mechanical energy and the surface selmanocrystallization treatment of steel substrate. For oil-casing steel and pipeline steel with high mechanical properties, a combined low-temperature pack aluminizing for oil-casing steel and pipeline steel with surface nano-crystallization structure packed by powdeT with the addition of zinc was proposed. On the basis pf the potential corrosion resistance improvement of aluminized oil-casing steel and pipeline steel by combined low-temperature pack aluminizing, it can be concluded that the as-mentioned combined low-temperature pack aluminizing is hopeful for the wide application of aluminizing for the corrosion protection of oil-casing steel and pipeline steel.

  4. Al-5Ti-B-RE细化剂对热浸渗铝层的组织与性能的影响%The effect of Al-5Ti-B-RE refiner on the microstructure and property of the hot dip aluminized coatings

    Institute of Scientific and Technical Information of China (English)

    李安敏; 胡武; 王海超; 李松浩

    2013-01-01

    In order to study the effects of refiner on the microstructure and the high temperature oxi-dation resistance of the hot dip aluminized coatings , the hot dip aluminized coatings on the surface of Q235 steel were prepared by flux method , and Al-5Ti-B-RE refiner was added in the aluminum melt.The microstructure of aluminized coating was analyzed by X-ray diffractometer and scanning e-lectron microscope , and the resistance to high temperature oxidation of aluminized coating was tested by the oxidation weight increase method .The results showed that all the hot dip aluminized coatings were formed by surface layer and alloy layer;the thickness of the coating decreased when refiner was added , and the needles ( FeAl3 ) in the surface layer were refined and the dentate alloy layer became thiner, close and less bifurcation;with the increase of refiner , the high temperature oxidation resist-ance of the aluminized steel increased mitially and then decreased , and the hot dip aluminizing with 0.3%Al-5Ti-B-RE refiner was the best.%采用熔剂法在Q235钢表面热浸渗铝,并在铝熔体中添加Al-5Ti-B-RE中间合金细化剂,利用金相显微镜、X射线衍射仪、扫描电子显微镜等研究渗铝层的显微组织,运用氧化增重法测试渗铝钢的抗高温氧化性能,以研究细化剂对热浸渗铝层的显微组织和抗高温氧化性能的影响。结果表明:渗铝层都是由表面层和合金层组成;铝液中加入细化剂后,表面层和合金层的厚度都降低,表面层的针状物( FeAl3)细化,合金层的齿状整齐,齿峰分叉减少;随着细化剂含量的增加,渗铝钢的抗高温氧化性能先增加后降低,添加0.3%(质量百分比)细化剂的渗铝钢的抗高温氧化性能最好。

  5. Effects of aluminizing and laser shock processing on high temperature tensile properties of 00Cr12 alloy steel%渗铝激光冲击复合处理对00Cr12合金钢高温拉伸性能的影响

    Institute of Scientific and Technical Information of China (English)

    张田; 张永康; 任旭东; 姜大伟; 皇甫喁卓; 阮亮

    2012-01-01

    Aluminizing and laser shock processing(LSP) with high power Nd:YAG laser were carried out on 00Cr12 alloy steel and tensile experiment were tested at high temperature.Effects of aluminizing and laser shock processing on high temperature tensile properties were analyzed based on the mechanical test results and fracture morphologies.The results indicate that the aluminized coating formed on 00Cr12 steel surface has excellent thermal stability and oxidation resistance and shows outstanding thermal fatigue property.LSP on aluminized coating makes the layer structure more compact and increases the bonding strength between aluminized layer and substrate.%利用大功率Nd:YAG激光对渗铝后的00Cr12合金钢进行了冲击强化处理,并在不同温度下对其进行了高温拉伸试验,从力学性能及断口形貌等分析了渗铝复合激光冲击对其高温拉伸性能的影响。结果表明,00Cr12合金钢渗铝后表面形成的铝化物涂层在高温拉伸过程中具有较高的热稳定性及抗氧化性能,表现出优异的热疲劳性能,而且激光冲击处理可以使渗铝层组织更加致密并且与基体结合更加紧密。

  6. Microstructure and texture of oxide film on 8407 steel formed by aluminization and oxidation treatment%8407钢渗铝氧化处理形成的氧化膜组织与结构

    Institute of Scientific and Technical Information of China (English)

    孙健; 王晓鸣; 邹宗树

    2011-01-01

    对渗铝后的8407钢试样进行常温硬质阳极氧化处理,使其表面形成氧化膜.通过金相显微镜观察氧化膜横截面组织,并探讨了氧化膜的形成机制;采用扫描电镜观察氧化膜表面形貌,并检测氧化膜沿厚度方向的化学成分及其分布;利用X射线衍射仪对氧化膜相组成进行分析.结果表明,渗铝8407钢经过常温硬质阳极氧化后,试样表面分为3层,从基体向外侧依次为基体、渗层、氧化膜.氧化膜连续致密,厚度均匀,与基体结合紧密,其主要成分为O、Al和Fe,且各元素分布均匀,主要相组成为Fe3O4和Al2O3.%Room-temperature hard anodization treatment was carried out for aluminized 8407 steel sample in order to form an oxide film on the surface. The sectional microstructure was observed by means of OM to explore the formation mechanism of the oxide film. The surface morphology of the film was observed under SEM, chemical compositions and their distribution along the direction of thickness were also examined. The phase component in the film was analyzed by using XRD. The results show that, after room-temperature hard anodizing for the aluminized 8407 steel, the sample surface is divided into three layers, which followed by substrate, aluminization layer and oxide film from the substrate to the outer surface. The uniform, compact and tightly united film mainly consists of O, A1 and Fe elements which distribute homogeneously in the film,and its phases are mainly composed of Fe3O4, Al2O3.

  7. Transient characteristics for working process of pulse detonation engine with aluminized gelled fuels%含铝凝胶燃料脉冲爆轰发动机工作过程瞬态特性

    Institute of Scientific and Technical Information of China (English)

    胡洪波; 翁春生

    2016-01-01

    In order to understand the transient mechanism of pulse detonation engine with gelled fuels during the working process,the mathematical and physical model of pulse detonation engine with aluminized gelled fuels was established.The flow field of a single cycle pulse detonation engine with aluminized gelled fuels was simulated numerically by using the conservation element and solution element method,and the transient characteristics during the detonation reaction and impulse generation processes were analyzed.The calculation results show that the strip of the aluminized gelled fuels droplet under the detonation wave is predominant. The aluminum particles scatter into the detonation tube accompanying with the strip of droplets,and participate in reaction,so the a⁃luminum quantity accumulated in the final stage is small.And the process of the gelled fuels'detonation exhaust can be divided into three typical stages,which are expansion stage attached to detonation,gas"choked" expansion stage and weaken expansion stage in sequence.The results have some significant references for application research on pulse detonation engine with gelled fuels.%为了解含铝凝胶燃料脉冲爆轰发动机工作过程的瞬态机理,建立了含铝凝胶燃料脉冲爆轰发动机数学物理模型。采用守恒元与求解元数值计算方法,对单循环含铝凝胶燃料脉冲爆轰发动机流场进行了数值仿真,分析了其爆轰反应过程与冲量产生过程的瞬态特征。计算结果表明,爆轰波作用下,凝胶燃料液滴变化以剥离破碎为主,燃料液滴中铝颗粒随液滴剥离弥散于爆轰管内并参与反应,累积在最后阶段反应的铝颗粒较少。凝胶燃料爆轰燃气排放过程可划分为爆轰附着膨胀、燃气“壅塞”膨胀和膨胀减弱等3个典型特征阶段。研究结果对凝胶燃料脉冲爆轰发动机的应用研究具有参考意义。

  8. Dielectric relaxation of samarium aluminate

    Energy Technology Data Exchange (ETDEWEB)

    Sakhya, Anup Pradhan; Dutta, Alo; Sinha, T.P. [Bose Institute, Department of Physics, Kolkata (India)

    2014-03-15

    A ceramic SmAlO{sub 3} (SAO) sample is synthesized by the solid-state reaction technique. The Rietveld refinement of the X-ray diffraction pattern has been done to find the crystal symmetry of the sample at room temperature. An impedance spectroscopy study of the sample has been performed in the frequency range from 50 Hz to 1 MHz and in the temperature range from 313 K to 573 K. Dielectric relaxation peaks are observed in the imaginary parts of the spectra. The Cole-Cole model is used to analyze the dielectric relaxation mechanism in SAO. The temperature-dependent relaxation times are found to obey the Arrhenius law having an activation energy of 0.29 eV, which indicates that polaron hopping is responsible for conduction or dielectric relaxation in this material. The complex impedance plane plot of the sample indicates the presence of both grain and grain-boundary effects and is analyzed by an electrical equivalent circuit consisting of a resistance and a constant-phase element. The frequency-dependent conductivity spectra follow a double-power law due to the presence of two plateaus. (orig.)

  9. The effects of stress concentrations on reaction progress: an example from experimental growth of magnesio-aluminate spinel at corundum - periclase interfaces under uniaxial load

    Science.gov (United States)

    Jerabek, Petr; Abart, Rainer; Rybacki, Erik; Habler, Gerlinde

    2014-05-01

    The study aims to understand the reaction progress and chemical, microstructural and textural evolution of magnesio-aluminate spinel reaction rims formed at varying experimental settings (load, temperature and experiment duration). The spinel rims were grown at the contacts between periclase and corundum at temperatures of 1250°C to 1350°C and dry atmosphere, maintained by a constant argon gas flow, under uniaxial load of 0.026 and 0.26 kN per 9 mm2 of initial contact area. Single crystals of periclase with [100] and of corundum with [0001] perpendicular to the polished reaction interface as well as polycrystalline corundum were used as starting materials. Two loading procedures, immediate application of the load before heating and loading after the desired temperature had been reached, were used. An important byproduct of our experiments stemmed from the immediate application of the load, which led to deformation twinning and fracturing of corundum. This internal deformation of corundum disturbed the reaction interface and introduced loci of concentrated stress due to opening of void spaces in between the reactant crystals. Whenever cracks formed in the initial stages of an experiment, the void space opened immediately and no spinel formed along these interface segments. In the case of deformation twinning, the decreased rim thickness indicates later opening of void spaces. This is because next to twins, the reaction interface is characterized by tight physical contact on the one side and less tight contact on the other side of the twin individual. The tight contacts are characterized by enhanced reaction progress which together with the overall positive volume change of the reaction and limits on plasticity of the studied phases led to the opening of void spaces at places characterized by less tight contacts. The thickness variations are less pronounced in our high load (0.26 kN) experiments where periclase behaves plastically and to some extent reduces the

  10. 镁合金表面铝化及其合金涂层研究现状%Research Status of Aluminized and Aluminum Alloy Coating on Surface of Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    陈刚; 章国伟; 马力; 张立君

    2012-01-01

    总结了国内外镁合金表面铝化及其合金涂层研究现状,分析了镁合金表面铝化及其涂层防护特点,介绍了渗铝法、磁控溅射法、冷喷涂和热喷涂法制备研究铝及其涂层的制备工艺及研究成果.%The international research on the protective characters of the aluminum coating and aluminum alloy on the surface of magnesium alloy was summarized. The progress of aluminized, magnetron sputtering, cold spraying and thermal spraying methods to prepare the aluminum coating and the research results were introduced.

  11. 低品位菱镁矿与工业铝灰制备镁铝尖晶石%Preparation of magnesium aluminate spinel from low-grade magnesite and industrial alumina ash

    Institute of Scientific and Technical Information of China (English)

    钟鑫宇; 罗旭东; 张国栋; 曲殿利; 王闯

    2012-01-01

    Magnesium aluminate spinel material was prepared by solid reaction with low-grade magnesite and industrial alumina ash as raw materials.The effect of sintering temperature on composition and microstructure of industrial alumina ash was discussed firstly.For further study,the effects of sintering temperature on composition,crystal cell parameters,and microstructure of magnesium aluminate spinel material were studied.Crystalline phases and microstructure of the sintered sample were determined by XRD and SEM respectively .The lattice parameters of main crystalline phase and crystallinity of the samples sintered at different temperatures were calculated and compared by X'Pert plus software.Results showed that lattice parameters of hexagonal corundum that is main crystalline phase in the industrial alumina ash presented a nonisotropic variation tendency with the increase of sintering temperature.Magnesium aluminate spinel material could be prepared by solid reaction of low-grade magnesite and industrial alumina ash at 1 400℃.The cell parameter of main crystalline phase of the magnesium aluminate spinel material prepared at this temperature reached maximum, and relatively well-distributed grains in the material and relatively compact microstructure were both observed.%以低品位菱镁矿与工业铝灰为原料制备镁铝尖晶石材料.分析讨论了不同煅烧温度对工业铝灰材料组成与微观结构的影响,并进一步研究了煅烧温度对制备镁铝尖晶石材料的组成、镁铝尖晶石相晶胞常数及材料微观结构的影响.用X射线衍射(XRD)和扫描电镜(SEM)对煅烧后试样的物相和显微结构进行研究.利用X′ pert plus软件对试样中主晶相的品格常数进行计算,比较不同温度煅烧试样的相对结晶度.结果表明:随着工业铝灰煅烧温度的升高1材料中主晶相六方晶型的刚玉相晶胞常数呈现各向异性的变化趋势.低品位菱镁矿与工业铝灰经1 400℃高温煅烧

  12. Spectrographic Determination of Impurities in Ceramic Materials for Nuclear fusion Reactors. II. Analysis of Magnesium Aluminate; Determinacion Espectrografia de Impurezas en materiales Ceramicos para Fusion Nuclear. II. Analisis de Aluminato de Magnesio

    Energy Technology Data Exchange (ETDEWEB)

    Rucandio, M. I.; Roca, M.; Melon, A.

    1990-07-01

    The determination of minor and trace elements in the magnesium aluminate, considered as possible material in thermonuclear fusion reactors, has been studied. The concentration ranges are 0.1 - 0.3 % for Ca, SI and Y, and at the ppm level for Co, Cr, Fe, Hf, K, Li, Mn, Na, Ni, Se, Ta, Ti, V and Zr. Atomic emission spectroscopy with direct current are excitation and photographic detection has been employed. For Hf, Ta and Zr the use of 40% of copper fluoride as a carrier and of Nb as internal standard provide suitable sensitivities and precessions, while for the rest of elements the best results are obtained with graphite powder in different proportions and Rb or Sn as internal standard. (Author)4 refs.

  13. 低碳钢热浸镀铝微弧氧化陶瓷层厚度研究%Thickness of Micro- Arc Oxided Ceramic Layer on Hot Dip Aluminized Carbon Steel

    Institute of Scientific and Technical Information of China (English)

    高殿奎; 沈德久; 王玉林

    2001-01-01

    研究了影响低碳钢热浸镀铝微弧氧化陶瓷层生长厚度的因素,指出了获得最大厚度的氧化时间并对其原因进行了分析。结果表明,影响陶瓷层厚度的主要因素是氧化时间,热浸镀最佳温度为720~730 ℃。%The factors affecting the thickness of micro- arc oxided ceramic layer on hot dip aluminized low carbon steel were discussed.The experimental results showed that the predominant affecting factor was time for oxidation.

  14. Coat Structure Analysis and Formation Mechanismof Deformation 12CrMoV Steel Hot-Dip Aluminizing%形变12CrMOV钢热浸铝的镀层组织及形成机制

    Institute of Scientific and Technical Information of China (English)

    高聿为

    2000-01-01

    The coat microstructures of deformation 12CrMoV steel hot-dip aluminizing were analyzed by optical mi-croscope, TEM and X-ray diffraction, and the formation mechanism was discussed in the paper%用金相显微镜、透射电子显微镜及X射线衍射仪对形变热浸镀铝的镀层微观组织进行了分析,并探讨了其形成机制。所得结果对完善形变钢热浸镀铝的镀层组织及形成机制提供一定的参考依据,对制定形变件的浸镀工艺也有一定的指导意义。

  15. High Temperature Wear Characteristics of Paste Boron-aluminized Layer on 5CrMnMo Steel%5CrMnMo钢膏剂硼铝共渗层的高温磨损特性

    Institute of Scientific and Technical Information of China (English)

    陈九磅; 刘少光; 束德林; 郭新成

    2001-01-01

    In this paper,the high temperature wear characteristics of paste boron-aluminized layer on 5CrMnMo steel were investigated.It has been shown that fatigue-spalling is the main wear mechanism,abrasive wear also exist.The spalling cracks are initiated from microporosity,cavity,etc.existing in the cases,then are propagated by the cyclic mechanical stress and the cyclic thermal stress.%研究了5CrMnMo钢膏剂硼铝共渗层的高温磨损特性。结果表明,渗层磨损机制以疲劳剥落为主,兼有磨粒磨损。剥落裂纹源于渗层中疏松、孔洞等缺陷处,并在周期机械应力和周期热应力作用下扩展。

  16. Chemical elimination of alumina in suspension in nuclear reactors heavy water; Elimination de l'alumine en suspension dans l'eau lourde des reacteurs nucleaires par voie chimique

    Energy Technology Data Exchange (ETDEWEB)

    Ledoux, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-02-01

    Corrosion of aluminium in contact with moderating water in nuclear reactor leads to the formation of an alumina hydrosol which can have an adverse effect on the operation of the reactor. Several physical methods have been used in an attempt to counteract this effect. The method proposed here consists in the elimination of the aluminium by dissolution and subsequent fixation in the ionic form on mixed-bed ion-exchange resin. In order to do this, the parameters and the values of these parameters most favorable to the dissolution process have been determined. If the moderator is heavy water, the deuterated acid can be prepared by converting a solution in heavy water to a salt of the acid using a deuterated cationic resin. (author) [French] La corrosion de l'aluminium au contact de l'eau moderatrice des reacteurs nucleaires, donne lieu a la formation d'un hydrosol d'alumine nuisible au bon fonctionnement des reacteurs. Plusieurs methodes physiques ont ete mises en oeuvre pour pallier ces inconvenients. On propose ici d'eliminer l'alumine par solubilisation pour la fixer ensuite sous forme ionique par des resines echangeuses d'ions, en lit melange. A cette fin on determine les parametres et leurs grandeurs favorables a cette solubilisation. Si le moderateur est de l'eau lourde la preparation d'acide deutere peut etre effectuee par passage d'une solution en eau lourde a un sel de l'acide sur resine cationique deuteree.

  17. 镁铝尖晶石-堇青石抗结皮浇注料性能研究%Research on properties of crust-resistant magnesium aluminate spinel-cordierite castables

    Institute of Scientific and Technical Information of China (English)

    杨圣玮; 王杰曾; 汪澜; 于龙泉

    2013-01-01

    对以镁铝尖晶石为主要原料,以氧化镁微粉-硅灰-氧化铝微粉-水作为结合剂研制的镁铝尖晶石-堇青石浇注料MA及其优化浇注料MA’的抗结皮性、抗水泥熟料和碱硫的侵蚀性、强度以及抗热震性等特性进行了研究,并与常规的高强耐碱浇注料(13NL)和高铝碳化硅抗结皮浇注料(50S)进行了对比.结果表明:1)浇注料MA、MA’都具有优异的抗结皮性;2)通过加入合成堇青石制得的浇注料MA’具有良好的抗热震性,并具有更为优异的综合性能.%The crust-resistant magnesium aluminate spinel-cordierite castable MA and the optimized castable MA' were prepared with magnesium-aluminate spinel as the main starting material and MgO mi-cropowder-SiO2 fume-AI2O3 micropowder-H2O system as binder. The crust resistance, corrosion resistances to cement clinker,alkali and sulfates,strength,and thermal shock resistance were researched. The two castables were compared with the conventional high strength alkali-resistant castable (named 13NL) and the crust-resistant high alumina-SiC castable (named 50S).The results show that:(1)both castables MA and MA' have excellent crust resistance;(2)castable MA' added with pre-synthesized cordierite has better thermal shock resistance and more excellent over all properties.

  18. Study on thermal fatigue behavior of 8407 steel with surface aluminization and oxidation treatment%渗铝氧化8407钢表面热疲劳行为研究

    Institute of Scientific and Technical Information of China (English)

    孙健

    2012-01-01

    Thermal fatigue test was performed with cycle heating method to compare thermal fatigue behaviors of 8407 steel samples with and without aluminization and oxidation treatment. In the test, thermal fatigue crack morphology formed on the surface was observed by SEM after 400 cycles, and then variations of initiating rate and propagating rate of thermal fatigue main crack with cycles were investigated. Moreover, the thermal fatigue property was judged according to the length of the thermal fatigue main crack. The results show that the surface aluminization and oxidation treatment can improve both the initiating resistance and propagating resistance of thermal fatigue crack.%采用循环加热法进行热疲劳实验,对比研究了表面未处理和表面渗铝氧化处理8407钢样的热疲劳行为.实验中,利用扫描电镜观察循环400周次后试样表面产生的热疲劳裂纹形貌,考察了热疲劳主裂纹的萌生与扩展速度随循环周次的变化.此外,根据主裂纹长度L的大小评判了热疲劳性能.研究结果表明,表面渗铝氧化处理能够同时提高热疲劳裂纹萌生抗力和扩展抗力.

  19. 耐热钢HP40Nb的中温粉末法渗铝及其抗渗碳特性%Pack aluminizing at moderate temperature on HP40Nb heat-resistant steel and its anti-carburization behaviour

    Institute of Scientific and Technical Information of China (English)

    潘建伟; 谢飞; 孙力; 焦世辉; 翟建祥

    2012-01-01

    Pack aluminizing at temperature of 800-900 ℃ was investigated on HP40Nb heat-resistant steel with a media composed of master alloy of Fe-Al powder as Al supplier,NH4Cl as activator and SiC as filler.The anti-carburizing behaviour of the treated specimen was studied by employing an intensified pack carburization test.The results show that the aluminizing case has high surface quality and adheres very well with the substrate.The case is mainly composed of a deposition zone and a following transition zone.The thickness of the case is thinner than that by higher temperature aluminizing.Direct current field has few influence on the types of phase structure of the aluminized cases,while it can enhance the aluminizing rate at 800 ℃ by nearly 7 times.The aluminized cases studied show excellent anti-carburization ability in the intensified carburization test at 1000 ℃.%以铝铁为供铝剂、氯化氨为活化剂、碳化硅为填充剂,研究了耐热钢HP40Nb在800~900℃间的粉末法渗铝特性,采用固体强化渗碳方式来研究不同状态试样的抗渗碳能力。研究表明:渗层表面质量很高,渗层与基体结合良好,渗层主要由沉积区和过渡区两部分组成,较之高温渗铝,渗层厚度较薄;采用直流电场增强法对HP40Nb粉末法渗铝渗层相组成种类影响不大,但能使其800℃时的渗铝速度提高近7倍。所试验渗铝层在1000℃强化渗碳条件下表现出优良的抗渗碳特性。

  20. Preparation and characterization of magnesium aluminate spinel powder%镁铝尖晶石粉体的制备与表征

    Institute of Scientific and Technical Information of China (English)

    武小娟; 李俊寿; 王明远; 李苏

    2016-01-01

    以Mg、Al、TiO2和B2 O3粉体为原料,采用自蔓延高温合成法合成了 MgAl2 O4和 TiB2复合粉体,用稀硝酸除去产物中的TiB2及残余反应物后,获得了较高纯度的MgAl2 O4。然后用MgO 部分取代 Mg 研究了不同Mg源对合成产物的影响,用XRD和SEM检测了两组反应获得的MgAl2 O4粉体,用激光粒度测试仪分析了产物的粒径大小及分布,用红外光谱仪测试了粉体性能较佳的反应酸洗产物的红外透光率。结果表明,以单一Mg 粉为Mg源时,MgAl2 O4的相对含量为85.96%,且颗粒较小,平均粒径为5.36μm,粒径分布较集中,0.1~10μm 的颗粒占80.68%;以(Mg+MgO)为Mg源时,MgAl2 O4的相对含量为71.55%,且颗粒较大,平均粒径为11.18μm,粒径分布较分散,0.1~10μm的颗粒占54.96%;综合考虑,以Mg为镁源获得的MgAl2 O4粉体性能好,经红外光谱分析,可得,MgAl2 O4透过率高,透过波段范围宽,在1100~2978 cm-1之间的红外透过率达到50%以上,高透光率的镁铝尖晶石具有低的辐射率,可应用于红外隐身材料。%The composite powders of MgAl2 O4 and TiB2 were prepared by self-propagating high-temperature synthesis method with Mg powder,Al powder,TiO2 powder and B2 O3 powder as raw materials.Then relative-ly high purity magnesium aluminate spinel powders were obtained after ultrasonic pickling by using 20wt% ni-tric acid to remove TiB2 and residual reactants in the product.The effect of different magnesium sources on the product was studied by MgO partially replacing Mg;the productivity and the particle size of the two reaction system were analyzed in contrast by XRD and SEM.And also the purity of MgAl2 O4 after acid pickling was studied.The results show that MgAl2 O4 in the products account for 85.96% with Mg as magnesium source,the particles are fine with average particle size 5.36μm and 80.68% of the particles range from 0.1 to 10μm;MgAl2 O4 in the products account for 71.55% with Mg and

  1. Effects of Al Content in Pack Powder on Microstructure and Mechanical Properties of Aluminized N80 Oil Casing Steel%包埋渗剂Al含量对N80套管钢渗层组织和性能的影响

    Institute of Scientific and Technical Information of China (English)

    史新勃; 王宇; 黄敏

    2012-01-01

    Aluminized N80 oil casing steel was packed by different Al content of pack powder. The aluminizing process was introduced. The metallographic, element distribution, phase composition, microhardness of aluminized N80 casing steel were analyzed using optical microscope, SEM, XRD, microhardness equipment in respective. The results show that the aluminizing layer with a thickness from 450 to 650 u.m can be obtained on the surface of N80 casing steel after high-temperature vacuum-pack processing by different Al content of pack powder. With the increase of Al content in the pack powder, the thickness of aluminizing layer increase. From the surface to the matrix, the Al content gradiently decreases in the aluminized layer microstructure. The different Al content in the pack powder causes the different phase in the surface of aluminized layer. The Fe3Al phase is obtained with the pack powder of 10% and 20%Al content, but the 35%A1 content pack powder get the FeAl phase. The microhardness of aluminized layer with different Al content in the pack powder is higher than that of the microhardness of matrix. Microhardness gradually reduces and tends to constant from the surface to the matrix.%选用不同Al含量配比的渗铝剂,对N80套管钢进行包埋渗铝处理,形成渗铝层.阐述了包埋渗铝过程,并依次表征了不同Al含量渗剂所得渗铝层的金相组织、元素分布、物相组成和显微硬度.结果表明:采用不同Al含量的渗剂在950℃真空条件下可以在N80钢基体表面获得450~650 μm厚度连续的渗铝层组织;渗铝层厚度随渗剂中Al含量增加而增厚;渗层组织从表面向基体方向Al含量呈梯度减少;渗剂中Al含量的不同引起渗层的物相变化,10%和20%Al含量的渗剂所得渗层组织为FeAl相,35%Al含量的渗剂所得渗层组织为FeAl相:不同Al含量渗剂下所得渗铝试样渗层组织的显微硬度均高于基体,从渗层表面向基体方向延伸,显微硬度逐渐降低趋于平缓.

  2. Détermination de l'énergie de surface d'alumines et de titanates de baryum utilisés pour la préparation de céramiques : influence d'un traitement thermique

    Science.gov (United States)

    Papirer, E.; Perrin, J. M.; Siffert, B.; Philipponneau, G.

    1991-05-01

    Surface characteristics of powders used for the preparation of ceramics determine the physical interactions potential between constituents and condition, in particular, the stability of slurries. Inverse Gas Chromatography (I.G.C.) applied to aluminas and barium titanates, appears to be a well suited method for the measurement, on the one hand, of the dispersive component (γ^D_S) of the surface energy and, on the other hand, of a specific interaction parameter (I_{sp}) which accounts for all possible interactions, except London interactions. It is shown that, firstly, the chemical surface composition (presence of impurities or Ba/Ti ratios) influences strongly the values of γ^D_S and I_{sp} and, secondly, the heat treatment of certain aluminas (below 500 °C) modifies in an unexpected way the same values. In that case, the results may be explained supposing the existence, on the alumina surfaces, of a thin hydrated oxide layer which is formed during ageing in humid atmosphere. This layer, of the boehmite type, transforms into γ alumina around 350-400 °C, a transformation accompanied by important variations of γ^D_S This study underlines the importance of a thorough physico-chemical control of the ceramic powders and of their conditioning. Les caractéristiques de surface des poudres entrant dans la préparation des céramiques déterminent les capacités d'interactions physiques entre constituants et conditionnent, en particulier, la stabilité des barbotines. La chromatographie gazeuse inverse (C.G.I.), appliquée aux alumines et aux titanates de baryum, s'avère comme une méthode de choix pour la mesure d'une part, de la composante dispersive (γ^D_S) de l'énergie de surface et d'autre part, d'un paramètre d'interaction spécifique (I_{sp}) qui rend compte de toutes les possibilités d'interactions à l'exception de celles de London. On montre, premièrement, que la composition chimique de surface (présence d'impuretés, ou rapport Ba/Ti) influe

  3. Pre-desilication of Sodium Aluminate Solution from Aegirine-augite Syenite:An Experimental Study%霓辉正长岩制取铝酸钠溶液预脱硅的实验研究

    Institute of Scientific and Technical Information of China (English)

    王霞; 马鸿文; 俞子俭; 王晓艳; 邹丹

    2011-01-01

    霓辉正长岩提钾滤渣的主要物相为沸石Na_6[AlSiO_4]_6·4H_2O,富含氧化铝和氧化硅.采用高压水化学法对其进行碱热浸取可得到高苛性比的铝酸钠溶液,通过添加不同类型的脱硅剂对其进行一步脱硅法对比实验研究.正交实验结果表明,在脱硅的过程中,影响因素的顺序为:脱硅剂类型>脱硅时间>脱硅温度.通过进一步单因素实验,确定优化脱硅条件为:采用水合铝酸钙为脱硅剂,在160℃下反应3.5h,即可制得硅量指数大于1 800的铝酸钠精制液.经X射线衍射分析,脱硅产物的主要物相为水化石榴石;扫描电镜及能谱分析结果显示,生成物水化石榴石的晶型较好,在晶粒细小处SiO_2杂质容易附着,从而达到更好的脱硅效果.%The principal phase of potassium-distilled filter residue of aegirine-augite syenite is sodium aluminum silicate hydrate rich in Al2O3 and SiO2. The high caustic ratio sodium aluminate solution was obtained from filter residue treated by high pressure hydrochemical process. The desilication reaction was experimentally studied by adding different types of desilication agents. The orthogonal experimental results show that in the process of the desilication from sodium aluminate solution, the descending order of affecting factors is as follows: desilication agent type, desilication time, desilication temperature. The optimal conditions of desilication are that the desilication agent is tricalcium hydroaluminate, and desilication temperature is 160 ℃ and the desilication time is 3.5 h. The silicon index of the refined aluminate solutions was obtained to be above 1,800 by one-step desilication procedure. According to X-ray diffraction analysis, the major phase of derived products is hydrogarnet. The diffraction intensity of hydrogarnet increases sharply with the desilication time increasing. The results of scanning electron microscopy and EDS analysis show that hydrogarnets reveal high

  4. Chromium substitution in mullite type bismuth aluminate: Bi{sub 2}Cr{sub x}Al{sub 4−x}O{sub 9} with 0≤x≤2.0

    Energy Technology Data Exchange (ETDEWEB)

    Debnath, Tapas, E-mail: debnath@du.ac.bd [Department of Chemistry, University of Dhaka, Dhaka (Bangladesh); Ullah, Ahamed [Department of Chemistry, University of Dhaka, Dhaka (Bangladesh); Rüscher, Claus H. [Institute of Mineralogy, Leibniz University of Hannover, Hannover (Germany); Hussain, Altaf [Department of Chemistry, University of Dhaka, Dhaka (Bangladesh)

    2014-12-15

    Nominal compositions Bi{sub 2}Cr{sub x}Al{sub 4−x}O{sub 9} with 0.0≤x≤2.0 (Δx=0.2) were prepared using appropriate amounts of nitrates dissolved in glycerine and heated at 800 °C for 24 h as we previously used for the preparation of solid solution series Bi{sub 2}M{sub x}/M′{sub 4−x}O{sub 9} (M/M′=Fe/Al, Ga/Al and Fe/Ga). The samples were characterized using XRD, FTIR and optical microscopic techniques. Analyses of XRD data show mullite type single phase can be prepared up to x=1.2. The lattice parameters (a, b and c) increases with increasing Cr content. Further increase in x (i.e., x≥1.4) show the presence of some additional phases indicating a limiting value for Cr doping is in the range of 1.2≤x<1.4. The effect of Cr incorporation could also be observed in the infrared absorption spectra via systematic hard mode shifts of certain lattice modes, e.g. the Bi–O related vibration changes from 96 cm{sup −1} to 93 cm{sup −1} with increasing x up to 1.2 and certain intensity changes together with shift in peak positions. Interestingly, the absence of any splitting and shift of the high energy IR absorption peak at 821 cm{sup −1} as assigned to the characteristic tetrahedral type dimer, Al{sub 2}O{sub 7}, indicate that the Cr thus partially substitutes only the octahedrally coordinated Al. This is confirmed by Rietveld structure refinements, too. - Graphical abstract: Structural model of Cr doped bismuth aluminate, Bi{sub 2}Cr{sub x}Al{sub 4−x}O{sub 9}. - Highlights: • Chromium doped bismuth aluminate, Bi{sub 2}Cr{sub x}Al{sub 4−x}O{sub 9} with mullite type structure are synthesized. • The samples are characterized by XRD and FTIR techniques. • Cr can replace only certain amount of octahedrally coordinated Al in Bi{sub 2}Al{sub 4}O{sub 9} under present experimental conditions.

  5. Establishment and application of calculation model of sodium oxalate solubility in sodium aluminate solution%铝酸钠溶液中草酸钠溶解度计算模型的建立及应用

    Institute of Scientific and Technical Information of China (English)

    李小斌; 徐旺; 张玉通; 齐天贵

    2014-01-01

    应用Bromley方程,结合草酸钠溶解热力学理论及其在水溶液、氢氧化钠溶液中的溶解度数据,得出草酸钠的Bromley参数为−0.045,并以此为基础建立铝酸钠溶液中草酸钠的溶解度计算模型。应用该模型计算纯铝酸钠溶液体系中草酸钠的溶解度,结果与文献数据吻合较好。在此基础上,模拟计算了拜耳法氧化铝生产过程中草酸钠平衡浓度的变化规律。结果表明:碱浓度越高、温度越低、苛性比越高,铝酸钠溶液中草酸钠平衡浓度越低;铝酸钠溶液体系中,碳酸钠、硫酸钠对草酸钠溶解度的影响很小。这些结果可以解释草酸钠在生产氧化铝过程中的积累和析出规律,有助于生产过程铝酸钠溶液中草酸钠含量的控制。%The calculation model of sodium oxalate’s solubility in sodium aluminate solution was established by Bromley equation with the solubility values of sodium oxalate in the aqueous and sodium hydroxide solution, and Bromley parameter of sodium oxalate calculated by this model is−0.045. Using this calculation model, the solubility values of sodium oxalate in sodium aluminate solution were calculated and a high degree of agreement can be reached compared with the data in literatures. On this basis, the equilibrium concentration values of sodium oxalate in Bayer liquors were calculated. The results show that, the higher the alkali concentration and caustic ratio are or the lower the temperature is, the lower the equilibrium concentration of sodium oxalate is. The concentration of sodium carbonate or sodium sulfate has little effect on the solubility of sodium oxalate. These results can explain the law of the accumulation and precipitation of sodium oxalate in alumina production process, and contribute to controlling the concentration of sodium oxalate in the process.

  6. Effect of RDX and Al Contents on the Heat Explosion Temperature for RDX-based Aluminized Explosives%RDX和铝含量对RDX基含铝炸药热爆发温度的影响

    Institute of Scientific and Technical Information of China (English)

    郑亚峰; 常海; 刘子如; 邵颖惠; 岳璞; 刘文亮

    2011-01-01

    The explosion temperatures Tb of 5 s delay for aluminized explosives of different RDX contents were determined by heat explosion test, and the effects of RDX and aluminum powder contents on explosion temperatures were studied. The results show that the Tb values first fall down and then rise with the increasing of RDX contents. A linear empiric equation, in which Tb is correlated with RDX and aluminum powder contents, was obtained. It is considered that the energies necessary to heat explosion under the test conditions are obtained from two ways, I. E. From thermal decomposition for energetic materials and from heating medium. The former is related to energetic reactant content, while the later is related to the heat conduction of the system. Moreover.it is proposed that the thermal conductivity of RDX-based aluminized explosives is related to aluminum powder content. Based on above view,a linear relation, which is in agreement with experiment results and can represent the correlation of Tb with RDX and aluminum powder contents,is educed in theory.%通过热爆发延滞期试验测定了含铝炸药的5s延滞期热爆发温度Tb,研究了RDX和铝粉含量对热爆发温度的影响.结果表明,随着RDX含量的增加,Tb先下降后升高,获得了描述Tb与RDX和铝粉含量关系的线性经验方程.认为在热爆发试验中体系是从含能材料热分解和加热介质两个途径获得能量(热量),前者与含能反应物的含量有关,后者与体系的热传导有关,同时认为该含铝炸药的导热系数与铝含量有关,基于这种观点,从理论上导出了符合实验结果的描述爆发温度Tb与RDX和铝粉含量关系的线性关系式.

  7. H 2 O2湿式氧化法脱除铝酸钠溶液中的有机物%Removal of Organics From Industrial Sodium Aluminate Solution by Hydrogen Peroxide Wet Oxidation

    Institute of Scientific and Technical Information of China (English)

    杜振华; 李军旗; 金会心; 米秋秋

    2014-01-01

    By wet hydrogen peroxide oxidation ,the effects of alkali concentration ,oxidation time ,the amount of hydrogen peroxide and oxidation temperature on the removal of organics in Bayer liquor were investigated .The experiment results show that wet hydrogen peroxide oxidation method can effectively eliminate most of the organics in the sodium aluminate solution .T he better oxidation conditions is alkali concentration of 280 g/L ,oxidation temperature of 80 ℃ ,the amount of hydrogen peroxide of 80 mL ,oxidation time of 120 min for sodium aluminate solution of 80 mL .The removal rate of sodium oxalate is 65 .31% and the removal rate of total organic carbon is 60 .86% at the best conditions .T he process is simple ,no impurity is introduced in the system .%研究了采用 H2 O2湿式氧化法脱除某铝厂分解母液中的有机物,考察了母液苛性碱浓度、氧化时间、双氧水用量、温度对脱除有机物的影响。结果表明:H2 O2湿式氧化法可有效脱除铝酸钠溶液中的大部分有机物;试验获得的适宜工艺条件为苛性碱质量浓度280 g/L ,氧化时间120 min ,氧化温度80℃,双氧水用量80 mL。适宜条件下,草酸钠脱除率为65.31%,总有机物脱除率为60.86%。H2 O2湿式氧化法脱除铝酸钠溶液中有机物工艺简单,系统中不引入杂质。

  8. 铁铝酸盐水泥生料配比倒推计算方法%The proportioning of the raw meal of ferro-aluminate cement by reverse calculating method

    Institute of Scientific and Technical Information of China (English)

    陈宏; 吕树合; 姜振然

    2001-01-01

    The pre- designed main mineral composition of clinker and the corresponding calculated moduli were determined as the guiding control value. The multi- factor and linear non- similar equation group for raw meal proportion was established on the basis of the balance of the compositions of clinker without coal ash and of the ignited raw materials and fuel. The proportioning plan was thus solved through the step- by- step calculation, and the proportioning of the raw meal of high early strength ferro- aluminate special cement by reverse calculating was realized.%以事先设定熟料主要矿物组成含量和计算出与之相适应熟料率值为目标控制值,在灼烧基原燃材料与无灰熟料相对应氧化物含量单项平衡的基础上,建立多元系统线性非齐次配料方程组,从中求解出配比未知量,由此逐步计算,实现早强铁铝酸盐特种水泥生料配比的倒推计算。

  9. Tululite, Ca14(Fe3+,Al)(Al,Zn,Fe3+,Si,P,Mn,Mg)15O36: a new Ca zincate-aluminate from combustion metamorphic marbles, central Jordan

    Science.gov (United States)

    Khoury, Hani N.; Sokol, Ella V.; Kokh, Svetlana N.; Seryotkin, Yurii V.; Nigmatulina, Elena N.; Goryainov, Sergei V.; Belogub, Elena V.; Clark, Ian D.

    2016-02-01

    Tululite (Ca14(Fe3+,Al)(Al,Zn,Fe3+,Si,P,Mn,Mg)15O36 (the hypothetical end-member formula Ca14{Fe3+O6}[SiO4][Zn5Al9]O26) (IMA2014-065) is a new natural Ca zincate-aluminate, identified in medium-temperature (800-850 °C) combustion metamorphic (CM) spurrite-fluorellestadite marbles from central Jordan. The type locality (Tulul Al Hammam area) is situated in the northern part of the Siwaqa complex, the largest area of the "Mottled Zone" Formation in the Dead Sea region. The marbles originated from bitumen-rich chalky marine sediments of the Maastrichtian-Paleogene Muwaqqar Chalk Marl Formation, which have low clay content (and, consequently, low Al) and high Zn, Cd, and U enrichments. The bulk CM rocks derived from the low-Al protolith have unusually high (Zn + Cd)/Al ratios ( 0.2) and, as a result, a mineralogy with negligibly small percentages of Ca aluminates having low Ca:Al molar ratios (minerals of mayenite supergroup, Ca:Al = 6:7) common to most of calcareous CM rocks in the Mottled Zone. Instead, the mineral assemblage of the Zn-rich marbles contains tululite, with high Ca:Al = 2.55 molar ratios and Zn substituting for a large portion of Al (Zn:Al = 1.1). Tululite occurs in thin clusters as irregular grains with indented outlines (20-100 μm in size), having typical open-work textures associated with rock-forming calcite, fluorellestadite, spurrite, and accessory Zn-rich periclase, lime-monteponite solid solutions, calcium uranates, and zincite. Marbles also bear brownmillerite, dorrite, fluormayenite, high-fluorine Ca aluminate, and lakargiite. Secondary phases are brucite, gel-like calcium silicate hydrates and calcium silicate aluminate hydrates, including Zn- and U-bearing and Cd-rich compounds, Si-bearing hydrated compounds after calcium uranates, and basic Cd chlorides. The empirical formula of the holotype tululite (a mean of 32 analyses) is (Ca13.29Cd0.75)Σ14.04(Al5.46Zn5.20Fe3+ 2.23Si0.95Mn3+ 1.01Mg0.78P0.41)Σ16.04O36. Tululite is cubic, space

  10. Relationship between Drop Energy and Heat Explosion Parameters of RDX-based Aluminized Explosives%RDX基含铝炸药的特性落高能与热爆发参数的关系

    Institute of Scientific and Technical Information of China (English)

    郑亚峰; 常海; 张修博; 刘子如; 陆洪林; 任晓宁; 王晓红

    2012-01-01

    The thermal explosion temperature (Tb) was determined by heat explosion test and the drop height ( H50) was obtained by impact sensitivity test for 12 types of RDX-based aluminized explosives with different contents of RDX and aluminum powder respectively. The heat explosion parameters decreased to the lowest when RDX content reaches 89% ( Tb, heat explosion activation energy(Eb) and logarithm of pre-expontential factor(InA)), and drop energies ( Edr) were calculated with experiment data. The results show that the drop height ( H50) first fall down and then rise with the increasing of RDX contents. Additionally, it is found that a linear relationship exists between the drop energies ( Edr) and heat explosion parameters ( Tb, fb and In/A).%分别采用热爆发延滞期试验和撞击感度试验测定了12种不同RDX和铝粉含量的含铝炸药的5 s爆发点(Tb)和特性落高(H50),并根据实验数据计算出热爆发参数(Eb和InA)和特性落高能(Edr).结果表明:随着RDX含量的增加,特性落高先减小后逐渐升高,特性落高能(Edr)与热爆发参数(Tb、Eb和InA)之间存在线性关联关系.

  11. Effect of tin oxide on properties of magnesium aluminate spinel castables%氧化锡加入量对镁铝尖晶石浇注料性能的影响

    Institute of Scientific and Technical Information of China (English)

    员文杰; 商恒; 朱青友; 邓承继; 祝洪喜

    2015-01-01

    Effects of tin oxide additions (5%,7.5% and 10% by mass)on the properties and microstructure of magnesium aluminate spinel castables adopting tabular corundum T60 or reactive alumina CL370 as the matrix were researched in order to improve the properties of magnesium aluminate spinel castables.The results show that with the tin oxide addition increasing,the apparent porosity and linear change on heating of castables made from tabular alumina decrease,and the cold modulus of rupture increases;the apparent porosity and linear change on heating of castables made from reactive alumina with 7.5% SnO2 addition is the lowest,and the cold modulus of rupture reaches the maximum value;the main reaction products include Mg2 SnO4 ,CaSnO3 and Ca2 SnO4 in castables after calcined at 1 450 ℃ for 5 h;tin oxide addition can strengthen the bonding between the components of castables by in-situ reactions,and promote the sintering.%为了提高镁铝尖晶石浇注料的性能,研究了氧化锡加入量(质量分数分别为5%、7.5%和10%)对基质中分别采用板状刚玉 T60和活性氧化铝 CL370的镁铝尖晶石浇注料性能和显微结构的影响。结果表明:在镁铝尖晶石浇注料中添加氧化锡,随着氧化锡添加量的增加,采用板状刚玉试样的显气孔率和烧后线变化率减小,常温抗折强度增大;而采用活性氧化铝试样则以氧化锡添加量为7.5%(w)时显气孔率和烧后线变化率最小,常温抗折强度最大。添加氧化锡的镁铝尖晶石浇注料在1450℃煅烧5 h 后均含有 Mg2 SnO4、CaSnO3和Ca2 SnO4。可见,氧化锡在高温下与镁砂和铝酸钙水泥发生一系列原位反应提高组分之间的结合,并促进浇注料的烧结。

  12. Reaction behavior of MgO in desilication process of sodium aluminate solution%氧化镁在铝酸钠溶液脱硅中的反应行为

    Institute of Scientific and Technical Information of China (English)

    刘桂华; 齐天贵; 田侣; 周秋生; 彭志宏; 李小斌

    2013-01-01

    通过分析含硅铝酸钠溶液脱硅过程二氧化硅浓度、脱硅渣成分和物相,研究氧化镁在铝酸钠溶液中的反应行为。结果表明,在95~100℃的常压脱硅条件下,氧化镁在铝酸钠溶液中易形成水合碳铝酸镁,对溶液基本无脱硅效果,氧化铝损失较多,但氧化镁能显著促进石灰的脱硅作用,且在石灰用量一定时随氧化镁添加量的增加,溶液的脱硅率显著升高;在190℃的高压脱硅条件下,氧化镁对铝酸钠溶液石灰脱硅作用的促进不明显,但它可使脱硅渣的钠硅比(质量比)显著降低;无论是单独采用石灰(CaO),还是采用石灰和氧化镁混和物脱硅,含硅铝酸钠溶液高温脱硅渣中均含有钠硅渣相,这与热力学分析结果一致。%The reaction behavior of MgO in the desilication process of sodium aluminate solution was studied by analyzing SiO 2 concentration variation in solution and compositions and phases of the desilication slag. The results indicate that under desilication conditions of 95−100 ℃ and normal pressure, MgO can react with SiO 2-containing sodium aluminate solution to form the magnesium hydroaluminocarbonate and cause the loss of alumina. MgO has almost no desilication effect in the normal pressure desilication process, but it can promote the desilication rate of CaO significantly and the desilication rate increases with the increase of MgO amount when the dosage of CaO is constant. Under desilication conditions of 190 ℃ and high pressure, MgO has little effect on the desilication rate of CaO, but it can decrease the mass ratio of soda to silica of desilication slag. The sodium aluminosilicate hydrate is one of the main phases of the slags produced from high temperature desilication process with either MgO or mixture of MgO and CaO as desilication agent, which agrees with the result of thermodynamic calculation.

  13. 氯化镁对铝酸钙水泥结合浇注料性能的影响%Influence of magnesium chloride on properties of calcium aluminate cement bonded castables

    Institute of Scientific and Technical Information of China (English)

    王青峰; 王亚娟; 李坤鹏; 宋秀娟; 张传银; 叶国田

    2014-01-01

    为了改善铝酸钙水泥结合浇注料的高温体积稳定性,以 w (Al2 O3)≥99.5%的板状刚玉为骨料, w(Al2O3)≥99.7%的活性Al2O3微粉和板状刚玉细粉(≤0.044 mm)为基质,以铝酸钙水泥Secar 71为结合剂,添加适量氯化镁制备铝酸钙水泥结合浇注料,分别在1100℃3 h和1450℃3 h进行热处理,测定浇注料试样的常温物理性能,并分析基质试样的物相组成和显微结构。结果表明:氯化镁的加入会导致浇注料经高温处理后的体积密度下降,显气孔率升高,并降低浇注料高温处理后的力学性能;但是,含氯化镁的浇注料经高温处理后的线膨胀较小。通过显微结构分析发现,在含氯化镁的浇注料基质中有发育良好的板片状CA6,氯化镁分解所产生的孔隙可以为高温下CA6的形成提供部分可膨胀的空间,从而降低CA6形成所带来的体积膨胀,有利于改善浇注料经高温处理后的体积稳定性。%To improve the volume stability at high tempeartures,calcium aluminate cement bonded castables were prepared using tabular alumina (Al2O3≥99.5 mass%)as aggregate,reactive alumina micropowder (Al2O3≥99.7 mass%),and tabular alumina fines (≤0.044 mm)as matrix,calcium aluminate cement (Se-car 71)as binder,and magnesium chloride as additive.The castables were fired at 1 100 ℃ and 1 450 ℃for 3 h,respectively.Then physical properties of the castables were tested,and phase composition and mi-crostructure of castable matrix specimens were analyzed.The results show that the castable with magnesi-um chloride has the decreased bulk density,the increased apparent porosity and the decreased mechani-cal properties and linear expansion after firing at high temperatures.It is found in the microstructure that the well developed tabular CA6 crystals disperse in the matrix of the castable with magnesium chloride.There-fore,these voids generated from the decomposition of

  14. 钢中高熔点钙铝酸盐类夹杂物聚集行为%Aggregation of inclusions for calcium aluminate with high-melting point

    Institute of Scientific and Technical Information of China (English)

    初仁生

    2015-01-01

    The size,area,composition,type and distribution of non-metallic inclusions with high-melting point (CA2 and CA6,which C:CaO,A:Al2O3) in inspection substandard samples were analyzed by aspex explorer automated scan-ning electron microscope. To analyze the reason that why the center is the concentrated area of the large-size inclusions, three aspects for the causes of calcium aluminate with high-melting point causing the aggregation behavior for flaw sub-standard is focused on:features of non-metallic inclusions,the characteristics of continuous casting machine and the be-havior of nonmetallic inclusions during the process of solidification. The results show that calcium aluminate with high-melting point gathered together,and is easy to aggregate. The casting speed is slow for the curved continuous casting ma-chine compared with the average arc caster. The thickness of slab is thin and the molten steel solidifies rapidly,which makes the solidification end generate early,and form an easy gathering area near the center during the steel solidification. The inclusions are pushed and engulfed in the shell and will aggregate. While the space and time of floatation is reduced, combined with the effect of promoting the capture,the center forms a concentrated area of the large-size inclusions.%利用Aspex Explorer自动扫描电镜对探伤不合格试样中非金属夹杂物CA2和CA6(C为CaO,A为Al2O3)的尺寸、面积、成分、类型及分布等进行全面分析。从非金属夹杂物本身性质、连铸机本身特性和凝固过程非金属夹杂物行为3个方面集中探讨了高熔点钙铝酸盐类非金属夹杂物聚集行为。结果表明:高熔点钙铝酸盐类非金属夹杂物本身聚集能力很强,极易聚集;弧形连铸机拉速慢,铸坯厚度较一般的中厚板薄,凝固较快,使得凝固终点提前,造成在凝固过程中夹杂物在靠近中心处形成容易聚集区,同时上浮的空间和时间减少,加上推

  15. Hot dip aluminizing on 17-4PH stainless steel and its high-temperature oxidation resistance%17-4PH不锈钢热浸镀铝及其高温耐氧化性能

    Institute of Scientific and Technical Information of China (English)

    王院生; 熊计; 王均; 李海丰; 张太平; 石树坤

    2011-01-01

    Hot-dip aluminizing and diffusion annealing were carried out on 17-4PH stainless steel. The microstructure and microhardness of the coating and its high-temperature oxidation resistance were studied. The results showed that the coating consists of three layers including rich aluminum layer, alloy layer and substrate layer.The major phase of the alloy layer is Fe2Al5. After diffusion annealing treatment at 950 ℃ for 1 h, the rich aluminum layer transforms into the alloy layer completely with a thickness of ca. 100 μm. The alloy layer can divide into an inner diffusion layer and an outer diffusion layer. The inner diffusion layer is ca.40 μm thick and its main phase is Fe3Al.The outer diffusion layer is mainly composed of FeAl. The microhardness of alloy layer reduces gradually from the surface to the substrate and the maximum value is 714 HV. After hot dip aluminizing, the high-temperature oxidation resistance of 17-4PH stainless steel is greatly improved. The high-temperature oxidation resistance of 17-4PH stainless steel is approximately seven times that of the common one at 1 000 ℃. During the oxidation process, r-A12O3 in the surface layer and intermetallic compounds FeAl and Fe3Al play a role in the high-temperature oxidation resistance.%在17-4PH不锈钢上热浸镀铝,然后进行扩散退火处理.研究了热浸镀铝层的显微组织和显微硬度的变化,并考察了其高温耐氧化性能.结果表明:17-4PH不锈钢热浸镀铝后表面分为富铝层、合金层、基体层等3层,合金层主要相为Fe2Al5.经950℃.1 h的扩散处理后,富铝层全部转变为合金层,厚度约为100 μM,且分为内扩散层与外扩散层.内扩散层厚度约为40 μm,主要相为Fe3Al;外扩散层主要相为FeAl.合金层的显微硬度从表面到基体逐渐降低,表面显微硬度最高达到714 HV.17-4PH不锈钢经热浸镀铝后,其高温耐氧化性能显著提高.在1000℃,热浸镀铝件的高温耐氧化性能约是未镀铝件的7倍.

  16. 硫化钠对铝酸钠种分母液蒸发排盐的影响%Effect of Sodium Saulfide on Evaporation Desalting From Sodium Aluminate Seeded Precipitation Mother Solution

    Institute of Scientific and Technical Information of China (English)

    王家伟; 贾永真; 李军旗; 吕常胜

    2014-01-01

    The effect of sodium sulfide on evaporation desalting from sodium aluminate seeded precipitation mother solution in bayer process was studied .The results show that after depth evaporation ,Na2 CO3 · H2 O and NaAlO2 · 1 .25H2 O are mainly phases in the desalting .Sodium carbonate can precipitated effectively but NaAlO2 doesn’t when NK is 300-310 g/L .Na2CO3 ,sulfursalt and NaAlO2 precipitation rate increase with increasing of Na2 S additive amount .The desalting effect is good when NS is 4 .5 g/L .There are Na2 CO3 · H2 O ,NaAlO2 · 1 .25H2 O ,Na2 S ,Na2 S2 O3 ,Na2 SO3 and Na2 CO3 · Na2 SO3 in desalting slag when the sodium aluminate solution (NS is 4 .5 g/L) is evaporated to NK =310 g/L . S2 - of about 7% and 4% is oxidated to S2+ and S4+ .T he sodium sulfite crystallize to form double salts with sodium carbonate .The double salts is easy to precipitate .Desalting effect is influenced by the interaction of sodium carbonate and each valence state sulfur compounds .%研究了硫化钠对拜耳法铝酸钠种分母液蒸发排盐的影响。结果表明:铝酸钠溶液深度蒸发排盐渣中主要存在Na2 CO3· H2 O和NaAlO2·1.25H2 O ;当苛性碱质量浓度(NK )为300~310 g/L时,碳酸钠能有效析出且不导致NaAlO2析出过高;随硫化钠添加量增加,Na2 CO3、硫盐和NaAlO2析出率提高,排盐率提高且均在60%以上,硫化钠质量浓度( NS )为4 g/L时排盐效果最佳;将硫质量浓度( NS )为4.5 g/L的铝酸钠溶液蒸发至苛性碱质量浓度(NK )为310 g/L时,排盐渣中存在Na2 CO3· H2 O、NaAlO2·1.25H2 O、Na2 S、Na2 S2 O3、Na2 SO3及Na2 CO3· Na2 SO3,同时,约有7%和4%的S2-分别被氧化为S2+和S4+,而亚硫酸钠与碳酸钠更容易结晶形成复盐Na2 CO3· Na2 SO3而析出;碳酸钠和各价态硫化合物交互作用,影响蒸发排盐效果。

  17. 铝酸钙系冶金熔剂和CaF2对镁碳砖的侵蚀比较%Corrosion comparison of calcium aluminate system metallurgy flux and CaF2 to magnesia carbon brick

    Institute of Scientific and Technical Information of China (English)

    李文平; 李士明; 陈俊红; 孙加林; 吴克芳; Christoph Wohrmeyer

    2013-01-01

    为了降低精炼渣对钢包渣线镁碳砖的侵蚀,分别以20%(w)的冶金熔剂铝酸钙、铝镁酸钙和CaF2与80%(w)的初始钢渣配制成三种精炼渣,以镁碳砖为感应炉的坩埚,在坩埚内放入钢样,待钢样熔化并升温到1 600℃时,加精炼渣持续冶炼5h(期间共更换渣8次),冷却后测镁碳砖渣线部位的侵蚀(渗透)深度并进行SEM分析.结果表明:以铝酸钙和铝镁酸钙为熔剂的精炼渣都比以CaF2为熔剂的精炼渣对镁碳砖的渗透浅、侵蚀小,而以铝镁酸钙冶金熔剂为精炼渣比以铝酸钙冶金熔剂为精炼渣对镁碳砖的渗透和侵蚀性都大大降低.这是由于铝镁酸钙中含有饱和的MgO,减缓了镁碳砖中MgO向CMA渣中的溶解,从而降低了渣对镁碳砖的侵蚀.%In order to reduce the corrosion of refining slag to ladle slag line MgO-C brick,three kinds of refining slags were prepared with 20 mass% metallurgy fluxes of calcium aluminate (CA) and calcium magnesia aluminate (CMA) and CaF2 and 80 mass% original steel slag,and MgO-C bricks were made into crucibles of electric induction furnace. Add steel sample into the crucible,heat up to 1 600 ℃after the steel sample melts,then add refining slag,and hold for 5 h. In the meantime,the refining slags were replaced for 8 times. The corrosion (penetration) depth of the MgO-C brick in slag line was determined and the corroded brick was observed by SEM. The research shows that the MgO-C brick can better resist the penetration and corrosion of refining slags containing CA flux and CMA flux than those of refining slag containing CaF2; refining slag containing CMA flux penetrates and corrodes MgO-C brick obviously slightly than refining slag containing CA flux. CMA flux contains the saturated MgO which reduces the dissolving speed of MgO from MgO-C brick to refining slag containing CMA flux,corresponding decreases the corrosion of the slag.

  18. Sr/Al比对铝酸锶体系长余辉材料发光性能的影响%Influence of Sr/Al on Luminescence Properties of Strontium Aluminates System Long Persistence Phosphors

    Institute of Scientific and Technical Information of China (English)

    武玉亮; 吕梦林; 张小博

    2013-01-01

    Europium and dysprosium co-doped strontium aluminates long persistence phosphors was synthesized by the solid phase. This kind of material could respectively emit purple, blue, blue-green, yellow-green, yellow light by means of the alteration of Sr/Al. Spectra test revealed the material had the best luminescence intensity and the longest afterflow when Sr/Al=0.4, it emited yellow-green light. Wave length of emission spectra peak shifted to shortwave with the reduction of Sr/Al. While wave length of excitation spectra peak firstly shifted to shortwave after shift to longwave. XRD showed the alteration of Sr/Al made crystal structure change, therefore, Sr/Al affected on lumi-nescence properties of this material.%  用高温固相法制备了铕镝掺杂的铝酸锶长余辉发光材料,通过改变Sr/Al使该类材料各自发紫光、蓝光、蓝绿光、绿光、黄绿光和黄光。光谱分析表明,当Sr/Al=0.4时发光强度最强,余辉时间最长,此时材料发黄绿光。随着Sr/Al的减小,材料的发射光谱峰值波长蓝移,激发光谱峰值波长先红移后蓝移。XRD分析可知,Sr/Al的改变使材料的晶形结构发生改变,从而影响了材料的发光性能。

  19. DNAN 基含铝熔铸炸药倒药方法研究%Study on the Charge-inverted Method of DNAN-based Aluminized Melt-cast Explosive

    Institute of Scientific and Technical Information of China (English)

    刘艳萍; 金大勇; 高玉玲; 付改侠

    2014-01-01

    In order to re-use unqualified warhead shell and its filling explosive, the characteristics of DNAN-based aluminized melt-cast explosive were analyzed. The advantages and disadvantages of several common charge inversions, including mechanical disruption, chemical dissolution, melting through indirect heating and so on, were compared. The last method was finally selected to suit this explosive system best. Meanwhile, the safety analysis was conducted in the charge-inverted process. The simulated process parameters had a good agreement with real results according to test verifica-tion. The application of this method not only can save cost, but also avoids environmental pollution to achieve the recycling of resources.%为了重复利用不合格战斗部壳体及炸药,针对战斗部装填的 DNAN 基含铝熔铸炸药进行了特性分析,对比了机械破碎法、化学试剂溶解法、间接加热熔化法等几种常用倒药方法的优缺点,最终选定了适合该炸药体系的间接加热熔化倒药方法。同时,对倒药过程的安全性进行了分析,并利用计算模型对倒药工艺参数进行了预估。试验结果表明,计算模型预估与实际结果较为吻合。该方法的应用,既节约了成本,又避免了环境污染,实现了资源的循环使用。

  20. 静电纺丝参数对镁铝尖晶石纤维制备的影响%Influence of electrospinning parameters on preparation of magnesium aluminate spinel fibers

    Institute of Scientific and Technical Information of China (English)

    王合洋; 王忠奎; 魏恒勇; 王鹏; 魏颖娜; 李慧; 卜景龙; 林健; 杨金萍; 杨旸

    2015-01-01

    This work aims at obtaining continuous nano-diameter magnesium aluminate spinel fibers.Firstly, magnesium aluminate spinel precursor dry gel was synthesized by the non-hydrolytic sol-gel method using non-aqueous magnesium chloride,non-aqueous aluminum chloride,absolute alcohol and methylene chlo-ride as starting materials.Then electrospinning precursor solution was prepared by adding absolute alco-hol,polyvinyl pyrrolidone (PVP)as spinning aid,ethanol and N,N -dimethyl formamide (DMF)as solvent into the precursor dry gel.Finally precursor fibers were prepared via electrospinning technology and then calcined at 900 ℃.The influences of the spinning voltage (12,15,and 18 kV),spinning flow rate (0.8,1.1, and 1.4 mL·h -1 )and the needle diameter (0.6,0.8,and 1.2 mm)on preparation of magnesium alumi-nate spinel fibers were studied.The results show that the electrospinning voltage and flow rate have great influence on the morphology of magnesia alumina spinel fibers but mild influence on the fibers phase com-position;the needle diameter influences the diameter and morphology slightly;but when the needle aver-age diameter is 1.2 mm or above,a little periclase exists.The optimized spinning parameters are the elec-trospinning voltage of 15 kV,the electrospinning flow rate of 0.8 mL·h -1 ,and the needle diameter of 0.8 mm;and the obtained fibers have diameter of 50 -250 nm and the average of 121 nm.%为了制备直径为纳米级的镁铝尖晶石连续纤维,以无水氯化铝、无水氯化镁、无水乙醇和二氯甲烷为原料采用非水解溶胶-凝胶法制备镁铝尖晶石前驱体干凝胶,再加入无水乙醇、聚乙烯吡咯烷酮(PVP)和 N,N -二甲基甲酰胺(DMF)制成静电纺丝液,然后采用静电纺丝法制备镁铝尖晶石前驱体纤维,最后经900℃煅烧制成镁铝尖晶石纤维,主要研究了静电纺丝电压(12、15、18 kV)、进料流速(0.8、1.1、1.4 mL·h -1)及纺丝针头直径(0

  1. Effect of surface mechanical attrition on surface and properties of low temperature aluminized layer of 316L stainless steel%机械研磨对316L不锈钢表面及其低温渗铝层性能的影响

    Institute of Scientific and Technical Information of China (English)

    宋月鹏; 刘自平; 陈义祥; 李江涛; 高东升; 陈苗苗; 杨增朝; 贺刚

    2016-01-01

    利用扫描电镜(SEM),表面粗糙度测试仪,电化学工作站等仪器,分析了机械研磨对316L不锈钢件表面及其低温渗铝层性能的影响.结果表明:机械研磨过程中,材料表面在研磨球撞击、旋压等多种作用下产生大塑性变形,形成大量组织结构缺陷并细化表层晶粒,导致试样表面粗糙度变大,硬度提高,直接影响到热处理过程及其渗层性能;机械研磨处理的316L不锈钢试样经低温渗铝后,与对比试样相比,渗铝层硬度可提高2倍以上,抗高温氧化性及耐腐蚀性能均有显著提高,同时进行了相关机理的分析探讨.%Effect of surface mechanical attrition(SMA) on properties of aluminized layer of a 316L stainless steel was analyzed by means of scanning electron microscopy (SEM),surface roughness test and corrosion resistance test on an electrochemical workstation.The results indicate that the surface roughness and hardness increase due to the SMA treating.In the SMA process,with the impacting and spinning action of the grinding balls on the material surface,severe plastic deformation,a large number of defects like dislocation,subgrain boundary and grain refining occur.After SMA and aluminizing at low temperature,the properties of the aluminized layer of the 316L stainless steel are improved:hardness of the layer is three times than that of the substrate,high temperature oxidation and corrosion resistance increase significantly.Furthermore,the influence mechanism of the SMA on the properties of the aluminized layer is also explored.

  2. Cinética de hidratação de ligantes à base de alumina hidratável ou aluminato de cálcio Kinetics of hydration of binders based on hydratable alumina or calcium aluminate cement

    Directory of Open Access Journals (Sweden)

    I. R. Oliveira

    2007-03-01

    Full Text Available O estado de dispersão da matriz de um concreto refratário apresenta uma grande influência no comportamento reológico desse material, determinando as técnicas utilizadas para a sua aplicação. Tais métodos normalmente exigem a preparação de concretos com elevada fluidez, que possam ser bombeados com facilidade e sejam capazes de preencher moldes de formato complexo sem a necessidade de aplicação de vibração. Entretanto, embora tais requisitos favoreçam uma boa trabalhabilidade do concreto, tendem a aumentar o tempo requerido para efetuar a desmoldagem do corpo conformado. Uma vez que o desenvolvimento da resistência mecânica do concreto está intimamente relacionado ao processo de hidratação do ligante hidráulico, este necessita ser controlado quando se busca a redução do tempo para a desmoldagem. Tal controle depende de um profundo conhecimento das variáveis que determinam a cinética das reações. Neste contexto, o objetivo deste trabalho foi o de avaliar a influência do tipo de ligante hidráulico, da temperatura e da presença de finos (matriz ou de aditivos inorgânicos adicionados ao concreto sobre o processo de hidratação por meio de medidas de temperatura e ensaios reológicos oscilatórios em função do tempo.The dispersion of refractory castables matrix presents a great influence on their rheological behavior, which defines the most appropriate methods for placing these materials. The growing demand for automatically transported refractory castables has promoted the use of pumpable castables, usually specified as self flow compositions. Nevertheless, castables with higher fluidity present longer workability, leading to extended demoulding times. Because the strength development is intimately linked to the hydration process of calcium aluminate cement or hydratable alumina, it needs to be controlled in order to reach the minimum time for demoulding, contributing to reducing overall costs. The control of cement

  3. Synthesis of Cobalt-Aluminate Nanocrystallites by Hydrothermal Process%水热法制备钴铝尖晶石型纳米晶液体陶瓷颜料

    Institute of Scientific and Technical Information of China (English)

    黄剑锋; 王雅琴; 李春文; 曹丽云

    2012-01-01

    以硝酸钴、硝酸铝和氢氧化钠为主要原料,采用水热法通过一系列正交对比实验制备了较纯净、结晶完整,直径为100 nm左右且分散性良好的CoAl2O4纳米晶.用X射线衍射仪(XRD)、透射电子显微镜(TEM)及X射线能量色散谱仪(EDS)测定了粉体的晶相组成、微观形貌和元素组成.实验结果表明:水热法制备CoAl2O4纳米晶的最佳工艺条件为水热温度T=200℃、水热时间t-16h、前驱液摩尔浓度C=0.25 mol·L-1、pH值=11、Al3+∶Co2+=4∶1(摩尔比).球形的CoAl2O4粉体是单晶且沿[311]方向取向生长.%Cobalt-aluminate nanocrystallites were synthesized by hydrothermal method using Co(NO3 )2 o 6H2G、A1(NO3 )3 · 9H2O and NaOH as raw materials. The spinel structured CoAl2 O4 nano-powder with high purity, crystallization integrity, fine grain size (100 nm) , and perfect dispersity were obtained through a series of orthogonal experiment. The phase composition, micro-structure and consisting of elements were characterized by XRD, TEM and EDS. Results show that the optimum process conditions for prepar-ing CoAl2O4 nanocrystallites were T=200 ℃ (hydrothermal temperature), t=16 h (hydrothermal time), C = 0. 25 mol·L-3 (mol concentration of precursor), pH=11(pH value of precursor)、Al3+ Co2+ =4 ∶l(mol ratio of Al3+∶Ca2+ ), The as -prepared pow-ders possess spherical structure are single crystals with preferred orientation along the [311] direction.

  4. Eu{sup 3+}-site occupations and peculiar reddish orange luminescence in aluminates Sr{sub 3}RAl{sub 2}O{sub 7.5}:Eu{sup 3+} (R=Y, Lu)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wansong; Lin, Chundan [State Key Laboratory of Heavy Oil Processing, College of Science, China University of Petroleum, Beijing 102249 (China); Huang, Yanlin [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Cai, Peiqing; Kim, Sun Il [Department of Physics and Center for Marine-Integrated Biomedical Technology, Pukyong National University, Busan 608-737 (Korea, Republic of); Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr [Department of Physics and Center for Marine-Integrated Biomedical Technology, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2014-10-15

    A novel reddish orange-emitting phosphor of Eu{sup 3+}-doped aluminate Sr{sub 3}RAl{sub 2}O{sub 7.5} (R=Lu, Y) was successfully synthesized by wet-chemistry sol–gel method. The samples were characterized by X-ray powder diffraction (XRD) and scanning electron microscope (SEM). The luminescence properties such as photoluminescence excitation and emission spectra, decay curves, CIE color coordinates and luminescence quantum efficiency were investigated. This phosphor can be efficiently excited by UV and near-UV light and exhibits a bright reddish orange luminescence with the abnormally strongest {sup 5}D{sub 0}→{sup 7}F{sub 0} transition. Two distinct Eu{sup 3+} sites can be observed on the emission spectra under the excitation of UV light (excitation at charge transfer band of Eu{sup 3+} ions) or dye laser in the {sup 5}D{sub 0}→{sup 7}F{sub 0} wavelength region (selective excitation into each site). The site-selective luminescence decay curves have been investigated in the {sup 5}D{sub 0}→{sup 7}F{sub 0} region of each Eu{sup 3+} site by using a pulsed, tunable, and narrowband dye laser. Each Eu{sup 3+} site presents the distinct luminescence lifetime with different rise time. The Stark energy levels of two Eu{sup 3+} sites were assigned from the site-selective emission spectra. The energy transfer can happen between the closely neighbored Eu{sup 3+} sites in Sr{sub 3}RAl{sub 2}O{sub 7.5} (R=Lu, Y). The luminescence mechanism responsible for the abnormally strong {sup 5}D{sub 0}→{sup 7}F{sub 0} transition was discussed. - Highlights: • A novel phosphor of Eu{sup 3+}-doped Sr{sub 3}RAl{sub 2}O{sub 7.5} (R=Lu, Y) was synthesized with fine crystalline particles. • It can be efficiently excited by UV- or near UV light and presents bright reddish-orange color. • Eu{sup 3+}-doped Sr{sub 3}RAl{sub 2}O{sub 7.5} (R=Lu, Y) presents the strongest {sup 5}D{sub 0}→{sup 7}F{sub 0} emission lines. • Two distinct Eu{sup 3+} sites can be observed in the lattice

  5. Structural characterization of the high-temperature phase transitions in Ca{sub 8}[Al{sub 12}O{sub 24}] (MoO{sub 4}){sub 2} aluminate sodalite using X-ray powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Smaalen, S. van; Dinnebier, R. [Univ. of Bayreuth (Germany); Katzke, H.; Depmeier, W. [Univ. of Kiel (Germany)

    1997-02-15

    The structures are reported of the room-temperature and the three high-temperature phases of Ca{sub 8}[Al{sub 12}O{sub 24}] (MoO{sub 4}){sub 2} aluminate sodalite CAM. Structure refinements have been performed with the Rietveld method using synchrotron radiation X-ray powder diffraction data. The cubic phase has symmetry I{bar 4}3m with a = 9.29377 (4) {Angstrom}. The tetragonal phases have symmetry P{bar 4}c2, and their unit cells corresponds to a {radical}2a x {radical}2a x c supercell of the cubic phase. The second tetragonal phase (T2) exists for 614

  6. Effects on Technology of Aluminizing after Laser Shock Processing in 1Cr11Ni2W2MoV Steel%1Cr11Ni2W2MoV钢激光冲击强化后渗铝工艺研究

    Institute of Scientific and Technical Information of China (English)

    李玉琴; 何卫锋; 李应红; 王学德; 龙霓东; 刘海雷

    2011-01-01

    提出了1Cr11Ni2W2MoV不锈钢激光冲击强化(LSP)后渗铝提高材料疲劳性能的工艺方法,采用振动疲劳试验方法研究了激光冲击强化后渗铝处理对材料疲劳性能的影响,并与激光冲击强化、渗铝状态进行了对比分析,实验结果表明,激光冲击强化后渗铝工艺方法显著提高材料的疲劳寿命.采用X射线衍射(XRD)、透射电子显微镜(TEM)和扫描电子显微镜(SEM)分析研究了激光冲击强化后渗铝对材料微观组织的影响,讨论了这种工艺方法对材料性能提高的机理.结果表明,激光冲击强化后渗铝工艺增加了渗铝层厚度,但不影响其渗铝层的性能,同时使1Cr11Ni2W2MoV不锈钢基体表面晶粒呈梯度分布,从而提高了试样疲劳寿命.%A new technology, aluminizing after laser shock processing (LSP), for improving the fatigue performance of lCrllNi2W2MoV-steel is advanced. The fatigue lives of samples are measured by the vibration fatigue experiment. These experimental tests show that the. Fatigue lives of aluminizing after LSP are greatly improved. The microstructures are examined by means of X-ray diffractometry (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The mechanism of fatigue life improvement is also discussed. Experimental results show that the thickness of aluminizing layer is found to increase because of this new technology, and the surface crystal of lCrllNi2W2MoV-steel is distributed in a gradient manner.

  7. Preparation and Characterization of Manganese Ferrite Aluminates

    Directory of Open Access Journals (Sweden)

    R. L. Dhiman

    2008-01-01

    Full Text Available Aluminum doped manganese ferrites MnAlxFe2−xO4 with 0.0≤x≤1.0 have been prepared by the double ceramic route. The formation of mixed spinel phase has been confirmed by X-ray diffraction analysis. The unit cell parameter `aO' is found to decrease linearly with aluminum concentration due to smaller ionic radius of aluminum. The cation distributions were estimated from X-ray diffraction intensities of various planes. The theoretical lattice parameter, X-ray density, oxygen positional parameter, ionic radii, jump length, and bonds and edges lengths of the tetrahedral (A and octahedral (B sites were determined. 57Fe Mössbauer spectra recorded at room temperature were fitted with two sextets corresponding to Fe3+ ions at A- and B-sites. In the present ferrite system, the area ratio of Fe3+ ions at the A- and B-sites determined from the spectral analysis of Mössbauer spectra gives evidence that Al3+ ions replace iron ions at B-sites. This change in the site preference reflects an abrupt change in magnetic hyperfine fields at A- and B-sites as aluminum concentration increases, which has been explained on the basis of supertransferred hyperfine field. On the basis of estimated cation distribution, it is concluded that aluminum doped manganese ferrites exhibit a 55% normal spinel structure.

  8. Sol-gel synthesis of lithium aluminate

    Energy Technology Data Exchange (ETDEWEB)

    Valenzuela, M.A. [Inst. Politecnico Nacional, Mexico City (Mexico); Jimenez-Becerril, J. [Inst. Nacional de Investigaciones Nucleares, Mexico City (Mexico). Dept. de Quimica]|[Univ. Autonoma Metropolitana, Iztapalapa (Mexico). Dept. de Quimica; Bulbulian, S. [Inst. Nacional de Investigaciones Nucleares, Mexico City (Mexico). Dept. de Quimica; Lara, V.H. [Univ. Autonoma Metropolitana, Iztapalapa (Mexico). Dept. de Quimica

    1996-02-01

    LiAlO{sub 2} was prepared by two sol-gel methods using simultaneous hydrolysis of the reagents: aluminum sec-butoxide/lithium methoxide and aluminum sec-butoxide/LiOH. The resulting ceramic powders were compared with those prepared by two conventional methods (i.e., solid-state fusion and peroxide). The sol-gel method provided powders with a very high {gamma}-LiAlO{sub 2} content after calcining at temperatures as low as 700 C when LiOH was used. The solids were characterized by AAS, DTA, TGA, XRD, and SEM.

  9. Aluminized Behavior Induced by Micro-wave on Surface Nanocrystalline Magnesium Alloy%表面纳米化镁合金的微波诱导渗铝行为

    Institute of Scientific and Technical Information of China (English)

    王继娜; 徐开东

    2011-01-01

    Powder cladding diffusionalloying on the surface before and after nanocrystallined treatment of Mg-Gd series wrought magnesium alloy was carried out by vacuum high-temperature microwave oven. Microstructure features and structure refinement at different deformed zones on surface along thickness direction were observed by OM (optical microscope) and TEM (transmission electron microscope), and phase constituent in the alloyed layer at different microwave treatment conditions was analyzed by XRD (X-ray diffraction). The results show that microstructure and its structure in the deformed zone exhibit gradient distribution, and nano-crystalline with clear boundary and 10~20 nm in diameters can be observed on surface of the Mg-Gd alloy specimens. Aluminized behavior on the nanocrystallined surface of Mg-Gd alloy is realized at 320 °C as a result of microwave induction greatly decreasing diffusion-alloying temperature. In addition, diffusion-alloy process is promoted due to high volumetric fraction grain boundary and severe distortion. At the same experimental conditions, thickness of alloyed layer on surface nanocrystallined Mg-Gd alloy is 2~3 times thicker than that without nanocrystallined ones.%采用真空高温微波炉对表面自身纳米化处理前后的Mg-Gd系稀土变形镁合金试样进行了粉末包覆扩散合金化试验.通过光学显微镜和高分辨透射电镜研究了由表层沿厚度方向不同变形层区的微观结构特点及微观组织细化特征,并通过X射线衍射仪对不同条件下微波处理的合金化层的物相进行了分析.结果表明,塑性变形层的微观组织和结构呈梯度分布,在试样表层形成了尺寸为10~20 nm晶界清晰的纳米晶粒;微波诱导显著降低了扩散合金化温度,具有纳米化表层的镁合金在320℃实现了Al元素合金化;高体积分数的晶界和严重的畸变,促进了扩散合金化进程,且在相同试验条件下,纳米化处理的合金化层厚度

  10. 一种可作为FCC基质的新型改性镁铝尖晶石材料%Novel Modified Magnesium-Aluminate Spinels as Potential FCC Matrix Components

    Institute of Scientific and Technical Information of China (English)

    许孝玲; 李春义; 山红红

    2011-01-01

    镁铝尖晶石作为硫转移剂被广泛应用于流体催化裂化(FCC)过程中,可降低再生烟气中的SO2排放.通过将镁铝尖晶石和Y分子筛纳米簇溶液混合在酸性条件下再次晶化的方法改性镁铝尖晶石,改性后尖晶石的酸性明显提高.改性尖晶石材料的酸性和碱性可通过改变体系的pH值得以调节.实验表明,此改性方法可以将分子筛的结构单元引入到尖晶石中,从而使尖晶石的微孔比表面、酸性和水热稳定性明显提高.与原尖晶石相比,改性尖晶石裂化减压瓦斯油(VGO)的活性和产物选择性均得到改善,同时还保留了部分碱性活性位,仍具有一定的脱硫活性.改性尖晶石裂化VGO的反应性能优于高岭土,同时以改性尖晶石作为部分基质的FCC催化剂的反应性能也优于以高岭土为主要基质的FCC催化剂.%Modified magnesium-aluminate spinels (MgAl2O4) were prepared by recrystallizing a mixture of MgAl2O4 and zeolite Y nanoclusters in acidic medium to improve the acidity of MgAl2O4,which was commonly used as a sulfur transfer agent in fluid catalytic cracking (FCC) units.The acidity and basicity of these samples can be tuned by varying the pH value of the synthesis system.From the characterization and catalytic cracking tests the introduction of zeolitic building units into the spinels contributed to the increased microporosity,acidity,and hydrothermal stability.The catalytic results indicate that the activities and the product selectivities of the modified spinels for vacuum gas oil (VGO) cracking improved remarkably compared to the parent spinel.These samples exhibited even better performance than Kaolin clay for VGO cracking while retaining a part of the basic sites for oxidative SO2 uptake.Moreover,the FCC catalyst prepared using the modified spinel as a partial matrix,after equilibration,also gave superior catalytic behavior compared to a reference FCC catalyst with Kaolin clay as the main matrix.

  11. 成型压力与热处理温度对合成镁铝尖晶石材料的影响%Effects of molding pressure and heat treatment temperature on synthesis of magnesium aluminate spinel material

    Institute of Scientific and Technical Information of China (English)

    田玉明; 陈战考; 周少鹏; 李秋书; 柴跃生; 吕德富; 李晓松

    2014-01-01

    以特级铝矾土和轻质氧化镁为主要原料,按m(Al2 O3)m(MgO)=2.54配料,采用一步烧结法制备尖晶石材料,研究了成型压力(分别为25、50、75、100、125、150 MPa)和热处理温度(分别为1250、1300、1350、1400、1450、1500、1550℃)对合成材料的物相组成、显微结构、体积密度、显气孔率、荷重软化温度的影响。结果表明:1)以50 MPa压力成型的试样在1450℃保温4 h热处理后显气孔率最小,以100、125和150 MPa成型的试样在1450℃保温4 h热处理后存在开裂或扭曲现象;2)1250~1550℃热处理后试样的主晶相均为MgAl2 O4,MgAl2 O4晶粒随热处理温度的升高逐渐发育完整并长大;3)随着热处理温度的升高,试样的致密度逐渐升高,但以1400℃为转折点,致密度升高速率前高后低;4)随着热处理温度的升高,试样的荷重软化温度逐渐升高。%Magnesium-aluminate spinel materials were prepared by one-step sintering process with special grade bauxite and light weight magnesia as main starting materials with the ratio of m(Al2 O3 )m(MgO)=2.54.Effects of molding pressure (25,50,75,100,125,and 150 MPa)and heat treatment temperature (1 250,1 300,1 350,1 400,1 450,1 500,and 1 550 ℃)on phase compositions,microstructure,bulk density, apparent porosity,and refractoriness under load of specimens were studied.The results show that:(1 )the specimen pressed under 50 MPa and fired at 1 450 ℃ for 4 h has the lowest apparent porosity,while the specimens pressed under 100,125,and 150 MPa fired at 1 450 ℃for 4 h crack or distort;(2)the specimens fired at 1 250-1 550 ℃ have main crystal phase of MgAl2O4,and the MgAl2O4 crystals develop and grow as heat treatment temperature rises;(3)as heat treatment temperature rises,the bulk density of specimens increases,and the increasing rate slows down after 1 400 ℃;(4)as heat treatment temperature rises,the refractoriness under load

  12. Catalytic oxidation of cyclohexane over meta-aluminic acid supported iron meso-tetra (4-caboxylpheny1) porphyrin%偏铝酸四(4-羧基)苯基铁卟啉催化氧化环己烷

    Institute of Scientific and Technical Information of China (English)

    罗宗昌; 黄冠; 彭艳; 蔡景莉; 宁星星; 蒋月秀; 危素娟

    2012-01-01

    为考察偏铝酸[MAA]负载四(4-羧基)苯基铁卟啉[Fe TCPP]选择性催化氧化环己烷生成环己酮和环已醇(K/A油)的能力,采用溶胶-凝胶-煅烧法制备了偏铝酸负载四(4-羧基)苯基铁卟啉[Fe TCPP/MAA]催化剂,采用紫外(UV-Vis)、傅立叶红外(FT-IR)、X射线衍射(XRD)、热重分析(TG)以及透射电镜(TEM)等技术手段对该固体催化材料进行结构表征.研究其在无外加溶剂和助催化剂的条件下选择性催化空气氧化环己烷生成K/A油的产率.结果显示:在较优的催化条件下(155℃和0.8 MPa),用仅含1.14×10-6mol四(4-羧基)苯基铁卟啉的负载催化剂,既可回收又可重复有效催化11次,平均的环己烷转化率达到13.6%,K/A油的产率为10.8%,转化数为2.4 ×105,比未负载的四(4-羧基)苯基铁卟啉催化效率高11倍,也比当今工业用钴盐催化空气氧化环己烷生产环己酮和环己醇的收率(3.2%)高.%To investigate the catalytic ability of iron meso-tetra (4-carboxylphenyl) porphyrin ( Fe TCPP) supported on meta aluminic acid (MAA) for selective oxidation of cyclohexane to cyclo-hexanone and cyclohexanol (K/A oil) , Fe TCPP/MAA was prepared via a method of gelation and calcination and characterized by the techniques of UV-Visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Thermogravimetric analysis, Transmission electron microscopy. The catalytic oxidation of cyclohexane with air was carried out in absence of any solvent and co-catalyst. The results show that with a quantity of catalyst containing only 1. 14 × 10-6mol of Fe TCPP, 13. 6 % of average conversion rate, 10. 8 % of yield (K/A oil) and a catalyst turnover number of 2. 4 × 105 were reached under the optimum reaction conditions of 155 ℃ and 0.8 MPa. The catalytic efficiency of the supported catalyst is 11 times higher than that of Fe TCPP and the yield of K/A oil is higher than that obtained from the cyclohexane oxidation (3. 2 % ) by

  13. 广义C-J条件在计算含铝炸药波头参数中的应用%Application of Generalized C-J Condition at Detonation of Aluminized Explosives

    Institute of Scientific and Technical Information of China (English)

    王庭辉; 段祝平; 苏健军; 田清政

    2013-01-01

    含铝炸药的爆轰过程属于典型的非理想爆轰过程,其波头反应区处于多相反应流动状态,因此其波头处爆轰参数的计算一直是一个难点.在假定铝颗粒于波头处不参与化学反应且爆轰产物和铝颗粒压力、速度一致的条件下,应用连续介质模型描述了爆轰产物和铝颗粒两相之间的平衡关系,采用广义C-J条件给出了计算波头处爆压、物质速度和爆热的一组简单完备方程组.由实测得到的爆速,可以求得相应的爆压、物质点速度和波头处释放的热量.对三组不同含铝量(10%,20%,30%)的TNT含铝炸药和HMX含铝炸药的计算结果表明随着爆速的降低,对应的爆压、波头处物质速度和热量都会降低,不同含铝量的同一炸药在同一爆速条件下,含铝量越高对应的爆压值、波头处爆热值越大.同时,对计算假定和采用模型进行了一定的讨论.%The detonation performances of aluminized explosives are the typical non-ideal detonations. Because of the multiphase flowing and reacting at the front of detonation, it was difficult to obtain the detonation parameters by calculation. Assumed that the metal particles have no reaction at the front of detonation,and have the same pressure and velocity with the detonation products, using the continuum model and the general C-J relation,the full equations were obtained. Given the data of experimental detonation velocity,we can obtain the detonation pressure,particles velocity and the released heat at the front of detonation by solving the full equations. The calculations of two explosives with different aluminium content show that with the decrease of detonation velocity, the detonation pressure,mass velocity and explosion heat also deceased. When the explosives with different aluminium contents have the same detonation velocity,the higher the aluminium content,the larger the detonation pressure and the explosion heat. The calculation assumptions

  14. Thermal treatment of aluminous phosphates of the crandallite group and its effect on phosphorus solubility Tratamento térmico de fosfatos aluminosos do grupo da crandallita e seu efeito na solubilidade do fósforo

    Directory of Open Access Journals (Sweden)

    Eros Artur Bohac Francisco

    2007-06-01

    Full Text Available Optimization in the use of phosphate rocks is important and the residues of fertilizer production in the form of crandallite may be suitable for agronomic use after calcination. With the objective of evaluating the effect of thermal treatment of the aluminous phosphates of the crandallite group as related to solubility, crystalline structure and morphology, samples from the mine residues of three Brazilian phosphate deposits (Tapira-MG, Catalão-GO, and Juquiá-SP were collected, air-dried, and screened to 100 mesh. Sub samples were thermally treated at 300, 500, 700, and 900°C for 2 hours. Treated and untreated materials were analyzed by X-ray diffraction, scanning electronic microscopy, energy dispersive X-ray spectrometry, and for the total and soluble P contents. The treatment of samples: (i raised P solubility in neutral ammonium citrate solution, (ii caused the disorganization of the crystalline structure of crandallite at 500°C and above, and (iii altered their morphology (cracking and rounding. The increase in P solubility of samples after calcination indicates that the agronomic utilization of these marginal P sources may be of interest since plant growth may be favored due to higher P availability. New studies to evaluate these materials in order to determine their agronomic effectiveness must be carried out to establish adequate conditions that favor their use by plants.A otimização do uso de rochas fosfáticas é importante e resíduos da indústria de fertilizantes fosfatados na forma de crandallita poderão ser agronomicamente eficientes após calcinação. Com o objetivo de avaliar o efeito do tratamento térmico em fosfatos aluminosos do tipo crandallita quanto à solubilidade, estrutura cristalina, e morfologia, amostras do rejeito de mineração de três depósitos fosfáticos brasileiros (Tapira-MG, Catalão-GO e Juquiá-SP foram coletadas, secas ao ar e separadas por peneiramento 100 mesh. Sub-amostras foram submetidas ao

  15. Effects of Tin Oxide on Preparation and Properties of Calcium Aluminate/Magnesium-Aluminum Spinel Composites%氧化锡对铝酸钙/镁铝尖晶石复相材料制备和性能的影响

    Institute of Scientific and Technical Information of China (English)

    商恒; 员文杰; 朱青友; 邓承继; 祝洪喜

    2016-01-01

    With the advantages of their components such as high melting point, low thermal conductivity and good corrosion resistance, calcium aluminate/magnesium-aluminum spinel composites have a very wide application prospect in high temperature industries. Calcium aluminate/magnesium-aluminum spinel composites were prepared at 1300-1600 °C by using light-burned dolomite, alumina and tin oxide as raw materials. Effects of tin oxide on the phase composition, microstructure and properties of calcium aluminate/magnesium-aluminum spinel composites were investigated by X-ray diffraction and scanning electron microscopy. The results showed that the mass loss and shrinkage of sintered samples varied due to the sublimation of tin oxide and the decomposition of light-burned dolomite. Tin oxide not only enhanced the formation of calcium hexaluminate and magnesium-aluminum spinel but also made monocalcium aluminate and CaSnO3 involved in composites as a result of the effect of SnO2 on the reaction process. Moreover, the morphology of the phases was changed because of the solution of SnO2 in calcium hexaluminate and magnesium-aluminum spinel. With the increase of SnO2 addition, the apparent porosity of composites ifrstly increased and then decreased. When the SnO2 content was 35%, the composites sintered at 1600℃achieved the highest compressive strength of 240 MPa.%结合组分高熔点、低热导率和抗侵蚀等优点,铝酸钙/镁铝尖晶石复相材料在高温工业中具有十分广泛的应用前景。以轻烧白云石、氧化铝和氧化锡为原料,在1300-1600℃烧结合成铝酸钙/镁铝尖晶石复相材料。利用X射线衍射和扫描电子显微镜等测试方法,研究添加氧化锡对铝酸钙/镁铝尖晶石复相材料的物相组成、显微结构和性能的影响。结果表明:因氧化锡的分解,反应烧结过程中试样的失重和收缩率均有明显相应变化。氧化锡不仅促进六铝酸钙和镁铝尖晶石的形成,同时

  16. 表面机械研磨处理对N80套管钢低温渗铝层的影响%Influence of surface mechanical attrition treatment on low-temperature rapid pack aluminizing layer of oil casing steel N80

    Institute of Scientific and Technical Information of China (English)

    黄敏; 王宇

    2011-01-01

    Pack aluminizing processing was carried on oil casing steel N80 for 2h by surface mechanical attrition treatment (SMAT) with use of pack powder at a relatively low-temperature. The metallograph and microhard-ess of oil casing steel N80 after SMAT for 90min was analyzed by means of metallographic microscope and mir-cohardness test instrument. The microstructure and element distribution spectrum as well as microhardness of aluminizing N80 steel were also analyzed with SEM, EDS and microhardness test instrument. The study results show that a plastic deformed layer with a thickness around 50μm can be formed after SMAT, and the grain size whthin the layer reduces. The microhardess of oil casing steel N80 can be obviously improved in the thickness range of deformation layer after SMAT. Compared with original N80 steel, the aluminizing layer of oil casing steel N80 after SMAT shows a denser and more continuous microstructure, a bigger thickness as well as a higher microhardness. Consequently, SMAT can not only improve the thickness of aluminizing layer but also improve its structure and corrosion resistance ability.%通过表面机械研磨处理(SMAT),采用低温渗铝剂在470℃的相对低温下对N80套管钢进行2h粉末包埋渗铝.分别采用金相显微镜、显微硬度仪、扫描电镜、能谱仪等分析了SMAT对N80套管钢金相组织、渗铝层微观结构和断面元素分布、渗铝套管钢的显微硬度及表面腐蚀形貌的影响.结果表明SMAT90min后,可以在N80套管钢表面形成厚度约为50μm的变形层,变形层内晶粒尺寸明显减小,N80套管钢基体硬度在变形层深度范围内明显提高;与原始N80套管钢渗铝层相比,SMATedN80套管钢渗铝层表面致密,渗层连续,厚度较大,显微硬度增加更为明显.因此,SMAT可以增加N80套管钢低温渗铝层的厚度,改善渗铝层的结构,提高渗铝层对基体的腐蚀防护能力.

  17. Study on the Aging Effect on the Explosion Heat and Detonation Velocity of HMX/RDX Based Aluminized Explosive%老化对HMX/RDX基含铝炸药爆热及爆速性能的影响研究

    Institute of Scientific and Technical Information of China (English)

    黄亚峰; 赵省向; 李文祥; 杨建刚; 李欣; 刘文亮

    2013-01-01

      为了研究老化对HMX/RDX基含铝炸药的性能影响,在71℃下对组成为65(HMX/RDX)/30Al/5粘结剂的含铝炸药老化55d,然后测试炸药的爆热与爆速。试验结果表明:药柱体积随着老化时间的增长呈现先变大后缩小的趋势,质量随着老化时间的增长呈现逐渐减小的趋势,但变化率都在0.1%内;爆热和爆速随着老化时间的增长几乎没有变化。%  In order to investigate the aging effect on the performance of the HMX/RDX based aluminized explosive, the aluminized explosive of (HMX/RDX)/Al/ binder-65/30/5 was aged 55 days at 71℃, then the explosion heat and detonation velocity were tested. The aging results show that the charge bulk has a trend of first increase and then decrease with the increase of aging time, and the charge weight has a trend of decrease with the increase of aging time, but the change rate of bulk and weight was in 0.1%. The explosion heat and detonation velocity changed little with the increase of aging time.

  18. Etude du comportement chimique des additifs dispersants sur les surfaces métalliques. Réaction des fonctions amide sur l'alumine Study of the Chemical Behavior of Dispersant Additives on Metal Surfaces. Reaction of Amide Functions on Aluminum

    Directory of Open Access Journals (Sweden)

    Nechtschein J.

    2006-11-01

    Full Text Available Ce travail a pour objet la mise en évidence des réactions chimiques qui apparaissent entre les fonctions amides qui entrent dans la constitution de nombreuses formules de dispersants pour carburants et lubrifiants et la surface de l'aluminium. On montre que la réaction des amides sur la surface de l'alumine s'opère en deux étapes: La première étape, ou étape de chimisorption, fait intervenir les sites de Lewis et les groupements OH voisins de l'alumine pour fixer la fonction amide par le groupement carbonyle (liaison acide-base de Lewis et par l'azote (liaison hydrogène. La deuxième étape, ou étape d'hydrolyse, conduit à la formation d'un carboxylate de surface et d'une amine. The aim of this study was to analyze the chemical reactions that appear between the amide functions entering into the composition of numerous dispersant formulas for fuels and lubricants and the surface of aluminum. The reactions of amides on an aluminum surface is shown to take place in two stages. The first stage, or chemisorption stage, involves Lewis sites and the OH groups next to the aluminum oxide sa as to fix the amide function by the carbonyl group (Lewis acid-basic bonds and by nitrogen (hydrogen bond. The second stage, or hydrolysis stage, leads to the formation of a surface carboxylate and an amine.

  19. 黑索今基含铝炸药的铝氧比对爆轰性能及其水下爆炸性能的影响%Effect of Al/O Ratio on Detonation Performance and Underwater Explosion of RDX-based Aluminized Explosive

    Institute of Scientific and Technical Information of China (English)

    项大林; 荣吉利; 李健; 冯晓军; 王浩

    2013-01-01

    为了分析铝氧比对爆压和爆速的影响规律,采用试验方法测定了黑索今(RDX)基含铝炸药的爆轰参数,应用KHT程序计算分析了试验测试结果;针对RDX基含铝炸药,进行了1 kg柱形装药水下4.7m爆炸试验,测量了距爆心1~3m处的冲击波压力峰值与气泡脉动周期,拟合得到了冲击波压力峰值与衰减时间常数的相似律系数.研究结果表明:RDX基含铝炸药的爆压和爆速随铝氧比的增加呈现线性减小变化,爆热在铝氧比为0.997时达到最大值;当铝氧比为0.366时,冲击波压力峰值与冲击波能达到最大值;当铝氧比为0.633时,冲击波冲量与冲击波能量密度达到最大值;当铝氧比为0.997时,气泡第一次脉动周期与半径达到最大值.%The detonation parameters of RDX-based aluminized explosive were measured by test, and the test result was verified by KHT code. The influence law of Al/O ratio on detonation pressure, detonation velocity and heat was analyzed. Underwater explosion experiments were carried out on shock wave propagation and bubble pulse of 1 kg cylindrical RDX-based aluminized explosive under water 4. 7 m. The coefficients of similitude equation for peak pressure and attenuation time constant were fitted. The study indicates that the detonation pressure and velocity reduce linearly with the increasing of Al/O ratio and the detonation heat achieves a maximum value when Al/O ratio equals to 0. 997. When Al/O ratio equals to 0. 366, the peak pressure and shock wave energy reach the maximum value, but the shock wave impulse and flux density reach the maximum value when Al/O ratio equals to 0. 633, and the first bubble pulsation period and radius reach the maximum values when Al/O ratio equals to 0. 997.

  20. 粉煤灰对硅酸盐水泥-铝酸盐水泥-硬石膏体系性能的影响%Influence of fly ash on compressive strength with portland cement-aluminate cement-anhydrite system

    Institute of Scientific and Technical Information of China (English)

    李海南; 马保国; 张承志

    2014-01-01

    This paper studies the influence of amount of mixed fly ash (0 %, 10 %, 20 %, 30 %) on compressive strength with portland cement-aluminate cement-anhydrite system. Experimental results show that with the increase of fly ash, the compressive and transverse strength decreases; With the prolonging of curing age, the compressive and transverse strength decrease slowly.%研究了不同掺量的粉煤灰(0%,10%,20%,30%)对硅酸盐水泥-铝酸盐水泥-硬石膏三元复合体系力学性能的影响。试验结果表明:随着粉煤灰掺量的增加,该三元体系浆体的抗压、抗折强度均减小,但减小的程度不一致,与养护龄期有关。随着养护龄期的延长,砂浆抗压、抗折强度降低幅度减小。这可能是由于在浆体水化后期,粉煤灰的火山灰作用起了一定的作用。

  1. Study of the interactions between alumina and metallic ion in solution at the liquid/oxide interface during catalysts synthesis; Etude des interactions alumine/ion metallique en solution a l`interface oxyde/liquide lors de la preparation des catalyseurs

    Energy Technology Data Exchange (ETDEWEB)

    Mertens de Wilmars, D.

    1998-01-15

    This work concerns the formation of compounds including metal and Al(III) ions during impregnation of gamma alumina with a solution of the metal precursor. Formation of Li/Al hydroxy-carbonate (Li/Al HDC) on alumina during impregnation by a neutral or basic solution containing Li{sup +} is established. Zeta potential measurements are used to determine the ratio overlay of the alumina by HDC Li/Al. By this technique, residual positive charges are observed on HDC Li/Al surface. The formation of two different compounds including Mo(VI) and Al(III) ions during impregnation of alumina with molybdate or hepta-molybdate solution is reported here for the first time. The use of sodium molybdate solution as impregnation precursor leads to the formation of hydroxy-molybdo-luminate, while the ammonium hepta-molybdate solution forms ammonium hexa-molybdo-aluminate by contact with alumina.Dissolution kinetics of alumina in aqueous solution in absence or in presence of metal ions (Li{sup +}, K{sup +}, Zn{sup 2+}, MoO{sub 4}{sup 2-}, Mo{sub 7}O{sub 24}{sup 6-}) are investigated at different pH. Results show that the support is not inert in aqueous solution, even at neutral pH (near ZPC). The homogeneous nucleation of Li/Al HDC observed for Li/Al{sub 2}O{sub 3} system evidence the permeability of the solid/solution interface: diffusion processus through the interface is more important than previously reported. A dissolution-precipitation mechanism is proposed to account for the formation of Al(III)-containing compounds on alumina surface. Alumina dissolves when contacted with aqueous solution. When Al(III) ions concentration in solution is bigger than the sur-saturation needed for heterogenous nucleation of the Al(III) containing compounds, this one precipitates. This mechanism agrees with all our results. (author) 169 refs.

  2. Caracterização estrutural, textural e morfológica de aluminato de lítio (LiAlO2 sintetizado por coprecipitação Structural, textural and morphological characterization of lithium aluminate (LiAlO2 synthesized by coprecipitation

    Directory of Open Access Journals (Sweden)

    A. C. Nascimento

    2012-12-01

    Full Text Available Aluminato de lítio (LiAlO2 foi sintetizado por coprecipitação. O material foi calcinado em diferentes temperaturas e caracterizado por difração de raios X, espectroscopia na região do infravermelho com transformada de Fourier, adsorção gasosa, microscopia eletrônica de varredura (MEV e microscopia eletrônica de transmissão (MET, possibilitando sua caracterização estrutural, morfológica e textural. Diferentes fases cristalinas foram observadas à medida que a temperatura foi elevada de 550 para 1150 ºC. Texturalmente o material foi classificado como não-poroso e particulado a 550 e 750 ºC, apresentando microporos a 950 ºC. Análises comparativas de imagens de MET e MEV possibilitaram a identificação nanoflocos e microfolhas como as principais morfologias presentes no material.Lithium aluminate (LiAlO2 was synthesized by coprecipitation. The material was calcined at different temperatures and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, gas adsorption, scanning electron microscopy (SEM and transmission electron microscopy (TEM, providing a structural, morphological and textural characterization. Different crystalline phases were observed as the temperature was raised from 550 to 1150 ºC. Texturally, the material was classified as non-porous and particulate at 550 and 750 ºC showing micropores at 950 ºC. Comparative analysis of TEM and SEM images allowed the identification of nanoflakes and microsheets as the main morphology present in the material.

  3. EFFECT OF PROCESSING TEMPERATURE AND TIME ON MICROSTRUCTURE OF Al-Zn ALLOYED LAYER PREPARED BY CO-ALUMINIZING-ZICIZING ON MAGNESIUM ALLOY%扩渗温度和时间对镁合金表面Al-Zn共渗层显微组织的影响

    Institute of Scientific and Technical Information of China (English)

    马幼平; 杨蕾; 李秀兰

    2009-01-01

    采用扩渗法在镁合金表面共渗Al-Zn,研究了扩渗时间和温度对表面合金层显微组织的影响.结果表明:当温度为390%时,随着扩渗时间的增加,生成的表面合金层由不连续金属间化合物层(Al6Mg10Zn、Al5Mg11Zn4)+过渡层变为连续金属间化合物层+过渡层;此过程应是物理置换扩散机制和反应扩散机制同时存在,生成的金属间化合物相主要为Al6Mg10Zn和Al5Mg11Zn4两种类型金属间化合物,其中Al5Mg11Zn4是较为稳定的相;当温度提高到410℃时,晶界扩散活性提高,晶界扩散通道增强,仅为2小时已出现了严重的沿晶界扩渗,造成合金层中金属间化合物沿晶界呈网状不均匀分布.%An Al-Zn alloyed surface layer on magnesium alloy was prepared by a co-aluminizing-zicizing process with Al and Zn powders. The effect of processing time and temperature on the microstructure of surface alloyed layer was studied. The result showed that with the time increase from 2 h to 6h at 390℃, the formed surface alloyed zone seemed to be consisted of discontinuous islets of intermetallic compounds (Al6Mg10Zn and Al5Mg11Zn4+transition layer, and then transformed to ones consisted of continuous in-termetallic compound layer+transition layer. The intermetallic compounds formed in the alloyed layer are Al6Mg10Zn and Al5Mg11Zn4 ,the latter being much stable. When the temperature increases to 410℃, serious grain boundary diffusion started by 2 h, when a network like microstructure of intermetallics ap-peared along grain boundary in the front of the alloyed layer.

  4. In-Situ Preparation and Thermal Shock Behavior of Corundum-Mullite-Magnesium Aluminate Spinel Composite Ceramic%刚玉–莫来石–镁铝尖晶石复合陶瓷的原位合成及热震行为

    Institute of Scientific and Technical Information of China (English)

    徐晓虹; 马雄华; 吴建锋; 张锋意; 张亚祥; 李坤

    2012-01-01

    以α-Al2O3、苏州土、滑石和石英为主要原料,采用无压烧结制备了刚玉–莫来石–镁铝尖晶石多相复合陶瓷,研究了烧结温度对样品的体积密度、线性收缩率和吸水率等烧结性能以及机械性能的影响。通过X射线衍射和扫描电子显微镜分析了复相陶瓷热震前后的物相组成和显微结构。结果发现:经1480℃烧结的样品吸水率为0.19%,体积密度为3.06g/cm3,抗折强度达99.59MPa,复合材料有较好的热震性能,1100℃空冷热震损失率仅6.9%,可耐受17次热冲击。该复相陶瓷可作为潜在的太阳能热发电材料。%A corundum–mullite–magnesium aluminate spinel composite ceramic as a solar thermal power generation material was fabricated by a pressureless sintering method with alumina(α-Al2O3),Kaolin clay,talc and quartz as main raw materials.The effect of sintering temperature on the sintering properties(i.e.,bulk density(Db),linear shrinkage rate(Sf) and apparent porosity(Pa)) and the mechanical properties were investigated.The phase composition and microstructure of the composite ceramics were analyzed by X-ray diffraction and scanning electron microscopy.The results show that the sample sintered at 1 480 ℃ has water absorption of 0.19%,bulk density of 3.06 g/cm3and bending strength of 99.59 MPa.The composite ceramic has a superior thermal shock resistance.The bending strength loss rate is only 6.9% at 1 100 ℃ by air quenching-strength test,and the sample can endure 17-times thermal shock cycling.This composite ceramic could be used as one of potential solar thermal power materials.

  5. Adição de cimento de aluminato de cálcio e seus efeitos na hidratação do óxido de magnésio Effects of calcium aluminate cement addition on magnesia hydration

    Directory of Open Access Journals (Sweden)

    R Salomão

    2010-06-01

    Full Text Available Cimento de aluminato de cálcio (CAC e óxido de magnésio (MgO são duas importantes matérias primas para a indústria de concretos refratários e apresentam grande tendência à hidratação. Os efeitos dessa reação em cada caso isolado são distintos e bem conhecidos: enquanto o CAC hidratado atua como ligante e garante a resistência mecânica do material antes da sinterização, a hidratação do MgO pode causar sua total desintegração em alguns casos. Devido ao interesse tecnológico nesses materiais, é importante investigar as peculiaridades desses processos e as potenciais interações entre eles. Neste trabalho, os efeitos da adição de diferentes teores de CAC na hidratação do MgO foram investigados em suspensões aquosas usando medidas de expansão volumétrica aparente, pH das suspensões e difração de raios X. Foi observado que os efeitos danosos da hidratação do MgO podem ser significativamente reduzidos com um controle adequado do teor de CAC nas formulações.Calcium aluminate cement (CAC and magnesium oxide (MgO are two of the most important raw materials for refractory castables industry and both present a high driving force for hydration. The effects of this reaction for each compound are well known: whereas the hydrated CAC behaves as a binder, hardening the castable, MgO hydration can cause the total disintegration of the material. Due to the technological interests involved, it is important to study the peculiarities in these processes and their potential interactions. In the present work, the effects of the addition of different CAC contents on MgO hydration were investigated in aqueous suspensions by means of apparent volumetric expansion, pH measurements and qualitative X-ray diffraction. It was found out that the deleterious effects of MgO hydration can be significantly reduced with a proper control of the CAC content for the formulations.

  6. Photostimulated luminescence properties of Eu2+ -doped barium aluminate phosphor.

    Science.gov (United States)

    He, Quanlong; Qiu, Guangyu; Xu, Xuhui; Qiu, Jianbei; Yu, Xue

    2015-03-01

    An intense green photostimulated luminescence in BaAl2 O4 :Eu(2+) phosphor was prepared. The thermoluminescence results indicate that there are at least three types of traps (T1 , T2 , T3 ) with different trap depths in BaAl2 O4 :Eu(2+) phosphor according to the bands located at 327, 361 and 555 K, respectively, which are closely associated with the phosphor's long persistent luminescence and photostimulated luminescence properties. In addition, as a novel optical read-out form, a photostimulated persistent luminescence signal can be repeatedly obtained in BaAl2 O4 :Eu(2+) phosphor. This shows that re-trapping of the electron released from a deep trap plays an important role in photostimulated persistent luminescence.

  7. Hydration of tricalcium aluminate in the presence of gypsum

    Directory of Open Access Journals (Sweden)

    Triviño Vázquez, F.

    1974-06-01

    Full Text Available Not availabePara el estudio del comportamiento del cemento Portland tiene una importancia fundamental el conocimiento de la hidratación del aluminato tricálcico, por ser uno de sus componentes que primero se hidrata y porque se le achacan la mayoría de los defectos que sufre la pasta de cemento; tales son: retracciones, contracciones, fenómenos exotérmicos y sensibilidad a agentes exteriores de tipo químico. En lo que sigue se estudia por métodos fisicoquímicos la hidratación del aluminato tricálcico junto con el yeso, ya que éste se emplea como regulador del fraguado en los cementos Portland.

  8. Phase transition in aluminous silica in the lowermost mantle

    Science.gov (United States)

    Tronnes, R. G.; Andrault, D.; Konopkova, Z.; Morgenroth, W.; Liermann, H.

    2012-12-01

    Lower mantle basaltic lithologies contain 35-40% Mg-perovskite, 20-30% Ca-perovskite, 15-25% Al-rich phases (NAL and Ca-ferrite phases) and 15-20% silica-dominated phases. The Fe-rich Mg-perovskite makes basaltic material denser than peridotite throughout the lower mantle below 720 km depth, with important implications for mantle dynamics. Partial separation of subducted basaltic crust from depleted lithosphere might occur within the strongly heterogeneous D" zone. Further details on phase transitions and equation of states for the various minerals, however, are needed for more complete insights. The silica-dominated phases have considerable solubility of alumina [1]. We investigated silica with 4 and 6 wt% alumina to 120 GPa, using LH-DAC at the Extreme Conditions Beamline (P02.2) at PETRA-III, DESY. Powdered glass mixed with 10-15 wt% Pt-powder was compressed and heated in NaCl pressure media in Re-gaskets. The transition from the CaCl2-structured phase to seifertite (alpha-PbO2-structure) occurs at about 116 GPa at 2500 K. This is intermediate between the transition pressures of about 122 GPa and 100-113 GPa reported for similar temperatures for pure SiO2 [2] and a basalt composition [1], respectively. The CaCl2-structured silica phase crystallized along with seifertite, consistent with a binary phase loop trending towards lower pressure with increasing Al-content. The presence of an Al-rich Ca-ferrite phase (near the MgAl2O4-NaAlSiO4-join) in basaltic material indicates that the Al-solubility limits for the silica-dominated phases in basaltic compositions may be similar to those in the binary system SiO2-AlO1.5. Based on the X-ray pattern refinement, our samples show no significant volume change across the transition. Even so, the transition could be associated with a significant density change if the Al substitution mechanisms are different in CaCl2-structured phase and seifertite. The most likely situation is that Al-substitution occurs via O-vacancies in the CaCl2-phase and via extra interstitial Al in seifertite. That would result in a ~1.5% density increase at the transition pressure for silica containing 5 wt% Al2O3. This value is similar to the estimated difference in density between peridotitic mantle and basaltic lithologies in the lowermost mantle. References: [1] Hirose et al. 2005, EPSL; [2] Murakami et al. 2003, GRL

  9. Heterometallic aluminates: alkali metals trapped by an aluminium aryloxide claw.

    Science.gov (United States)

    Muñoz, M Teresa; Cuenca, Tomás; Mosquera, Marta E G

    2014-10-14

    A series of heterometallic aluminium-alkali metal species [AlMMe2{2,6-(MeO)2C6H3O}2]n have been isolated for lithium, sodium and potassium. These compounds can be generated by the reaction of [AlMe2{2,6-(MeO)2C6H3O}]2 with the metallated phenol [M{2,6-(MeO)2C6H3O}]n or through the reaction of the mixture of AlMe3 and the appropriate alkali metal alkyl base with two equivalents of 2,6-dimethoxyphenol. In the heterometallic species obtained, the {AlMe2{2,6-(MeO)2C6H3O}2}(-) moiety is observed and could be described as a claw which fixes the alkali ion by the phenoxide oxygen atoms while the methoxy groups help to stabilize their coordination sphere. All compounds have been characterized by NMR spectroscopy and X-ray diffraction methods. Catalytic studies reveal that these compounds are active in ring-opening polymerization of L-lactide.

  10. Effects of Aluminized Fiberglass on Representative Chesapeake Bay Marine Organisms

    Science.gov (United States)

    1977-11-23

    hours of feeding by test oysters, Cra~sostrea virgnica. Long Forjm: Starting Density: 1.303 x 106 Control lOOX lODOX .259 x 105 .297 .549 .607 .324 .694...100 19 100 39 100 Table 13 Wet weights of !Iytilus edulis. Wet Weight (grams) Concentration Day 0 Day 21 Replicate 1 173.3 173.4 lOOX 213.8 213.7 lODOX ...182.1 187.0 Crlct 162.3 160.1 (1dead) lOOX 193.1 195.7 lOQOX 148.4 148.7 Replicate 3 Control 143.2 158.8 1 OOX 183.0 176.0 (1 dead) lODOX 164.5 158.8

  11. Involvement of crystallinity in various luminescent bands in yttrium aluminate

    Energy Technology Data Exchange (ETDEWEB)

    Morimoto, Takaaki, E-mail: takaaki.morimoto@akane.waseda.jp [Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo 169-8555 (Japan); Harima, Masayuki; Horii, Yosuke [Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo 169-8555 (Japan); Ohki, Yoshimichi, E-mail: yohki@waseda.jp [Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo 169-8555 (Japan); Research Institute for Materials Science and Technology, Waseda University, Shinjuku, Tokyo 169-8555 (Japan)

    2016-01-01

    When single crystal YAlO{sub 3} was implanted with P{sup +} or B{sup +} ions, optical absorption increases significantly at energies slightly lower than the band gap energy, indicating that localized electronic states were induced. Furthermore, the ion implantation decreases the intensity of an X-ray diffraction peak and changes its position randomly, which indicates that the crystalline structure of the sample was deformed. The intensities of photoluminescence (PL) bands due to impurities of Cr{sup 3+} and Er{sup 3+} and those originating in self-trapped excitons and antisites become smaller or disappear after the ion implantation. On the other hand, the intensity of the PL due to oxygen vacancies does not change. Such contrasting effects of the sample’s crystallinity on the luminescence intensity are explained by the different manners of involvement of the crystal structure in the luminescence mechanism among these PLs in YAlO{sub 3}.

  12. Jaguar Analyses of Experimental Detonation Values for Aluminized Explosives

    Science.gov (United States)

    Stiel, Leonard I.; Baker, Ernest L.; Capellos, Christos

    2004-07-01

    Comparisons of JAGUAR C-J velocities with experimental detonation values for a number of explosives indicate that only slight, if any, aluminum reaction occurs at the detonation front even if small or sub-micron particles are utilized. For sub-micron particles, it is important to account for the presence of aluminum oxide in the explosive formulation. The agreement with the calculated JAGUAR values for zero aluminum reaction is within 2% for most experimental detonation velocities considered. Comparisons of experimental cylinder velocities by JAGUAR analytical procedures indicate that with small aluminum particles substantial aluminum reaction occurs at low values of the radial expansion, even though little reaction is observed at the detonation front.

  13. Pressure induced reactions amongst calcium aluminate hydrate phases

    KAUST Repository

    Moon, Ju-hyuk

    2011-06-01

    The compressibilities of two AFm phases (strätlingite and calcium hemicarboaluminate hydrate) and hydrogarnet were obtained up to 5 GPa by using synchrotron high-pressure X-ray powder diffraction with a diamond anvil cell. The AFm phases show abrupt volume contraction regardless of the molecular size of the pressure-transmitting media. This volume discontinuity could be associated to a structural transition or to the movement of the weakly bound interlayer water molecules in the AFm structure. The experimental results seem to indicate that the pressure-induced dehydration is the dominant mechanism especially with hygroscopic pressure medium. The Birch-Murnaghan equation of state was used to compute the bulk modulus of the minerals. Due to the discontinuity in the pressure-volume diagram, a two stage bulk modulus of each AFm phase was calculated. The abnormal volume compressibility for the AFm phases caused a significant change to their bulk modulus. The reliability of this experiment is verified by comparing the bulk modulus of hydrogarnet with previous studies. © 2011 Elsevier Ltd. All rights reserved.

  14. Pozzolanic reactivity of silico-aluminous fly ash

    Institute of Scientific and Technical Information of China (English)

    Pierre Adamiec; Jean-Charles Benezet; Ali Benhassaine

    2008-01-01

    For some years it has been possible to control the particle size of fly ashes, by-products of thermal power stations. Incorporating these very fine particles (obtained by grinding and/or pneumatic selection) improves the physical-mechanical characteristics of mortars and concretes. In this study, we measured the lime consumption of the various fractions (granulometric and densimetric) and identified by X-ray diffraction the neoformed phases by the pozzolanic reaction, to show that it is not sufficient to simply define the pozzolanicity of products based on lime consumption since it does not take into account the nature of the phases formed. The size of the particles used in the test samples also has a determining effect on the quantity of lime consumed. Before comparing results, it is necessary to ensure that the size of the particles (of the global ash and its constituents) be the same. Two distinct neoformed phases appear: CSH in the largest granular fractions (d>40 μm) and C<3AH6 in the smaller fractions.

  15. 硝基甲烷爆轰区热作用下铝、铝热剂和含铝炸药颗粒的温度响应%Temperature Response of Aluminum, Thermit and Aluminized Explosive Particles under Thermal Effects in Nitromethane Detonation Region

    Institute of Scientific and Technical Information of China (English)

    胡荣祖; 高红旭; 赵凤起; 徐司雨; 张海; 马海霞

    2011-01-01

    A formula describing the temperature response of materials heated by thermal effects of explosive detonation was derived.A numerical method of estimating the relation between temperature (T) and penetration depth (x) of materials was presented. With the help of the data of initial temperature, specific heat capacity, density and thermal conductivity of aluminum particle ( system I ),3Fe304-8Al thermit particle (system Ⅱ ) and aluminized explosive (59/20/20/0. 5/0. 5-RDX/AP/Al/binder/additive)particle (system Ⅲ ), and temperature in detonation region and detonation stabilization time of nitromethane,the Tvs x relation diagrams for systems I - Ⅲ were constructed by numerical calculation using derived formula. The results show that under thermal effects in nitromethane detonation region the values of x arrived at ignition temperature of 2070 K for system I,1209.15 K for system Ⅱ and 485.68 K for system Ⅲ is 1.053 μm,1.880 μm and 0. 1905 μm,respectively,and the values of x arrived at original temperature (300 K) is 10.5 μm for system I ,9.6 μm for system Ⅱ and 0.6 μm for system Ⅲ.%推导了描述炸药爆炸作用所致材料温度响应的表达式.提出了估算材料渗透深度(x)与温度(T)关系的数值方法.借助铝颗粒(体系I)、铝热剂(3FeO-8AI)颗粒(体系Ⅱ)和含铝炸药(59/20/20/0.5/0.5-RDX/AP/AI/binder/additive)颗粒(体系Ⅲ)的初温、比热容、密度、热导率和硝基甲烷的爆轰区温度和爆轰持续时间数据,用导出的表达式,通过数值计算,构筑了体系I、Ⅱ和Ⅲ的T-x关系图.结果表明,在硝基甲烷爆轰区热作用下使体系达点火温度2070 K(体系I)、1209.15 K(体系Ⅱ)和485.68 K(体系Ⅲ)的x值分别为1.053,1.880,0.1905 μm,至体系达初温300 K的x值分别为10.5,9.6,0.6μm.

  16. Texture study of divided solids by gas adsorption: application to beryllia, alumina and to gels and oxides; Contribution a l'etude, par adsorption gazeuse, de la texture des solides divises. Application a l'alumine, a la glucine et a differents gels et oxydes

    Energy Technology Data Exchange (ETDEWEB)

    Rouquerol, F. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-12-01

    particulier dans le cas des solides mtcroporeux) pour la determination du volume de gaz adsorbe dans une couche monomoleculaire et que l'azote est sensible aux interactions chimiques ou electriques avec l'adsorbant: il convient de le remplacer par l'argon. Les methodes de calcul de la distribution de taille des pores sont analysees et discutees. Nos resultats experimentaux ont montre que l'epaisseur de la couche multimoleculaire doit etre calculee a partir du nombre de couches donne par Shull et d'une epaisseur de 3,6 angstrom par couche. Enfin, nous proposons une nouvelle methode d'analyse de la branche de desorption. Nous montrons que certains systemes lamellaires, non poreux, tels que Be(OH){sub 2}, donnent une hysteresis sur une isotherme d'adsorption du type I ou II. En nous basant sur les resultats numeriques fournis par notre methode ainsi que sur des observations obtenues par microscopie electronique, nous concluons que cette hysteresis est due au manque de rigidite du solide. Inversement, nous avons caracterise des solides poreux qui ne donnent pas lieu au phenomene d'hysteresis. C'est le cas des echantillons de glucine de texture microporeuse (r < 20 A). Les conclusions precedentes nous permettent de decrire l'evolution de texture subie par deux series d'echantillons (glucine et alumine) au cours de leur deshydratation progressive (traitement thermique allant de 150 a 1100 C). (auteur)

  17. 不同Al2O3含量的镁铝尖晶石抗钢包渣侵蚀性研究%Corrosion resistance of magnesium aluminate spinels with different Al2O3 contents to ladle slag

    Institute of Scientific and Technical Information of China (English)

    张艳奎; 韩兵强; 邱文冬; 贺恒星; 龚柳百; 鄢文; 李楠

    2013-01-01

    The specimens were prepared using magnesium aluminate spinel with different AI2O3 contents (S67,S70,S78,and S90,respectively) as starting materials,and sulphite lye as binder,mixing well,and pressing shaping. After drying and heating at 1 600 °C for 3 h,the specimens were used for ladle slag corrosion test at 1 600 °C for 3 h. The corroded specimens were analyzed by SEM and their corrosion resistances to ladle slag were compared. The results show that: with the AI2O3 content increasing in the spinel materials,the spinel shows worse corrosion resistance, but better penetration resistance except that the penetration resistance of S90 gets worse. The SEM analysis shows the formed MgO-FeOx solid solution and the complex spinel (Mg,Mn,Fe)(Fe,AI)2O4) in the corrosion process can depress the corrosion and penetration of slag;in the penetration layer,free Al2O3 will react with CaO from the slag forming high melting point phases CA2 and CA6 interweaving with the spinel, which is favorable to prevent the further slag penetration. The S78 spinel has better resistance to ladle slag.%分别以四种不同Al2O3含量的镁铝尖晶石粉S67、S70、S78、S90为原料,纸浆废液为结合剂,混匀后压制成型,经烘干和1 600 ℃ 3 h热处理后,进行1 600℃保温3h的抗钢包渣侵蚀试验,并对侵蚀后的四种尖晶石试样进行显微结构分析,以比较其抗钢包渣侵蚀性能的差异.结果表明:随着尖晶石原料中Al2O3含量的增加,抗渣侵蚀性能逐渐减弱,抗渣渗透性逐渐增强,但Al2O3质量分数增加到约90%(即S90)时其抗渗透反而有所减弱.SEM分析显示:在尖晶石受渣侵蚀过程中生成的MgO-FeOx固溶体和(Mg,Mn,Fe)(Fe,Al)2O4复合尖晶石,能起到抑制渣侵蚀和渗透的作用;而渗透层中游离的Al2O3与渣中CaO反应生成高熔点的CA6和CA2相,并以网络结构贯穿于尖晶石中间,有利于阻止渣的进一步渗透.综合考虑抗侵蚀性能和渗透性能认为,尖晶石原料S78

  18. Luminescence in Sr4 Al14 O25 :Ce(3+) aluminate phosphor.

    Science.gov (United States)

    Nikhare, G N; Gedam, S C; Dhoble, S J

    2015-03-01

    Cerium-doped Sr4 Al14 O25 phosphor is prepared using a single-step combustion synthesis and its X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) and thermoluminescence (TL) properties are characterized. XRD reveals the formation of the desired phase in the prepared sample. SEM micrographs of the prepared Sr4 Al14 O25 phosphor show that the particle size is 10 µm. The prepared Sr4 Al14 O25 , along with Sr4 Al14 O25 :Cex (x = 0.5-5 mol%) shows a PL emission peak at 314 nm under UV excitation of 262 nm wavelength due to 5d → 4f transition. The phosphor is suitable for higher concentrations of Ce ions. The TL glow peak reveals three clearly visible distinct peaks at temperatures around 130, 231 and 336ºC. The three peaks are separated by deconvolution and kinetic parameters calculated using Chen's peak shape method. The calculation shows that the reaction follows second-order kinetics with activation energy (E) values of 0.52, 0.81 and 1.12 eV, and frequency factor (s) values of 5.58 × 10(5) , 4.53 × 10(7) and 4.57 × 10(8) s(-1) for the three individual peaks.

  19. On the luminescence of bismuth aluminate (Bi2Al4O9)

    NARCIS (Netherlands)

    Blasse, G.; Boen Ho, O.

    1980-01-01

    The luminescence of Eu3+ and Tb3+ in Bi2Al4O9 is reported. It is shown that the Bi3+ excitation energy does not migrate through the lattice. The Cr3+ ion shows 704.5 nm line emission in this host lattice.

  20. Temperature Dependent Mössbauer Spectra of Aluminous Perovskite and Implications for the Earth's Lower Mantle

    Science.gov (United States)

    Liu, J.; Mysen, B. O.; Fei, Y.; Mao, H.; Hemley, R. J.; Li, J.

    2011-12-01

    Perovskite in the Earth's lower mantle contains 4.0~5.3 weight % Al (Wood and Rubie, Science. 1996). To date Mössbauer data on Al-PV under cryogenic conditions have not been reported. In this study, we measured Mössbauer spectra of an Al-PV sample at 65 to 300 K and 1 bar. The temperature dependence of the center shift, fitted by Debye model, gives recoil-free fractions of fFe2+ and fFe3+, which are critical for calculating Fe3+/⊙Fe ratio. The high relative concentration of Fe3+ of our Al-PV sample is consistent with previous studies on Al-PV samples containing a similar amount of aluminum (Lauterbach et al., Contrib Mineral Petrol. 2000). However, it cannot be attributed to disproportionation of Fe2+ (Frost et al., Nature. 2004), because neither metallic iron nor wüstite was observed in the Mössbauer spectra or electron probe analysis. In comparison to other capsule materials used in previous studies, such as graphite, iron, or rhenium, the gold capsule used in our synthesis is chemically inert, and does not influence the oxidation environment. A likely candidate to oxidize Fe2+ into Fe3+ in PV structure is H2O trapped as moisture. Earth's lower mantle may contain 2.5~5 times H2O of the present ocean's mass (Murakami et al., Science. 2002; Litasov et al., Earth Planet. Sci. Lett. 2003), a high Fe3+/⊙Fe ratio in lower mantle Al-PV can be achieved without disproportionation of Fe2+. Recent studies (McCammon et al., Nature Geosci. 2008; Lin et al., Nature Geosci. 2008) found a high quadrupole splitting (QS) (~4 mm s-1) component in Al-free PV at pressures above 30 GPa, and assigned it to intermediate-spin ferrous iron. The high QS component in our Al-PV sample has similar hyperfine parameters. Its relative concentration changes with temperature, possibly due to a temperature-induced change in the degree of lattice distortion (Bengtson et al., Geophys. Res. Lett. 2009).

  1. Helium and fission gas behaviour in magnesium aluminate spinel and zirconia for actinide transmutation

    NARCIS (Netherlands)

    Damen, P.M.G.

    2003-01-01

    In order to reduce the long-term radiotoxicity of spent nuclear fuel, many studies are performed on partitioning and transmutation of actinides. In such a scenario, the long-lived radio-isotopes (mostly actinides) are partitioned from the nuclear waste, and subsequently transmuted or fissioned in a

  2. In vitro biological and tribological properties of transparent magnesium aluminate (Spinel) and aluminum oxynitride (ALON®).

    Science.gov (United States)

    Bodhak, Subhadip; Balla, Vamsi Krishna; Bose, Susmita; Bandyopadhyay, Amit; Kashalikar, Uday; Jha, Santosh K; Sastri, Suri

    2011-06-01

    The purpose of this first generation investigation is to evaluate the in vitro cytotoxicity, cell-materials interactions and tribological performance of Spinel and ALON® transparent ceramics for potential wear resistant load bearing implant applications. Besides their non-toxicity, the high surface energy of these ceramics significantly enhanced in vitro cell-materials interactions compared to bioinert commercially pure Ti as control. These transparent ceramics with high hardness in the range of 1334 and 1543 HV showed in vitro wear rate of the order of 10⁻⁶ mm³ Nm⁻¹ against Al₂O₃ ball at a normal load of 20 N.

  3. Densification during hot-pressing of carbon nanotube-metal-magnesium aluminate spinel nanocomposites

    OpenAIRE

    Peigney, Alain; Rul, Sébastien; Lefèvre-Schlick, Florent; Laurent, Christophe

    2007-01-01

    International audience; The densification by hot-pressing of ceramic-matrix composites containing a dispersion of carbon nanotubes (CNT), mostly single-walled, is studied for the first time. Fifteen different CNT-Co/Mo-MgAl2O4 composite powders containing between 1.2 and 16.7 vol.% CNT were prepared by catalytic chemical vapour deposition. The in situ growth of CNT within the oxide powder made it possible to obtain a highly homogeneous distribution of CNT. Low contents of CNT (up to 5 vol.%) ...

  4. Effects of normal acceleration on transient burning rate augmentation of an aluminized solid propellant

    Science.gov (United States)

    Northam, G. B.

    1972-01-01

    Instantaneous burning rate data for a polybutadiene acrylic acid propellant, containing 16 weight percent aluminum, were calculated from the pressure histories of a test motor with 96.77 sq cm of burning area and a 5.08-cm-thick propellant web. Additional acceleration tests were conducted with reduced propellant web thicknesses of 3.81, 2.54, and 1.27 cm. The metallic residue collected from the various web thickness tests was characterized by weight and shape and correlated with the instantaneous burning rate measurements. Rapid depressurization extinction tests were conducted in order that surface pitting characteristics due to localized increased burning rate could be correlated with the residue analysis and the instantaneous burning rate data. The acceleration-induced burning rate augmentation was strongly dependent on propellant distance burned, or burning time, and thus was transient in nature. The results from the extinction tests and the residue analyses indicate that the transient rate augmentation was highly dependent on local enhancement of the combustion zone heat feedback to the surface by the growth of molten residue particles on or just above the burning surface. The size, shape, and number density of molten residue particles, rather than the total residue weight, determined the acceleration-induced burning rate augmentation.

  5. Effects of the acceleration vector on transient burning rate of an aluminized solid propellant.

    Science.gov (United States)

    Northam, G. B.

    1971-01-01

    Experimental results concerning the transient burning-rate augmentation of a 16% aluminum polybutadiene acrylic acid (PBAA) propellant burned in a 2-in. web motor at pressure levels from 300 to 1200 psia with centrifugal accelerations from 0 to 140 g. The orientation of the acceleration vector was varied to determine its effect on the transient burning rate. The burning-rate augmentation was strongly dependent on (1) acceleration level, (2) propellant distance burned (or burn time), and (3) orientation of the acceleration vector with respect to the burning surface. This transient rate augmentation resulted from the retention of molten metallic residue on the burning surface by the normal acceleration loading. The presence of the residue altered the combustion zone heat transfer and caused increased localized burning rates, as evidenced by the pitted propellant surfaces that were observed from extinction tests conducted at various acceleration levels.

  6. Vibrational and dielectric properties of magnesium aluminate spinel: A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Qingfeng, E-mail: qfzeng@nwpu.edu.cn [National Key Laboratory of Thermostructure Composite Materials, Northwestern Polytechnical University, Xi' an, Shaanxi 710072 (China); Zhang, Litong [National Key Laboratory of Thermostructure Composite Materials, Northwestern Polytechnical University, Xi' an, Shaanxi 710072 (China); Zhang, Xian; Chen, Qichao [School of Technical Physics, Xidian University, Xi' an, Shaanxi 710071 (China); Feng, Zhiqiang [School of Mechanics and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 611756 (China); Laboratoire de Mecanique et d' Energetique, Universite d' Evry, Evry 91020 (France); Cai, Yongqing [Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Cheng, Laifei; Weng, Zuohai [National Key Laboratory of Thermostructure Composite Materials, Northwestern Polytechnical University, Xi' an, Shaanxi 710072 (China)

    2011-09-19

    The vibrational and dielectric properties of MgAl{sub 2}O{sub 4} are investigated within the framework of density functional perturbation theory. Results of phonon frequencies at the Brillouin zone center, static dielectric constant, and electronic dielectric constant are reported. In comparison with experimental results, we find that the generalized gradient approximation potential results in more accurate phonon frequencies than local density approximation potential does. Dielectric, refractive index, extinction coefficient and infrared reflectance spectra of MgAl{sub 2}O{sub 4} are given, and the figures suggest that MgAl{sub 2}O{sub 4} presents good transmission properties in the spectrum range above 1000 cm{sup -1} and below 300 cm{sup -1}. -- Highlights: → MgAl{sub 2}O{sub 4} has an electronic dielectric constant smaller than the lattice component. → GGA potential results in more accurate phonon frequencies compared to LDA potential. → Weak reflection peaks at 321 cm{sup -1} and 596 cm{sup -1} result in narrow LO-TO bands. → Infrared spectrum suggests good transmission above 1000 cm{sup -1} and below 300 cm{sup -1}.

  7. A hazardous waste from secondary aluminium metallurgy as a new raw material for calcium aluminate glasses.

    Science.gov (United States)

    López-Delgado, Aurora; Tayibi, Hanan; Pérez, Carlos; Alguacil, Francisco José; López, Félix Antonio

    2009-06-15

    A solid waste coming from the secondary aluminium industry was successfully vitrified in the ternary CaO-Al(2)O(3)-SiO(2) system at 1500 degrees C. This waste is a complex material which is considered hazardous because of its behaviour in the presence of water or moisture. In these conditions, the dust can generate gases such as H(2), NH(3), CH(4), H(2)S, along with heat and potential aluminothermy. Only silica sand and calcium carbonate were added as external raw materials to complete the glasses formula. Different nominal compositions of glasses, with Al(2)O(3) ranging between 20% and 54%, were studied to determine the glass forming area. The glasses obtained allow the immobilisation of up to 75% of waste in a multicomponent oxide system in which all the components of the waste are incorporated. The microhardness Hv values varied between 6.05 and 6.62GPa and the linear thermal expansion coefficient, alpha, varied between (62 and 139)x10(-7)K(-1). Several glasses showed a high hydrolytic resistance in deionised water at 98 degrees C.

  8. Effect of Zn, Cu, Cr and Pb Chlorides on the Formation of Tricalcium Aluminate Trisulfate Hydrate

    Institute of Scientific and Technical Information of China (English)

    Wafaa S.Hegazi; Eisa E.Hekal; Essam A.Kishar; Maha R.Mohammed

    2008-01-01

    The effect of addition of Zn,Cu,Pb and Cr chlorides as admixtures on the hydration reaction of the system 3CaO·Al2O3-gypsum with molar ratio 1:3 was studied.Different ratios of each salt were used,namely 0.5%,2% and 4% by weight of the solid mixture.Hydration reaction was carried out at 35℃ for various time intervals from 0.5 h to up to 7 d.Hydration rate of the system 3CaO-Al2O3-CaSO4·2H2O in absence and presence of different salts was studied via the determination of the combined water contents.X-ray diffraction analysis showed that the ettringite was the only hydration product formed in the different mixes.The hydration products were investigated by scanning electron microscopy (SEM) and thermal gravimetric analysis.The results indicated that the rate of formation of ettringite and its microstructure depend on the admixture and its dosage.

  9. Surfactant-free hydrothermal synthesis of lithium aluminate microbricks and nanorods from aluminium oxide nanoparticles.

    Science.gov (United States)

    Joshi, Upendra A; Chung, Soo Hyun; Lee, Jae Sung

    2005-09-21

    Beta-LiAlO2 microbricks and rectangular nanorods have been successfully synthesized from Al2O3 nanoparticles by a simple hydrothermal process without any surfactant or template, by simply changing the Li/Al molar ratio.

  10. Synthesis of zinc aluminate (ZnAl2O4) spinel and its application as photocatalyst

    OpenAIRE

    Battiston,Suellen; Rigo,Caroline; Severo,Eric da Cruz; Mazutti,Marcio Antonio; Kuhn,Raquel Cristine; Gündel,André; Foletto,Edson Luiz

    2014-01-01

    ZnAl2O4 spinel was synthesized by co-precipitation using ammonia as precipitating agent, followed by thermal treatment at 750 ºC. The structural properties of particles were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), differential thermal analysis (DTA), and N2 adsorption/desorption isotherms (BET) techniques. The photocatalytic activity was evaluated in the degradation of organic pollutant in aqueous solution under sunlight. The results showed that the ZnAl2O4 par...

  11. Development of Commercially Useable Codes to Simulate Aluminized Propellant Combustion and Related Issues

    Science.gov (United States)

    2009-11-03

    Torquato, Frank H. Stillinger, and Robert Connelly, J. Appl. Phys. 95, 989 2004. 24 Alexander Bezrukov, Monika Bargiel, and Dietrich Stoyan, Part...Avalon, G., Ugurtas, B., Grisch, F. and Bresson , A. “Numerical computations and visualization tests of the flow inside a cold gas simulation with

  12. CHROMIZING-ALUMINIZING AND CHROMIZING-SILICONIZING COATING OF A FERRITIC STEEL

    OpenAIRE

    Choquet, P.; Harper, M.; Rapp, R.

    1989-01-01

    Simultaneous deposition of Cr-Al and Cr-Si as diffusion coatings for ferritic steel (Fe-12Cr) substrate have been carried out using the pack cementation method. A computer-assisted thermodynamic study of the equilibrium vapor pressures of volatile halide species formed by the pack components was performed. The simultaneous codeposition of Cr with Al is thermodynamically possible for chloride-activated packs when the activity of Al is about three orders of magnitude lower than the chromium act...

  13. Finite element analysis on stresses field of normalized layer thickness within ceramic coating on aluminized steel

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Multilayer ceramic coatings were fabricated on steel substrate using a combined technique of hot dipping aluminum(HDA)and plasma electrolytic oxidation(PEO). A triangle of normalized layer thickness was created for describing thickness ratios of HDA/PEO coatings. Then, the effect of thickness ratio on stresses field of HDA/PEO coatings subjected to uniform normal contact load was investigated by finite element method. Results show that the surface tensile stress is mainly affected by the thickness ratio of Al layer when the total thickness of coating is unchanged. With the increase of Al layer thickness, the surface tensile stress rises quickly. When Al2O3 layer thickness increases, surface tensile stress is diminished. Meanwhile, the maximum shear stress moves rapidly towards internal part of HDA/PEO coatings. Shear stress at the Al2O3/Al interface is minimal when Al2O3 layer and Al layer have the same thickness.

  14. Simultaneous chromizing and aluminizing using chromium oxide and aluminum: (II) on austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Heo, N.H.; Kim, M.T.; Shin, J.H.; Kim, C.Y. [Korea Electr. Power Res. Inst., Taejon (Korea). Machinery and Mater. Group

    2000-02-01

    For pt.I see ibid., vol.123, p.227-30, 2000. The codeposition of Cr and Al on 304 stainless steel has been investigated, using the conversion reaction of Cr{sub 2}O{sub 3} to halide. An increase in ratio of Cr{sub 2}O{sub 3} to Al in the pack composition tends to form a chromide coating, which is very poor in high temperature oxidation resistance. A codeposited coating layer, which shows high oxidation resistance, is mainly characterized by three zones: an outer layer of iron aluminide, a nickel-rich iron aluminide, and an interdiffusion zone consisting of alpha ferrite and nickel aluminide precipitates. Oxidation resistance increased as the thickness of the outer iron aluminide layer increased. This means that the aluminum in the outer layer, rather than that in nickel aluminide precipitates or alpha ferrite, acts as a strong aluminum source forming a protective Al{sub 2}O{sub 3} scale at the coating surface. Using a pack mixture containing 10 wt.% Cr{sub 2}O{sub 3} and 10 wt.% Al, a coating, which shows excellent oxidation resistance at 1100 C, was obtained after codeposition of aluminum and chromium on 304 stainless steel at 1050 C for about 6-8 h. (orig.)

  15. Effect of diffusion on coating microstructure and oxidation resistance of aluminizing steel

    Institute of Scientific and Technical Information of China (English)

    夏原; 于升学; 姚枚; 李铁藩

    2001-01-01

    The effect of diffuse treatment on coating microstructure and oxidation resistance at high-temperature of hotdip aluminum were studied by means of TEM, SEM and XRD. The results show that, the diffusion temperature has significant effect on structure of coatings and its oxidation resistance. After diffusion at 750 ℃, the coating consists of thick outer surface layer (Fe2Al5+FeAl2 ), thin internal layer (FeAl+stripe FeAl2), and its oxidation resistance is poor. After diffusion at 950 ℃, the outer surface layer is composed of single FeAl2 phase, the internal layer is composed of FeAl phase, and its oxidation resistance declines due to the occurrence of early stage internal oxidation cracks in the coating.After diffusion at 850 ℃, the outer surface layer becomes thinner and consists of FeAl2+Fe2Al5 (small amount), the internal layer becomes thicker and consists of FeAl+spherical FeAl2, and the spheroidized FeAl2 phase in the internal layer and its existing in FeAl phase steadily improve the oxidation resistance of the coating.

  16. Growth Kinetics and Diffusion Behavior of Pack Aluminizing Coating on China Low-activation Martensitic Steel

    Institute of Scientific and Technical Information of China (English)

    YUAN; Xiao-ming; YANG; Hong-guang; ZHAO; Wei-wei; ZHAN; Qin; ZHU; Xin-xin

    2013-01-01

    In ITER TBM and future CFETR blanket,tritium permeation through structural materials into coolant or environment is an important issue.Especially,in liquid metal blankets,a high Magnet-hydro-dynamic(MHD)drop and corrosion of structural material in liquid lead-lithium become a very serious problem.To solve the above trouble,a Fe-Al/Al2O3 composite coating on China Low

  17. 渗铝钢管的焊接方法%Welding Method for Aluminized Steel Tube

    Institute of Scientific and Technical Information of China (English)

    吴凡

    2009-01-01

    渗铝钢的焊接一直是国内外尚未解决的难题,阻碍着渗铝钢的推广使用.详细分析了碳钢渗铝后焊接存在的问题,提出了新的渗铝钢管焊接方法,使其焊缝区的性能基本上与渗铝钢母材性能相当.当钢管壁厚<12 mm时,宜采用钎焊法焊接:当钢管壁厚≥12 mm时,宜采用堆焊法焊接.

  18. Immobilisation of lead smelting slag within spent aluminate-fly ash based geopolymers.

    Science.gov (United States)

    Ogundiran, M B; Nugteren, H W; Witkamp, G J

    2013-03-15

    This study presents the solidification/stabilisation and immobilisation of lead smelting slag (LSS) by its incorporation in coal fly ash - blast furnace slag based geopolymers. It also explores the use of a spent aluminium etching solution (AES) as geopolymer activator instead of the commonly used silicate solutions. The compressive strength of the geopolymers produced with the AES was lower than when applying a K-silicate solution as activator (100MPa versus 80MPa after 28 days). Compressive strength was not affected when up to 10% of the FA was replaced by LSS. NEN 12457-4, TCLP, SPLP and NEN 7375 leaching tests indicated that mobile Pb from LSS was highly immobilised. The diffusion leaching test NEN 7375 revealed exceeding of the Dutch Soil Quality Regulation threshold limits only for Se and Sb. On the condition that the remaining excess leaching can be reduced by further refinement of the mixture recipes, the proposed process will have the potential of producing waste-based construction materials that may be applied under controlled conditions in specific situations.

  19. Can zinc aluminate-titania composite be an alternative for alumina as microelectronic substrate?

    Science.gov (United States)

    Roshni, Satheesh Babu; Sebastian, Mailadil Thomas; Surendran, Kuzhichalil Peethambharan

    2017-01-01

    Alumina, thanks to its superior thermal and dielectric properties, has been the leading substrate over several decades, for power and microelectronics circuits. However, alumina lacks thermal stability since its temperature coefficient of resonant frequency (τf) is far from zero (−60 ppmK−1). The present paper explores the potentiality of a ceramic composite 0.83ZnAl2O4-0.17TiO2 (in moles, abbreviated as ZAT) substrates for electronic applications over other commercially-used alumina-based substrates and synthesized using a non-aqueous tape casting method. The present substrate has τf of + 3.9 ppmK−1 and is a valuable addition to the group of thermo-stable substrates. The ZAT substrate shows a high thermal conductivity of 31.3 Wm−1K−1 (thermal conductivity of alumina is about 24.5 Wm−1K−1), along with promising mechanical, electrical and microwave dielectric properties comparable to that of alumina-based commercial substrates. Furthermore, the newly-developed substrate material shows exceptionally good thermal stability of dielectric constant, which cannot be met with any of the alumina-based HTCC substrates. PMID:28084459

  20. Synthesis of cobalt aluminate nanopigments by a non-aqueous sol-gel route.

    Science.gov (United States)

    Karmaoui, Mohamed; Silva, Nuno J O; Amaral, Vitor S; Ibarra, Alfonso; Millán, Ángel; Palacio, Fernando

    2013-05-21

    Here we report the chemical synthesis of cobalt aluminum oxide (CoAl2O4) nanoparticles by a non-aqueous sol-gel route. The one-pot procedure is carried out at mild temperatures (in the 150 to 300 °C range), and consists of the reaction between cobalt acetate and aluminium isopropoxide in benzyl alcohol. The resulting CoAl2O4 nanoparticles show an unusually low average size, between 2.5 and 6.2 nm, which can be controlled by the synthesis temperature. The colorimetric properties of the nanoparticles are also determined by the synthesis temperature and the characteristic blue color of CoAl2O4 pigments is achieved in samples prepared at T ≥ 200 °C. The nanoparticles are antiferromagnetically ordered below ∼27 K with an uncompensated configuration. The uncompensated moment shows the typical features of strongly interacting superparamagnetic nanoparticles and spin-glass systems.

  1. Selective liquid phase oxidation of benzyl alcohol catalyzed by copper aluminate nanostructures

    Science.gov (United States)

    Ragupathi, C.; Judith Vijaya, J.; Thinesh Kumar, R.; John Kennedy, L.

    2015-01-01

    In this paper, a simple and economic route for the preparation of CuAl2O4 is proposed. The method was developed with the objective of obtaining a material with greater surface area, when compared to the spinel prepared by conventional combustion method (CCM). The catalytic properties of CuAl2O4 spinel prepared by CCM are compared with the one prepared microwave combustion method (MCM). Nano-sized CuAl2O4 were synthesized by both CCM and MCM using Opuntia dillenii haw as the plant extract, and were characterized by X-ray diffraction analysis (XRD), high resolution scanning electron microscopy (HR-SEM), N2 adsorption/desorption isotherms, and diffuse reflectance spectroscopy (DRS). Oxidation to their corresponding carbonyl compounds, high selectivity, and inexpensive precursors make this catalytic system a useful oxidation method for benzyl alcohol. The XRD results confirmed the formation of a cubic CuAl2O4. The formation of CuAl2O4 nanorices and nanorods structures were confirmed by HR-SEM. Through MCM method, CuAl2O4 (sample B) with a high specific surface area of was obtained. The band gap values of the (2.30 and 2.35 eV) for the obtained oxides are due to the nanometric dimensions of the nanostructures. The effect of the solvent, temperature, and oxidant on the oxidation of benzyl alcohol is reported.

  2. Tensile properties of aluminized V-5Cr-5Ti alloy after exposure in air environment

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Soppet, W.K. [Argonne National Lab., IL (United States)

    1997-08-01

    The objectives of this task are to (a) develop procedures to modify surface regions of V-Cr-Ti alloys in order to minimize oxygen uptake by the alloys when exposed to environments that contain oxygen, (b) evaluate the oxygen uptake of the surface-modified V-Cr-Ti alloys as a function of temperature an oxygen partial pressure in the exposure environment, (c) characterize the microstructures of oxide scales and oxygen trapped at the grain boundaries of the substrate alloys, and (d) evaluate the influence of oxygen uptake on the tensile properties of the modified alloys at room and elevated temperatures.

  3. Studies on Natural CXN Zeolite:Modification, Framework De-alumination and lon-exchange

    Institute of Scientific and Technical Information of China (English)

    LONG,Ying-Cai(龙英才); XIA,Xiao-Hui(夏晓慧); YANG,Bo(杨波); ZHANG,Ling-Mei(张玲妹); ZHOU,Wei-Zheng(周伟正); GAO,Zhi-Long(曹智龙); LI,Cai-Yun(李彩云)

    2004-01-01

    A natural CXN zeolite (stilbite, type code-STI) discovered in China was modified with NH4+ exchange by using ammonium salt and calcinations (procedure Ⅰ), or with NH4+ exchange followed by treatment with acid (procedure Ⅱ). The coordination state of Si and Al atoms in the framework, the property of ion exchange, and the adsorption of the H-STI zeolite samples prepared by different modification procedure were investigated with XRD,EDX, 29Si and 27Al MAS NMR, Ag+ ion exchange and N2 adsorption. The results of the investigations indicate that different procedure of the modification made variety on the distribution of the framework Si atoms and Al atoms,the content of non-framework aluminum, and the blocking channels and the shielding effect to the positions of the exchangeable cations. The H-STI zeolite prepared by the procedure Ⅱ possesses high ion exchange capacity, open and perfect pore system, and high thermal stability.

  4. On the processing, structure and properties of aluminum oxide-magnesium aluminate nanocomposites

    Science.gov (United States)

    McEnerney, Bryan William

    Improvement in the mechanical properties of ceramic materials is required to better integrate them into new technological applications, such as ballistic armor. While considerable attention has been given to advanced power preparation and powder processing techniques, there has been comparatively little investigation of the nanostructure of the materials. No systematic study has been performed to correlate very fine grain sizes with dynamic mechanical properties of ceramic materials. The purpose of this study is to investigate the high-strain-rate behavior of nanocomposite ceramic materials fabricated by a cost-effective, scalable processing. The starting powders chosen were Baikowski RC-SPT DBM Al 2O3 and Malakoff S30CR MgAl2O4, both being high-purity sub-1 mum powders. The test compositions studied were Al2O3---20 vol. % MgAl2O4, Al2O3---40 vol. % MgAl2O4, and Al2O3---60 vol. % MgAl2O4. The powders were consolidated by spray drying and then melting in a direct current (DC) arc plasma and, subsequently, quenched in water. The metastable powders were comminuted, cold pressed, and densified using hot isostatic pressing. The Vickers hardness of the materials was measured as a function of indentation load, and the strength was measured using a Split-Hopkinson Pressure Bar. The hardness of all three compositions was found to be unexpectedly high. This high hardness was attributed to the unique nanostructure of the materials. This nanostructure developed during decomposition of the metastable, plasma melted powder to the thermodynamically stable phases by solid state diffusion during hot isostatic pressing. With decreasing processing temperatures, the hardness of the samples improved significantly for the Al2O 3---40 vol. % MgAl2O4 and Al2O 3---60 vol. % MgAl2O4 compositions. It was further found that, within the standard deviation, there was minimal deviation between the hardness behaviors of these compositions, which was contrary to the behavior of the control samples. High-strain-rate testing indicated better than expected performance, albeit with a small sample size at a single processing temperature. The grindability of the compositions was also evaluated and found to be excellent, with some evidence of surface plasticity. The grindability of the ceramic materials varied with the MgAl2O4 content.

  5. Steel treatment with calcium-aluminate synthetic slag and addition of titanium oxide

    Directory of Open Access Journals (Sweden)

    Putan, A.

    2013-02-01

    Full Text Available The paper introduces the results of the experiments on synthetic slag desulphurization and deoxidizing using slag belonging to the ternary system CaO-Al2O3-TiO2. The experiments have been done in a 10 kg induction furnace. In order to obtain the reducing slag we used a mixture of lime, alumina and titanium oxide, representing 2 % of the charge weight. The experiments were done on mechanical mixtures produced according to various recipes; for each experiment, the slag was sampled in order to determine its chemical composition and the steel was also sampled, in order to determine its contents in sulphur and oxygen. The resulting data have been processed in EXCEL, which gave the correlation equations between the desulphurization and deoxidizing output and the chemical composition of the synthetic slag, respectively the ratio and sum of the oxides.

    En el trabajo se presentan los resultados del experimento que se refiere a la desulfuración y desoxidación de las escorias sintéticas con escorias del sistema ternario CaO-Al2O3-TiO2.. Los experimentos se hicieron en un horno con inducción de 10 kg de capacidad. Para formar las escorias reductoras se ha utilizado una mezcla compuesta de cal, alúmina y óxido de titanio en porcentaje de 2 % del peso de la carga de acero más escoria sintética. Para los experimentos se usaron mezclas mecánicas producidas por varias recetas y de cada experimento se tomaron muestras de escorias para determinar la composición química y muestras de acero para determinar el contenido de azúfre y oxígeno. Los datos obtenidos fueron procesados en el programa de cálculo EXCEL, obteniéndose ecuaciones de correlación entre la eficiencia de la desulfuración y desoxidación y la composición química de la escoria sintética.

  6. Characterization of Point Defects in Lithium Aluminate (LiAlO2) Single Crystals

    Science.gov (United States)

    2015-09-17

    systems studied with EPR, the concept of the spin Hamiltonian was introduced to describe the behavior of an unpaired electron in a crystalline...the true wave function of the defect system . The spin Hamiltonian is given by H = HEZ +HFS +HHF +HNZ +HQ [J] (2.15) HEZ = µBŜ · g ·B electron Zeeman...sample through various planes. In the defect coordinate system the g matrix is diagonal and is usually 53 expressed as [86] g =       gx 0 0 0

  7. Thermal stability and kinetics of defects in magnesium aluminate spinel irradiated with fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Yasuda, Kazuhiro E-mail: yasudak@nucl.kyushu-u.ac.jp; Kinoshita, Chiken; Fukuda, Korehisa; Garner, Frank A

    2000-12-01

    Thermal stability of interstitial-type dislocation loops and cavities in single crystals of MgAl{sub 2}O{sub 4} was examined during isochronal and isothermal annealing. The specimens were irradiated with fast-neutrons in FFTF/MOTA at 658 and 1023 K up to 249 dpa. During the isochronal annealing, dislocation loops started to shrink around 1000 K and completely disappeared at 1470 K without changing their character. Cavities grew slightly around 1570 K, and above this temperature, cavities shrunk with increasing annealing temperature. The recovery stage of point defects in MgAl{sub 2}O{sub 4} was discussed in terms of the thermal stability of defect clusters; vacancy migration starts around 1000 K (corresponding to stage III), whereas vacancy clusters start to dissociate around 1570 K (corresponding to stage V). The vacancy migration energy for rate controlling species was estimated from the shrinkage process of interstitial-type dislocation loops to be 2.0 {+-} 0.7 eV.

  8. Ceramic joining through reactive wetting of alumina with calcium aluminate refractory cements

    Indian Academy of Sciences (India)

    K Geetha; A M Umarji; T R N Kutty

    2000-08-01

    Compositions in CaO–Al2O3 system have been prepared by gel–to–crystallite conversion method. Reactive powders of 1 : 2, 1 : 1, 2 : 1 and 3 : 1 of CaO and Al2O3 compositions were obtained by calcining the product at 800–1200°C. Fine grained powders were used as refractory cement for joining alumina ceramics. An optimum temperature of 1450°C for 4 h produced joints of satisfactory strength. The microstructure and X-ray phase analysis of the fractured joint surface clearly indicate reactive wetting of the alumina ceramics. This wetting enhances the joining of alumina substrates and can be attributed to the formation of Ca12Al14O33 liquid phase. The results are explained by using CaO–Al2O3 phase diagram.

  9. Synchrotron Vacuum Ultraviolet Light and Soft X-Ray Radiation Effects on Aluminized Teflon FEP Investigated

    Science.gov (United States)

    Dever, Joyce A.; Townsend, Jacqueline A.; Gaier, James R.; Jalics, Alice I.

    1999-01-01

    Since the Hubble Space Telescope (HST) was deployed in low Earth orbit in April 1990, two servicing missions have been conducted to upgrade its scientific capabilities. Minor cracking of second-surface metalized Teflon FEP (DuPont; fluorinated ethylene propylene) surfaces from multilayer insulation (MLI) was first observed upon close examination of samples with high solar exposure retrieved during the first servicing mission, which was conducted 3.6 years after deployment. During the second HST servicing mission, 6.8 years after deployment, astronaut observations and photographic documentation revealed significant cracks in the Teflon FEP layer of the MLI on both the solar- and anti-solar-facing surfaces of the telescope. NASA Goddard Space Flight Center directed the efforts of the Hubble Space Telescope MLI Failure Review Board, whose goals included identifying the low-Earth-orbit environmental constituent(s) responsible for the cracking and embrittling of Teflon FEP which was observed during the second servicing mission. The NASA Lewis Research Center provided significant support to this effort. Because soft x-ray radiation from solar flares had been considered as a possible cause for the degradation of the mechanical properties of Teflon FEP (ref. 1), the effects of soft xray radiation and vacuum ultraviolet light on Teflon FEP were investigated. In this Lewisled effort, samples of Teflon FEP with a 100-nm layer of vapor-deposited aluminum (VDA) on the backside were exposed to synchrotron radiation of various vacuum ultraviolet and soft x-ray wavelengths between 18 nm (69 eV) and 0.65 nm (1900 eV). Synchrotron radiation exposures were conducted using the National Synchrotron Light Source at Brookhaven National Laboratory. Samples of FEP/VDA were exposed with the FEP surface facing the synchrotron beam. Doses and fluences were compared with those estimated for the 20-yr Hubble Space Telescope mission.

  10. Can zinc aluminate-titania composite be an alternative for alumina as microelectronic substrate?

    Science.gov (United States)

    Roshni, Satheesh Babu; Sebastian, Mailadil Thomas; Surendran, Kuzhichalil Peethambharan

    2017-01-01

    Alumina, thanks to its superior thermal and dielectric properties, has been the leading substrate over several decades, for power and microelectronics circuits. However, alumina lacks thermal stability since its temperature coefficient of resonant frequency (τf) is far from zero (‑60 ppmK‑1). The present paper explores the potentiality of a ceramic composite 0.83ZnAl2O4-0.17TiO2 (in moles, abbreviated as ZAT) substrates for electronic applications over other commercially-used alumina-based substrates and synthesized using a non-aqueous tape casting method. The present substrate has τf of + 3.9 ppmK‑1 and is a valuable addition to the group of thermo-stable substrates. The ZAT substrate shows a high thermal conductivity of 31.3 Wm‑1K‑1 (thermal conductivity of alumina is about 24.5 Wm‑1K‑1), along with promising mechanical, electrical and microwave dielectric properties comparable to that of alumina-based commercial substrates. Furthermore, the newly-developed substrate material shows exceptionally good thermal stability of dielectric constant, which cannot be met with any of the alumina-based HTCC substrates.

  11. THERMODYNAMIC PROPERTIES OF AQUEOUS ALUMINATE ION, Al (OH)4- (aq)

    Institute of Scientific and Technical Information of China (English)

    1994-01-01

    THERMODYNAMICPROPERTIESOFAQUEOUSALUMINATEION,Al(OH)_4 ̄-(aq)THERMODYNAMICPROPERTIESOFAQUEOUSALUMINATEION,Al(OH)_4 ̄-(aq)¥ChenQi...

  12. Structural parameters and X-ray Debye temperature determination study on copper-ferrite-aluminates

    Science.gov (United States)

    Lakhani, V. K.; Pathak, T. K.; Vasoya, N. H.; Modi, K. B.

    2011-03-01

    The compositional dependence of structural parameters and X-ray Debye temperature for CuAl xFe 2- xO 4 ( x = 0.0, 0.2, 0.4 and 0.6) spinel ferrite system has been studied by means of X-ray powder diffraction (XRD) patterns analysis at 300 K. The XRD data have been used to determine the lattice constant, X-ray density, distribution of cations among the tetrahedral and octahedral sites of spinel lattice, oxygen positional parameter, site radii, bond angle, bond length and interionic distances. The X-ray Debye temperatures have been determined from integrated intensities of selected Bragg reflections. It is found that Al 3+-substitution has marked influence on various parameters. A deficit of Cu 2+-cations at the octahedral sites of the spinel lattice leads to the absence of co-operative active Jahn-Teller distortion and the crystal structure retains into cubic. The increasing disagreement between observed and calculated intensities and reduction in intensity of diffracted beam with increasing Al-concentration have been explained based on preferred orientation and extinction effects. The effect of oxygen deficiency on intensity ratios of planes has been discussed in brief.

  13. Tritium removal from various lithium aluminates irradiated by fast and thermal neutrons (COMPLIMENT experiment)

    Science.gov (United States)

    Alvani, C.; Carconi, P. L.; Casadio, S.; Moauro, A.

    1994-02-01

    Within the frame of the COMPLIMENT experiment, γ-LiAlO 2 specimens with different microstructures (grain size distributions) were tested in the same environmental conditions to compare the effects caused by 6Li(n, α)T reaction and by fast neutron scattering, the damaging dose being held at about the same level (1.6-1.8 dpa). The tritium retention times were obtained by the tritium removal of isothermal annealing under He + 0.1% H 2 sweeping gas. In spite of the different Li burnups (2.5% and 0.25%) and the residual tritium concentrations which were found in the irradiated specimens (4.3 Ci/g and 0.09 Ci/g, respectively, for specimens held at 450°C during the irradiations), the kinetics of tritium removal was not found to be discriminated by the two different irradiations. Moreover, the results were found to agree with those previously obtained by the "in-situ" TEQUILA experiment, performed on the same type of Li ceramics. Hence, the apparent first order desorption mechanism has been confirmed to control the kinetics of tritium removal from the porous fine grain γ-LiAlO 2 ceramics.

  14. Tritium removal from various lithium aluminates irradiated by fast and thermal neutrons (COMPLIMENT experiment)

    Energy Technology Data Exchange (ETDEWEB)

    Alvani, C. (ENEA CRE Casaccia, INN/NUMA, Rome (Italy)); Carconi, P.L. (ENEA CRE Casaccia, INN/NUMA, Rome (Italy)); Casadio, S. (ENEA CRE Casaccia, INN/NUMA, Rome (Italy)); Moauro, A. (ENEA CRE Casaccia, INN/NUMA, Rome (Italy))

    1994-02-01

    Within the frame of the COMPLIMENT experiment, [gamma]-LiAlO[sub 2] specimens with different microstructures (grain size distributions) were tested in the same environmental conditions to compare the effects caused by [sup 6]Li(n, [alpha])T reaction and by fast neutron scattering, the damaging dose being held at about the same level (1.6-1.8 dpa). The tritium retention times were obtained by the tritium removal of isothermal annealing under He + 0.1% H[sub 2] sweeping gas. In spite of the different Li burnups (2.5% and 0.25%) and the residual tritium concentrations which were found in the irradiated specimens (4.3 Ci/g and 0.09 Ci/g, respectively, for specimens held at 450 C during the irradiations), the kinetics of tritium removal was not found to be discriminated by the two different irradiations. Moreover, the results were found to agree with those previously obtained by the ''in-situ'' TEQUILA experiment, performed on the same type of Li ceramics. Hence, the apparent first order desorption mechanism has been confirmed to control the kinetics of tritium removal from the porous fine grain [gamma]-LiAlO[sub 2] ceramics. (orig.)

  15. Surface Structures of the Metal-Oxide Materials Strontium Titanate and Lanthanum Aluminate

    Science.gov (United States)

    Kienzle, Danielle M.

    A wide array of techniques were applied in this research to investigate the perovskite materials SrTiO3 and LaAlO3 with the goal of furthering the understanding of oxide surfaces. Specifically, a combination of transmission electron diffraction, direct methods and density functional theory was used to determine the structure of the SrTiO3 (001) (√13x√13)R33.7° surface reconstruction. It has a TiO 2-rich surface with a 2D tiling of edge or corner-sharing TiO5 octahedra. By tiling these units and forming network surface structures ranging from ordered, like the 2x1 and c(4x2), to pseudo-ordered, like the c(6x2), to a disordered glass-like surface layer made up of TiOx units, dictated by local bond valence sums. The LaAlO3 (110) 3x1 surface reconstruction, here reported for the first time, was found to have a hydroxylated Al-rich surface with X-ray photoelectron spectroscopy. Transmission electron diffraction data and direct methods revealed a high resemblance to the previously solved SrTiO3 (110) 3x1 reconstruction leading to a hydrated version that fits the for LaAlO3 3x1 structure. The hydroxyl groups are necessary to balance the surface polarity, an issue arising from the difference in cationic valences between La/Sr and Al/Ti. Also reported and investigated here for the first time is a LaAlO3 (100) 5x2 reconstruction. A direct methods analysis was done for several sets of recorded diffraction pattern; however the results have yet to lead to an atomic surface structure solution. X-ray photoelectron spectra were collected over a range of detector-to-surface-normal angles elucidating an Al-rich surface layer. X-ray photoelectron intensities were calculated for a model of alternating Al and La layers over a range of grazing angles and varying amounts of Al in the top surface layer. An Al concentration of 0.5 was found to give the best fit to experimental results.

  16. The Experimental Mod 3 Firefighters’ Aluminized Crash-Rescue, Fire- Proximity Hood

    Science.gov (United States)

    1984-07-01

    if required, and then proposed for adoption to replace the current standard headwear . The main differences between the standard hood and the... headwear and are suitable for wear under the same conditions as the standard. In this evaluation you are being asked to wear the hood, as needed, during...In this connection, the new style should be compared with the standard. If you have any opinions as to how this headwear can be improved, kindly

  17. The Experimental MOD III Firefighter’s Aluminized, Crash-Rescue, Fire- Proximity Hood.

    Science.gov (United States)

    1984-07-01

    required, and then proposed for adoption to replace the current standard headwear . The main differences between the standard hood and the experimental hood...the ease of use of all type of breathing apparatus under the hood. The thermal qualities of these hoods are comparable to the standard headwear and...connection, the new style should be compared with the standard. If you have any opinions as to how this headwear can be improved, kindly offer your

  18. Model of apparent crystal growth rate and kinetics of seeded precipitation from sodium aluminate solution

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-bin; LIU Zhi-jian; XU Xiao-hui; ZHOU Qiu-sheng; PENG Zhi-hong; LIU Gui-hua

    2005-01-01

    Based on the population balance equation in a batch crystallizer characteristic of seeded precipitation, a model to calculate the rate of apparent crystal growth of aluminum hydroxide from the size distribution was deve-loped. The simulation results indicate that the rate of apparent crystal growth during seeded precipitation exhibits a manifest dependence on the crystal size. In general, there is an obvious increase in the apparent crystal growth rate with the augment in crystal size. The apparent activation energy increases with the increase of characteristic crystal size, which indicates that the growth of small crystals is controlled by surface chemical reaction; it is gradually controlled by both the surface reaction and diffusion with the augment in crystal size.

  19. Radiation-induced luminescence in magnesium aluminate spinel crystals and ceramics

    Science.gov (United States)

    Gritsyna, V. T.; Kazarinov, Yu. G.; Kobyakov, V. A.; Reimanis, I. E.

    2006-09-01

    Radioluminescence (RL) and thermoluminescence (TL) in spinel crystals and ceramics were investigated to elucidate the radiation-induced electronic processes in single crystals grown by Verneuil and Czochralski methods as well as transparent and translucent ceramics. Both RL and TL spectra demonstrate a UV-band related to electron-hole recombination luminescence at intrinsic defects; green and red luminescence are identified with emission of Mn 2+- and Cr 3+-ions, respectively. The kinetics of growth of different RL luminescence bands depending on dose at the prolonged X-irradiation shows the competitive character of charge and energy transfer between defects and impurity ions. The dependence of RL intensity on the temperature of the sample was measured in the range of 300-750 K and compared with TL for different emission bands. The variety of maxima in the temperature dependence of RL and in the glow curves of TL measured for different luminescence bands in spinels of different origins and crystalline forms is used to show that charge carrier traps and luminescence centers are not isolated defects but are complexes of defects and impurities. The formation, structure and properties of these complexes depend on the processing conditions.

  20. Ceramic compositions based on nano forsterite/nano magnesium aluminate spinel powders

    Energy Technology Data Exchange (ETDEWEB)

    Khattab, R.M. [Refractories, Ceramics and Building Materials Dept., National Research Centre, Dokki, 12622 Giza (Egypt); Wahsh, M.M.S., E-mail: mmswahsh@yahoo.com [Refractories, Ceramics and Building Materials Dept., National Research Centre, Dokki, 12622 Giza (Egypt); Khalil, N.M. [Refractories, Ceramics and Building Materials Dept., National Research Centre, Dokki, 12622 Giza (Egypt); Department of Chemistry, Faculty of Sciences and Arts, Khulais, University of Jeddah (Saudi Arabia)

    2015-09-15

    According to the wide applications in the field of chemical and engineering industries, forsterite (Mg{sub 2}SiO{sub 4})/spinel (MgAl{sub 2}O{sub 4}) ceramic compositions were the matter of interest of several research works during the last three decades. This work aims at preparation and characterization of improved ceramic bodies based on forsterite and spinel nano powders through controlling the forsterite and spinel contents in the prepared mixes. These prepared ceramic compositions have been investigated through measuring the densification parameters, cold crushing strength as well as volume resistively. Nano spinel was added from 0 to 30 mass% on expense of nano forsterite matrix and fired at 1550 °C for 2 h. The phase composition of the fired samples was examined using x-ray diffraction (XRD) technique. The microstructure of some selected samples was shown using scanning electron microscope (SEM). A pronounced improvement in the sintering, mechanical properties and volume resistively were achieved with increasing of nano spinel addition up to 15 mass%. This is due to the improvement in the matrix of the prepared forsterite/spinel bodies as a result of well distribution of spinel in the forsterite matrix as depicted by SEM analysis. - Highlights: • Ceramic compositions based on nano forsterite/nano-MgAl{sub 2}O{sub 4} spinel were synthesized. • CCS was improved (333.78 MPa) through 15 mass% of nano-MgAl{sub 2}O{sub 4} spinel addition. • Volume resistivity was enhanced to 203*10{sup 13} Ohm cm with 15 mass% of spinel addition. • Beyond 15 mass% spinel, CCS and volume resistivity were decreased.

  1. TL and OSL studies of carbon doped magnesium aluminate (MgAl2O4:C)

    Science.gov (United States)

    Raj, Sanu S.; Mishra, D. R.; Soni, Anuj; Grover, V.; Polymeris, G. S.; Muthe, K. P.; Jha, S. K.; Tyagi, A. K.

    2016-10-01

    The MgAl2O4:C has been synthesized by using two different methods by electron gun and vacuum assisted melting of MgAl2O4 in presence of graphite. The MgAl2O4:C phosphor thus developed by these two different methods have similar types of the TL/OSL defects with multiple overlapping TL glow peaks from 100 °C to 400 °C. The Computerized Curve De-convolution Analysis (CCDA) has been used to measure TL parameters such as thermal trap depth, frequency factor and order of kinetic associated with charge transfer process in TL phenomenon. The investigated TL/OSL results show that these two methods of incorporating carbon in MgAl2O4 have generated closely resemble the defects of similar types in MgAl2O4:C lattice. However, the MgAl2O4:C synthesized by electron gun shows relatively larger concentration of the TL/OSL defects as compared to MgAl2O4:C synthesized using vacuum assisted melting method. The photo-ionization cross-section (PIC) associated with fastest OSL component of MgAl2O4: C is found to be ∼ 0.5 times than that of fastest OSL component of commercially available dosimetric grade α-Al2O3:C. The MgAl2O4:C thus developed shows good dynamic OSL dose linearity from few mGy to 1 Gy. This work reveals that MgAl2O4:C could be developed as potential tissue equivalent OSL / TL material.

  2. 含镁铝尖晶石的铝酸盐水泥制备及力学性能研究%Preparation and mechanical properties of aluminate cements containing magnesium aluminate spinel

    Institute of Scientific and Technical Information of China (English)

    周文彩; 李金洪; 姜晓谦; 班建伟; 郭伟娟

    2010-01-01

    设计不同的水泥熟料物相组成,以石灰石、重烧氧化镁和铝矾土熟料为原料,于1400℃3 h处理后制备了含不同量镁铝尖晶石相的铝酸盐水泥.利用XRD和SEM对不同配比的合成产物的物相及形貌特征进行了分析,并对这种新型铝酸盐水泥浇注料进行了抗压强度的测试.结果表明:含镁铝尖晶石的铝酸盐水泥的主要物相为一铝酸钙(CA)、镁铝尖晶石(MA)和二铝酸钙(CA2),还有少量的硅铝酸二钙(C2AS)和残余刚玉(α-Al2O3);浇注料的强度随MA含量的减小而增大,且随水化时间延长,其强度增进稳定.

  3. Land use, physiography and degradation in the northeastern department Alumine, Neuquén Uso de las tierras, fisiografía y degradación, en el noreste del departamento Aluminé, Neuquén

    Directory of Open Access Journals (Sweden)

    Marcos Damián Mare

    2009-01-01

    Full Text Available Kilca River basin is one of the major river systems before the mountain region, located in the center of the province of Neuquen. In this zone, humid climates, the dominant land use is "veranada", which consists of three annual steps of one type of livestock transhumance, based on the exploitation of natural grassland forage. Given the physiographic formation of these landscapes, there is in them a high propensity to develop geomorphological processes of erosion and landslides. Historical factors linked to the evolution of livestock activity in the region on both sides of the mountain axis, have been identified since the late nineteenth century, land use patterns characterized by excessive seasonal stocking. This organization of the activity involved, not just a deterioration of pastures, but also the break out and acceleration of geomorphic processes. The aim of this paper is to analyze the current problems, focusing biophysical processes, linked to social practices. In this sense, we describe and explain physiographic conditions in terms of degree of instability and deterioration of the landLa cuenca del río Kilca es uno de los principales sistemas hidrográficos de la región antecordillerana, ubicada en el centro de la provincia de Neuquén. En esta zona, de clima subhúmedo, el uso de suelo dominante es el de "veranada", que consiste en una de las tres etapas anuales de un tipo de ganadería trashumante, basado en el aprovechamiento forrajero de pastizales naturales. Dada la constitución fisiográfica de estos paisajes, existe en ellos una gran propensión al desarrollo de procesos geomorfológicos de erosión y remoción en masa. Los factores históricos vinculados a la evolución de la actividad ganadera en la región a ambos lados del eje cordillerano, han determinado desde fines del siglo XIX, modalidades de uso de suelo caracterizadas por el exceso estacional de la carga ganadera. Esta organización de la actividad implicó, no sólo un deterioro de las pasturas, sino además el desencadenamiento y aceleración de los procesos geomorfológicos. El objetivo de este trabajo es analizar la problemática actual, enfocando los procesos del medio biofísico, vinculados con las prácticas sociales. En este sentido, se describen y explican las condiciones fisiográficas, en términos del grado de inestabilidad y deterioro de las tierras

  4. Chemical Equilibrium of Aluminate in Hanford Tank Waste Originating from Tanks 241-AN-105 and 241-AP-108

    Energy Technology Data Exchange (ETDEWEB)

    McCoskey, Jacob K. [Washington River Protection Solutions LLC, Richland, WA (United States); Cooke, Gary A. [Washington River Protection Solutions LLC, Richland, WA (United States); Herting, Daniel L. [Washington River Protection Solutions LLC, Richland, WA (United States)

    2015-09-23

    The purposes of the study described in this document follow; Determine or estimate the thermodynamic equilibrium of gibbsite in contact with two real tank waste supernatant liquids through both dissolution of gibbsite (bottom-up approach) and precipitation of aluminum-bearing solids (top-down approach); determine or estimate the thermodynamic equilibrium of a mixture of gibbsite and real tank waste saltcake in contact with real tank waste supernatant liquid through both dissolution of gibbsite and precipitation of aluminum-bearing solids; and characterize the solids present after equilibrium and precipitation of aluminum-bearing solids.

  5. Effect of particle size on the experimental dissolution and auto-aluminization processes of K-vermiculite

    Science.gov (United States)

    Viennet, Jean-Christophe; Hubert, Fabien; Tertre, Emmanuel; Ferrage, Eric; Robin, Valentin; Dzene, Liva; Cochet, Carine; Turpault, Marie-Pierre

    2016-05-01

    In acidic soils, the fixation of Al in the interlayer spaces of 2:1 clay minerals and the subsequent formation of hydroxyl interlayer minerals (HIMs) are known to reduce soil fertility. The resulting crystal structure of HIMs consist of complex mixed-layer minerals (MLMs) with contrasting relative proportions of expandable, hydroxy-interlayers (HI) and illite layers. The present study aims to experimentally assess the influence of particle size on the formation of such complex HIMs for vermiculite saturated with potassium (K). Based on chemical and structural data, this study reports the dissolution and Al-interlayer occupancy of three size fractions (0.1-0.2, 1-2 and 10-20 μm) of K-vermiculite, which were obtained at pH = 3 by using stirred flow-through reactors. The Al-interlayer occupancies were ordered 0.1-0.2 μm soils.

  6. Nickel-aluminium complex: a simple and effective precursor for nickel aluminate (NiAl2O4 spinel

    Directory of Open Access Journals (Sweden)

    Apirat Laobuthee

    2008-01-01

    Full Text Available A reaction of aluminium hydroxide, nickel nitrate and triethanolamine in ethylene glycol provided, in one step, a simple and effective nickel-aluminium complex precursor for NiAl2O4 spinel. On the basis of 1H-, 13C-NMR spectroscopy, and mass spectrometry, the possible structure of the complex was proposed as a trimetallic double alkoxide consisting of two four-coordinate TEA-Al (alumatrane moieties linked via a bridging TEA group enfolding the Ni2+ cation. Transformation of the nickel-aluminium complex to pure spinel occurred when the complex precursor was pyrolysed at 1000C for 5 h. The BET surface area of the pyrolysed product was found to be 31 m2/g. In addition, the morphology of the powder product was examined by SEM.

  7. Investigations on Valence-Change Behaviors of Europium Ions in Eu-Doped Aluminate and Silicate Phosphors

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Compounds of Sr3Al2O6∶Eu, Sr4Al14O25∶Eu, and BaZnSiO4∶Eu were synthesized by high-temperature solid state reactions. The doping Eu3+ ions were partially reduced to Eu2+ in Sr4Al14O25∶Eu and BaZnSiO4∶Eu prepared in an oxidizing atmosphere, N2+O2. However, such an abnormal reduction process could not be performed in Sr3Al2O6∶Eu, which was also prepared in an atmosphere of N2+O2. Moreover, even though Sr3Al2O6∶Eu was synthesized in a reducing condition CO, only part of the Eu3+ ions was reduced to Eu2+. The existence of trivalent and divalent europium ions was confirmed by photoluminescent spectra. The different valence-change behaviors of europium ions in the hosts were attributed to the difference in host crystal structures. The higher the crystal structure stiffness, the easier the reduction process from Eu3+ to Eu2+.

  8. Manufacturing issues and optical properties of rare-earth (Y, Lu, Sc, Nd) aluminate garnets composite transparent ceramics

    Science.gov (United States)

    Bonnet, Loïck; Boulesteix, Rémy; Maître, Alexandre; Sallé, Christian; Couderc, Vincent; Brenier, Alain

    2015-12-01

    In this work, a comparative study of reactive sintering and optical properties of three laser composite transparent ceramics doped with neodymium: Nd:YAG/Nd:YS1AG, Nd:YAG/Nd:LuAG and Nd:YS1AG/Nd:LuAG has been achieved. Samples were manufactured thanks to pressureless co-sintering under vacuum of bilayer powder compacts. The reaction sequence from primary oxides to final garnet phases has been investigated. Similar dilatometric behavior was observed during reactive-sintering for each composition. Differential shrinkage can be thus accommodated to some extent. Second, this work has shown that the intermediate zone at composites interface is composed of single-phased garnet solid-solution with continuous evolution from one side to the other. The thickness of the interdiffusion zone was found to be limited to about 100 μm in all cases and appeared to be well described by classical diffusion laws of Fick and Whipple-Le Claire. The analyses of spectroscopic properties of transparent ceramics composites have finally shown that composite ceramics should be suitable to produce dual wavelength emission for terahertz generation.

  9. An Welding Technology for Aluminizing Steel Pipe%渗铝钢管道的焊接工艺

    Institute of Scientific and Technical Information of China (English)

    黄圣正

    2004-01-01

    焊接接头的力学试验、金相组织分析及工程实践证明,采用A312SL焊条焊接20渗铝钢管只要采用正确的坡口加工方法和合理的焊接工艺,可获得具有抗高温氧化和耐磨性能的焊接接头.

  10. THE PREPARATION METHODS NANOSIZED COBALT ALUMINATE POWDERS%纳米钴蓝颜料的制备方法

    Institute of Scientific and Technical Information of China (English)

    于方丽; 周永强

    2006-01-01

    概述了化学共沉淀法、溶胶-凝胶法、有机配合物前驱体法、微乳液法以及水热合成法的制备原理、制备过程.重点介绍了这些方法在纳米钴蓝颜料制备中的应用.

  11. Improved efficiency of dye-sensitized solar cells by doping of strontium aluminate phosphor in TiO2 photoelectrode

    Directory of Open Access Journals (Sweden)

    Hwangbo Seung

    2015-06-01

    Full Text Available SrAl2O4:Eu2+, Dy3+ phosphor was synthesized by chemical solution route to use as a dopant in TiO2 layer employed as a photoelectrode for down conversion of ultraviolet and near-ultraviolet to visible and near-infrared light in a dye-sensitized solar cell. Nano-crystalline structure of the SrAl2O4:Eu2+, Dy3+ powder was confirmed by X-ray diffraction analysis and field emission scanning electron microscopy. Monitored at 520 nm, SrAl2O4:Eu2+, Dy3+ phosphor showed emission peaks at 460 to 610 nm due to 4f6 4f7 transitions of Eu2+ ions. For the study, SrAl2O4:Eu2+, Dy3+ phosphor-doped TiO2 layer was deposited on fluorine-doped tin oxide coated glass by electrostatic spray deposition. The short circuit current, open circuit voltage, fill factor, and conversion efficiency of the cells were measured. Experimental results revealed that the device efficiency for the SrAl2O4:Eu2+, Dy3+ phosphor-doped TiO2 layer increased to 7.20 %, whereas that of the pure-TiO2 photoelectrode was 4.13 %.

  12. Generation of White Light from Dysprosium-Doped Strontium Aluminate Phosphor by a Solid-State Reaction Method

    Science.gov (United States)

    Sahu, Ishwar Prasad; Bisen, D. P.; Brahme, N.; Tamrakar, Raunak Kumar

    2016-04-01

    A single-host lattice, white light-emitting SrAl2O4:Dy3+ phosphor was synthesized by a solid-state reaction method. The crystal structure of prepared SrAl2O4:Dy3+ phosphor was in a monoclinic phase with space group P21. The chemical composition of the sintered SrAl2O4:Dy3+ phosphor was confirmed by the energy dispersive x-ray spectroscopy technique. Under ultra-violet excitation, the characteristic emissions of Dy3+ are peaking at 475 nm, 573 nm and 660 nm, originating from the transitions of 4F9/2 → 6H15/2, 4F9/2 →&!nbsp; 6H13/2 and 4F9/2 → 6H11/2 in the 4f9 configuration of Dy3+ ions. Commission International de I'Eclairage color coordinates of SrAl2O4:Dy3+ are suitable for white light-emitting phosphor. In order to investigate the suitability of the samples as white color light sources for industrial uses, correlated color temperature (CCT) and color rendering index (CRI) values were calculated. Values of CCT and CRI were found well within the defined acceptable range. Mechanoluminescence (ML) intensity of SrAl2O4:Dy3+ phosphor increased linearly with increasing impact velocity of the moving piston. Thus, the present investigation indicates piezo-electricity was responsible for producing ML in sintered SrAl2O4:Dy3+ phosphor. Decay rates of the exponential decaying period of the ML curves do not change significantly with impact velocity. The photoluminescence and ML results suggest that the synthesized SrAl2O4:Dy3+ phosphor was useful for the white light-emitting diodes and stress sensor respectively.

  13. The component slope linear model for calculating intensive partial molar properties /application to waste glasses and aluminate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, Jacob G. [Washington River Protection Solutions, LLC, Richland, WA (United States)

    2013-01-11

    Partial molar properties are the changes occurring when the fraction of one component is varied while the fractions of all other component mole fractions change proportionally. They have many practical and theoretical applications in chemical thermodynamics. Partial molar properties of chemical mixtures are difficult to measure because the component mole fractions must sum to one, so a change in fraction of one component must be offset with a change in one or more other components. Given that more than one component fraction is changing at a time, it is difficult to assign a change in measured response to a change in a single component. In this study, the Component Slope Linear Model (CSLM), a model previously published in the statistics literature, is shown to have coefficients that correspond to the intensive partial molar properties. If a measured property is plotted against the mole fraction of a component while keeping the proportions of all other components constant, the slope at any given point on a graph of this curve is the partial molar property for that constituent. Actually plotting this graph has been used to determine partial molar properties for many years. The CSLM directly includes this slope in a model that predicts properties as a function of the component mole fractions. This model is demonstrated by applying it to the constant pressure heat capacity data from the NaOH-NaAl(OH){sub 4}-H{sub 2}O system, a system that simplifies Hanford nuclear waste. The partial molar properties of H{sub 2}O, NaOH, and NaAl(OH){sub 4} are determined. The equivalence of the CSLM and the graphical method is verified by comparing results determined by the two methods. The CSLM model has been previously used to predict the liquidus temperature of spinel crystals precipitated from Hanford waste glass. Those model coefficients are re-interpreted here as the partial molar spinel liquidus temperature of the glass components.

  14. Effect of SO2 and steam on CO2 capture performance of biomass-templated calcium aluminate pellets.

    Science.gov (United States)

    Erans, María; Beisheim, Theodor; Manovic, Vasilije; Jeremias, Michal; Patchigolla, Kumar; Dieter, Heiko; Duan, Lunbo; Anthony, Edward J

    2016-10-20

    Four types of synthetic sorbents were developed for high-temperature post-combustion calcium looping CO2 capture using Longcal limestone. Pellets were prepared with: lime and cement (LC); lime and flour (LF); lime, cement and flour (LCF); and lime, cement and flour doped with seawater (LCFSW). Flour was used as a templating material. All samples underwent 20 cycles in a TGA under two different calcination conditions. Moreover, the prepared sorbents were tested for 10 carbonation/calcination cycles in a 68 mm-internal-diameter bubbling fluidized bed (BFB) in three environments: with no sulphur and no steam; in the presence of sulphur; and with steam. When compared to limestone, all the synthetic sorbents exhibited enhanced CO2 capture performance in the BFB experiments, with the exception of the sample doped with seawater. In the BFB tests, the addition of cement binder during the pelletisation process resulted in the increase of CO2 capture capacity from 0.08 g CO2 per g sorbent (LF) to 0.15 g CO2 per g sorbent (LCF) by the 10(th) cycle. The CO2 uptake in the presence of SO2 dramatically declined by the 10(th) cycle; for example, from 0.22 g CO2 per g sorbent to 0.05 g CO2 per g sorbent in the case of the untemplated material (LC). However, as expected all samples showed improved performance in the presence of steam, and the decay of reactivity during the cycles was less pronounced. Nevertheless, in the BFB environment, the templated pellets showed poorer CO2 capture performance. This is presumably because of material loss due to attrition under the FB conditions. By contrast, the templated materials performed better than untemplated materials under TGA conditions. This indicates that the reduction of attrition is critical when employing templated materials in realistic systems with FB reactors.

  15. Evaluation of pH, calcium ion release and antimicrobial activity of a new calcium aluminate cement

    Directory of Open Access Journals (Sweden)

    Fernanda de Carvalho Panzeri Pires-de-Souza

    2013-07-01

    Full Text Available This study evaluated the pH, calcium ion release and antimicrobial activity of EndoBinder (EB, containing different radiopacifiers: bismuth oxide (Bi2O3, zinc oxide (ZnO or zirconium oxide (ZrO2, in comparison to MTA. For pH and calcium ion release tests, 5 specimens per group (n = 5 were immersed into 10 mL of distilled and deionized water at 37°C. After 2, 4, 12, 24, 48 h; 7, 14 and 28 days, the pH was measured and calcium ion release quantified in an atomic absorption spectrophotometer. For antimicrobial activity, the cements were tested against S. aureus, E. coli, E. faecalis and C. albicans, in triplicate. MTA presented higher values for pH and calcium ion release than the other groups, however, with no statistically significant difference after 28 days (p > 0.05; and the largest inhibition halos for all strains, with no significant difference (E. coli and E. faecalis for pure EB and EB + Bi2O3 (p > 0.05. EB presented similar performance to that of MTA as regards pH and calcium ion release; however, when ZnO and ZrO2 were used, EB did not present antimicrobial activity against some strains.

  16. Calcium aluminate silicate Ca2Al2SiO7 single crystal applicable to piezoelectric sensors at high temperature

    Science.gov (United States)

    Takeda, Hiroaki; Hagiwara, Manabu; Noguchi, Hiroaki; Hoshina, Takuya; Takahashi, Tomoko; Kodama, Nobuhiro; Tsurumi, Takaaki

    2013-06-01

    Ca2Al2SiO7 (CAS) bulk single crystals were grown by the Czochralski method. Material constants of the crystal were determined over the driving temperature range of a typical combustion pressure sensor. The electrical resistivity at 800 °C was found to be of the order of 108 Ωcm. We constructed a measurement system for the direct piezoelectric effect at high temperature, and characterized the crystals in a simulated engine cylinder combustion environment. Output charge signal against applied stress was detected at 700 °C. These observations suggest that CAS crystals are superior candidate materials for high temperature for stress sensing.

  17. Concurrent irradiation effects with ionization and displacement on the formation of defect clusters in magnesium aluminate spinel

    Energy Technology Data Exchange (ETDEWEB)

    Yasuda, Kazuhiro; Morisaki, Rieko; Kinoshita, Chiken [Kyushu Univ., Fukuoka (Japan). Faculty of Engineering; Abe, Hiroaki; Naramoto, Hiroshi

    1997-03-01

    Single crystals of MgAl{sub 2}O{sub 4} were irradiated concurrently with a homogeneous ion beam and a focused electron beam in TEM-accelerator facilities to get insight into the concurrent irradiation effects with ionization and displacements. Various kinds of 30 or 300 keV ions (He{sup +}, O{sup +}, Mg{sup +}, Ar{sup +} and Xe{sup +}) and 200 keV or 1 MeV electrons were used to provide a wide range of nuclear (S{sub n}) and ionizing (S{sub e}) stopping powers. Dislocation loops were formed both inside and outside the electron beam at 870 K under concurrent irradiation with 30 keV ions (He{sup +}, Ar{sup +} and Xe{sup +}) and 1 MeV electrons. In the case of irradiation with 300 keV ions and 200 keV electrons, on the other hand, a preferential formation of voids or bubbles and a suppressive formation of dislocation loops were observed inside the electron beam. On the basis of these results, we pointed out the importance of the nuclear stopping power which causes the diffusion of cations toward the outside of the focused electron beam. (author)

  18. Roles of crystal defects in the persistent luminescence of Eu2+, Dy3+ co-doped strontium aluminate based phosphors

    Institute of Scientific and Technical Information of China (English)

    L(U) Xingdong; SHU Wangen

    2007-01-01

    The roles of different point defects in persistent luminescence of SrAl2O4:Eu,Dy phosphors were investigated. phors. It can serve as the electron trap of suitable depth for persistent luminescence. V(o) does not serve as the electron trap work as an effective electron trap. The point defect of V"Sr can be hole trap, but the change of its density in crystal matrix does not arouse the obvious change of persistent luminescence.

  19. Morphologie de cristallites de palladium sur support d'alumine Morphology of Palladium Crystallites Supported on Alumina

    Directory of Open Access Journals (Sweden)

    Argile C.

    2006-11-01

    Full Text Available Nous avons étudié, par microscopie électronique à transmission, la structure tridimensionnelle des particules métalliques de catalyseurs Pd/Al2O3. Un modèle de cuboctaèdre tronqué est proposé pour des particules de taille de l'ordre de 30 nm. Pour des particules de taille inférieure (~ 5 nm l'observation des profils et des orientations cristallographiques vis-à-vis du support sont compatibles avec un modèle cuboctaédrique. Transmission electron microscopy has been used to study the three dimensional structure of metal particles in Pd/Al2O3 catalysts. A model in the form of a truncated cuboctahedron is proposed for particles of size about 30 nm. For smaller (~ 5 nm particles observations of profiles and crystallographic orientations with respect to the support are compatible with a cuboctahedron model.

  20. PCT MAO’s Enhanced Performance by Specially Designed Sealers for Superior Service & Environments

    Science.gov (United States)

    2014-11-01

    Micro-arc oxidation (lower energy) • Organo-ceramic sealing • Organic Sealing in Vacuum • Aluminized Steel 2 The PCT Layer Dense Oxide...Functional Layer Intermediate Bonding Layer Substrate 3 PCT Aluminized Steel For MAO Aluminized Steel Facts • Aluminized steel became commercially...reflectivity and corrosion protection. • Traditional Aluminized Steel (ASTM-A463) is hot-dip coated on both sides with an aluminum/silicon alloy coating

  1. Effective lattice stabilization of gadolinium aluminate garnet (GdAG via Lu3+ doping and development of highly efficient (Gd,LuAG:Eu3+ red phosphors

    Directory of Open Access Journals (Sweden)

    Jinkai Li, Ji-Guang Li, Zhongjie Zhang, Xiaoli Wu, Shaohong Liu, Xiaodong Li, Xudong Sun and Yoshio Sakka

    2012-01-01

    Full Text Available The metastable garnet lattice of Gd3Al5O12 is stabilized by doping with smaller Lu3+, which then allows an effective incorporation of larger Eu3+ activators. The [(Gd1−xLux1−yEuy]3Al5O12 (x = 0.1–0.5, y = 0.01–0.09 garnet solid solutions, calcined from their precursors synthesized via carbonate coprecipitation, exhibit strong luminescence at 591 nm (the 5D0 → 7F1 magnetic dipole transition of Eu3+ upon UV excitation into the charge transfer band (CTB at ~239 nm, with CIE chromaticity coordinates of x = 0.620 and y = 0.380 (orange-red. The quenching concentration of Eu3+ was estimated at ~5 at.% (y = 0.05, and the quenching was attributed to exchange interactions. Partial replacement of Gd3+ with Lu3+ up to 50 at.% (x = 0.5 while keeping Eu3+ at the optimal content of 5 at.% does not significantly alter the peak positions of the CTB and 5D0 → 7F1 emission bands but slightly weakens both bands owing to the higher electronegativity of Lu3+. The effects of processing temperature (1000–1500 °C and Lu/Eu contents on the intensity, quantum efficiency, lifetime and asymmetry factor of luminescence were thoroughly investigated. The [(Gd0.7Lu0.30.95Eu0.05]3Al5O12 phosphor processed at 1500 °C exhibits a high internal quantum efficiency of ~83.2% under 239 nm excitation, which, in combination with the high theoretical density, favors its use as a new type of photoluminescent and scintillation material.

  2. Properties of zinc-doped magnesium aluminate transparent ceramics%锌掺杂铝酸镁透明陶瓷性能的研究

    Institute of Scientific and Technical Information of China (English)

    付萍; 王子颖; 潘攀; 施浩浩

    2015-01-01

    采用放电等离子烧结技术制备了锌掺杂铝酸镁透明陶瓷,研究了烧结温度对透明陶瓷的微观结构﹑光学性能和微波介电性能的影响.结果表明:当烧结温度低于1325℃时,陶瓷试样的致密度随烧结温度的升高逐渐增大,直线透过率呈相同趋势变化,1325℃时直线透过率达到最大值为70%;随烧结温度进一步升高,致密度和直线透过率减小;透明陶瓷的介电常数值介于8.19至8.54之间,品质因数值在1325℃达到最大值66000 GHz,谐振频率温度系数值变化较小,其值介于-73×10-6/℃至-65×10-6/℃之间.%The zinc-doped magnesium a1uminate transparent ceramics were prepared by spark p1asma sinter-ing techno1ogy. The inf1uences of sintering temperature on the microstructure, optica1 and microwave die1ec-tric properties of zinc-doped magnesium a1uminate transparent ceramics were studied. The experimenta1 re-su1ts indicate that the density and the in-1ine transmittances increase with the increase of the sintering tem-peratures when the sintering temperature is 1ower than 1 325℃. The in-1ine transmittance at the wave1ength of 550 nm reaches the maximum of 70% at 1 325℃. However, the density and the in-1ine transmittances decrease with the further increase of the temperature. When the die1ectric constant maintains between 8.19 and 8.54, the va1ues of qua1ity factor reaches a maximum of 66 000 GHz at 1 325℃. The temperature coeffi-cient of resonance frequency va1ue is independent of the sintering temperature and remains between-73×10-6/℃and-65×10-6/℃.

  3. 醇盐水解法制备高纯镁铝尖晶石粉体%PREPARATION OF ULTRAFINE MAGNESIUM ALUMINATE SPINEL POWDERS BY ALKOXIDE HYDROLYSIS PROCESS

    Institute of Scientific and Technical Information of China (English)

    刘炜; 毋登辉

    2009-01-01

    以金属Mg、AL与正丁醇为原料,采用溶胶凝胶法合成平均粒径在25~35 μm之间的高纯镁铝尖晶石超微粉体.将金属Mg、Al同时加入正丁醇中反应,得到高纯度镁铝双金属醇盐,并通过红外光谱分析研究醇盐的结构.经过对醇盐水解反应的正交实验研究,确定了最优的水解条件.干凝胶在700℃煅烧开始出现镁铝尖晶石相,并于1 200℃形成晶相完全的镁铝尖晶石粉体.

  4. BaMgAl10O17:Eu蓝色荧光粉的研究进展%Progress in Research on Barium Magnesium Aluminate

    Institute of Scientific and Technical Information of China (English)

    唐永波; 朱宪忠; 王海波; 戚发鑫

    2006-01-01

    概述了Eu2+激活的钡镁多铝酸盐(BaMgAl10O17:Eu2+,BAM:Eu)蓝色荧光粉在等离子显示领域中的研究现状.介绍了BAM的晶体结构,并通过对BAM发射光谱的高斯函数的拟合说明了Eu2+可能存在的几种格位.评述了目前制备BAM的典型方法,分析了引起BAM光衰的基本原因,并提出了改进措施.

  5. Effect of an organic additive on the rheology of an aluminous cement paste and consequences on the densification of the hardened material

    Science.gov (United States)

    El Hafiane, Y.; Smith, A.; Bonnet, J. P.; Tanouti, B.

    2005-03-01

    The material used in the present work is Secar 71 (Lafarge) mixed with water containing an organic additive (acetic acid noted HOAc). The rheological behavior of these pastes is studied. The best dispersion is obtained when the mass content of the additive with respect to the cement is equal to 0.5%. The microstructural characterizations of samples aged 4 days at 20° C and 95 % relative humidity reveal a significant increase in the density and a reduction in porosity for very small percentages of additive. The remarkable effect of the acetic acid on the microstructure of hardened material is correlated with its good dispersing action.

  6. Synthesis, characterization, and Fischer–Tropsch performance of cobalt/zinc aluminate nanocomposites via a facile and corrosion-free coprecipitation route

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhenxin; Xing, Yu, E-mail: yuxing@zzuli.edu.cn; Xue, Yingying; Wu, Depeng; Fang, Shaoming, E-mail: smfang@zzuli.edu.cn [Zhengzhou University of Light Industry, Henan Provincial Key Laboratory of Surface and Interface Science, School of Materials and Chemical Engineering (China)

    2015-02-15

    Literature about ZnAl{sub 2}O{sub 4}-supported cobalt Fischer–Tropsch synthesis (FTS) catalytic materials is sparse. A series of cobalt-containing nanocomposites, supported by nanosized ZnAl{sub 2}O{sub 4} spinel (i.e., a complex oxide of about 6.4 nm) or alumina (i.e., a simple oxide of about 6.2 nm), were prepared via urea-gelation, coprecipitation, or impregnation methods followed by stepwise reduction. These materials were examined by XRD, TGA, nitrogen sorption, FESEM, and EDS. Effects of corrosion and pore size distributions on materials preparation were also investigated. The “coprecipitation/stepwise reduction” route is facile and suitable to prepare nanosized ZnAl{sub 2}O{sub 4}-supported Co{sup 0} nanocomposites. At similar CO conversions, the coprecipitated Co/ZnAl{sub 2}O{sub 4} exhibits significantly lower C{sub 1} hydrocarbon distribution, slightly lower C{sub 5+} hydrocarbon distribution, significantly higher C{sub 2}–C{sub 4} hydrocarbon distribution, and significantly higher olefin/paraffin ratio of C{sub 2}–C{sub 4} than Co/γ-Al{sub 2}O{sub 3}.

  7. Studies of Stability of Post-Alumination Synthesized Al-SBA-15%后铝化的Al-SBA-15稳定性研究

    Institute of Scientific and Technical Information of China (English)

    聂聪; 孔令东; 李全芝

    2002-01-01

    通过预处理后铝化的方法,合成了Al-SBA-15. 焙烧后的Al-SBA-15的27Al MAS NMR谱证明铝已化合到SBA-15的骨架中,并有少量非骨架铝存在. 用XRD、低温N2吸附等方法考察了Al-SBA-15在1 000 ℃焙烧2 h,800 ℃ 100%水蒸气处理8 h和在pH为2或11的酸碱溶液中的稳定性. 经处理后的Al-SBA-15具有比Si-SBA-15更好的热、水热稳定性以及酸碱溶液稳定性.

  8. The design of a bipodal bis(pentafluorophenoxy)aluminate supported on silica as an activator for ethylene polymerization using surface organometallic chemistry.

    Science.gov (United States)

    Sauter, Dominique W; Popoff, Nicolas; Bashir, Muhammad Ahsan; Szeto, Kai C; Gauvin, Régis M; Delevoye, Laurent; Taoufik, Mostafa; Boisson, Christophe

    2016-04-04

    A new class of well-defined activating supports for olefin polymerization was obtained via the surface organometallic chemistry approach. High activities in slurry polymerization of ethylene along with industrial-grade physical properties of the resulting polyethylene were obtained when these activators were combined with metallocene complexes in the presence of triisobutylaluminium.

  9. Effective lattice stabilization of gadolinium aluminate garnet (GdAG) via Lu3+ doping and development of highly efficient (Gd,Lu)AG:Eu3+ red phosphors

    OpenAIRE

    Jinkai Li, Ji-Guang Li, Zhongjie Zhang, Xiaoli Wu, Shaohong Liu, Xiaodong Li, Xudong Sun and Yoshio Sakka

    2012-01-01

    The metastable garnet lattice of Gd3Al5O12 is stabilized by doping with smaller Lu3+, which then allows an effective incorporation of larger Eu3+ activators. The [(Gd1−xLux)1−yEuy]3Al5O12 (x = 0.1–0.5, y = 0.01–0.09) garnet solid solutions, calcined from their precursors synthesized via carbonate coprecipitation, exhibit strong luminescence at 591 nm (the 5D0 → 7F1 magnetic dipole transition of Eu3+) upon UV excitation into the charge transfer band (CTB) at ∼239 nm, with CIE chromaticity coor...

  10. Effect of Ce and La additions in low temperature aluminization process by CVD-FBR on 12%Cr ferritic/martensitic steel and behaviour in steam oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, L. [Universidad Complutense de Madrid, Grupo de Investigacion de Ingenieria de Superficies y Materiales Nanoestructurados, Avenida Complutense s/n, Facultad de Ciencias Quimicas, 28040 Madrid (Spain)], E-mail: lsanche@quim.ucm.es; Bolivar, F.J. [Universidad de Antioquia, Facultad de Ingenierias, Medellin (Colombia); Hierro, M.P.; Perez, F.J. [Universidad Complutense de Madrid, Grupo de Investigacion de Ingenieria de Superficies y Materiales Nanoestructurados, Avenida Complutense s/n, Facultad de Ciencias Quimicas, 28040 Madrid (Spain)

    2008-08-15

    Two different coatings based of iron aluminide on 12% Cr ferritic-martensitic steel have been developed by CVD-FBR technique, which is modified by the introduction of Ce and La as powder in the fluidized bed. These elements change the gaseous environment, which composition is predicted by a thermodynamic approximation. Partial pressures of all gaseous precursors are drastically modified; in consequence AlCl has the highest partial pressure in the system leading to an increment of the coating thickness. Coatings are composed by (Fe, Cr){sub 2}Al{sub 5} or (Fe, Cr){sub 2}Al{sub 5} and (Fe, Cr)Al{sub 3} intermetallic phases. On the other hand, steam oxidation test at 650 deg. C was performed in order to observe improvements in the HCM12A oxidation resistant.

  11. Temperature dependence of the oxide growth on aluminized 9-12%Cr ferritic-martensitic steels exposed to water vapour oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, L., E-mail: lsanche@quim.ucm.e [Universidad Complutense de Madrid. Grupo de Investigacion de Ingenieria de Superficies y Materiales Nanoestructurados. Avenida Complutense s/n, Facultad de Ciencias Quimicas, 28040 Madrid (Spain); Bolivar, F.J. [Universidad de Antioquia. Facultad de Ingenierias. Medellin (Colombia); Hierro, M.P.; Perez, F.J. [Universidad Complutense de Madrid. Grupo de Investigacion de Ingenieria de Superficies y Materiales Nanoestructurados. Avenida Complutense s/n, Facultad de Ciencias Quimicas, 28040 Madrid (Spain)

    2009-04-02

    High temperature steam oxidation resistance of aluminide coatings obtained on 9-12% Cr ferritic-martensitic steels, which have been developed by chemical vapour deposition in fluidized bed reactor (CVD-FBR) using a bed modified with Zr particles, is presented here. The resulting coatings composed of (Fe,Cr){sub 2}Al{sub 5} intermetallic phase provide a high temperature steam oxidation resistance, which depends on the oxidation temperature. At 650 {sup o}C, after 1000 h of exposure, the alumina formed on the surface acts as a protective barrier. However, when the oxidation temperature increases up to 800 {sup o}C, the alumina scale fails before 1000 h of exposure giving rise to the formation of the Cr{sub 2}O{sub 3} and (Fe,Mn){sub 3}O{sub 4}, due to the high atomic diffusion rate at this temperature.

  12. Application of aluminate cement on refractory casting%铝酸盐水泥在耐火浇注料中的应用

    Institute of Scientific and Technical Information of China (English)

    郭利芳; 管红梅

    2003-01-01

    叙述了铝酸盐水泥的矿物组成及作用原理、碱对其应用效果的影响;介绍了不同品种铝酸盐水泥的性能和包钢生产低水泥浇注料的有关情况,并针对存在问题提出了改进意见.

  13. FeAl层对钢基铝镀层陶瓷化的影响%Effect of FeAl Layer on Ceramic Coating Fabricated on Aluminized Steel

    Institute of Scientific and Technical Information of China (English)

    吴振强; 夏原; 李光; 徐方涛

    2007-01-01

    热浸镀铝钢材在铝铁界面处易产成FeAl冶金结合层.本文就FeAl层对铝镀层等离子体电解氧化(PEO)陶瓷层的表面形貌、截面组织、相结构和元素分布的影响进行了研究.结果表明:由于FeAl参与,PEO陶瓷层局部区域出现了50 μm~80 μm的贯穿性孔洞,在孔洞/FeAl界面处出现了许多微观裂纹.EDS结果显示孔洞周围的Fe、Na元素含量增高了近8倍.陶瓷层主要由γ-Al2O3、莫来石相、α-Al2O3和Fe3O4相组成.与FeAl层相比,PEO陶瓷层具有较高的硬度和塑性变形能力.

  14. Simultaneous aluminizing and chromizing of steels to form (Fe,Cr){sub 3}Al coatings and Ge-doped silicide coatings of Cr-Zr base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, M.; He, Y.R.; Rapp, R.A. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

    1997-12-01

    A halide-activated cementation pack involving elemental Al and Cr powders has been used to achieve surface compositions of approximately Fe{sub 3}Al plus several percent Cr for low alloy steels (T11, T2 and T22) and medium carbon steel (1045 steel). A two-step treatment at 925 C and 1150 C yields the codeposition and diffusion of aluminum and chromium to form dense and uniform ferrite coatings of about 400 {micro}m thickness, while preventing the formation of a blocking chromium carbide at the substrate surfaces. Upon cyclic oxidation in air at 700 C, the coated steel exhibits a negligible 0.085 mg/cm{sup 2} weight gain for 1900 one-hour cycles. Virtually no attack was observed on coated steels tested at ABB in simulated boiler atmospheres at 500 C for 500 hours. But coatings with a surface composition of only 8 wt% Al and 6 wt% Cr suffered some sulfidation attack in simulated boiler atmospheres at temperatures higher than 500 C for 1000 hours. Two developmental Cr-Zr based Laves phase alloys (CN129-2 and CN117(Z)) were silicide/germanide coated. The cross-sections of the Ge-doped silicide coatings closely mimicked the microstructure of the substrate alloys. Cyclic oxidation in air at 1100 C showed that the Ge-doped silicide coating greatly improved the oxidation resistance of the Cr-Zr based alloys.

  15. Additive effect of Ce, Mo and K to nickel-cobalt aluminate supported solid oxide fuel cell for direct internal reforming of methane

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Bu Ho; Park, Jungdeok; Yoon, Heechul; Kim, Hyeon Hui; Kim, Lim; Chung, Jong Shik [POSTECH, Pohang (Korea, Republic of)

    2014-01-15

    Direct internal reforming of methane (steam/carbon=0.031, 850 .deg. C) is tested using button cells of Ni-YSZ/YSZ/LSM in which the anode layer is supported either on Ni-YSZ or on Ni-CoAl{sub 2}O{sub 4}. The Ni-CoAl{sub 2}O{sub 4} supported cell shows little degradation with operating time, as a result of higher resistance against carbon deposition, whereas the Ni-YSZ supported cell deactivates quickly and suffers fracture in 50 h. Upon incorporation of additives such as K, Ce, or Mo into the Ni-CoAl{sub 2}O{sub 4} support, cells with 0.5 wt% CeO{sub 2} exhibit the best stable performance as a result of reduced coke formation. Cells with 0.5 wt% Mo exhibit the lowest performance. Although no carbon deposit is detected in the cells with K{sub 2}CO{sub 3} additives, their performance is worse than that in the CeO{sub 2} case, and, in constant-current mode, there is a sudden voltage drop to zero after a certain period of time; this time becomes shorter with increasing K content. The injection of potassium into the anode side facilitates the generation of OH{sup -} and CO{sub 3}{sup 2-} in the anode and promotes the diffusion of these ions to the cathode. Increased polarization resistance at the cathode and increased electrolyte resistance result in such a sudden failure.

  16. Oxidation Resistance of Turbine Blades Made of ŻS6K Superalloy after Aluminizing by Low-Activity CVD and VPA Methods

    Science.gov (United States)

    Zagula-Yavorska, M.; Kocurek, P.; Pytel, M.; Sieniawski, J.

    2016-05-01

    Two aluminide layers (additive and interdiffusion) were deposited on a turbine blade made of ŻS6K superalloy by means of VPA and CVD methods. The additive and interdiffusion layers obtained by the VPA method consist of the NiAl phase and some carbides, while the additive layer deposited by the CVD method consists of the NiAl phase only. The residual stresses in the aluminide coating at the lock, suction side, and pressure side of the blade were tensile. The aluminide coating deposited by the CVD method has an oxidation resistance about 7 times better than that deposited by the VPA method. Al2O3 + HfO2 + NiAl2O4 phases were revealed on the surface of the aluminide coating deposited by the VPA method after 240 h oxidation. Al2O3 + TiO2 oxides were found on the surface of the aluminide coating deposited by the CVD method after 240 h oxidation. Increasing the time of oxidation from 240 to 720 h led to the formation of the NiO oxide on the surface of the coating deposited by the VPA method. Al2O3 oxide is still visible on the surface of the coating deposited by the CVD method. The residual stresses in the aluminide coating after 30 cycles of oxidation at the lock, suction side and pressure side of the turbine blade are compressive.

  17. Encapsulation research on persistent luminous powder of aluminate%铝酸盐系长余辉发光粉的表面包覆研究

    Institute of Scientific and Technical Information of China (English)

    李茂龙; 王轶; 吴粤宁; 隋玉龙

    2013-01-01

    采用正硅酸乙酯对铝酸盐系长余辉发光粉进行表面包覆.经耐水性、耐酸性和发光性以及扫描电镜的测试表明:发光粉的包覆效果良好,其耐水性和耐酸性得到明显提高.包覆后,发光粉的发光性未发生明显改变.

  18. Analysis on Quality of Self-piercing Riveting Connecting for Aluminous Sheets%铝板SPR连接质量分析

    Institute of Scientific and Technical Information of China (English)

    李永利; 佟铮

    2008-01-01

    介绍了新型自冲铆接(SPR)铝板的连接过程,根据试验和数值模拟结果阐述了其连接机理,重点对这种新型连接技术的连接质量进行了分析,其连接强度主要由镶嵌值决定,影响镶嵌值大小的主要因素是铆钉尺寸和模具结构.

  19. Synthesis Research of Zeolite 4A from Sodium Aluminate Solution%用铝酸钠溶液合成4A沸石的研究

    Institute of Scientific and Technical Information of China (English)

    幺海青

    2004-01-01

    研究了用氧化铝生产过程中的铝酸钠溶液采用水热合成法制备洗涤剂用4A沸石的合成条件,并介绍了结晶导向剂在合成4A沸石中的应用.用该方法合成4A沸石可以简化生产流程,降低生产成本,能取得较好的经济效益.

  20. 铝酸钠溶液直接合成冰晶石的研究%Investigation into Direct Synthesizing Cryolite by Sodium Aluminate

    Institute of Scientific and Technical Information of China (English)

    李民菁; 史智慧; 郑朝付; 冉俊生; 王志勇

    2008-01-01

    探讨了铝酸钠溶液直接合成冰晶石的工艺条件.研究表明,氢氟酸和铝酸钠溶液中的SiO2含量、合成温度、n6F/nAl、pH值、nAa/nAl等对冰晶石性能有显著影响.本工艺所确定的方法,在常温常压下合成的冰晶石有纯度高,流动性好,分子比在1.7~2.9可凋,市场前景广阔,有推广价值.

  1. Effects of Environment Oxygen Content on Heat of Detonation of Aluminized Explosive%环境氧含量对含铝炸药爆热的影响

    Institute of Scientific and Technical Information of China (English)

    李媛媛; 王晓峰; 牛余雷; 南海; 肖奇

    2014-01-01

    利用恒温式量热计测定了3种含铝炸药在不同环境中的爆热,研究了其能量释放规律.结果表明,含铝炸药在真空、空气和纯氧环境中的爆热逐渐增高,固体爆轰产物存在一定差异.3种含铝炸药在纯氧中的爆热基本相当,说明发生了完全燃烧反应.在真空和空气环境中,含细铝粉(中位径12.43μm)的含铝炸药爆热均低于含粗铝粉(中位径74.14μm)的炸药.两种粒度铝粉级配后的含铝炸药,在真空和空气环境中的爆热处于铝粉未级配的炸药爆热之间,原因是没有达到细铝粉先反应、粗铝粉后反应的理想状态.

  2. Evaluation of IKTS Transparent Polycrystalline Magnesium Aluminate Spinel (MgAl2O4) for Armor and Infrared Dome/Window Applications

    Science.gov (United States)

    2013-03-01

    4 Figure 3. Various magnification SEM images of spinels etched in boiling phosphoric acid : left...30,000X Figure 3. Various magnification SEM images of spinels etched in boiling phosphoric acid : left column, sample 205 (0.6 µm); right column...specimens were polished to a 0.25-µm finish and then chemically etched by immersing them in boiling phosphoric acid —30 s for the small-grained spinel

  3. Functional analysis of aluminous plastic door & window and its popularization & application%铝塑复合门窗的性能分析及推广应用

    Institute of Scientific and Technical Information of China (English)

    葛双俊

    2004-01-01

    针对铝塑复合窗产品的性能,从隔热保温、密封性好、经久耐用等多方面进行了分析,指出铝塑复合窗作为新型的节能环保门窗,性能优良,符合建筑材料推广应用要求,其前景广阔.

  4. 铝酸钙的微波合成与表征%The Microwave Radiation Synthesis and Characterization of Calcium Aluminate Hydrate

    Institute of Scientific and Technical Information of China (English)

    张丽芳; 刘建超; 荣华; 刘嘉赢

    2012-01-01

    In order to achieve the automatic needle percutaneous and reduce the surgical trauma, a shake block type automatic needle mechanism was developed on the basis of analysis of clinical needs of making the percutaneous surgery more scientific and controlled. First, use the forward kinematic analysis of the mechanism to describe the trajectory of the needle point, and then evaluate the stationary of the needle throughout the puncture procedure, and finally get the analytical value of the input torque through the kinetic analysis of The mechanism. Based on the above analysis and simulation, the automatic needle mechanism can basically meet the clinical requirements of the clinical, the size, the driving source, the needle trajectory and the needle speed.%铝酸钙是一种很有发展前景的环保型无机阻燃剂.以结晶氯化铝、氢氧化钠、氯化钙、氢氧化钙为原料,探讨了在微波辐射下合成铝酸钙(3CaO·Al2O3·6H2O)的方法.考察了反应温度、微波辐射时间、原料比等因素对反应的影响.通过优化试验,确定了合成3CaO · Al2O3·6H2O的适宜反应条件.结果表明:加入结晶氯化铝19.3g、氢氧化钠13.4g、氯化钙2.2 g、氢氧化钙3.0g、水75.8 mL,其中n(Al)∶n(OH-)=1∶4.2、n(Ca)∶n(Al)=3∶4.0、w(固)∶w(液)=1∶2.0;微波设定温度为100~115℃,微波辐射总时间为55 min时,产品产率约为90%.采用TG-OTA及FE-SEM分析方法对产品的性质进行表征,分析结果显示产品的脱水温度约为298℃,产品的粒径小于5μm .

  5. Transition of Blast Furnace Slag from Silicate-Based to Aluminate-Based: Structure Evolution by Molecular Dynamics Simulation and Raman Spectroscopy

    Science.gov (United States)

    Liang, Dong; Yan, Zhiming; Lv, Xuewei; Zhang, Jie; Bai, Chenguang

    2017-02-01

    To determine the effect of Al2O3 content and Al2O3/SiO2 mass ratio on the structure of molten aluminosilicate systems, CaO-SiO2-Al2O3-MgO-TiO2 systems were investigated by conducting molecular dynamics (MD) simulation and Raman spectroscopy. The capabilities of different elements to attract O on the basis of bond length are ranked as follows: Si > Al > Ca. The CNSi-O (approximately 4) and the average CNAl-O (approximately 4.09) demonstrate that the [AlO4] tetrahedron is not as stable as the [SiO4] tetrahedron and that some highly coordinated Al units exist in the slags. Non-bridging oxygen prefers to be coordinated with Si, and Al tends to be localized in polymerized environments as a network intermediate phase. In addition, Ca2+ is more energetically active than Mg2+ as the charge compensation ion. MD results and Raman analysis show that an increase in Al2O3 content complicates the structure at a fixed CaO/SiO2 ratio. In addition, the viscosity of the sample may increase with increasing Al2O3 content but is also influenced by polymerization strength. The substitution of Al2O3 for SiO2 simplifies the structure of the slag at a fixed CaO concentration when Al2O3/SiO2 is less than 0.92, as indicated by the (Q4 + Q3)/(Q2 + Q1) ratio of Al and the structure complexity. The results of MD and Raman analysis agree with those of viscosity measurement.

  6. 铝酸钠溶液中离子溶剂化作用%Solvent effect of species in sodium aluminate solution

    Institute of Scientific and Technical Information of China (English)

    张牧群; 尹周澜; 陈启元; 李洁; 胡慧萍; 张平民

    2004-01-01

    应用量子化学从头算密度泛函理论以及DFT/COSMO溶剂模型,基于 UHF/BLYP/DNP水平对高苛性比中等浓度铝酸钠溶液中各类离子(分子)的溶剂化作用进行研究.根据离子(分子) 的几何构型、总能量、振动频率、相关热力学数据以及相应的水合自由能,对溶液中离子(分子)的存在形式以及不同离子(分子)间的平衡转化关系进行分析.结果表明,在高苛性比中等浓度铝酸钠溶液中,铝主要是以水合Al(OH)-4离子和Na(H2O)+6Al(OH)-4离子对形式存在,同时还存在有中性水合分子Al(OH)3H2O.

  7. The Experimental Mod II Firefighters’ Aluminized Crash-Rescue Fire-Proximity Hood: An Interim Report of a Limited Service Test

    Science.gov (United States)

    1982-07-01

    types of breathing apparatus under the hood. The thermal qualities of these hoods are comparable to the standard headwear and are suitable for wear...style should be compared to the 4 standard. A-2 31 :HW:pd 523-003-58 If you have any opinions as to how this headwear can be improved, kindly offer your...the best possible protective headwear for use by firefighting personnel. Your cooperation in taking part in this wear test evaluation is greatly

  8. Phase relationships in the area of the beta aluminate of the system K{sub 2}O-MgO-AL{sub 2}O{sub 3}; Phasenbeziehungen im Bereich der Beta-Aluminate des Systems K{sub 2}O-MgO-Al{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Kroon, P. de

    1996-12-01

    The aim of this work was to be able to make statements about the thermodynamic stability of K-{beta}``-Al{sub 2}O{sub 3} in the pseudo-binary system K{sub 2}O-Al{sub 2}O{sub 3} and in the pseudo-ternary system K{sub 2}O-MgO-Al{sub 2}O{sub 3} relative to the adjacent phases of KAlO{sub 2} {alpha}-Al{sub 2}O{sub 3}, MgAl{sub 2}O{sub 4} and K-{beta}-Al{sub 2}O{sub 3}. (orig./MM) [Deutsch] Ziel dieser Arbeit war es, Aussagen ueber die thermodynamische Stabilitaet von K-{beta}``-Al{sub 2}O{sub 3} im pseudobinaeren System K{sub 2}O-Al{sub 2}O{sub 3} und im pseudoternaeren System K{sub 2}O-MgO-Al{sub 2}O{sub 3} relativ zu den benachbarten Phasen KAlO{sub 2}, {alpha}-Al{sub 2}O{sub 3}, MgAl{sub 2}O{sub 4} und K-{beta}-Al{sub 2}O{sub 3} machen zu koennen. (orig./MM)

  9. 热浸镀铝钢Al2O3/渗铝层界面空洞生长动力学研究%Growth Kinetics of Voids Along Interface Between Al2O3 and Aluminized Layer of Aluminized Steel

    Institute of Scientific and Technical Information of China (English)

    张伟

    2007-01-01

    通过高温氧化实验和SEM,XRD分析,研究了热浸镀铝钢在1000℃氧化期间Al2O3/渗铝层界面空洞的生长过程,分析了界面空洞的生长机理.结果表明,界面空洞的生长受氧化过程制约,生长速度与渗铝层表面的氧化速度存在一定的对应关系,生长动力学遵循近似的抛物线规律;随氧化时间延长,单位面积上的空洞数量先快速增加而后逐渐减少.

  10. Modeling of Defects in Transparent Ceramics for Improving Military Armor

    Science.gov (United States)

    2009-06-01

    on a transparent magnesium aluminate spinel, MgAl2O4, striking-ply backed by polycarbonate. Finite element modelling is used to predict unsuccessful...edge-form-growth sapphire, magnesium aluminate spinel, aluminium oxynitride — one was selected for the current pursuit, magnesium aluminate spinel...ballistic testing to validate armor designs based on a transparent magnesium aluminate spinel, MgAl2O4, striking-ply backed by polycarbonate

  11. Mechanical and microstructural behaviour of alumina-zirconia ceramic filaments for high temperature applications; Comportement mecanique et microstructure de filaments ceramiques alumine-zircone pour applications a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Poulon-Quintin, A

    2002-04-01

    This thesis is a contribution to the development and to the study of two-phase alumina-zirconia ceramic filaments resistant to creep and chemical and microstructural degradation. The materials studied are experimental two-phase filaments (diameter of few millimeters) with a fibrillary structure obtained by coextrusion of sol-gels or of powder pastes and a nanocrystalline fiber of thin diameter (11{mu}m) with a homogeneous structure. They have been respectively perfected and chosen for their very promising microstructures and compositions concerning the creep resistance. This study is concentrated on the mechanical characterization at high temperature of these materials and especially on the understanding of the deformation and rupture mechanisms in relation with the microstructural evolution. The commercial fiber (Nextel 650) is a {alpha} alumina (grain size {>=}0.1{mu}m) in which the grains of the second phase zirconia are dispersed in a homogeneous way in intra (5-10 nm) as in inter-granular (20-30 nm). After a heat treatment at temperatures superior to 1200 C, it can be noted a strong grains growth preferentially to the axis of the fiber. The tensile properties decrease to a considerable extent with high temperatures ({>=}1000 C). The creep behaviour has been determined between 1000 and 1300 C (value of 2.5 for the stress exponent and of 850 kJ/mol for the activation energy). The evolution of the microstructure to a long grains microstructure is favourable for the creep resistance. A comparison with other fibers of compositions near the Nextel 650 fiber show that the Nextel 650 fiber has interesting properties for being used at high temperatures (until 1200 C). The study of co-extruded alumina-zirconia filaments with a fibrillary structure has at first required those of filaments which composition are each of the phases obtained from pastes (powder-thermoplastics or sol-gels). The composition of each of the phases has been optimized in order to adapt the rheology of the two pastes and to obtain after co-extrusion and sintering, a material presenting the less of defects possible ( porosity, cracks..). The microstructure of the different filaments (two-phase or not) has been observed to explain the consequences of the multi-extrusion on the microstructure (phases alignment, grains size and orientation). A particular attention has been dealt with the study of interfaces between the fibrilla of the different phases of the co-extruded material. It has revealed crystallographic orientation relations between the juxtaposed grains of each phases. These strong interfaces are responsible of the non division of the cracks. By tensile tests (4-points), we show at 1300 C, a decrease of the mechanical properties (two-phase or non material). In creep at 1300 C, the co-extruded filaments present creep rates superior to those of the {alpha} alumina mono-filaments. The predominant role of the {alpha} alumina and those of the strong interfaces has been revealed with the creep study. (O.M.)

  12. Research on the Preparation of Ultrafine Magnesium Aluminate Spinel Powders by Sol-Gel Process%溶胶凝胶法制备超细镁铝尖晶石粉体的研究

    Institute of Scientific and Technical Information of China (English)

    刘炜; 王修慧

    2008-01-01

    以Mg、Al双金属正丁醇盐为原料,采用溶胶凝胶法合成一次粒子粒径在100~300nm之间的高纯镁铝尖晶石超微粉体.干凝胶在800℃煅烧开始出现镁铝尖晶石相,在1200℃保温2h,形成晶相完全的镁铝尖晶石粉体.

  13. Effect of Magnesium Aluminate Spinel on Microstructure and Performance of Aluminum-corundum Composites%镁铝尖晶石对铝-刚玉复合材料结构和性能的影响

    Institute of Scientific and Technical Information of China (English)

    李勇; 洪炀; 岳丹丹; 马佳佳; 仝尚好; 蒋朋; 薛文东

    2016-01-01

    Al–MgAl2O4–Al2O3 composite was sintered at 1 300℃in N2 made from tabular alumina, fused white corundum,α-Al2O3 fine powder, metal Al powder and MgAl2O4 fine powder (addition with 3%, 6%, 9%, 12%, 15%respectively) and phenolic resin as binder. The results show that the cold crushing strength and the high temperature bending strength of the Al–MgAl2O4–Al2O3 composite was increased with more MgAl2O4 powder added. Besides corundum and some amount of spinel solid solution as the major crystalline phases, new phases such as Al4O4C, AlN–Al2OC solid solution and minor AlxOyNz have been synthesized, with some Al as residue. Although the content of Al added into the Al–MgAl2O4–Al2O3 composite reach 12%, neither independent AlN nor Al4C3 has been detected after sintering. It is the AlN–Al2OC solid solution that exists in the composite. Therefore, the complete disruption of the samples and the performance degradation won’t occur because of the hydration of AlN and Al4C3. The AlxOyNz phase is detected in the samples and the solid solution of generated AlxOyNz in MgAl2O4 can’t realize on account of the low sintered temperature. MgAlON solid solution hasn’t been detected.%以板状刚玉、电熔白刚玉、α-Al2O3微粉、金属Al粉、MgAl2O4微粉[含量分别为3%(质量分数)、6%、9%、12%和15%]为原料,酚醛树脂为结合剂制备Al–MgAl2O4–Al2O3样品。样品经200℃烘干后于1300℃氮气气氛烧成。结果表明:样品常温耐压强度呈增加趋势、样品高温抗折强度增加。样品中除主晶相刚玉和镁铝尖晶石固溶体外,形成新相 Al4O4C、AlN–Al2OC固溶体和少量AlxOyNz等,还有部分金属铝粉剩余。样品中金属铝的含量为12%,但经1300℃氮气气氛烧成后,样品中既无独立AlN,也无独立的Al4C3存在,而是以AlN–Al2OC固溶体形式存在,因此不会出现因AlN或Al4C3水化导致样品性能降低或样品完全散裂的现象。样品中有AlxOyNz相生成,但因烧成温度低,未能检测到MgAlON。

  14. Effect of Bi on Microstructure and Thickness of Hot-dip Aluminizing Coating on Magnesium Alloy%Bi对镁合金热浸镀铝镀层组织和厚度的影响

    Institute of Scientific and Technical Information of China (English)

    薛寒松; 陈祖权; 向军军

    2013-01-01

    采用热浸镀方法在AZ31镁合金表面镀覆一层铝合金层.利用光学显微镜和配有能谱分析的扫描电镜等对镀层微观组织、元素分布等进行了研究;测定了试样在不同浸镀条件下的镀层厚度.结果表明:镀液添加Bi后,在浸镀温度不变情况下,镀层厚度增加速度加快,过渡层厚度变大,镀层中粗大的树枝晶增多,但是Bi在镀层中含量极少.通过对试验结果分析得出:Bi元素对Mg、Al液态互扩散具有显著的促进作用,使得镀层形成速度加快,但是也造成镀层组织粗大.%The aluminum coating on AZ31 Mg alloy surface was prepared by hot dipping process. The microstructure of coating, distribution of element were studied by OM and SEM. The thickness of the coating was measured. The results show that after adding Bi into the hot-dipping solution, with the dipping temperature being constant, the increasing rate of the thickness of the coating becomes higher, the thickness of intermediate layer and the amount of coarse dendrite increases, but the amount of Bi in coating is extremely low. An analysis on the result of experiment shows that Bi can promote liquid mutual diffusion between Mg and Al, speed up the formation of coating, but also causes the formation of coarse structure.

  15. 氧化物添加剂在合成和烧结镁铝尖晶石过程中的作用%Role of Oxide Additives in the Synthesis and Sintering of Magnesium Aluminate Spinel

    Institute of Scientific and Technical Information of China (English)

    杨杨

    2010-01-01

    在钢铁窑炉以及水泥和石灰回转窑中镁铝尖晶石砖已经成功地替代了镁铬砖.利用软件和热力学基本数据解释添加剂在尖晶石形成过程中所起到的作用.为了使镁基耐火材料形成更好的结合结构,分析了镁铝合金粉末添加二价和四价氧化物添加剂在相对较低的温度下合成和烧结过程中所起的作用.利用X-射线衍射图谱中峰位移动的数据研究了活性阳离子在氧化镁-尖晶石和尖晶石-尖晶石的表面扩散情况.

  16. Effect of Nd2O3 addition on reaction-sintered magnesium aluminate spinel%Nd2O3对反应烧结合成镁铝尖晶石的影响

    Institute of Scientific and Technical Information of China (English)

    田忠凯; 王周福; 王玺堂; 张保国

    2008-01-01

    研究稀土氧化物Nd2O3对反应烧结镁铝尖晶石的影响.结果表明,添加Nd2O3能促进镁铝尖晶石结晶化,有利于促进镁铝尖晶石烧结致密化及晶粒生长发育.试样中添加3%(质量分数)的Nd2O3,经1 650 ℃烧结能制备出相对密度为92%、晶粒发育良好的镁铝尖晶石.

  17. Analysis and Spectroscopy of Rare Earth Doped Magnesium Aluminate Spinel%涂有稀土元素的镁铝尖晶石的分析和光谱学分析

    Institute of Scientific and Technical Information of China (English)

    张丽

    2005-01-01

    采用稀土阳离子隔离镁铝尖晶石的作法已经被考虑到,并且利用校对过的扫描电镜做了分析.在Daresbury实验室的超级扫描电镜表明铕离子沿尖晶石颗粒边界将尖晶石单层分离.电子能量损失光谱分析证明,铕存在于颗粒边界的0.5mm范围内.由于尖晶石具有较好的透光性、固有的硬度、较大的断裂韧性和较好的抗热、化学侵蚀性能而作为硬质窗玻璃的一种侯选材料.涂有稀土阳离子的尖晶石在可见光和红外线波长范围内具有较好的透光性.

  18. INFLUENCE OF TITANIUM DIOXIDE ON CRYSTALLINE STRUCTURE OF MAGNESIUM ALUMINATE SPINEL SYNTHESIZED FROM WASTE ALUMINUM SLAG%氧化钛对铝厂污泥合成的镁铝尖晶石晶相结构的影响

    Institute of Scientific and Technical Information of China (English)

    于岩; 阮玉忠; 吴任平

    2007-01-01

    用铝型材厂污泥和碱式碳酸镁[(MgCO3)4·Mg(OH)2·5H2O]为主要原料合成镁铝尖晶石(MgAl2O4),探讨氧化钛(TiO2)矿化剂对合成的MgAl2O4晶相结构、晶胞参数及微观形貌的影响.用X射线衍射,扫描电镜及相关分析软件,如:Philips plus,Rietveld quantification等表征得到的MgAl2O4.结果表明:当TiO2添加的质量分数(下同)低于2%时,MgAl2O4的相对含量及晶格参数随TiO2的增加而增加,TiO2的最佳添加量确定为2%,此时,生成的MgAl2O4相对含量达到92%,TiO2可与MgAl2O4形成固溶体,固溶量约为2%.TiO2添加超过2%则会形成含钛化合物.

  19. A study of damage evolution during annealing of helium-implanted magnesium-aluminate spinel%铝镁尖晶石中He离子注入引起损伤的退火行为研究

    Institute of Scientific and Technical Information of China (English)

    杨义涛; 张崇宏; 周丽宏; 李炳生

    2008-01-01

    利用卢瑟福沟道背散射技术结合表面的原子力显微分析,对注He的铝镁尖晶石晶体的晶格损伤及表面形变随退火温度变化的关系进行了研究.结果表明,不同注入剂量的样品中晶格损伤和表面形变表现出显著不同的退火行为.分析认为造成损伤演化的这种差异与注入的He原子在晶体中不同的聚集状态有关.

  20. 钡镁多铝酸盐蓝色荧光粉的研究进展%Advance in Investigation of Barium-Magnesium Aluminate Blue-emitting Phosphor

    Institute of Scientific and Technical Information of China (English)

    李璠; 李样生

    2002-01-01

    综述了具有β-Al2O3结构的钡镁多铝酸盐蓝色荧光粉在灯用及等离子显示平板领域中的研究与发展.重点介绍了其在各领域中制备、发光性能、光谱特性、应用性能等方面的研究工作,指出了国内蓝粉存在的主要问题及与国外产品的差距,并提出了几点展望.