Development of glass-ceramics by sintering and crystallization of fine powders of calcium-magnesium-aluminosilicate glass

Development of glass-ceramics by sintering and crystallization of fine powders of calcium-magnesium-aluminosilicate glass

12 Refractories/ceramics organic matrix and is potentially dangerous due to the heavy metals, oils filter and halogenated plastics content. The first ...

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12 Refractories/ceramics organic matrix and is potentially dangerous due to the heavy metals, oils filter and halogenated plastics content. The first step of the work is the chemical, physical and toxicological characterization of this material. Then the fluff injection in a blast furnace tuyere is theoretically analysed with a mathematical model. Finally, experimental trials are conducted in a pilot plant, simulating the most important part of the blast furnace: the raceway, in order to analyse process and industrial aspects. In view of an industrial application a first economical evaluation is carried out on the basis of model and experimental results. 03/00818 Applications of chemical engineering thermodynamics on supercritical technology Cheng, K.-W. and Chen, Y.-P. Guoli Tuiwan Dame Gongcheng Xuekan. 2002, (84), 45-57. (In Chinese) Supercritical fluid technology is becoming more and more important because of increasing industrial applications. The experimental detection of phase equilibrium data at high pressure and theoretical study for supercritical fluid are the fundamentals for process design in industry. This paper reviews the apparatus for measurement of equilibrium data. It also discusses the thermodynamic consistency test, and the correlation of phase equilibrium data for supercritical fluids with liquid or solid solutes. Typical research results from the authors’ laboratory are presented and supply useful references for industrial applications.

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REFRACTORIES/ CERAMICS Properties,

production,

applications

Benchmark analysis of neutronics performances 03/00819 of a SIC block irradiated with 14 MeV neutrons Angelone, M. ct al. Fusion Engineering and Design, 2002, 63 64, 415479. Silicon carbide (SIC) in the form of ceramic matrix is a low activation structural material proposed for fusion reactors. Its development is pursued in the European Fusion Technology Program. A Sic block (457 x 457 x 711 mm ), borrowed from JAERI, was irradiated with 14 MeV neutrons at the FNG facility of ENEA Frascati. Activation reaction rates, neutron fluxes and spectra, as well as nuclear heating were measured in four selected experimental positions inside the block. The experimental analysis was performed using the Monte Carlo transport code MCNP-4C and point-wise cross sections derived from FENDL-2.0, EFF-2.4 and EFF-3.0 evaluated nuclear data files. Deterministic transport calculations were also performed using the discrete ordinates code DORT. The sensitivity and uncertainty analysis were performed as well using the SUSD3D code. Results indicate that calculation based on EFF-3.0 nuclear data file estimates the neutron flux and spectra with a reasonable uncertainty that is still lower than 130% for all measured quantities. Ceramic filter element for particle separation from 03/00820 hot gases and filter purification with pressurized gas Westerheide, R. Ger. Offen. DE 10,108,394 (Cl. BOlD46/24), 12 Sep 2002, Appl. 10,108,394, 22 Feb 2001. 6. (In German) The invention concerns a ceramic filter element for particle separation from hot gases, with an extended hollow base consisting of a macroporous ceramic material, which is provided with a fine-porous ceramic filter bed and an inlet opening for fixing a carrier at a first end, whereby the porosity of the ceramic base changes over its filtereffective axial extension continuously, or in several steps. The filter cake of the filter element is uniformly removed during treatment of the filter element with pressurized gas, thus the damage by mechanical oscillations is decreased. The filter elements may be formed as filter candles and are used for the filtration of hot gases from coal combustion, or coal gasification in the power plant techniques. 03/00821 Conversion to glass-ceramics from glasses made by MSW incinerator fly ash for recycling P&k, Y. J. and Heo, J. Ceramics Interna&nal~2002, 28, (6), 689.-694. Glasses were made using fly ash from municipal solid waste (MSW) incinerators with the addition of Si02, MgO and TiOz. The glasses were then converted to glass-ceramics for further recycling to construction materials. The optimum heat-treatment schedule for the

(properties, production,

applications)

ceramization of glasses was 720°C for 90 min for nucleation and 870°C for 10 h for crystal growth. Diopside (CaMgSizOh was formed as a major crystal phase). The glass-ceramics showed good mechanical properties with hardness 6730 MPa, fracture toughness 1.86 MPam”* and bending strength 127 MPa. Glasses and glass-ceramics with a composition of 20Si02-5MgO-75fly ash-2weight% Ti02 showed an excellent resistance against leaching of heavy metal icms in water. The amount of heavy metal ions leached after 18 h at 23°C was well below regulation with Cd2+ c 0.04 ppm, Cr3+ < 0.004 ppm, Cu*+ < 0.03 ppm and Pb*+ < 0.15 ppm, respectively. Current status of dense ceramic membranes for 03/00822 hydrogen separation Balachandran. U. et rd. Proceedings of the J~~tcrrtational Technical Cmferente on CONI Utilixtion & Fuel SI’Y~(JMI~.2002, 2. (27), 11551165. Novel cermet (i.e. ceramic-metal composite) membranes have been developed for separating hydrogen from gas mixtures at high temperature and pressure. The hydrogen permeation rate in the temperature range of 600-900°C has been measured for three classes (ANL-1, -2. and -3) of cermet membranes. ANL-3 membranes provide the highest hydrogen flux (16.2 cm”(STP)/min-cm’ for 40 pm-thick ANL-3a at 900°C using 100% H2 as the feed gas). The effects of membrane thickness and hydrogen partial pressure on the hydrogen flux indicate that the bulk diffusion of hydrogen is rate-limiting for ANL-3 membranes with thickness >0.04 mm. ANL-3b membranes were tested in simulated syngas at several temperatures for times approaching ~200 h, and no degradation in performance was observed. The lack of degradation in simulated syngas suggests that the membrane is chemically stable and may be suitable for long-term operation. 03/00823 Development of glass-ceramics by sintering and crystallization of fine powders of calcium-magnesiumaluminosilicate glass Tulyaganov, D. U. et al. Ccrwvics Irztrrtwtiontrl. 2002, 28, (51,5 15-520. (In Japanese) Natural raw materials normally used in the ceramic and glass industry were studied for the production of calcium magnesium aluminosilicate glass or glass-ceramic materials. Sintering and crystallization processes of fine powders of parent glass with chemical composition. (weight%) 46.00 SiOZ, 15.90 A1203, 1.20Fe203, 0.42 TiOz, 23.50 CaO, 9.37 MgO, 0.04 Na20, 0.98 K20, 1.95 P205 and 0.35 CaF:* were studied. Crystallization kinetics of glass-ceramics was carefully examined by DTA, XRD, and SEM techniques and by dilatometric studies. The desired sequence of events, i.e. nucleation, sintering and devitrification occurred by heat-treating the glassy powder. However, crystallization of the parent glass did not follow phase diagram predictions, since anomalous appearance of akermanite phase was detected along with expected anorthite and diopside proportion A reasonable explanation for this unexpected observation is given. Glass-ceramics from mixtures of coal ash and 03/00824 soda-lime glass by the petrurgic method Francis, A. A. et (11..Journal of Muteriula Sc~rtlw Lc,ttcrs, 2002, 2 1, ( 12), 975-980. The effect of the cooling rate on the crystallization behaviour in mixtures with different soda-lime contents is studied. The cooling rate and the amount of added soda-lime glass are dominant factors in controlling the crystallization and microstructure vf these iron-rich glass-ceramics. Melts of coal ash containing 40 ancl 60% soda-lime glass addition yield plagioclase (Na.Ca~(Si,Al)~,Ox and augite Ca(Mg,Fe)-SiTOx as the maior crvstal ohases on cooling at l”/min. A fasiercooiing-rate (lO”/minj allows the crystallization if a magnefite phase, and consequently the samples exhibit magnetic properties. Thus, the petrurgic method represents a simple, inexpensive: route to achieve magnetic glass-ceramics from iron-containing silicate wastes. 03/00825 Kinetics of slag hydration in the presence of calcium hydroxide Biernacki, J. J. et al. Journcrl of the Anrrriczn C’c~rrmlcSoc.icjt>y,2002, 85. (9), 2261-2267. The reaction between ground granulated blast furnace slag (GGBFS) having an empirical formula of C , sx-S7 .19M1A and calcium hydroxide (CH) was investigated. The kinetics of the reaction were explored. Thermogravimetric analysis was used to monitor the consumption of CH from which rate constants were detected. Basl;d on Knudsen’s kinetic model, activation energies of 14.5, 17.9, and 22.6 kJ/mol were detected for three different mass ratios of slag and C’H reacted over a temperature range of 15-50” and hydrated for a period of time from 0 to 32 days. A comparison of the kinetics of the slag,iCH reaction was made with slag/Portland cement hydration. The basic features of both appear similar. Fuel and Energy Abstracts

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