Thermal stability of one-part metakaolin geopolymer composites containing high volume of spodumene tailings and glass wool

The present project investigated the thermal stability of cold-setting refractory composites under high-temperature cycles. The proposed route dealt with the feasibility of using fillers with different particle sizes and studying their influence on the thermo-mechanical properties of refractory geopolymer composites. The volumetric shrinkage was studied with respect to particle sizes of fillers (80, 200 and 500 µm), treatment temperature (1050–1250 °C) and amount of fillers (70–85 wt.%). The results, combined with thermal analysis, indicated the efficiency of refractory-based kyanite aggregates for enhancing thermo-mechanical properties. At low temperatures, larger amounts of kyanite aggregates promoted mechanical strength development. Flexural strengths of 45, 42 and 40 MPa were obtained for geopolymer samples, respectively, at 1200 °C, made with filler particles sieved at 80, 200 and 500 µm. In addition, a sintering temperature equal to 1200 °C appeared beneficial for the promotion of densification as well as bonding between kyanite aggregates and the matrix, contributing to the reinforcement of the refractory geopolymer composites without any sign of vitrification. From the obtained properties of thermal stability, good densification and high strength, kyanite aggregates are efficient and promising candidates for the production of environmentally friendly, castable refractory composites.

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Study on Thermal Stability of Nano-Silica Thermal Insulating Composites

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.488-489.588 ◽

2012 ◽

Vol 488-489 ◽

pp. 588-591

Author(s):

Jin Peng Feng ◽

De Ping Chen ◽

Wen Ni ◽

Shao Jian Ma

Keyword(s):

Thermal Stability ◽

Fumed Silica ◽

High Volume ◽

High Specific Surface Area ◽

Volume Shrinkage ◽

Nano Silica ◽

Excellent Thermal Stability ◽

Thermal Insulating ◽

Different Temperatures ◽

Thermal Stability Of

This work investigated the thermal stability of nano-silica thermal insulating composites, which consisted of fumed silica, fibers and opacifiers. The volume shrinkage was introduced as an evaluation index to characterize thermal stability of the composites at different temperatures. The effects of serving temperature, serving time, particle size of fumed silica and mass ratio of SiC were discussed. The results indicated nano-silica thermal insulating composites have excellent thermal stability under the temperature of 800°C. The volume shrinkage was correlated positively with serving time. High specific surface area of fumed silica could bring good thermal insulating performance, but at the same time caused high volume shrinkage when applied at high temperatures. SiC as an opacifier has little influence on volume shrinkage, but too much amount may yet increase solid heat transfer and lead to the drop of thermal insulating properties.

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Characteristics of Hg-Based Superconductors Prepared at 0.2 GPa by Hip

International Journal of Modern Physics B ◽

10.1142/s0217979299000886 ◽

1999 ◽

Vol 13 (09n10) ◽

pp. 1017-1022 ◽

Cited By ~ 4

Author(s):

G. Celotti ◽

A. Tampieri ◽

D. Rinaldi

Keyword(s):

Thermal Stability ◽

Magnetic Susceptibility ◽

Single Phase ◽

Volume Fraction ◽

Hot Isostatic Pressing ◽

High Volume ◽

Bulk Sample ◽

The Other ◽

Phase Synthesis ◽

Thermal Stability Of

The preparation of Hg(Pb)BCCO (1201) and (1223) phases was performed by hot-isostatic-pressing (HIP) using simple oxides as precursors canned in silver tube. In the case of Hg 0.8 Pb 0.2 Ba 2 CuO 4+δ the preparation, carried out at 800 °C and 0.2 GPa for 5 hrs, yielded a single phase bulk sample. On the other hand the preparation of Hg 0.8 Pb 0.2 Ba 2 Ca 2 Cu 3 O 8+δ at 820 °C and 0.2 Gpa for 5 hrs allowed the attainment of a high volume fraction of 1223 phase. Magnetic susceptibility of 1201 phase showed a granular transition around 90 K; in the case of 1223 the value was ≈128 K followed by a broadened intergranular transition. These results show the feasibility of 1201 phase synthesis with high purity and of 1223 phase in large amount (>80%). The possibility to obtain the samples directly in form of dense bulks (with density ≥ 85%) stresses the importance of this technique in relation to the intrinsic low thermal stability of the superconducting phases.

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The Ordered Phase Formation in Ti-Al-Ga Alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069193 ◽

1970 ◽

Vol 28 ◽

pp. 440-441

Author(s):

Shiro Fujishiro ◽

Harold L. Gegel

Keyword(s):

Thermal Stability ◽

High Temperature ◽

Titanium Alloys ◽

Growth Kinetics ◽

Stoichiometric Composition ◽

Good Potential ◽

Alpha Titanium ◽

Cold Rolled ◽

Kinetics Of ◽

Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

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Microstructure studies of tungsten silicide schottky contacts on Gaas

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126445 ◽

1987 ◽

Vol 45 ◽

pp. 328-329

Author(s):

Yih-Cheng Shih ◽

E. L. Wilkie

Keyword(s):

Thermal Stability ◽

Field Effect Transistors ◽

Schottky Contact ◽

Schottky Contacts ◽

Excellent Thermal Stability ◽

Barrier Heights ◽

Gaas Substrates ◽

Film Adhesion ◽

Threshold Voltages ◽

Thermal Stability Of

Tungsten silicides (WSix) have been successfully used as the gate materials in self-aligned GaAs metal-semiconductor-field- effect transistors (MESFET). Thermal stability of the WSix/GaAs Schottky contact is of major concern since the n+ implanted source/drain regions must be annealed at high temperatures (∼ 800°C). WSi0.6 was considered the best composition to achieve good device performance due to its low stress and excellent thermal stability of the WSix/GaAs interface. The film adhesion and the uniformity in barrier heights and ideality factors of the WSi0.6 films have been improved by depositing a thin layer of pure W as the first layer on GaAs prior to WSi0.6 deposition. Recently WSi0.1 has been used successfully as the gate material in 1x10 μm GaAs FET's on the GaAs substrates which were sputter-cleaned prior to deposition. These GaAs FET's exhibited uniform threshold voltages across a 51 mm wafer with good film adhesion after annealing at 800°C for 10 min.

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