The Effect of Varied Amounts of LiF Sintering Aid on the Transparency of Alumina Rich Spinel Ceramic with the Composition MgO · 1.5 Al2O3

2012 ◽  
Vol 95 (6) ◽  
pp. 1807-1810 ◽  
Author(s):  
Anthony C. Sutorik ◽  
Gary Gilde ◽  
Christopher Cooper ◽  
Jared Wright ◽  
Corydon Hilton
Keyword(s):  
Author(s):  
W. W. Davison ◽  
R. C. Buchanan

Yttria stabilized zirconia (YSZ) has become a significant technological material due to its high ionic conductivity, chemical inertness, and good mechanical properties. Temperatures on the order of 1700°C are required, however, to densify YSZ to the degree necessary for good electrical and mechanical properties. A technique for lowering the densification temperature is the addition of small amounts of material which facilitate the formation of a liquid phase at comparatively low temperatures. In this study, sintered microstructures obtained from the use of Al2O3 as a sintering aid were examined with scanning, transmission, and scanning transmission microscopy (SEM, TEM, and STEM).


2008 ◽  
Vol 591-593 ◽  
pp. 436-440
Author(s):  
João Marcos K. Assis ◽  
Francisco Piorino Neto ◽  
Francisco Cristóvão Lourenço de Melo ◽  
Maria do Carmo de Andrade Nono

A comparative study between alumina added niobia ceramics and two alumina zirconia composites from nanostructured TZP (7% and 14% weight) was made. On this composites the zirconia were yttria stabilized and the alumina were submicron structured. As sintering aid a mixture of magnesia, niobia and talc were used on all samples. The sintering was performed at 1450 oC during 60 minutes. The characteristic grain size and shape of an alumina and zirconia powders, aggregates and agglomerates were characterized. The sintering ceramics were evaluated through hardness, fracture toughness and 4 point bending test. Weibull statistic was applied on the flexural results. Although the fracture toughness result from ZTA were lower, and seems to be affected by the liquid fase, the hardness and Weibull modulus were higher than alumina niobia. The grains size and the homogeneity of its distributions on the microstructure of this ceramics was correlated to these higher values. The results from these alumina zirconia composites showed a potential to apply as a ballistic armor material.


Author(s):  
Yuanye Huang ◽  
Rotraut Merkle ◽  
Joachim Maier

The effects of 0.125-0.2 wt% NiO added as sintering aid for highly refractory Ba(Zr,Ce,Y)O3-δ proton conducting ceramics are investigated. The complex nature of the solid state reactive sintering method shows...


1999 ◽  
Vol 25 (2) ◽  
pp. 115-123 ◽  
Author(s):  
Amitava Chakraborty ◽  
Himadri S. Maiti
Keyword(s):  

1992 ◽  
Vol 287 ◽  
Author(s):  
Y. Sato ◽  
C. Sakurai ◽  
M. Ueki ◽  
K. Sugita

ABSTRACTA homogeneous mixture of Y2O3, CeO2 and MgO with a final weight ratio of 3:1: 2 was prepared by the alkoxide method. The powder mixture was then added into Si3N4 powder in amounts ranging from 4 to 12 wt%, andconsolidated by hot-pressing. Microstructure and mechanical properties of the sintered bodies were determined and compared to those of materials prepared by the conventional route of mixing the oxide powders as sintering aids individually in essentially same composition. The β-fraction (modification ratio) in same composition was higher in thesintered bodies made through the alkoxide method than those made through the conventional one. The room temperature flexural strength was maximized with 6wt% addition of the alkoxide derived oxide, whereas, 12wt% addition of the total oxide was required to maximize the strength by conventional processing.


Materialia ◽  
2019 ◽  
Vol 5 ◽  
pp. 100182
Author(s):  
S.F. Li ◽  
Y.F. Yang ◽  
K. Kondoh ◽  
S. Kariya ◽  
Q.S. Zhu ◽  
...  

2020 ◽  
Author(s):  
Eduardo Araújo ◽  
Marcelo Silva ◽  
Mauricio Pereira ◽  
Antonio Sombra ◽  
Igor Vasconcelos ◽  
...  

Abstract Molybdates from A2Mo3O12 family have been widely investigated due to its low sintering temperature, low thermal expansion coefficient, and low dielectric loss. Fe2Mo3O12 (FMO) is an oxide from this family and widely used in the catalytic field. The aim of this work is to evaluate the influence of the Bi2O3-B2O3 as a sintering aid in the microstructure and dielectric properties of FMO. The diffraction results showed that the FMO with the monoclinic structure phase was obtained after the calcination process (650 °C). Mössbauer spectroscopy showed the formation of Fe2O3 after the sintering process at 800 °C. The scanning electron-microscopic demonstrates an increase of the grain as a function of sintering aid concentration. The samples were analyzed by using the impedance spectroscopy at radiofrequency with temperature variation. The Nyquist diagram obtained in this temperature range was fitted from an equivalent circuit with three R-CPE associations, corresponding to the morphology of the electroceramics. For dielectric properties in the microwave, all the samples showed values of εr lower than 10. Values of Q x f above 14132.35 GHz were achieved. The thermal stability was evaluated by the temperature coefficient of resonant frequency (τf). The lowest τf values of -6.55 ppm/°C and -4.35 ppm/°C (near-zero) were measured to FMO and FMO mixed with 7.5 wt% Bi2O3-B2O3, respectively. Based on these results, FMO can be used to low permittivity ceramic for low temperature co-fired ceramics (LTCC) applications, antenna substrate, and millimeter-wave range.


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