Fabrication and evaluation of sol-gel derived magnesium aluminate spinel-clad sapphire fiber

Superfine, high-purity and well-distributed magnesium aluminate spinel powders were fabricated by controlling alkoxides hydrolysis process. Magnesium aluminate alkoxides were prepared by sol-gel with magnesium, aluminum and n-butyl alcohol as starting materials. Magnesium aluminate spinel powders were fabricated by double alkoxides sintering at 1200 °C for 1h. Controlling hydrolyzing process could obtain the optimum gel time and spinel powders were analyzed by OMEC LS-800 type Laser Particle Size Analyzer. Integrated gel time and particle size, the optimum hydrolyzing parameters are obtained for double metal alkoxides: the concentration of the double metal alkoxides is below 0.3 mol/L, hydrolysis temperature is 20 °C, the molar rate of alkoxides and water is 1: 10 and the mechanism of the hydrolysis is investigated. Nicolet Avatar 360 type FTIR spectrometer shows that acetylacetone and alkoxides can form a stable hexatomic ring which restrains hydrolysis reaction and controls particle size.

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Synthesis of ZrTiO4 and MgAl2O4 Powders via Non-Hydrolytic Sol-Gel Route Using Alcohol as Oxygen Donor

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.284-286.1471 ◽

2011 ◽

Vol 284-286 ◽

pp. 1471-1474

Author(s):

Heng Yong Wei ◽

Rui Sheng Wang ◽

Jun Hong Zhao ◽

Jing Long Bu ◽

Rong Lin Wang ◽

...

Keyword(s):

Sol Gel ◽

Milling Process ◽

Magnesium Aluminate ◽

Magnesium Aluminate Spinel ◽

Zirconium Titanate ◽

X Ray Diffraction ◽

Laser Scattering ◽

X Ray ◽

Oxygen Donor ◽

Sol Gel Process

Zirconium titanate and magnesium aluminate spinel precursors were prepared by non-hydrolytic sol-gel method using ethanol as oxygen donor. The gels and calcined powders were investigated by differential thermal analysis (DTA), thermogravimetry analysis (TG), X-ray diffraction (XRD). The results show that the ZrTiO4and MgAl2O4crystallized at low temperature of 550 °C and 700 °C, respectively. It indicated that the highly homogeneous zirconium titanate and magnesium aluminate gels were aslo obtained by nonhydrolytic sol-gel process using ethanol as oxygen donor. The particle size distribution measured by laser scattering exhibit that ZrTiO4and MgAl2O4powders were large soft agglomerates which could be broken through milling process.

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Effects of In Situ Formation of Magnesium Aluminate Spinel on Performance of Modified Sizing Nozzle

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.750-752.1130 ◽

2013 ◽

Vol 750-752 ◽

pp. 1130-1136

Author(s):

Guang Liang Yuan ◽

Qun Hu Xue ◽

Xiang Li ◽

Yuan Yang

Keyword(s):

Corrosion Resistance ◽

Sol Gel ◽

Magnesium Aluminate ◽

Magnesium Aluminate Spinel ◽

Sintering Process ◽

Stabilized Zirconia ◽

Composite Powders ◽

The Stability ◽

Better Than

The modified sizing nozzle with excellent performances was successfully prepared by using of Mg,Y-PSZ as aggregates, Mg,Y,Ca-PSZ as fines, adding a certain amount of Al2O3-ZrO2 composite powders prepared by sol-gel. Effects of magnesium aluminate spinel in-situ synthesized in modified sizing nozzle on its performances were studied in this experiment. The results show that, the content of cubic zirconia in the sizing nozzle was decreased with the increasing of Al2O3-ZrO2 composite powders; the samples of modified sizing nozzle have no diameter-expanded after 30 hours service. The use effects are obviously better than that of Al2O3-ZrO2 composite powders free. The main reason is that a new bond phase magnesium aluminate spinel was in-situ generated through the reaction between Al2O3 in Al2O3-ZrO2 composite powders and the stabilizer MgO from partially stabilized zirconia in the sintering process at high temperature. The spinels embedded in the substrate of zirconia grow further and fill between zirconia particles. This prevents the stabilizer of CaO further desolventizing and also stop losing the eutectics formed by the reaction with compositions of molten steel. Therefore, the stability of zirconia and the corrosion resistance of the sizing nozzle were improved.

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