Low-temperature sintering of sodium beta alumina ceramics using nanosized SnO2 sintering aid

Sodium beta alumina ceramics (Na1.67Al10.67Li0.33O17) is used in sodium sulphur batteries as solid electrolyte. In the present work, sodium beta alumina powder has been synthesized by the solid state method using Al2O3, Na2CO3 and Li2CO3 as the starting materials. The effect of nanosized SnO2 additive on sintering behaviour, microstructure, mechanical and electrical properties of sodium beta alumina ceramics has been investigated. The results indicated that the addition of 1mol% of nanosized SnO2 particles, determined as the optimal amount, can decrease the sintering temperature of sodium beta alumina ceramics for about 100?C, and lead to the excellent densification and proper microstructure, as well. Improvement in sintering behaviour of beta alumina ceramics in the presence of nanosized SnO2 additive is apparently due to the formation of a liquid phase during the sintering process and lower sodium loss. The results also proved that by SnO2 addition, ionic conductivity at 300?C, fracture strength and Weibull modulus of the sintered samples are improved by 66%, 58%, and 45%, respectively. These improvements could be attributed to the higher amount of ???-Al2O3 phase, higher density and more uniform microstructure.

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A Dramatic Reduction in the Sintering Temperature of the Refractory Sodium β’’-Alumina Solid Electrolyte via Cold Sintering

Journal of Materials Chemistry A ◽

10.1039/d1ta05933e ◽

2021 ◽

Author(s):

Zane A. Grady ◽

Arnaud Ndayishimiye ◽

Clive A Randall

Keyword(s):

Solid State ◽

Solid Electrolyte ◽

Sintering Temperature ◽

Sodium Ion ◽

Dramatic Reduction ◽

Sintering Process ◽

Sodium Beta Alumina ◽

Beta Alumina

The cold sintering process is successfully applied to one of the most refractory solid-state sodium-ion electrolytes, namely sodium beta alumina (SBA). By using a hydroxide-based transient solvent, SBA is densified...

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Tribological Behaviour of Alumina Ceramics with Nano TiO2 as a sintering aid in Non-Conformal Contact

Journal of Tribology ◽

10.1115/1.4053128 ◽

2021 ◽

pp. 1-21

Author(s):

Partha Haldar ◽

Tapas Kumar Bhattacharya ◽

Nipu Modak

Keyword(s):

Mechanical Properties ◽

Secondary Phase ◽

Alumina Ceramics ◽

Alumina Matrix ◽

Tribological Behaviour ◽

Nano Tio2 ◽

Sintering Aid ◽

Tio2 Addition ◽

Sintering Behaviour ◽

Hexagonal Columnar

Abstract The study emphasized the sintering behaviour and tribo-mechanical properties of alumina ceramics by nano TiO2 addition as a sintering aid. With increase in sintering temperature, the bulk density of alumina has increased gradually and optimized at 1600°C. The optimizing effect of densification at 1600°C is 98.25% by the addition of 1 wt.% nano TiO2. The maximum solid solubility of titania in alumina grains was at 1600°C, causes optimisation of densification by 1 wt. % addition. The excess addition of TiO2 formed low dense Al2TiO5, appear as a secondary phase at grain boundaries and does not significantly improved densification. Fracture toughness increases and coefficient of friction decreases with the addition of nano TiO2 in alumina matrix. The 1wt.% nano TiO2 addition improved hardness to 8.82% and reduces specific wear rate to 45.56%. The 1wt.% nano TiO2 addition greatly influenced the microstructure of sintered Al2O3. The morphology was sharply changed from hexagonal columnar shape to order sub round orientation which also directly impact the tribo-mechanical properties of sintered alumina. The 1wt.% addition substantially decreases wear track depth as observed by 3D surface profilometer. Microscopic observation of the worn-out surface showed that wearing is majorly caused by plastic deformation and abrasion.

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