Manufacture of-Alumina Electrolyte Tubes

The manufacture of P -Pl20 tubes for batteries should result in a product with high sintered density, fine closed porosity, low electrical resistivity, good mechanical strength, and close dimensions. The formation of 73 -alumina electrolyte depends on the starting materials as well as on the production process itself Different starting materials necessitate different production routes. Some key requirements which strongly influence the production process must be mentioned  

The difficulty of obtaining pure / -material for the electrolyte has been tackled in many production processes worked out in the past. Unless precautions are taken, sintering of a-alumina-derived / -alumina compositions invariably results in the duplex microstructure and a low-strength ceramic. Therefore a balance has to be struck between conductivity and strength. The problem arises because the conversion from -alumina to / -alumina is slow compared with rapid densification and grain growth. Barrow and Duncan have classified the process into four main routes [20]  

1) Rapid firing followed by a subsequent anneal. This process relies on sintering quickly before any grain growth can occur, and then an anneal at a lower temperature where little growth can occur, to aid conversion from /S-alumina to /3 -alumina. 

3) Zeta process. This process improves the mixing and uses the -spinel LiAljOs as a spinel-former additive. In doing this the proportion of y3 -alumina at 

4) Seeding. This process rebes on addition of approximately 2% of -alumina seeds to powders, which increases the amount of y -alumina formed. 

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