Sodium corrosion resistance of translucent alumina: effect of additives and sintering conditions

Abstract

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Thermodynamic Analysis of Alumina Refractory Corrosion by Sodium or Potassium Hydroxide in Glass Melting Furnaces

“…Corrosion of alumina by sodium has been of interest for some time due to its use in low-pressure sodium discharge lamp envelopes, 6,7 in composites, 8,9 and structural ceramics. Using various qualitative and semiquantitative methods, the stability of alumina-containing refractories in glass-melting environments has been evaluated.…”

Light scattering in polycrystalline alumina with bi-dimensionally large surface grains

“…14 Some impurities or additives, like CaO and MgO, segregated at grain-boundaries decrease the resistance against sodium corrosion. 31 Second-phase particles, usually located at alumina grain-boundaries, can also affect corrosion rate. Spinel particles seem to promote the formation of ␤-Al 2 O 3 and accelerate sodium attack, while YAG particles are resistant to this attack.…”

Translucent Polycrystalline Alumina with Improved Resistance to Sodium Attack

“…YAG scavenges calcium and silicon impurities, 13 which are known to be detrimental to sodium resistance. 8,10,19 Additionally, yttrium was found to segregate to grain boundaries by TEM/EDXA, 20 with an enrichment ratio of 7.1%-9% (cation sites) quantified via SIMS imaging. 21 This was reported to decrease the grain-boundary transport rates in Al 2 O 3 , as exhibited by a lower creep rate, 22,23 and a lower densification rate.…”

“…The cylindrical PCA tube containing sodium vapor was a closed system, which in a way rendered the diffusion process the rate-determining step. If the sodium-PCA reaction experiments involved a configuration different from the lamp's arc tube such as those using PCA samples placed inside capsules, 8,17 the drastic effects of the dopants shown in Fig. 2, could never be discovered.…”