Al2O3-CaO macroporous ceramics containing hydrocalumite-like phases

Author(s)

Borges, O. H. ^{[1, 2]} ; Santos Jr, T. ; Salvini, V. R. ^[3] ; Pandolfelli, V. C. ^{[4, 5]}

Affiliation

^[1] Univ Fed Sao Carlos, Grad Program Mat Sci & Engn, Sao Carlos, SP - Brazil

^[2] Univ Fed Sao Carlos, Mat Microstruct Engn Grp GEMM, FIRE Associate Lab, BR-13565905 Sao Carlos, SP - Brazil

^[3] Sao Paulo State Technol Coll FATEC, Rua Jordao Borghetti 480, BR-14160050 Sertaozinho, SP - Brazil

^[4] Santos Jr, Jr., T., Univ Fed Sao Carlos, Grad Program Mat Sci & Engn, Sao Carlos, SP - Brazil

^[5] Santos Jr, Jr., T., Univ Fed Sao Carlos, Mat Microstruct Engn Grp GEMM, FIRE Associate Lab, BR-13565905 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: CERAMICS INTERNATIONAL; v. 46, n. 5, p. 5929-5936, APR 1 2020.
• Web of Science Citations: 0

Abstract

A mechanism to explain the lower onset strengthening temperature induced by CaCO3 in alumina-based macroporous ceramics is proposed, which relies on hydrocalumite-like phase formation during processing. Close to 600 degrees C, such phases are decomposed to lime and mayenite (12CaO center dot 7Al(2)O(3)), where the latter, due to its intrinsic nanoporosity and high thermal reactivity, generates bonds between the ceramic particles at similar to 700 degrees C, resulting in microstructure strengthening. Based on this premise, the authors concluded that other Ca2+ sources could act similarly. Indeed, compositions containing Ca(OH)(2) or CaO showed the same effect on the onset strengthening temperature, which reinforces the proposed mechanism. The results attained indicated that macroporous insulators could be thermally treated at lower temperatures, just to acquire enough mechanical strength for installation, finishing in-situ their firing process. Besides that, lower sintering temperatures could be used to produce macroporous ceramics that would be applied in low thermal demand environments, e.g. aluminum industries. (AU)

• FAPESP's process: 18/07745-5 - Dimensional control of Macroporous ceramics by in situ CA6 formation
• Grantee: Otávio Henrique Borges
• Support Opportunities: Scholarships in Brazil - Master