Direct foaming of macroporous ceramics containing colloidal alumina. Issue 11 (1st June 2021)

• Record Type: Journal Article
• Authors: Finhana, I.C.; Machado, V.V.S.; Santos, T.; Borges, O.H.; Salvini, V.R.; Pandolfelli, V.C.
• Is Part Of: Ceramics international. Volume 47:Issue 11(2021)
• Page Start: 15237
• Page End: 15244
• Publication Date: 2021-06-01
• Subjects: Colloidal alumina -- Direct foaming -- Liquid foam -- Particle-stabilised foam -- Foam stability; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2021.02.086
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Liquid foams containing Al2 O3 nanoparticles were obtained after direct foaming of a colloidal alumina suspension with ammonium stearate. These systems were stable for at least 24 h and were comprised by small cells (<35 μm). Up to 10 wt% of these foams were added to an ultrastable Al2 O3 -stabilised one and resulted in macroporous samples with high total porosity (>70%). Their green mechanical strength was proportional to the amount of colloidal alumina added, but lower than a composition with calcium aluminate cement. When compared with compositions prepared with colloidal alumina suspension, the colloidal foams resulted in samples with a higher number of small pores (<30 μm) and lower linear shrinkage after firing at 1600 °C for 5 h (~9%). Thus, colloidal alumina foams can be used for processing macroporous refractory ceramics with smaller pores, lower dimensional changes after firing and higher porosity. Graphical abstract: Image 1