Ultrahigh‐strength alumina ceramic foams via gelation of foamed boehmite sol

Abstract

Ceramic foams with significant porosity and robust mechanical properties have received extensive attentions. However, it is still difficult to achieve excellent compressive strength at high porosity levels. In this work, a gelation of foamed boehmite sol method is proposed to settle this issue. The technological parameters during preparation process are systematically investigated. As‐prepared alumina ceramic foams possess unprecedentedly high compressive strength of 34.1‐89.1 MPa at high porosity levels of 66.0%‐87.2%, which is attributed to the present of hierarchical pore structure, small grain size and pore size. This work demonstrates a facile and novel method for the fabrication of high‐performance alumina ceramic foams toward practical applications.

Synthesis and mechanical properties of lightweight hybrid geopolymer foams reinforced with carbon nanotubes

“…The mechanical strength of ceramic composites is mainly determined by the intrinsic strength and decreases exponentially with the increase in porosity. However, the pore structure (pore size, pore wall thickness, and pore formation distribution) also has a comprehensive influence on the strength of final composites 48,49 …”

Ceramic foams with highly open channel structure from direct foaming method in combination with hollow spheres as pore-former

“…As illustrated in Fig. 1, the foams are subjected to solidi cation with the assistance of agar molecules in the case of ZrO 2 based foams [11] , and rapid gelation of boehmite nanoparticles was triggered by decreasing pH in the case of Al 2 O 3 based foams [12] . Therefore, the dried foams exhibit favorable strength, that keep the whole porous green body holding together and be free of breaking.…”

Ceramic foams with highly open channel structure from direct foaming method in combination with hollow spheres as pore-former.

“…As illustrated in Figure 1, the foams are subjected to solidification with the assistance of agar molecules in the case of ZrO 2 based foams [11,12], and rapid gelation of boehmite nanoparticles was triggered by decreasing pH in the case of Al 2 O 3 based foams [13]. Therefore, the dried foams exhibit favorable strength, that keeps the whole porous green body holding together and be free of breaking.…”