Reticulated Open-Celled Zinc Oxide Ceramic Foams: Manufacturing, Microstructure, Mechanical, and Thermal Properties

Abstract

Open-celled zinc oxide ceramic foams were prepared by the polymer sponge replication (Schwartzwalder) technique from aqueous ZnO dispersions with Sb2O3 and Bi2O3 as sintering additives, and mechanically stable ZnO foams with an average porosity of 93.6% were obtained. Their microstructure consists of ZnO grains with a Bi-containing grain boundary phase together with a Zn-Sb-O secondary phase with spinel structure. The obtained ZnO ceramic foams were characterized with respect to their morphology by computed tomography; in addition, the compressive strength and the thermal conductivity were determined, and the data were applied for modelling of the mechanical and thermal properties of the bulk ZnO strut material.

Reticulated open‐cellular aluminum nitride ceramic foams: Effect of sintering aids on microstructural, thermal, and mechanical properties

“…The mean compressive strength at a failure probability of 63.2% is 0.18 ± 0.11 MPa for the foams made with 1.7 mol% yttria, 0.14 ± 0.07 MPa (2.5 mol% Y 2 O 3 ), and 0.07 ± 0.03 MPa (2.5 mol% Dy 2 O 3 ), respectively. The overall strength is low due to the high total porosity of 94 vol.% or above, and it is in good agreement with cellular ceramics made of other materials like ZnO (0.15 MPa at P = 93.6 vol.%) 7 and Al 2 O 3 (0.19 MPa at P = 94 vol.%) 34 . The course of the strength results fits well with the trend in the average total porosity, which is highest for the foams made with 2.5 mol% Dy 2 O 3 (94.6 vol.%) and lowest for the samples with 1.7 mol% Y 2 O 3 (94.0 vol.%).…”

“…Interestingly, the microstructure of all foams investigated differs from the typical microstructure of liquidphase sintered ceramics, which show the formation of secondary phases from a molten phase at the grain boundaries as well as grain triple points. 7,19,24 For high contents of sintering aids, even a percolating arrangement of secondary phases is formed. 16 Consequently, the particulate arrangement of secondary phases for the AlN foam samples in this work indicates that no formation of a liquid phase has taken place over larger areas in the microstructure.…”

“…2,3 These materials are mostly used for the industrial production of ceramic foam filters for foundry applications in quantities exceeding 10 8 pieces per year. 4 Nevertheless, the process has also been adapted for more specialized engineering and functional ceramics, for example, Al 2 O 3 -ZrO 2 composites (ZTA), 5,6 ZnO, 7 CeO 2 , 8 Si 3 N 4 , 9 and also, AlN. 10 Aluminum nitride features the unique combination of being an electrical insulator and possessing a high thermal conductivity of up to 180 W m −1 K −1 for typical sintered parts of AlN.…”

Mechanical and Surface-Chemical Properties of Polymer Derived Ceramic Replica Foams

“…Ten samples of every foam series were measured, whereby the samples were put on the plane site. The measurement settings were selected according to the test configurations chosen in References [40,41]. A photo of the setup and a tested specimen is shown in Figure 1.…”

Luminescence Properties of Nano Zinc Oxide Doped with Al(III) Ions Obtained in Microwave-Assisted Hydrothermal Synthesis

“…It belongs to the amphoteric oxides. Due to its properties, it has become a material willingly used in many branches of industries, such as: rubber [1], pharmaceutical [2][3][4], dye [5][6][7], ceramic [8,9], and the chemical industry [10].…”