Fabrication of Porous Alumina Ceramics by New Eco-Friendly Process

Abstract

We have developed a new ecofriendly fabrication process for porous ceramics using hydraulic alumina (HA) and water. In the present study, we fabricated porous alumina ceramics using this new process. A boehmite gel 3D network was formed by the hydration of HA in HA slurry. The HA slurry was hardened by the formation of this 3D network. Even without the addition of an organic binder, green bodies containing the 3D network demonstrated high compressive strength. Furthermore, the water acted as a fugitive material in the green bodies.Consequently, the open porosity of sintered alumina ceramics could be controlled over a wide range of 56.6 69.1÷ by addition of water (ratio of water to HA powder: 1.0 to 2.0 by weight) without the use of organic fugi tive materials. The results of evolved gas analysismass spectrometry measurements showed that the emissions from the hardened green body mostly consisted of water. Consequently, the new fabrication process for porous alumina ceramics was confirmed to be ecofriendly.

Extrusion of Alumina Ceramics with Hydraulic Alumina without Organic Additives

“…13 A small peak representing bayerite was observed in the cured samples after hydration for 24 h. 13 As the curing time increased, the peak intensity of the bayerite increased and that of the boehmite gel decreased, respectively. The sample cured for 192 h was mostly composed of bayerite and a small amount of boehmite gel.…”

“…13 In this new process, green bodies were able to be fabricated by the same way to make castable by casting. The obtained green bodies had high compressive strength by the formation of 3-D boehmite gel networks instead of organic binders for the conventional process.…”

“…In this process, employing HA and water, the green body is composed of alumina hydrates, such as boehmite gel and bayerite. 13 This boehmite gel is expected to act as an inorganic plasticizer for extrusion.…”

Eco-friendly processing and methods for ceramic materials - A review

“…42) Table 1 summarizes some physical properties of the ceramics as a function of composition and sintering temperature. For each set, density increased with increasing sintering temperature and reached ≥ 97% density.…”

Fabrication of Porous Titania Using Anisotropic Particles

“…13 On the other hand, one of the simplest procedures is just connecting ceramic particles by sintering 1 ,2 and this procedure emits no green house gas. In this procedure, pore size distribution and porosity of the materials significantly depend on the morphology of particles and their alignment.…”