Wet Foam Stability from Colloidal Suspension to Porous Ceramics: A Review

Abstract

Porous ceramics are promising materials for a number of functional and structural applications that include thermal insulation, filters, bio-scaffolds for tissue engineering, and preforms for composite fabrication. These applications take advantage of the special characteristics of porous ceramics, such as low thermal mass, low thermal conductivity, high surface area, controlled permeability, and low density. In this review, we emphasize the direct foaming method, a simple and versatile approach that allows the fabrication of porous ceramics with tailored microstructure, along with distinctive properties. The wet foam stability is achieved under the controlled addition of amphiphiles to the colloidal suspension, which induce in situ hydrophobization, allowing the wet foam to resist coarsening and Ostwald ripening upon drying and sintering. Different components, like contact angle, adsorption free energy, air content, bubble size, and Laplace pressure, play vital roles in the stabilization of the particle stabilized wet foam to the porous ceramics. The mechanical behavior of the load-displacements curves of sintered samples was investigated using Herzian indentations testes. From the collected results, we found that microporous structures with pore sizes from 30 µm to 570 µm and the porosity within the range from 70% to 85%.

Properties of Surface Heating Textile for Functional Warm Clothing Based on a Composite Heating Element with a Positive Temperature Coefficient

“…Screen-printing of composite materials relies on the preparation of an optimal paste [ 27 , 28 ]. A composite paste with PTC behavior was prepared by mechanically mixing commercially available PTC carbon ink (Ink−1M7511, 1-Material) and MWCNT (7311, 1-Material) powders.…”

Core–shell-structured Fe3O4 nanocomposite particles for high-performance/stable magnetorheological fluids: preparation and characteristics

“…Han et al [5] have applied the Pickering-emulsion polymerization method using the ferromagnetic magnetite (Fe 3 O 4 ) nanoparticles, because it shows not only higher surfactant activity due to its amphiphilicity but also higher magnetic saturation value than that of Fe 2 O 3 [38][39][40][41]. PS (core)/ Fe 3 O 4 (shell) structured particles were synthesized by Pickeringemulsion polymerization method.…”

“…Recent studies have shown that fabricating core-shell nanoparticles of a low-density polymeric material encapsulated by fine magnetic particles or introduction of a protective light polymer layer on the magnetic particles is a fairly efficient and promising method for lighter and therefore more stable suspensions [15][16][17]. In this regard, Fe 3 O 4 is being studied intensively due to its lower density than CI and relatively high magnetic properties as well as its excellent surface activities [6,18,41]. This is useful for fabricating core-shell particles using the Pickering-emulsion process since the solid Fe 3 O 4 particles can be used as a solid surfactant instead of conventional organic molecular surfactants.…”

Foam forming of fiber products: a review

“…Wet foams are extensively used, for example, in foods and cosmetics. As for material applications, wet foams are used to produce porous biomaterials [32] and ceramics, [33,34] and one of the most common applications of dry foams is found in the foam extrusion and foam injection molding of polymer composites. [35] Besides foam forming, foam coating is also being developed at the moment.…”