New Processing Techniques of Ceramic Foams

Abstract

stantial (Fig. 4b), especially for small Monte Carlo models. Nonetheless, the scatter diminished steadily upon increasing number of spheres, and the estimates obtained with 1000 spheres were already rather uniform. But strikingly, the ensemble minimum estimates obtained with a given, small number of spheres were practically stationary, and they delivered surprisingly accurate predictions for the results obtained with Monte Carlo models with 1000 spheres. We also conducted studies at four other sphere volume concentrations between 0.2 and 0.5, and saw the same picture, namely that the ensemble minimum estimates obtained with Monte Carlo models with a few dozen spheres delivered remarkably accurate estimates for the results obtained with 1000 spheres. These results indicate that small computer models with a few dozen spheres are already large enough to accommodate the local microstructural configurations that control the onset of catastrophic damage propagation.Technologically, by loading inclusions with a high dielectric permittivity into a polymer, one obtains a composite material with an increased effective permittivity. However, because of the local electric field magnifications, this improvement is accompanied by a parallel decrease in the effective voltage breakdown field. Table 1 presents results obtained for the random composite studied in this work, and one can see that the unwanted decrease in the effective voltage breakdown field is considerably more pronounced than the targeted increase in the effective dielectric constants. One could expect that the regular microstructure composites should exhibit a less pronounced decrease in the voltage breakdown of the composite. Results presented in Table 1 confirm this premise, but nonetheless they also indicate that the unwanted decrease in the voltage breakdown field of the composite is still stronger than the increase seen in the effective dielectric constants.To conclude, our results suggest that in random microstructure composites, the voltage breakdown is a strongly localized phenomenon and that it is feasible to employ remarkably small computer models to extract reliable estimates for the voltage breakdown field characteristic of large, laboratory samples.Ceramic foams are lightweight materials with a cellular structure. Due to the combination of properties resulting from the ceramic material and the cellular structure, these foams have a high potential for many applications. To have access to all these applications, the shaping techniques that are used to produce these ceramic foam structures must result in sufficient mechanical strength and in a well-controlled macroand microstructure. As the obtained structure is strongly related to the manufacturing route, the ceramic-processing group of Vito focuses on the development of new ceramic foam synthesis routes aiming at materials with improved properties.Three different manufacturing ways are tested: a reaction bonded-modified (RB) polyurethane replica technique, gel casting, and a method of hollow building ...

Reticulated Replica Ceramic Foams: Processing, Functionalization, and Characterization

“…If there is a complete beam path through the sample, measurement will fail, thus it is limited to a porosity of 90% [115] and to a pore size <100 mm. At bigger pore sizes, the accuracy of measurement decreases.…”

“…Typical applications are found in molten metal filtration [118] or in porous ceramic burners. [115] The thermal shock coefficient D for dense ceramic materials is determined by quenching; D is defined in ref. [119] and shown in Equation 9:…”

“…In contrast to dense materials, porous materials show a faster temperature gradient decrease resulting in faster thermomechanical relaxation and a lower level of thermally induced mechanical stresses. The thermally induced mechanical stress s t is expressed after [115] as:…”

Short Review: Ceramic Foam Fabrication Techniques for Wastewater Treatment Application

“…It can be classified as lightweight materials that exist as a cellular structure, struts, and windows [2]. Ceramic foams are porous and brittle materials comprising of large void cells, with linear dimensions in the range of 10 µm to 5mm [3].…”

Experience on a Low Cost Way to Obtainal-Ti Ceramic Foams

“…Several processing routes using replica, sacrificial templates or direct foaming methods are nowadays available for the production of macroporous ceramics. Three manufacturing routes are usually followed: gel casting, particulate sacrificial fillers, hollow building blocks and reaction bonded-modified polyurethane replica technique as a way to producing cellular ceramics 1 . These routes differ greatly in terms of processing conditions and properties of the resulting microstructure 2,3 .…”