China
Africa
Explore chapters and articles related to this topic
Carbonate Apatite Scaffolds for Regenerative Medicine
Published in Gilson Khang, Handbook of Intelligent Scaffolds for Tissue Engineering and Regenerative Medicine, 2017
Therefore, a porous structure is important not only for regenerative medicine scaffold but also for artificial bone substitutes. One of the interesting porous structures is the so-called ceramic foam. Basically, ceramic foam was proposed by Bridgestone and has been used as a molten metal filter and a high-temperature gas filter. This method employs polyurethane foam or sponge as a template. Polyurethane foam is immersed in a ceramic slurry so that ceramic powder will cover the surface of the polyurethane strut. Usually, mullite, aluminum silicate with a composition of Al4+2x Si2–2x O10–x is used for the ceramic foam aimed for the molten metal filter or high-temperature gas filter. When polyurethane foam is immersed in a mullite slurry, mullite-covered polyurethane foam is fabricated. Polyurethane is the thermosetting plastic and thus it will keep its structure at high temperature. When mullite-covered polyurethane foam is heated, mullite is sintered along with the burning out of polyurethane. As a result, ceramic foam or mullite foam will be fabricated, as shown in Fig. 5.8.
Design of an activated carbon equipped-cyclone separator and its performance on particulate matter removal
Published in Particulate Science and Technology, 2020
Jeffrey Z. Duran, Eugene B. Caldona
Incorporating a filter to the outlet of the cyclone may help collect the remaining particulates with smaller aerodynamic diameters. Common filters, such as diesel- and gasoline-particulate filter (DPF and GPF, respectively), assure high particulate removal efficiency from internal combustion engine exhausts (Guan et al. 2015). PM collection may also be done through adsorption. Recent studies show that ceramic foam and zeolites are potential alternatives to commercial filters. Developed ceramic foam filters, such as Al2O3 foams, allow the collection of PM because of the microstructure voids inherent in the material (Ciambelli et al. 2007). Zeolites were also found to be capable of straining small particles in their microscopic pores and channels. However, in their natural state, they are prone to rupture. Zeolites, alongside with gypsum as a binder, were not only found to significantly reduce the PM emissions from diesel-run vehicles, but also offer excellent thermal stability during engine operations (Muñoz-Boado and Caldona 2017).
Setting up the production process of diatomite-based ceramic foams
Published in Materials and Manufacturing Processes, 2018
Barbara Galzerano, Letizia Verdolotti, Ilaria Capasso, Barbara Liguori
The paper described a manufacturing approach related to the setup and optimization of an innovative hybrid insulating materials based on metakaolin and/or diatomite powder. In particular, the combination of two different foaming processes, chemical and mechanical, respectively, led to the formation of a hybrid ceramic foam, having an inorganic structure (metakaolin and diatomite) linked to an organic phase (whipped vegetal surfactant). In particular, the whipped vegetable surfactant had the important role to stabilize the hybrid foam structure through the formation of a cross-linked organic network with the inorganic phase. This structure was achieved with a suitable optimized experimental setup of the process parameters and mix design formulation.
A review on porous ceramics with hierarchical pore structure by 3D printing-based combined route
Published in Journal of Asian Ceramic Societies, 2021
Yiran Man, Guoqiang Ding, Luo Xudong, Kaihua Xue, Dianli Qu, Zhipeng Xie
Although the team’s research has strengthened the link between SLS technology and porous ceramics, only porous ceramics with micropores have been prepared. On this basis, the team prepared hierarchical porous mullite ceramics with adjustable bimodal pore structures for the first time in a similar way [39]. In this study, calcined FAHSs and PA12 were mixed by mechanical mixing to prepare feedstock for SLS. Then, 3D printing, debinding, and sintering were performed in succession. The macroscopic morphology, micromorphology, and printing process are shown in Figure 2(b-d). The porosity of the material and products can be easily observed. The effects of PA12 addition of feedstock for SLS printing on porosity, pore size distribution, compressive strength, and thermal conductivity were investigated. With increasing PA12 content from 10% to 25%, the porosity of the porous ceramics increases, but the strength decreases. the total porosity firstly increased from 85.1% to 85.2% and then obviously increased to 86.7%. The thermal conductivity of the lightweight ceramics was also relatively low which could be as low as 0.06 W/(m·K) due to the special pore structures formed from the FAHSs and SLS technique. When the porosity of porous ceramics reaches a maximum of 85.2 ± 0.4%, its strength reaches 2 MPa, which is higher than that of porous ceramics prepared by traditional methods. The design of pore structures and microstructures can enhance pore control and strength using ceramic hollow spheres as feedstock for SLS. This work also lays the foundation for the preparation of lightweight porous ceramics with adjustable bimodal pore structures. The printed porous ceramics can be widely used in applications such as thermal insulators, sound absorption materials, filters and catalyst supports [40,41]. In another study by their team, the enhancement mechanism of the compressive strength of porous mullite ceramics prepared by SLS using FAHSs as feedstock was investigated [42]. With the increase of sintering temperature from 1250°C to 1400°C, the average closed pore size of ceramic foam decreases from 58.7 mm to 46.0 mm, while the average open pore size distribution kept constant with average pore size of 32.9 mm. Consequently, the total porosity of mullite ceramic foams decreases from 89.1 ± 0.1% to 81.5 ± 0.6% mainly due to the reduction of enclosed hollow spaces of FAHSs. The compressive strength of ceramic foams shows the opposite tendency increasing from 0.12 ± 0.02 MPa to 4.86 ± 0.18 MPa.The study found that the liquid phase diffusion of K, Ca, and Ti can reinforce sintering necks between FAHSs and improve the thickening and densification of sphere shell walls. The porous mullite ceramic with bimodal pore structures and its microstructure are shown in Figure 2(e-f). It is helpful to design porous ceramics with high compressive strength and high porosity. This kind of highly porous mullite ceramics are desirable for a widespread industrial applications in thermal insulators, particle filters, catalyst supports, separation membranes, etc [43–46].