Enforcing of Mechanical Properties of Alumina Foams

Zierath, Bodo; Greil, Peter; Stumpf, Martin; Fey, Tobias

doi:10.1002/9781119321682.ch16

Cited by 9 publications

(14 citation statements)

References 31 publications

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“…[7,16] This is questionable, as no information is given about the distribution and localization within the foam of the added material. Investigations with m-CT on specimens infiltrated by A50 proved, that only a part of the struts is filled, a significant difference to the fully infiltrated struts of B65 specimens (Figure 2).…”

Section: Infiltrationmentioning

confidence: 99%

“…[16] Unfortunately, it is not possible to compare the strength directly, due to different measuring geometry, sample geometry (size, relative density, cell size), or other missing measurement parameters. [7,16,18] The Weibull moduli m range from 1.9 to 5.7 and exhibit no obvious correlation to varied parameters (T max1 , T max2 , colloid, infiltration technique; Table 2). The scattering range suggests an influence of the sample preparation, but differences in preparation were not identified, and the Weibull moduli as calculated are in the range as reported for comparable cellular materials.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

“…The scattering range suggests an influence of the sample preparation, but differences in preparation were not identified, and the Weibull moduli as calculated are in the range as reported for comparable cellular materials. [7,23] Nevertheless, the infiltration process is associated with a weight gain, and the relative density change must be considered. [22][23][24][25][26] (7) 21 (7) B65I [b] 8.9(1) 90.1(6) 1.5 (5) 15 (5) 90.6(8) 0.5 (7) 5 (7) [a] non-infiltrated RPC_0.5 P low sintered at T max1 ¼ 1350 C and T max2 ¼ 1650 C.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

“…[14] A similar approach using colloids is discussed recently, using colloidal silica on an alumina foam and colloidal alumina on an oxide bonded SiC foam. [7,15] The use of ball-milled colloidal alumina suspension for vacuum infiltration of alumina foams is also reported. [16] In none of these studies the infiltration process was investigated with respect to the particle size of the colloid used.…”

Section: Introductionmentioning

confidence: 99%

“…[6] At the corners of this triangle, a peak stress in the material is discussed, resulting in a failure of replica foams while loading. [7,8] The 3rd order porosity are cracks and part of microstructure defects, which are not equally distributed over the struts. Cracks cause a weakening of the mechanical stability of foams.…”

Section: Introductionmentioning

confidence: 99%

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Increased Mechanical Stability and Thermal Conductivity of Alumina Reticulated Porous Ceramics (RPC) by Nanoparticle Infiltration Processing

et al. 2017

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Infiltration processing of reticulated porous alumina ceramics (RPC) from reticulated foam manufacturing is investigated by micro computed tomography. Infiltration is carried out with colloidal alumina slurries. Successful infiltration is found to be a function of the RPCs starting microstructure and the particle size of the alumina in the colloidal infiltration system. Suitable infiltration conditions are specified. As a result, RPCs with a low relative density show a fivefold compressive strength after infiltration, as compared to their non-infiltrated RPC counterparts. The highest strength of infiltration processed alumina RPCs at a porosity of 90% is found to be 1.6 MPa, and besides a significant increase of the compressive strength, the thermal conductivity is improved to be 1.5 W m À1 K À1 after infiltration.

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Section: Infiltrationmentioning

confidence: 99%

Section: Mechanical Propertiesmentioning

confidence: 99%

Section: Mechanical Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Increased Mechanical Stability and Thermal Conductivity of Alumina Reticulated Porous Ceramics (RPC) by Nanoparticle Infiltration Processing

et al. 2017

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Reticulated Replica Ceramic Foams: Processing, Functionalization, and Characterization

et al. 2017

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Reticulated ceramic foams are used in a wide range of applications such as filters, catalyst supports, lightweight materials, energy absorptions materials, or as scaffolds for tissue engineering as the most common ones. Based on gaseous foaming processes of polymers, a stochastic distribution of closed pores is obtained. By reticulation processing thin foam windows are removed between cells turning a closed cell into an open cell structure. These foams are used as template for porous ceramics manufacturing: With different processing approaches, for example, with dip coating of a ceramic slurry and a subsequent (multistep) thermal treatment ceramic reticulate foams are obtained. A variety of material properties strongly depend on the cell and strut size, as well on material composition. Functionalization of ceramic foam surfaces (outer surface functionalization), for example, with zeolites or nanosized aggregates lead to an increase of the specific surface area or provides catalytic or heat storage functionality. Filling of struts (inner surface functionalization) may lead to improved mechanical stability or may provide functionalities such as electric conductivity. The present work summarizes the processing steps from the template foam to the final cellular ceramic, functionalization strategies, and the most common characterization techniques.

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Influence of Cell Size on Mechanical and Piezoelectric Properties of PZT and LNKN Ceramic Foams

et al. 2017

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Piezoceramic foams made of lead zirconate titanate (PZT) and lithium sodium potassium niobate containing an open porosity >75 vol% are manufactured with varying cell size from 1369 to 265 mm and accordingly, strut size from 346 to 46 mm by replica method. Pore size distribution and strut thickness are determined by X-ray micro tomography investigations of PZT foams with 10, 30, 45, and 80 pores per inch (ppi). Fracture strengths s b between 0.29 and 1.52 MPa (PZT) and 0.04 and 0.07 MPa (LNKN-6) are determined by compression test and compared to Gibson and Ashby's model of open-and closed-cell foams and in dependence of the cell size. The longitudinal and transversal coupling coefficients d 33 and d 31 decrease in a range of 38 to 178 pCN À1 or À13 to À100 pCN À1 compare to dense reference material. In dependence of the cell size, the values of the coupling coefficients change about 79-93%. The relative permittivity decreases 93% by decreasing the cell size of the PZT and LNKN-6 foams.

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Enforcing of Mechanical Properties of Alumina Foams

Cited by 9 publications

References 31 publications

Increased Mechanical Stability and Thermal Conductivity of Alumina Reticulated Porous Ceramics (RPC) by Nanoparticle Infiltration Processing

Increased Mechanical Stability and Thermal Conductivity of Alumina Reticulated Porous Ceramics (RPC) by Nanoparticle Infiltration Processing

Reticulated Replica Ceramic Foams: Processing, Functionalization, and Characterization

Influence of Cell Size on Mechanical and Piezoelectric Properties of PZT and LNKN Ceramic Foams

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