Determining the fracture toughness of ceramic filter materials using the miniaturized chevron-notched beam method at high temperature

Zielke, H.; Abendroth, Martin; Kuna, Meinhard; Kiefer, Björn

doi:10.1016/j.ceramint.2018.04.248

Cited by 6 publications

(3 citation statements)

References 12 publications

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“…(4): where K IC is the stress intensity factor of the strut materials, Y is the dimensionless geometry function, c s is the cell size as the critical defect, and f is the correlation constant. The used value of K IC for slip casting alumina and Y for the diametral compression test with no inclination between the loading direction and the defect orientation are selected from the literature [43,44]. Constant f with the value of 0.33 is found for the studied specimens.…”

Section: Correlation Between Structural Parameters and Tensile Failur...mentioning

confidence: 99%

Tensile strength and damage of open-cell ceramic foams under cylindrical splitting test

Dai,

Hubálková,

Voigt

et al. 2023

Journal of Advanced Ceramics

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To widen the understanding of tensile failure of reticulated ceramic foams and expand the available mechanical method, a cylindrical splitting test is developed in the present study based on alumina open-cell foams of three different pore densities. The biaxial method is validated by characterization of mechanical parameters, and the in-situ fracture process is validated by a digital image correlation, followed by a formula correction for effective tensile strength with consideration of discrete crack paths. For experimental setup curved loading platens, compliant pad and intermediate quasi-static loading rate are proposed for guaranteeing tensile failure under a radial compressive load. Tensile strength, fracture energy, and brittleness increase with the foam pore density, and the fracture behavior is a balanced result of materials and foam structural support strength. An analytical model of splitting tensile strength with structural parameters is derived, which implies its dependence on cell size and critical stress intensity factor of strut materials.

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Section: Correlation Between Structural Parameters and Tensile Failur...mentioning

confidence: 99%

Tensile strength and damage of open-cell ceramic foams under cylindrical splitting test

Dai,

Hubálková,

Voigt

et al. 2023

Journal of Advanced Ceramics

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“…Furthermore, optical and scanning electron microscopy as well as determination of the mechanical properties, from samples of the cast product have been performed to extrapolate the filtration efficiency from these data . The mechanical properties of the CFF have been also evaluated by standardized test …”

Section: Introductionmentioning

confidence: 99%

“…[4] The mechanical properties of the CFF have been also evaluated by standardized test. [5] In this context numerical methods are often used, although modeling of the filtration process is considerably challenging due to its complexity and hence several simplifying assumptions are invoked. [6] The primary objective of all these approaches is to increase the filtration efficiency either by modifying the filter surface [7] or by improving the filter geometry with respect to the flow characteristics [8] and resistance to the melt flow.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigations of the Depth Filtration inside Open‐Cell Foam Filters Supported by High‐Resolution Computed Tomography Scanning and Pore‐Scale Numerical Simulations

et al. 2019

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The removal of nonmetallic inclusions from metal melts is a crucial step in producing high‐quality castings that have to meet strict requirements regarding strength, toughness, and machinability. To separate the unwanted impurities, the liquid metal is usually passed through ceramic foam filters (CFF), in which the inclusions adhere to the surface of a complex strut network. The development of improved CFF structures requires a good understanding of the physical phenomena involved in the filtration process. In this respect, an experimental investigation of the real system is challenging, due to the opacity of the melt, high temperature, and the presence of a protective atmosphere. Therefore, the present study relies on water model experiments, which are conducted for different pore counts and flow velocities. To achieve a high degree of similarity to the real system, the wetting properties of the filters and particles are adjusted accordingly. Experimentally evaluated filtration efficiencies are compared with predictions obtained from a detailed numerical model that considers the CFF geometry, which is digitized using 3D X‐Ray micro‐computed tomography, and previously measured particle adhesion forces. The results suggest that a considerable fraction of particles does not remain attached after collision with the CFF struts.

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Determination of the Temperature-Dependent Fracture and Damage Properties of Ceramic Filter Materials from Small Scale Specimens

Abendroth,

Takht Firouzeh,

Kuna

et al. 2024

Springer Series in Materials Science

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Open cell ceramic foam filters are used to improve the quality of metallic cast products. They play a major role on reducing the number of inclusions within the microstructure of the cast product and restraining the liquid flow inside the mold. The newly developed carbon-bonded alumina ceramics are investigated considering the mechanical and thermal loads of the filtration process. The aim of this project is to assess the strength, the fracture mechanical behavior, and the damage properties of the filter material. Since the tiny struts of the foam have different properties than the common bulk material specimen, small specimens of millimeter size are needed. Within this work, a combination of experiments and numerical simulations are conducted for various mechanical tests at temperatures up to 1500 $${}^{\circ }\text {C}$$ ∘ C . The first test is the small punch test (SPT), where a small disk-like specimen is supported on a circular die and loaded with a spherical tipped punch until failure of the disk occurs. The small punch fracture stress is obtained from the experiments, as well as the corresponding parameters of the Weibull distribution necessary for the evaluation of the cold modulus of rupture (CMOR). Furthermore, a modified version of the SPT, the so called ball on three ball test (B3B), is carried out. In the B3B test, miniaturized disk-shaped specimens are supported with three spherical balls and loaded with a spherical tipped punch until failure. Hereby, the fracture mechanical parameters, such as the fracture toughness, are identified with the help of numerical simulations. Moreover, the Chevron notched beam test (CNB) is used to determine the fracture toughness of the ceramics. The final test is the Brazilian disc test (BDT), where compressive loads are exerted on the specimen leading to tensile stresses along the specimen diameter, perpendicular to the applied load direction. This test is employed to determine the Young’s modulus, the yield stress and the fracture toughness. In general the simplicity of all these tests, their setup, application, and results evaluation, in addition to the ease of specimens production, make them very attractive. The size of these specimens is about one order of magnitude smaller than that of common standard tests. The accompanying numerical simulations are inevitable to extract from the measurements the wanted mechanical properties.

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Determining the fracture toughness of ceramic filter materials using the miniaturized chevron-notched beam method at high temperature

Cited by 6 publications

References 12 publications

Tensile strength and damage of open-cell ceramic foams under cylindrical splitting test

Tensile strength and damage of open-cell ceramic foams under cylindrical splitting test

Experimental Investigations of the Depth Filtration inside Open‐Cell Foam Filters Supported by High‐Resolution Computed Tomography Scanning and Pore‐Scale Numerical Simulations

Determination of the Temperature-Dependent Fracture and Damage Properties of Ceramic Filter Materials from Small Scale Specimens

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