Abstracts: General References: Brittle Fracture: Test Apparatus and Specimens; Experimental Techniques; Data Analysis; Fracture Surface Characterization; Fracture Criteria; Crack Propagation Models; Fracture Toughness Prediction

1990 ◽  
Vol 42-43 ◽  
pp. 231-258
Keyword(s):  
Fracture Toughness ◽  
Data Analysis ◽  
Brittle Fracture ◽  
Fracture Surface ◽  
Crack Propagation ◽  
Surface Characterization ◽  
Test Apparatus ◽  
Fracture Test ◽  
Fracture Criteria ◽  
Propagation Models

The effect of water vapor containing hydrogenous atmospheres on the microstructure and tendency to brittle fracture of anode materials of YSZ–NiO(Ni) system

2021 ◽  
Vol 2 (108) ◽  
pp. 49-67
Author(s):  
V.V. Kulyk ◽  
B.D. Vasyliv ◽  
Z.A. Duriagina ◽  
T.M. Kovbasiuk ◽  
I.A. Lemishka
Keyword(s):  
Fracture Toughness ◽  
Water Vapor ◽  
Brittle Fracture ◽  
Fracture Surface ◽  
Anode Material ◽  
Optical Microscope ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Three Point Bending ◽  
Partial Pressures

Purpose: The purpose of this work is to estimate the tendency to brittle fracture of the YSZ–NiO(Ni) anode cermet in a hydrogenous environment with various concentrations of water vapor. Design/methodology/approach: YSZ–NiO ceramic plates were fabricated by sintering in an argon atmosphere. The treatment of material was performed in a hydrogenous environment with various concentrations of water vapor. The strength test was performed under three-point bending at 20°C in air. The microstructure and morphology of the fracture surface of the specimens were studied using a scanning electron microscope (SEM) Carl Zeiss EVO-40XVP. The chemical composition was determined using an INCA ENERGY 350 spectrometer. Microhardness measurements were performed on a NOVOTEST TC-MKB1 microhardness tester. The configuration of the imprints and cracks formed was studied on an optical microscope Neophot-21. The porosity of the materials was investigated by analysing the SEM micrographs using the image processing technique. Findings: Peculiarities of changes in the microstructure, the morphology of specimens fracture surface, physical and mechanical characteristics of YSZ–NiO(Ni) material for solid oxide fuel cell (SOFC) anodes of different preconditioning modes aged under various partial pressures of water vapor in a hydrogenous environment are found. Research limitations/implications: To study the actual behaviour of the YSZ–NiO(Ni) anode material in the operating environment, it is necessary to evaluate its strength, Young’s modulus, microhardness, and fracture toughness by changing with a certain step the partial pressure of water vapor in the whole range noted in this work. Practical implications: Based on the developed approach to assessing the propensity to brittle fracture of the formed cermet microstructure, it is possible to obtain an anode material that will provide the necessary functional properties of a SOFC. Originality/value: An approach to estimating the propensity to brittle fracture of a formed cermet structure is proposed based on the microhardness and fracture toughness characteristics obtained by the Vickers indentation method.

scholarly journals Fracture resistance of railway ballast rock under tensile and tear loads

2021 ◽  
Vol 9 (3) ◽  
pp. 271-280 ◽  
Author(s):  
A. Bahmani ◽  
S. Nemati
Keyword(s):  
Experimental Data ◽  
Fracture Toughness ◽  
Crack Propagation ◽  
Fracture Resistance ◽  
Propagation Path ◽  
Tensile Fracture ◽  
Fracture Test ◽  
Railway Ballast ◽  
Point Bend ◽  
Loading Type

The influence of loading type on tensile and tearing fracture resistance of ballast rock was assessed using edge-notched diametrically compressed disc (ENDC) and edge-notched disc bend (ENDB) test geometries. The geometry of these two specimens was similar; however, their loading type (i.e., three-point bend and diametral compressive) was different affecting the geometry factors. The obtained pure tensile fracture toughness (KIc) using the ENDB test was higher than the ENDC test. In contrast to tensile fracture toughness, the pure tearing fracture toughness (KIIIc) in the ENDC test was higher than the ENDB fracture test. The obtained experimental data were explained in terms of crack propagation path, since two distinct trajectories were observed for both configurations under tearing deformation.

Effects of yttria content and sintering temperature on the microstructure and tendency to brittle fracture of yttria-stabilized zirconia

2021 ◽  
Vol 2 (109) ◽  
pp. 65-79
Author(s):  
V.V. Kulyk ◽  
Z.A. Duriagina ◽  
B.D. Vasyliv ◽  
V. Vavrukh ◽  
T.M. Kovbasiuk ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Brittle Fracture ◽  
Fracture Surface ◽  
Physical And Mechanical Properties ◽  
Ceramic Materials ◽  
Optical Microscope ◽  
Operating Conditions ◽  
Vickers Indentation ◽  
Indentation Method ◽  
Young’S Moduli

Purpose: The purpose of this work is to evaluate the propensity to brittle fracture of YSZ ceramics stabilized by the various amount of yttria, based on a study of changes in the microstructure, phase composition, and fracture micromechanisms. Design/methodology/approach: The series of 3YSZ, 4YSZ, and 5YSZ ceramic specimens were sintered in an argon atmosphere. Three sintering temperatures were used for each series: 1450°C, 1500°C, and 1550°C. Microhardness measurements were performed on a NOVOTEST TC-MKB1 microhardness tester. The configuration of the imprints and cracks formed was studied on an optical microscope Neophot-21. The fracture toughness of the material was estimated using both the Vickers indentation method and a single-edge notch beam (SENB) test performed under three-point bending at 20°C in air. The microstructure and morphology of the fracture surface of the specimens were studied using a scanning electron microscope Carl Zeiss EVO-40XVP. The chemical composition was determined using an INCA ENERGY 350 spectrometer. Findings: Peculiarities of changes in the microstructure, the morphology of specimens fracture surface, and mechanical characteristics of YSZ ceramic materials of different chemical and phase compositions sintered in a temperature range of 1450°C to 1550°C are found. Research limitations/implications: To study the actual behaviour of YSZ ceramic materials under operating conditions, it is necessary to evaluate their Young’s moduli, strength, microhardness, and fracture toughness in an operating environment of the corresponding parameters (temperature, pressure, etc.).Practical implications: Based on the developed approach to estimating the propensity to brittle fracture of the formed YSZ ceramic microstructure, it is possible to obtain YSZ ceramic material that will provide the necessary physical and mechanical properties of a wide variety of precision ceramic products. Originality/value: An approach to estimating the propensity to brittle fracture of YSZ ceramics stabilized by the various amount of yttria is proposed based on two methods of evaluating crack growth resistance of materials, namely, the Vickers indentation method and SENB method.

Adhesion of polymer–inorganic interfaces by nanoindentation

2001 ◽  
Vol 16 (12) ◽  
pp. 3378-3388 ◽  
Author(s):  
Min Li ◽  
C. Barry Carter ◽  
Marc A. Hillmyer ◽  
William W. Gerberich
Keyword(s):  
Fracture Toughness ◽  
Atomic Force Microscopy ◽  
Fracture Surface ◽  
Surface Characterization ◽  
Process Zone ◽  
Crack Arrest ◽  
Force Microscopy ◽  
Atomic Force ◽  
Glass Interface ◽  
Good Agreement

Nanoindentation combined with atomic force microscopy was applied to measure the fracture toughness of polystyrene/glass interfaces. Film delamination occurs when the inelastic penetration depth approximately equals or exceeds the film thickness. The delamination size was accurately measured using atomic force microscopy. Using multilayer indentation and annular-plate analyses, the interfacial fracture toughness was then assessed. The values obtained from the two analyses are in good agreement with the fracture toughness of the interface being approximately 350 mJ/m2. By appropriate fracture surface characterization, it was shown that fracture occurs along the polystyrene/glass interface. Crack arrest marks were observed, and their possible cause discussed. On the basis of the morphology of the fracture surface, the fracture toughness was also evaluated using a process zone analysis. The result agrees well with those obtained from the other two analyses.

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