CNT‐induced TiC toughened Al 2 O 3 /Ti composites: Mechanical, electrical, and room‐temperature crack‐healing behaviors

2020 ◽  
Vol 103 (8) ◽  
pp. 4573-4585
Author(s):  
Shengfang Shi ◽  
Sunghun Cho ◽  
Tomoyo Goto ◽  
Tohru Sekino
Keyword(s):  
Room Temperature ◽  
Crack Healing ◽  
Temperature Crack

scholarly journals Electrochemically assisted room‐temperature crack healing of ceramic‐based composites

2019 ◽  
Vol 102 (7) ◽  
pp. 4236-4246 ◽  
Author(s):  
Shengfang Shi ◽  
Tomoyo Goto ◽  
Sunghun Cho ◽  
Tohru Sekino
Keyword(s):  
Room Temperature ◽  
Crack Healing ◽  
Temperature Crack

scholarly journals Room temperature crack-healing in an atomically layered ternary carbide

2021 ◽  
Vol 7 (33) ◽  
pp. eabg2549
Author(s):  
Hemant J. Rathod ◽  
Thierry Ouisse ◽  
Miladin Radovic ◽  
Ankit Srivastava
Keyword(s):  
Room Temperature ◽  
Ceramic Materials ◽  
Crack Healing ◽  
Ternary Carbide ◽  
Catastrophic Fracture ◽  
Crystallographic Planes ◽  
Traditional Approaches ◽  
Hostile Environments ◽  
Layered Ceramic ◽  
Temperature Crack

Ceramic materials provide outstanding chemical and structural stability at high temperatures and in hostile environments but are susceptible to catastrophic fracture that severely limits their applicability. Traditional approaches to partially overcome this limitation rely on activating toughening mechanisms during crack growth to postpone fracture. Here, we demonstrate a more potent toughening mechanism that involves an intriguing possibility of healing the cracks as they form, even at room temperature, in an atomically layered ternary carbide. Crystals of this class of ceramic materials readily fracture along weakly bonded crystallographic planes. However, the onset of an abstruse mode of deformation, referred to as kinking in these materials, induces large crystallographic rotations and plastic deformation that physically heal the cracks. This implies that the toughness of numerous other layered ceramic materials, whose broader applications have been limited by their susceptibility to catastrophic fracture, can also be enhanced by microstructural engineering to promote kinking and crack-healing.

Development of Ti dispersed ZrO2 composites and their room-temperature crack-healing behaviors

2021 ◽  
Vol 851 ◽  
pp. 156895
Author(s):  
Shengfang Shi ◽  
Tomoyo Goto ◽  
Sunghun Cho ◽  
Tohru Sekino
Keyword(s):  
Room Temperature ◽  
Crack Healing ◽  
Temperature Crack

Effect of Healing Temperature on Crack-Healing of Al2O3 Toughened by SiC Particles

2010 ◽  
Vol 650 ◽  
pp. 109-114 ◽  
Author(s):  
Chun Yan Shi ◽  
Ying Kui Guo ◽  
Shu Jin Zhao ◽  
Chun Mei Song
Keyword(s):  
Reaction Mechanism ◽  
Oxidation Reaction ◽  
Room Temperature ◽  
Adsorption Mechanism ◽  
Bending Strength ◽  
Surface Cracks ◽  
Crack Healing ◽  
Hot Press ◽  
Sic Particles ◽  
Healing Temperature

Al2O3 Toughened by SiC particles was hot-press sintered. Cracks of ~300μm in diameter were introduced in the surfaces of specimens, which then healed at 1000°C, 1200°C, 1300°C, 1400°C, and individually for 2h, 4h, 6h and 8h. Effect of healing temperature on bending strength, healing mechanism were systematically investigated, the results show that the best bending strength recovered at room temperature was 583.61MPa obtained at 1300°C for 4h, which was the same value as perfect specimens. The recovery of bending strength contributes to three kinds of mechanisms. When specimens were healed individually at 1000°C, 1200°C, 1300°C for 2h, adsorption mechanism and proliferation mechanism were as the dominant healing mechanisms; when healed at 1400°C for 2h, oxidation reaction mechanism was the important healing mechanism. Also, the length of surface cracks is shorter as healing temperature increasing.

Ductile Fracture Simulation of Pipe under Bending with Initial Defects

2011 ◽  
Vol 462-463 ◽  
pp. 443-448
Author(s):  
Masanori Kikuchi ◽  
Ryotaro Senda
Keyword(s):  
Numerical Simulation ◽  
High Temperature ◽  
Ductile Fracture ◽  
Mixed Mode ◽  
Loading Condition ◽  
Room Temperature ◽  
Thickness Effect ◽  
Ductile Material ◽  
Central Research ◽  
Temperature Crack

Crack propagating evaluation is needed to predict and prevent structural damages since many structure defects from numerous crack propagating. It is widely known that ductile fracture occurs when external load is exerted to the material, these load include strong and unpredictable load such as earthquakes and collision of objects. Ductile material fractures via nucleation of void, growth of void and coalescence of voids. Many studies have been conducted; Kikuchi and Sannoumaru have published papers on the studies of ductile fracture. In the first paper [1], the thickness effect on the microscopic fracture process and fracture toughness is studied experimentally. In the second paper [2], dimple fracture tests were performed using three point bending specimens. In the test, loading condition is changed from mode I to mixed mode condition to study the effect of the mixed mode loading. Numerical simulation is conducted using Gurson’s constitutive equation. It is found that crack growth direction is affected significantly by the loading condition. Ductile fracture of a pipe used in Light Water Reactor components is researched in this paper. Four point bending of a pipe experiment had been done by the Central Research Institute of Electric Power Industry [3]. They were experimented in two conditions; one at room temperature (23 ) and second at high temperature (300 ). As a result, crack propagation behavior differs largely form each other. At room temperature, crack propagates parallel from the pre crack, and at high temperature, crack propagates in a slanting direction from the pre crack. Results show that that difference from the two temperature distinction of a tensile test in a stress strain curve is very little. In this paper, this problem is studied at first by experiments, observation of fracture surface and numerical simulation.

High-temperature crack-healing behaviour and strength recovery of (MoNb)Si2

2015 ◽  
Vol 343 ◽  
pp. 41-48 ◽  
Author(s):  
Gaoming Zhu ◽  
Xiaohong Wang ◽  
Qiong Lu ◽  
Guangzhi Wu ◽  
Peizhong Feng
Keyword(s):  
High Temperature ◽  
Crack Healing ◽  
Strength Recovery ◽  
Temperature Crack

Mechanism of crack healing at room temperature revealed by atomistic simulations

2015 ◽  
Vol 95 ◽  
pp. 291-301 ◽  
Author(s):  
J. Li ◽  
Q.H. Fang ◽  
B. Liu ◽  
Y. Liu ◽  
Y.W. Liu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Atomistic Simulations ◽  
Crack Healing

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

1973 ◽  
Vol 31 ◽  
pp. 150-151
Author(s):  
J. E. Doherty ◽  
A. F. Giamei ◽  
B. H. Kear ◽  
C. W. Steinke
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Nickel Base Superalloy ◽  
Boundary Shear ◽  
Room Temperature Ductility ◽  
Solid Solution Matrix ◽  
Nickel Base ◽  
Solution Matrix ◽  
Different Levels ◽  
Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

Hepatocyte Alterations in Guinea Pigs FED Polychlorinated Biphenyls (PCBs), Dibenzodioxins (PCDD), AND DIBENZOFURANS (PCDF)

1982 ◽  
Vol 40 ◽  
pp. 56-57
Author(s):  
J. N. Turner ◽  
D. N. Collins
Keyword(s):  
Guinea Pigs ◽  
Room Temperature ◽  
Dose Group ◽  
Methyl Cellulose ◽  
Uranyl Acetate ◽  
Target Organ ◽  
Office Building ◽  
Lead Citrate ◽  
Control Groups ◽  
Cooling Fluid

A fire involving an electric service transformer and its cooling fluid, a mixture of PCBs and chlorinated benzenes, contaminated an office building with a fine soot. Chemical analysis showed PCDDs and PCDFs including the highly toxic tetra isomers. Guinea pigs were chosen as an experimental animal to test the soot's toxicity because of their sensitivity to these compounds, and the liver was examined because it is a target organ. The soot was suspended in 0.75% methyl cellulose and administered in a single dose by gavage at levels of 1,10,100, and 500mgm soot/kgm body weight. Each dose group was composed of 6 males and 6 females. Control groups included 12 (6 male, 6 female) animals fed activated carbon in methyl cellulose, 6 males fed methyl cellulose, and 16 males and 10 females untreated. The guinea pigs were sacrificed at 42 days by suffocation in CO2. Liver samples were immediately immersed and minced in 2% gluteraldehyde in cacadylate buffer at pH 7.4 and 4°C. After overnight fixation, samples were postfixed in 1% OsO4 in cacodylate for 1 hr at room temperature, embedded in epon, sectioned and stained with uranyl acetate and lead citrate.

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