Effect of SiC Shape on The Crack-Healing Mechanism of Alumina/SiC Composite

2005 ◽  
Vol 888 ◽  
Author(s):  
Wataru Nakao ◽  
Toshio Osada ◽  
Kazuya Yamane ◽  
Masahiro Yokouchi ◽  
Koji Takahashi ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Crack Size ◽  
Surface Cracks ◽  
Crack Healing ◽  
Weak Point ◽  
Strength Recovery ◽  
Sic Particles ◽  
Sic Whiskers ◽  
Monolithic Alumina ◽  
Surface Length

ABSTRACTCrack-healing of structural ceramics is a most valuable technique to overcome their weak point such as surface cracks. Crack-healing ability appeared by admixing SiC to ceramics, because this function is to use the oxidation of SiC. Endowment of crack-healing ability as well as improvement in fracture toughness was expected to be achieved by compositing SiC whiskers. For this purpose, alumina / 30 vol% SiC whiskers and alumina/ 20vol% SiC whiskers/ 10 vol% SiC particles multi-composites were developed. Crack-healing ability and fracture toughness of these composites were investigated. Alumina/ 20 vol% SiC whiskers/ 10 vol% SiC particles multi-composite and alumina/ 30vol% SiC whiskers composite were found to have 1.43 times and 1.65 times higher fracture toughness than monolithic alumina, respectively. From the results of the strength recovery by crack-healing, alumina/ 20 vol% SiC whiskers/ 10 vol% SiC particles multi-composite and alumina / 30vol% SiC whiskers composite were found to be able to heal the pre-crack below 0.250 μm and 0.200 μm in surface length, respectively. In spite of the same SiC content, SiC particles and SiC whiskers multi-compositing enlarged the limit crack size to be able to crack-heal. On the other hand, increasing SiC whiskers content enhanced strength recovery of the specimen with the large crack above limit crack-size.

Crack-Healing Behavior of Mullite/SiC Particle/SiC Whisker Multi-Composite and Mechanical Properties of the Multi-Composite

2005 ◽  
Vol 475-479 ◽  
pp. 2071-2074
Author(s):  
Wataru Nakao ◽  
Sang Kee Lee ◽  
Masahiro Yokouchi ◽  
Koji Takahashi ◽  
Kotoji Ando
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Fracture Toughness ◽  
Crack Healing ◽  
Strength Recovery ◽  
Sic Particles ◽  
Sic Whiskers ◽  
Surface Length ◽  
Sic Particle

For improving fracture toughness as well as endowing with excellent self-crack-healing ability, mullite/SiC particles /SiC whiskers multi-composites were developed. Crack-healing ability and the mechanical properties of the specimens were investigated. Mullite/ 20 vol% SiC whiskers, mullite/ 25 vol% SiC whiskers and mullite/ 15 vol% SiC whiskers/ 10 vol% SiC particles composites can completely heal the pre-crack of 100 ım in surface length by heat-treatment at 1300 oC for 2 h in air. However, not completeness of the strength recovery was caused for mullite/ 15 vol% SiC whiskers composite by crack-healing. In spite of the same SiC content, the crack-healing ability of mullite/ 15 vol% SiC whiskers/ 10 vol% SiC particles composite is superior to that of mullite/ 25 vol% SiC whiskers composite. Admixing with SiC whisker was effective for improvement in fracture toughness. Additionally, the fracture toughness was not reduced by admixing with SiC particles.

scholarly journals Crack-Healing Mechanism by Alumina/SiC Particles/SiC Whiskers Multi-Composite

2005 ◽  
Vol 69 (8) ◽  
pp. 663-666 ◽  
Author(s):  
Wataru Nakao ◽  
Toshio Osada ◽  
Kazuya Yamane ◽  
Koji Takahashi ◽  
Kotoji Ando
Keyword(s):  
Crack Healing ◽  
Sic Particles ◽  
Sic Whiskers

CRACK-HEALING BEHAVIOR AND BENDING STRENGTH PROPERTIES OF SiC CERAMICS BASED ON THE TYPE OF ADDITIVE SiO2 EMPLOYED

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2869-2874 ◽  
Author(s):  
KI WOO NAM ◽  
JONG SOON KIM ◽  
SEUNG WON PARK
Keyword(s):  
Fracture Toughness ◽  
Silicon Carbide ◽  
Surface Crack ◽  
Bending Strength ◽  
Crack Size ◽  
Strength Properties ◽  
Crack Healing ◽  
Sic Ceramics ◽  
Maximum Crack ◽  
Atmospheric Level

Silicon carbide ( SiC ) exhibits good strength at high temperatures and resistance to radioactivity. However, it has poor fracture toughness. The ability to heal cracks represents a very desirable means of overcoming this weakness. This study focuses on the crack-healing behavior and bending strength of SiC ceramics to which sintering additives have been added. Optimized crack-healing condition was found to be 1hr at an atmospheric level of 1100 °C. The maximum crack size that can be healed at the optimized condition was a semi-elliptical surface crack of 450 µm in diameter. Si oxide was revealed to be the principle material involved in crack-healing.

scholarly journals Improvement of the Contact Strength of Al2O3/SiC by a Combination of Shot Peening and Crack-Healing

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Tomoya Oki ◽  
Hiroki Yamamoto ◽  
Toshio Osada ◽  
Koji Takahashi
Keyword(s):  
Fracture Toughness ◽  
Shot Peening ◽  
Zirconium Oxide ◽  
Surface Cracks ◽  
Contact Strength ◽  
Crack Healing ◽  
Composite Ceramics ◽  
Apparent Fracture Toughness ◽  
Heat Treated ◽  
High Crack

Al2O3/SiC composite ceramics with high crack-healing ability were subjected to shot peening (SP) using zirconium oxide shots with several peening pressures and shot diameters. Specimens subjected to SP were heat-treated in air to heal the surface cracks induced by SP. The residual stress, the apparent fracture toughness, and the Weibull distribution of the contact strength were investigated, revealing that the combination of SP and crack-healing is effective for increasing the contact strength and decreasing the scatter of the contact strength of Al2O3/SiC.

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.

Threshold Stress for Crack-Healing of Silicon Nitride Ceramics

2004 ◽  
Author(s):  
Koji Takahashi ◽  
Kotoji Ando ◽  
Shoko Yoshida ◽  
Shinji Saito
Keyword(s):  
Fatigue Strength ◽  
Threshold Stress ◽  
Bending Strength ◽  
Surface Cracks ◽  
Bending Stress ◽  
Crack Healing ◽  
Composite Ceramics ◽  
Nitride Ceramics ◽  
Cracked Specimens ◽  
Surface Length

Si3N4/SiC composite ceramics were hot-pressed in order to investigate the crack-healing behavior under stress. Semi-elliptical surface cracks of 100 μm in surface length were introduced on each specimen. The pre-cracked specimens were crack-healed under cyclic or constant bending stress of 5 Hz at healing temperatures of 1000° and 1200°C and the resultant bending strength and fatigue strength were studied. The threshold stress for crack-healing, below which the pre-cracked specimens recovered their bending strength, was investigated. The mechanisms of crack-healing in Si3N4/SiC under stress were also discussed.

Influence of the crack area on the crack-healing performance of silicon carbide whisker reinforced silicon nitride composite

2019 ◽  
Vol 9 (5) ◽  
pp. 429-436
Author(s):  
Jun Feng Hu ◽  
Ming Yue Qiu ◽  
Xi Deng ◽  
Teng Zhou Xu ◽  
Zhou Chen
Keyword(s):  
Oxidation Reaction ◽  
Glass Phase ◽  
Crack Depth ◽  
Composite Ceramic ◽  
Crack Healing ◽  
Silicon Carbide Whisker ◽  
Strength Recovery ◽  
Sic Whiskers ◽  
Cracked Specimens ◽  
The Relationship

The crack healing properties of Si3N4 composite ceramic reinforced by SiC whiskers (Si3N4/SiCw) was studied. Six kinds of pre-cracks were introduced on the center of the tensile side of the specimens, and the relationship between the crack area and crack healing properties was studied. The results show that the healing effect of strength recovery is similar with that of smooth specimens for pre-cracked specimens with crack depth less than 60 μm. As for the propagated crack and the central through crack, the strength recovery rapidly decreases due to the increase of crack depth. It could be concluded that it is difficult to heal pre-cracked specimens with the crack depth over 90 μm. The main reason is considered to be that the melted glass phase blocked in the surface, and prevented the oxidation reaction in the inner of crack.

Self-Healing Behavior of Y2SiO5 Toughened by SiC Particles

2017 ◽  
Vol 728 ◽  
pp. 149-154 ◽  
Author(s):  
Huy Dinh Vu ◽  
Makoto Nanko
Keyword(s):  
Heat Treatment ◽  
High Temperature Oxidation ◽  
Treatment Temperature ◽  
Self Healing ◽  
Surface Cracks ◽  
Crack Healing ◽  
Temperature Oxidation ◽  
Sic Particles ◽  
Pulsed Electric Current ◽  
Oxidation In Air

Crack-healing effectiveness of Y2SiO5-based composites dispersed with 5 vol% SiC particles was investigated. Dense specimens of 5 vol% SiC/Y2SiO5 were fabricated by pulsed electric current sintering technique. Surface cracks were introduced by using a Vickers indenter to be a crack length of approximately 200 μm. Self-healing performance of SiC/Y2SiO5 composites via high-temperature oxidation in air was studied as a function of heat treatment temperature. As a result, surface cracks disappeared perfectly after heat treatment at 1300°C for 6 h in air.

scholarly journals Crack-Healing Behavior, High Temperature Strength and Fracture Toughness of Alumina Reinforced by SiC Whiskers

2004 ◽  
Vol 53 (6) ◽  
pp. 599-606 ◽  
Author(s):  
Kotoji ANDO ◽  
Masahiro YOKOUCHI ◽  
Sang-Kee LEE ◽  
Koji TAKAHASHI ◽  
Wataru NAKAO ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
High Temperature Strength ◽  
Crack Healing ◽  
Sic Whiskers
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