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.

Elastic Wave Signal Characteristics of SiC Ceramics with Crack Healing Ability by Wavelet Analysis

2005 ◽  
Vol 297-300 ◽  
pp. 2046-2051 ◽  
Author(s):  
Jin Wook Kim ◽  
B.W. Park ◽  
Seok Hwan Ahn ◽  
Ki Woo Nam
Keyword(s):  
Elastic Wave ◽  
Bending Strength ◽  
Spectral Characteristics ◽  
Compressive Load ◽  
Limited Range ◽  
Bending Test ◽  
Crack Healing ◽  
Sic Ceramics ◽  
Signal Characteristics ◽  
Ae Signals

This paper reports for signal characteristics of before-and-after healing treatment SiC ceramics with crack healing ability. The elastic wave signals generated during the compress load by a Vickers indenter on the brittle materials were recorded in real time, and the waveforms of the individual signals were examined and classified based on their spectral characteristics. The compress loads were applied with the range from 9.8N to 294N. In a bulk SiC specimen, the AE signals occurred only when the load was compressive loading and unloading. But, in the after crack healing specimen of 294N only, even though the external compressive load was stopped and kept on holding constant load states, the AE signals occurred irregularly and continuously. The results of the WT and frequency analysis showed that these existed as the property of frequency in the limited range between 100kHz and about 200kHz. Three-point bending test was performed for the cracked and healed SiC specimens. Consequently the bending strength of the crack healed specimens was recovered completely, but most of the samples with the crack healed showed that the properties of the dominant frequency were comparatively lower than that of the bulk SiC samples. The classification of the wave signals can be used to develop algorithms for autonomous health monitoring systems of brittle material structures.

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 and resultant strength properties of silicon carbide ceramic

2005 ◽  
Vol 25 (5) ◽  
pp. 569-576 ◽  
Author(s):  
Sang-Kee Lee ◽  
Wataru Ishida ◽  
Seung-Yun Lee ◽  
Ki-Woo Nam ◽  
Kotoji Ando
Keyword(s):  
Silicon Carbide ◽  
Strength Properties ◽  
Crack Healing ◽  
Silicon Carbide Ceramic

scholarly journals Evaluations of bending strength and fracture toughness by indentation method in silicon carbide ceramics.

1990 ◽  
Vol 39 (442) ◽  
pp. 895-900
Author(s):  
Shigemi K. SASAKI ◽  
Yasuo OCHI ◽  
Akira ISHII ◽  
Makoto KAWAI ◽  
Sunao KURAKAZU
Keyword(s):  
Fracture Toughness ◽  
Silicon Carbide ◽  
Bending Strength ◽  
Indentation Method ◽  
Carbide Ceramics ◽  
Silicon Carbide Ceramics

SILICON CARBIDE SC-221

Alloy Digest ◽  
1991 ◽  
Vol 40 (7) ◽  
Keyword(s):  
Fracture Toughness ◽  
Silicon Carbide ◽  
High Temperature ◽  
Mechanical Strength ◽  
Physical Properties ◽  
Bending Strength ◽  
Beta Phase ◽  
Pressureless Sintering ◽  
Bend Strength ◽  
Sintering Method

Abstract SILICON CARBIDE SC-221 is a beta-phase silicon carbide made from the pressureless sintering method. It possesses excellent mechanical strength at high temperature (4-point bending strength of 71ksi [490 MPa] at 1400 C [2552 F]). This datasheet provides information on physical properties, hardness, elasticity, and bend strength as well as fracture toughness. Filing Code: Cer-5. Producer or source: Kyocera America Inc..

Microstructure and Mechanical Properties of Heat-Resistant Silicon Carbide Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 1409-1413 ◽  
Author(s):  
Young Wook Kim ◽  
Yong Seong Chun ◽  
Sung Hee Lee ◽  
Ji Yeon Park ◽  
Toshiyuki Nishimura ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Carbide ◽  
Intergranular Phase ◽  
Sintering Additives ◽  
Heat Resistant ◽  
Sic Ceramics ◽  
Microstructure And Mechanical Properties ◽  
Carbide Ceramics ◽  
Silicon Carbide Ceramics

There has been a great progress in the development of heat-resistant silicon carbide ceramics, owing to the better understanding of composition-microstructure-properties relations. Based on the progress, it has been possible to fabricate heat-resistant SiC ceramics with improved fracture toughness. In this paper, three rare-earth oxides (Re2O3, Re=Er, Lu, and Sc) in combination with AlN were used as sintering additives for a β-SiC containing 1 vol% α-SiC seeds. The effect of intergranular phase, using Re2O3 and AlN as sintering additives, on the microstructure and mechanical properties of liquid-phasesintered, and subsequently annealed SiC ceramics were investigated. The microstructure and mechanical properties were strongly influenced by the sintering additive composition, which determines the chemistry and structure of IGP. The strength and fracture toughness of the Lu2O3-doped SiC were ∼700 MPa at 1400oC and ∼6 MPa.m1/2 at room temperature, respectively. The beneficial effect of the new additive compositions on high-temperature strength was attributed to the crystallization of the intergranular phase.

scholarly journals Effect of Ti Addition on the Microstructure and Mechanical Properties of SiC Matrix Composites Infiltrated by Al–Si (10 wt.%)–xTi Alloy

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 318
Author(s):  
Yajun Yu ◽  
An Du ◽  
Xue Zhao ◽  
Yongzhe Fan ◽  
Ruina Ma ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Intermetallic Compounds ◽  
Bending Strength ◽  
Al Alloys ◽  
Al Alloy ◽  
Matrix Composites ◽  
Sic Ceramics ◽  
Microstructure And Mechanical Properties ◽  
Ti Addition

This paper proposes a simple reactive melt infiltration process to improve the mechanical properties of silicon carbide (SiC) ceramics. SiC matrix composites were infiltrated by Al–Si (10 wt.%)–xTi melts at 900 °C for 4 h. The effects of Ti addition on the microstructure and mechanical properties of the composites were investigated. The results showed that the three-point bending strength, fracture toughness (by single-edge notched beam test), and fracture toughness (by Vickers indentation method) of the SiC ceramics increased most by 34.3%, 48.5%, and 128.5%, respectively, following an infiltration with the Al–Si (10 wt.%)–Ti (15 wt.%) melt. A distinct white reaction layer mainly containing a Ti3Si(Al)C2 phase was formed on the surface of the composites infiltrated by Al alloys containing Ti. Ti–Al intermetallic compounds were scattered in the inner regions of the composites. With the increase in the Ti content (from 0 to 15 wt.%) in the Al alloy, the relative contents of Ti3Si(Al)C2 and Ti–Al intermetallic compounds increased. Compared with the fabricated composite infiltrated by an Al alloy without Ti, the fabricated composites infiltrated by Al alloys containing Ti showed improved overall mechanical properties owing to formation of higher relative content Ti3Si(Al)C2 phase and small amounts of Ti–Al intermetallic compounds.

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