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.

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.

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

scholarly journals Study on Mechanical Properties of crack Healing of low carbon Steel based on cyclic Phase Transformation Heat treatment

2021 ◽  
Vol 2133 (1) ◽  
pp. 012046
Author(s):  
Lei Chu
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Carbon Steel ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Crack Healing ◽  
Properties Of Materials ◽  
Metal Materials ◽  
Cyclic Phase

Abstract With the rapid development of materials, metal materials are used less and less, but at this stage, metal materials are still widely used, and iron and steel materials are the most widely used. Cracks often appear in the process of metal material processing and use, and these cracks will have a certain impact on the use of metal materials. The existence of microcracks will affect the mechanical properties of materials to some extent, but in most cases, the mechanical properties of materials will be greatly reduced, and in serious cases, metal materials will break directly in the process of use or processing. The crack healing process needed after the emergence of cracks can effectively change this situation, but so far, the research on metal crack healing is still not perfect. In this paper, taking the internal crack of low carbon steel as the object, the recovery of mechanical properties of low carbon steel by cyclic phase transformation heat treatment was studied. The results show that with the increase of the healing area, the microhardness of the area after crack healing also increases, and the tensile strength of the specimen also increases after the healing. When the healing area is similar, increasing the healing time and temperature will result in grain coarsening, resulting in the decrease of microhardness and tensile strength in the crack healing zone.

Strain contrast in SiC whisker reinforced Al2O3

1986 ◽  
Vol 44 ◽  
pp. 498-499
Author(s):  
P. Angelini ◽  
W. Mader
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Thermal Expansion ◽  
Quantitative Analysis ◽  
Residual Stresses ◽  
Strain Field ◽  
Ceramic Materials ◽  
Spherical Particles ◽  
The Matrix ◽  
Sic Whiskers

Whisker reinforced ceramic materials offer the potential for increased fracture toughness and fracture strength. Residual stresses resulting from differences in thermal expansion properties of the matrix and the whisker can develop during cooling and affect mechanical properties. TEH strain contrast of large inclusions has previously been observed for nearly spherical particles of ZrO2 in Al2O3 matrix grains. The formation of strain contrast oscillations was explained and a quantitative analysis of strains around ZrO2 inclusions in Al2O3 was performed. The present research is concerned with characterizing by TEM the strain field present in Al2O3 reinforced with SiC whiskers.

UNILOY 888

Alloy Digest ◽  
1974 ◽  
Vol 23 (7) ◽  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
Magnetic Permeability ◽  
Cold Working ◽  
High Strength ◽  
Heat Treating ◽  
Magnetic Characteristics

Abstract UNILOY 888 is an iron-base, age-hardenable alloy designed primarily for applications requiring low magnetic permeability and high strength. It is austenitic at all times and its essentially non-magnetic characteristics are not impaired by various combinations of heat treatment and cold working used to produce desired mechanical properties. It is used primarily between 70 and 700 F. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as forming, heat treating, and machining. Filing Code: Fe-51. Producer or source: Cyclops Corporation.

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

2005 ◽  
pp. 2071-2074
Author(s):  
Wataru Nakao ◽  
Sang Kee Lee ◽  
Masahiro Yokouchi ◽  
Koji Takahashi ◽  
Kotoji Ando
Keyword(s):  
Mechanical Properties ◽  
Crack Healing ◽  
Sic Particle

Preparation and Flame Ablation/Oxidation Behavior of ZrB2/SiC Ultra-High Temperature Ceramic Composites

2007 ◽  
Vol 351 ◽  
pp. 142-146 ◽  
Author(s):  
Chang An Wang ◽  
Hai Long Wang ◽  
Yong Huang ◽  
Dai Ning Fang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Thermal Ablation ◽  
Oxidation Behavior ◽  
Ceramic Composites ◽  
Argon Atmosphere ◽  
Good Resistance ◽  
Sic Ceramic ◽  
Sic Whiskers ◽  
Sic Composites

ZrB2/SiC ceramic composites reinforced by nano-SiC whiskers and SiC particles have been prepared by hot-pressing at 1950°C for 1hr under 20 MPa pressure in flow argon atmosphere. Effects of SiC addition on microstructure, mechanical properties and thermal ablation/oxidation behavior of ZrB2/SiC composites were investigated. The results showed that the addition of SiC effectively improved the densification of ZrB2/SiC composites and almost full dense ZrB2/SiC composites were obtained when the amount of SiC increased up to 20 vol%. Flexural strength and fracture toughness of the ZrB2/SiC composites were also enhanced; the maximum strength and toughness reached 600 MPa and 8.81 MPa·m1/2 at SiC additions of 20 vol % and 30 vol%, respectively. The composites possessed good resistance to flame ablation and could keep the whole shape without distinct peeling or cracking after flame ablation by oxyacetylene flame for 3 mins. The more SiC added, the better resistance to flame ablation the composites displayed.

Effect of Heat Treatment on the Microstructure and Mechanical Properties of Cf/SiC Composites

2007 ◽  
Vol 336-338 ◽  
pp. 1291-1293
Author(s):  
Xin Gui Zhou ◽  
Chang Cheng Zhou ◽  
Chang Rui Zhang ◽  
Ying Bin Cao ◽  
Shi Qin Zou
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Fracture Toughness ◽  
Silicon Carbide ◽  
Shear Strength ◽  
Carbon Fiber ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Carbon Coatings ◽  
Sic Composites

3D braided carbon fiber reinforced silicon carbide (3D-Cf/SiC) composites were fabricated by precursor infiltration and pyrolysis(PIP), with carbon coatings prepared by chemical vapor deposition (CVD) before PIP. The effect of 1873K heat treatment on the mechanical properties of Cf/SiC composites were investigated. The results showed that heat treatment before PIP can increase the density of composites and lead to excellent properties of Cf/SiC composites. The flexual strength of the Cf/SiC composites with one cycle of 1873 K heat treatment reached 571 MPa, shear strength 51 MPa, and fracture toughness 18 MPa⋅m1/2.

Mechanical properties of hot isostatically pressed Si3N4 and Si3N4/SiC composites

1993 ◽  
Vol 8 (3) ◽  
pp. 626-634 ◽  
Author(s):  
O. Unal ◽  
J.J. Petrovic ◽  
T.E. Mitchell
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
High Hardness ◽  
High Resolution Electron Microscopy ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Sic Whiskers ◽  
Sic Composites ◽  
Increasing Temperature

The mechanical properties of hot isostatically pressed monolithic Si3N4 and Si3N4−20 vol. % SiC composites have been studied by microindentation at temperatures up to 1400 °C. Indentation crack patterns and microstructures have been examined by optical microscopy, scanning electron microscopy, and transmission electron microscopy. It is shown that dense Si3N4 base materials can be synthesized by HIPing without densification aids. Both the monolithic Si3N4 and the Si3N4/SiC composites exhibit high hardness values which gradually decrease with increasing temperature. Both types of material show low fracture toughness values apparently because of strong interfacial bonding. On the other hand, the fracture toughness of the composite is about 40% higher than that of the monolithic material, due to the presence of the 20 vol. % SiC whiskers. A crack deflection/debonding mechanism is likely to be responsible for the higher toughness observed in the composite. High resolution electron microscopy shows that the grain boundaries in both samples contain a thin SiO2 layer.

Microstructural and Mechanical Properties Changes of Silicon Nitride Based Ceramic Using Post-Sintering Heat Treatment

2012 ◽  
Vol 727-728 ◽  
pp. 1085-1091
Author(s):  
José Vitor C. Souza ◽  
O.M.M. Silva ◽  
E.A. Raymundo ◽  
João Paulo Barros Machado
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Fracture Toughness ◽  
Grain Size ◽  
Wear Resistance ◽  
High Hardness ◽  
Gas Pressure ◽  
Low Density ◽  
Nitrogen Gas ◽  
Structural Applications

Si3N4based ceramics are widely researched because of their low density, high hardness, toughness and wear resistance. Post-sintering heat treatments can enhance their properties. Thus, the objective of the present paper was the development of a Si3N4based ceramic, suitable for structural applications, by sintering in nitrogen gas pressure, using AlN, Al2O3, and Y2O3as additives and post-sintering heat treatment. The green bodies were fabricated by uniaxial pressing at 80 MPa with subsequent isostatic pressing at 300 MPa. The samples were sintered at 1900°C for 1 h under N2gas pressure of 0.1 MPa. Post-sintering heat treatment was performed at 1500°C for 48 h under N2gas pressure of 1.0 MPa. From the results, it was observed that after post-sintering heat treatment there was a reduction of α-SiAlON phase and increase of β-Si3N4phase, with consequent changing in grain size, decrease of fracture toughness and increase of the Vickers hardness.

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