Fracture Toughness of Highly Ordered Carbon Nanotube/Alumina Nanocomposites

2004 ◽  
Vol 126 (3) ◽  
pp. 238-244 ◽  
Author(s):  
Z. Xia ◽  
W. A. Curtin ◽  
B. W. Sheldon
Keyword(s):  
Experimental Data ◽  
Fracture Toughness ◽  
Carbon Nanotube ◽  
Residual Stresses ◽  
Cohesive Zone ◽  
Matrix Cracking ◽  
Frictional Stress ◽  
High Toughness ◽  
Alumina Composites ◽  
Bridging Law

The fracture toughness of highly-ordered multi-wall carbon-nanotube-reinforced alumina composites is calculated from experimental data on nanoindentation cracking. A combined analytical and numerical model, using cohesive zone models for both matrix cracking and nanotube crack bridging and accounting for residual stresses, is developed to interpret the indentation results and evaluate the fracture toughness of the composite. Results show that residual stress and nanotube bridging play important roles in the nanocomposite fracture. The contribution to toughness from the nanotube bridging for cracking transverse to the axis of the nanotubes is calculated to be ∼5 MPa-m1/2. From the nanotube bridging law, the nanotube strength and interfacial frictional stress are also estimated and range from 15–25 GPa and 40–200 MPa, respectively. These preliminary results demonstrate that nanotube-reinforced ceramics can exhibit the interfacial debonding/sliding and nanotube bridging necessary to induce nanoscale toughening, and suggest the feasibility of engineering residual stresses, nanotube structure, and composite geometry to obtain high-toughness nanocomposites.

High Toughness Ceramic Laminates by Design of Residual Stresses

2001 ◽  
Vol 702 ◽  
Author(s):  
Nina A. Orlovskaya ◽  
Jakob Kuebler ◽  
Vladimir I. Subotin ◽  
Mykola Lugovy
Keyword(s):  
Fracture Toughness ◽  
Residual Stresses ◽  
Damage Tolerance ◽  
High Strength ◽  
Ceramic Composites ◽  
Tensile Stresses ◽  
High Toughness ◽  
Apparent Fracture Toughness ◽  
Layered Ceramics ◽  
Compressive Residual Stresses

ABSTRACTMultilayered ceramic composites are very promising materials for different engineering applications. Laminates with strong interfaces can provide high apparent fracture toughness and damage tolerance along with the high strength and reliability. The control over the mechanical behavior of laminates can be obtained through design of residual stresses in separate layers. Here we report a development of tough silicon nitride based layered ceramics with controlled compressive and tensile stresses in separate layers. We design laminates in a way to achieve high compressive residual stresses in thin (100-150 micron) Si3N4 layers and low tensile residual stresses in thick (600-700 micron) Si3N4-TiN layers. The residual stresses are controlled by the amount of TiN in layers with residual tensile stresses and the layers thickness. The fracture toughness of pure Si3N4(5wt%Y2O3+2wt%Al2O3) ceramics was measured to be of 5 MPa m1/2, while the apparent fracture toughness of Si3N4/Si3N4-TiN laminates was in the range of 7-8 MPa m1/2 depending on the composition and thickness of the layers.

Failure Behaviour of High Toughness Multi-Layer Si3N4 and Si3N4-TiN Based Laminates

2005 ◽  
Vol 290 ◽  
pp. 175-182 ◽  
Author(s):  
Gurdial Blugan ◽  
Richard Dobedoe ◽  
I. Gee ◽  
Nina Orlovskaya ◽  
Jakob Kübler
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Residual Stresses ◽  
Crack Propagation ◽  
Failure Mechanisms ◽  
High Strength ◽  
Crack Deflection ◽  
High Toughness ◽  
Energy Absorbing ◽  
Crack Bifurcation

Multi-layer laminates were produced using alternating layers of Si3N4 and Si3N4+TiN. The differences in the coefficient of thermal expansions between the alternating layers lead to residual stresses after cooling. These are compressive in the Si3N4 layers and tensile in the Si3N4+TiN layers. The existence of these stresses in the laminates effect the crack propagation behaviour during failure. Different designs of laminates were produced with external layers under compression and tension exhibiting different failure mechanisms. Facture toughness was measured by SEVNB method. In systems with external layers under compression the measured fracture toughness was up to three times that of Si3N4, i.e. up to 17 MPa m1/2. In systems with external layers under tension during failure the energy absorbing effects of crack deflection and crack bifurcation were obtained. High temperature tests were performed to determine the onset temperature for residual stresses in these laminates. Micro-laminates with compressive layers of only 30 µm thickness with high strength and fracture toughness and were manufactured.

Effect of far-field stresses and residual stresses incorporation in predicting fracture toughness of carbon nanotube reinforced yttria stabilized zirconia

2017 ◽  
Vol 122 (14) ◽  
pp. 145104 ◽  
Author(s):  
Neelima Mahato ◽  
Ambreen Nisar ◽  
Pratyasha Mohapatra ◽  
Siddharth Rawat ◽  
S. Ariharan ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Carbon Nanotube ◽  
Residual Stresses ◽  
Yttria Stabilized Zirconia ◽  
Far Field ◽  
Stabilized Zirconia

High-Toughness Tetragonal Zirconia/Alumina Nano-Ceramics

2006 ◽  
Vol 317-318 ◽  
pp. 615-618 ◽  
Author(s):  
Oleg Vasylkiv ◽  
Yoshio Sakka ◽  
Valeriy Skorokhod
Keyword(s):  
Fracture Toughness ◽  
Grain Size ◽  
Tetragonal Zirconia ◽  
Low Temperature Sintering ◽  
Tetragonal Zro2 ◽  
Composite Ceramics ◽  
Nano Composite ◽  
High Toughness ◽  
Average Grain Size ◽  
Alumina Composites

The 0.75 to 3 mol% Y2O3-stabilized tetragonal ZrO2 and Al2O3/Y-TZP nano-composite ceramics with 0.2 to 0.7 wt% of alumina were produced by a colloidal technique and low-temperature sintering. The influence of the resulting density, microstructure, the yttria-stabilizer and the alumina content on toughness was determined. The bulk 2.7Y-TZP ceramic with an average grain size of 110 nm reached fracture toughness of 11.2 MPa·m1/2. A nano-grained alumina/zirconia composite with an average grain size of 92 nm was obtained. Y-TZP ceramics with a reduced yttria-stabilizer content were shown to reach fracture toughness of 13.8 MPa·m1/2 (2Y-TZP), and 14.5 MPa·m1/2 (1.5Y-TZP). Y-TZP/alumina composites with 0.35 wt% of Al2O3 were shown to reach fracture toughness of 15.7 MPa·m1/2 (2Y), 15.3 MPa·m1/2 (1.5Y).

Characterization of interfaces in CVD-coated nicalon fiber-reinforced SiC

1989 ◽  
Vol 47 ◽  
pp. 556-557
Author(s):  
K.L. More ◽  
R.A. Lowden
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Frictional Stress ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Carbon Coated ◽  
Fiber Matrix

The mechanical properties of fiber-reinforced composites are directly related to the nature of the fiber-matrix bond. Fracture toughness is improved when debonding, crack deflection, and fiber pull-out occur which in turn depend on a weak interfacial bond. The interfacial characteristics of fiber-reinforced ceramics can be altered by applying thin coatings to the fibers prior to composite fabrication. In a previous study, Lowden and co-workers coated Nicalon fibers (Nippon Carbon Company) with silicon and carbon prior to chemical vapor infiltration with SiC and determined the influence of interfacial frictional stress on fracture phenomena. They found that the silicon-coated Nicalon fiber-reinforced SiC had low flexure strengths and brittle fracture whereas the composites containing carbon coated fibers exhibited improved strength and fracture toughness. In this study, coatings of boron or BN were applied to Nicalon fibers via chemical vapor deposition (CVD) and the fibers were subsequently incorporated in a SiC matrix. The fiber-matrix interfaces were characterized using transmission and scanning electron microscopy (TEM and SEM). Mechanical properties were determined and compared to those obtained for uncoated Nicalon fiber-reinforced SiC.

AISI 4320

Alloy Digest ◽  
1959 ◽  
Vol 8 (2) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
Heat Treating ◽  
Case Hardening ◽  
High Toughness ◽  
Nickel Chromium ◽  
Steel Mills ◽  
Shock Resistance ◽  
Case Hardening Steel

Abstract AISI 4320 is a nickel-chromium-molybdenum case hardening steel having high toughness and shock resistance. 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, machining, and joining. Filing Code: SA-80. Producer or source: Alloy steel mills and foundries.

AISI 8630

Alloy Digest ◽  
1956 ◽  
Vol 5 (10) ◽  
Keyword(s):  
Fracture Toughness ◽  
Low Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Alloy Steel ◽  
Heat Treating ◽  
High Tempering ◽  
High Toughness ◽  
Steel Mills ◽  
Temperature Performance

Abstract AISI 8630 is a chromium, nickel, molybdenum alloy steel. It is of the moderate deep hardening type and develops high toughness at high tempering temperatures. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on low temperature performance as well as forming, heat treating, machining, and joining. Filing Code: SA-49. Producer or source: Alloy steel mills and foundries.

DILLIMAX 500

Alloy Digest ◽  
2012 ◽  
Vol 61 (3) ◽  
Keyword(s):  
Fracture Toughness ◽  
Yield Strength ◽  
Physical Properties ◽  
Structural Steel ◽  
Tensile Properties ◽  
High Strength ◽  
Heat Treating ◽  
Fine Grained ◽  
High Toughness ◽  
Minimum Yield

Abstract Dillimax 500 is a high-strength quenched and tempered, fine-grained structural steel with a minimum yield strength of 500 MPa (72 ksi). Plate is delivered in three qualities: basic, high toughness, and extra tough. This datasheet provides information on composition, physical properties, and tensile properties as well as fracture toughness. It also includes information on surface qualities as well as forming, heat treating, and joining. Filing Code: SA-645. Producer or source: Dillinger Hütte GTS.

CYCLOPS N9

Alloy Digest ◽  
1958 ◽  
Vol 7 (6) ◽  
Keyword(s):  
Fracture Toughness ◽  
Physical Properties ◽  
Tensile Properties ◽  
Fatigue Resistance ◽  
Heat Treating ◽  
High Toughness

Abstract CYCLOPS N-9 is a chromium-nickel oil hardening steel with high toughness and fatigue resistance. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on forming, heat treating, machining, and joining. Filing Code: TS-71. Producer or source: Cyclops Corporation.

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