Influence of Macro-Topography on Damage Tolerance and Fracture Toughness of 0.1 wt % Multi-Layer Graphene/Clay-Epoxy Nanocomposites

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.

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DEA and DSC study of cubic silsesquioxane epoxy resin nanocomposites

e-Polymers ◽

10.1515/epoly.2006.6.1.99 ◽

2006 ◽

Vol 6 (1) ◽

Author(s):

Newton Luiz Dias Filho ◽

Hermes Adolfo de Aquino

Keyword(s):

Mechanical Properties ◽

Activation Energy ◽

Fracture Toughness ◽

Differential Scanning Calorimetry ◽

Epoxy Resin ◽

Loss Factor ◽

Tensile Modulus ◽

Dielectric Analysis ◽

Epoxy Nanocomposites ◽

Scanning Calorimetry

AbstractNon-isothermal dielectric analysis (DEA) and differential scanning calorimetry (DSC) techniques were used to study the epoxy nanocomposites prepared by reacting 1,3,5,7,9,11,13,15-octa[dimethylsiloxypropylglycidylether] pentaciclo [9.5.1.13,9.15,15 .17,13] octasilsesquioxane (ODPG) with methylenedianiline (MDA). Loss factor (ε”) and activation energy were calculated by DEA. The relationships between the loss factor, the activation energy, the structure of the network, and the mechanical properties were investigated. Activation energies determined by DEA and DSC, heat of polymerization, fracture toughness and tensile modulus show the same profile for mechanical properties with respect to ODPG content.

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Effect of Heat Treatment on the Damage Tolerance Properties of Ti-6Al-2Zr-2V-1.5Mo ELI Alloy Plate

Materials Science Forum ◽

10.4028/www.scientific.net/msf.690.282 ◽

2011 ◽

Vol 690 ◽

pp. 282-285

Author(s):

Xiao Xiang Wang ◽

Song Xiao Hui

Keyword(s):

Heat Treatment ◽

Fracture Toughness ◽

Fatigue Crack ◽

Annealing Temperature ◽

Damage Tolerance ◽

Phase Zone ◽

Alloy Plate ◽

Β Phase ◽

Α Phase ◽

Treatment Conditions

Effect of heat treatment on the damage tolerance properties of a newly developed middle strength high damage tolerance Ti-6Al-2Zr-2V-1.5Mo ELI alloy plate has been investigated in this paper by testing fracture toughness and fatigue crack-extending rate of the plate under three heat treatment conditions and fractograph inspection of the samples. It has been found that with the increasing of the primary annealing temperature from 900°C to 950°C, the fracture toughness increased and the fatigue crack extending rate decreased significantly. Microstructural observation has found that the crack expanded through the α beaming and mainly are perpendicular to the α orientation in the lamellar structure which annealed in α+β phase zone. For the Widmanstaten structure, which can be obtained from annealing in single β phase zone, the continuous grain boundary α phase and α beaming boundary hinder the crack expanding significantly.

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Depth sensing indentation of nanoscale graphene platelets in nanocomposite thin films

MRS Proceedings ◽

10.1557/opl.2011.125 ◽

2011 ◽

Vol 1312 ◽

Cited By ~ 2

Author(s):

Ardavan Zandiatashbar ◽

Catalin R. Picu ◽

Nikhil Koratkar

Keyword(s):

Thin Films ◽

Mechanical Properties ◽

Fracture Toughness ◽

Characteristic Length ◽

Matrix Interface ◽

Depth Sensing ◽

Epoxy Nanocomposites ◽

Dramatic Decrease ◽

Graphene Platelet ◽

Nanocomposite Thin Films

ABSTRACTSignificant improvement of mechanical properties was observed recently in graphene platelet-epoxy nanocomposites relative to unfilled epoxy, such as an increase of the fracture toughness by 50% and dramatic decrease of fatigue crack growth rate. In this work, thin films of 0.1 wt.% of graphene platelet (GPL) – epoxy nanocomposites were fabricated and the nanoscale mechanical properties of the nanocomposite were investigated by nanoindentation. This provides information about the presence of characteristic length scales induced by the microstructure and the strength of the filler-matrix interface.

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