scholarly journals Toughening effect of mullite whisker within low-density ceramic proppants

2019 ◽  
Vol 28 ◽  
pp. 2633366X1989062 ◽  
Author(s):  
Jianying Hao ◽  
Baolin Mu ◽  
Yunfeng Gao ◽  
Pinbo Bai ◽  
Yuming Tian ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Low Density ◽  
Toughening Mechanism ◽  
Mullite Whiskers ◽  
Crystal Phases ◽  
Crack Bifurcation

Main crystal phases of low-density ceramic proppants prepared by bauxite and feldspar are granular corundum and whisker-shaped mullite. Mullite whiskers are interlocked with one another and piled up inside the pores. High aspect ratio of mullite whiskers inside the pores can greatly enhance the fracture toughness. The dominant toughening mechanism for the proppants is attributed to crack bifurcation and deflection and pulling out and bridging effect of mullite whiskers.

Preparation and Morphology of Mullite Whiskers by Sol-Gel Method

2007 ◽  
Vol 336-338 ◽  
pp. 1313-1315 ◽  
Author(s):  
Zhou Fu Wang ◽  
Chun Tian Du ◽  
Xi Tang Wang ◽  
Bao Guo Zhang
Keyword(s):  
Thermal Analysis ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Sol Gel ◽  
Gel Method ◽  
Sol Gel Method ◽  
Mullite Whiskers

Mullite whiskers were prepared by sol-gel method. The preparing conditions, the morphology and crystallite phase of the mullite whiskers were studied by Thermal analysis, XRD and SEM. The results demonstrate that the uniform mullite whiskers with high aspect ratio were obtained in properly preparing conditions and appropriate amount of fluorides.

Gouge Assessment for Pipes and Associated Transferability Problem

2009 ◽  
Vol 294 ◽  
pp. 15-25 ◽  
Author(s):  
Mohammed Hadj Meliani ◽  
G. Pluvinage ◽  
J. Capelle
Keyword(s):  
Fracture Toughness ◽  
Aspect Ratio ◽  
Internal Pressure ◽  
High Aspect Ratio ◽  
Fracture Resistance ◽  
Pipe Steel ◽  
Failure Assessment Diagram ◽  
Failure Assessment ◽  
Resistance Criterion ◽  
Two Parameter

The purpose of this work is to assess a gouge defect in a pipe submitted to internal pressure. To do that a method is used which is based upon a failure assessment diagram and, more precisely, upon a Modified Notch Failure Assessment Diagram (NMFAD) which has been proposed as a mesofracture approach. The safety factor has been determined under conservative conditions; i.e for a X52 pipe steel having a relatively low fracture toughness and a severe gouge defect with high aspect ratio and high constraint. In addition, a mesofracture approach to the fracture toughness transferability problem has been proposed. The crack (K-T) methodology has been modifed to create the ( –Teff) two-parameter fracture resistance criterion.

Multiscale toughness amplification in natural composites

2012 ◽  
Vol 1420 ◽  
Author(s):  
Francois Barthelat ◽  
Reza Rabiei ◽  
Ahmad Khayer Dastjerdi
Keyword(s):  
Fracture Toughness ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
High Performance ◽  
Mechanical Performance ◽  
Process Zone ◽  
Organic Matrix ◽  
Natural Composites ◽  
Fracture Tests ◽  
High Concentrations

ABSTRACTHard biological materials such as bone and nacre exhibit remarkable mechanical performance, particularly in terms of fracture toughness, despite the weakness of their constituents. Mechanical performance of nacre and bone can largely be explained through their staggered microstructure where stiff inclusions of high aspect ratio are embedded in a softer matrix. The mineral inclusions provide hardness and stiffness while the organic matrix introduces ductility. The high performance of these natural structures is unmatched by any synthetic ceramic, which therefore makes them a substantial source of inspiration for development of new artificial materials. While the modulus and strength of these structures are well understood, fracture toughness remains unclear and controversial. In this work, chevron double cantilever beam fracture tests show that the interfaces in nacre have a low toughness, comparable to that of the tablets (in J terms). This highlights the important role of structural design on fracture toughness. At the next step, a fracture model is presented to explain the toughness amplification observed in natural staggered structures based on two essential extrinsic toughening mechanisms: crack bridging and process zone. The modeling results show that toughness can be further amplified by incorporating high concentrations of small inclusions with high aspect ratio. This conclusion is applicable to construction and optimization of natural and biomimetic composites.

Effects of Ti(C,N) Nanoparticles on Mechanical Properties of the Si3N4 Ceramics

2011 ◽  
Vol 80-81 ◽  
pp. 119-122
Author(s):  
Qian Li ◽  
Fu Sheng Zhu ◽  
Zhi Meng Xiu ◽  
Xu Dong Sun
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Aspect Ratio ◽  
Relative Density ◽  
Hot Pressing ◽  
Bending Strength ◽  
Lateral Growth ◽  
Toughening Mechanism ◽  
Vacuum Sintering ◽  
Crack Bridging

Si3N4-Ti(C,N) nanocomposites fabricated by vacuum hot pressing with Al2O3 and Y2O3 as additives were investigated. The results showed that the α-Si3N4 phase converted completely into whisker-shaped β-Si3N4 grains after vacuum sintering at 1700°C. Suitable addition and well dispersion of the Ti(C,N) particles can restrained the lateral growth of the β-Si3N4 grains, increasing aspect ratio of the β-Si3N4 grains and improving bending strength of the composites. Fracture toughness of the composites is higher than that of the β-Si3N4 ceramics, and the main toughening mechanism is crack bridging due to the higher aspect ratio of the β-Si3N4 grains.With the addition of 1vol% of Ti(C,N), the composite has a relative density of 99.31%, Vicker’s hardness of 15.9 GPa, bending strength of 993 MPa, and fracture toughness of 9.9 MPa·m1/2.

A bifunctional hexa-filamentous microfibril multimetallic foam: an unconventional high-performance electrode for total water splitting under industrial operation conditions

2021 ◽  
Author(s):  
Hashikaa Rajan ◽  
Maria Christy ◽  
Vasanth Rajendiran Jothi ◽  
S. Anantharaj ◽  
Sung Chul Yi
Keyword(s):  
Aspect Ratio ◽  
Water Splitting ◽  
High Aspect Ratio ◽  
High Performance ◽  
Three Dimensional ◽  
High Strength ◽  
Low Density ◽  
Total Water ◽  
Current Collectors ◽  
Operation Conditions

Cellulose in various forms possesses high strength, low density, and high aspect ratio with a three-dimensional open network structure, making them ideal candidates as current collectors in energy conversion application.

Phase separation in sol gel-derived ceramic films of silica-zirconia, alumina-zirconia, and titania-zirconia system

1994 ◽  
Vol 52 ◽  
pp. 646-647
Author(s):  
J. Tong ◽  
L. Eyring
Keyword(s):  
Fracture Toughness ◽  
Phase Separation ◽  
Sol Gel ◽  
Great Influence ◽  
High Strength ◽  
Chemical Durability ◽  
Separation Method ◽  
Toughening Mechanism ◽  
Ceramic Films ◽  
Zirconia Toughened Alumina

There is increasing interest in composites containing zirconia because of their high strength, fracture toughness, and its great influence on the chemical durability in glass. For the zirconia-silica system, monolithic glasses, fibers and coatings have been obtained. There is currently a great interest in designing zirconia-toughened alumina including exploration of the processing methods and the toughening mechanism.The possibility of forming nanocrystal composites by a phase separation method has been investigated in three systems: zirconia-alumina, zirconia-silica and zirconia-titania using HREM. The morphological observations initially suggest that the formation of nanocrystal composites by a phase separation method is possible in the zirconia-alumina and zirconia-silica systems, but impossible in the zirconia-titania system. The separation-produced grain size in silica-zirconia system is around 5 nm and is more uniform than that in the alumina-zirconia system in which the sizes of the small polyhedron grains are around 10 nm. In the titania-zirconia system, there is no obvious separation as was observed in die alumina-zirconia and silica-zirconia system.

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