scholarly journals Cold Forming of Al-TiB2 Composites Fabricated by SPS: A Computational Experimental Study

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3456 ◽  
Author(s):  
Elad Priel ◽  
Nissim U. Navi ◽  
Brigit Mittelman ◽  
Nir Trabelsi ◽  
Moshe Levi ◽  
...  
Keyword(s):  
Yield Stress ◽  
Damage Mechanics ◽  
Mechanical Response ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Continuum Damage Mechanics ◽  
Tib2 Particle ◽  
Particle Volume ◽  
Cold Forming ◽  
Effective Yield

The mechanical response and failure of Al-TiB2 composites fabricated by Spark Plasma Sintering (SPS) were investigated. The effective flow stress at room temperature for different TiB2 particle volume fractions between 0% and 15% was determined using compression experiments on cylindrical specimens in conjunction with an iterative computational methodology. A different set of experiments on tapered specimens was used to validate the effective flow curves by comparing experimental force–displacement curves and deformation patterns to the ones obtained from the computations. Using a continuum damage mechanics approach, the experiments were also used to construct effective failure curves for each material composition. It was demonstrated that the fracture modes observed in the different experiments could be reproduced in the computations. The results show that increasing the TiB2 particle volume fraction to 10% results in an increase in material effective yield stress and a decrease in hardening. For a particle volume fraction of 15%, the effective yield stress decreases with no significant influence on the hardening slope. The ductility (workability) of the composite decreases with increasing particle volume fraction.

An investigation into the wear behaviour of TiB2 particle reinforced aluminium composites produced by mechanical alloying

2011 ◽  
Vol 18 (1-2) ◽  
pp. 5-12 ◽  
Author(s):  
Dursun Ozyurek ◽  
Ibrahim Ciftci
Keyword(s):  
Mechanical Alloying ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
A356 Alloy ◽  
Tib2 Particle ◽  
Wear Behaviour ◽  
Wear Loss ◽  
Mechanically Alloyed ◽  
Particle Volume ◽  
Alloy Matrix

AbstractIn this study, wear behaviour of TiB2 particle reinforced aluminium (Al) composites produced by the mechanical alloying method was investigated. TiB2 ceramic particles of four different volume fractions were mechanically alloyed with Al and A356 alloy matrix materials. The mechanically alloyed particles were cold presses and then sintered at 550°C. After the sintering process, the composites were characterised through hardness measurements, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Wear tests were also carried out on a pin-on-disc type wear apparatus under 10, 25 and 50 N loads. Wear loss of the composites were found to decrease with increasing hardness which increased with increasing TiB2 particle volume fraction. However, increasing the applied load and sliding distance increased the wear loss. Wear surface examinations showed that various wear mechanisms were effective in wear of the composites.

Comparative Study of Al/TiB2 Composites Manufactured by Underwater and Direct Shock Wave Consolidation

2011 ◽  
Vol 673 ◽  
pp. 231-236 ◽  
Author(s):  
H. Eskandari ◽  
H.M. Ghasemi ◽  
M. Emamy ◽  
Kazuyuki Hokamoto
Keyword(s):  
Shock Wave ◽  
Bending Strength ◽  
Volume Fraction ◽  
Direct Method ◽  
Particle Volume Fraction ◽  
Aluminum Matrix ◽  
Tib2 Particle ◽  
Aluminum Matrix Composites ◽  
Particle Volume ◽  
Tib2 Particles

Aluminum matrix composites containing of 10, 20 and 30 vol% TiB2 particles were compacted by underwater and direct shock wave consolidation methods. SEM and Optical Microscopic examination, hardness and bending strength measurements were used to characterize the samples. It is observed that there were different distributions of TiB2 particles in recovered compacts by each method. In the direct method, the distribution of TiB2 particles at the center and at the periphery of the sample was different whereas in the underwater method there was a uniform microstructure in the sample. The microhardness of the compacts increased with increasing TiB2 particle volume fraction in both methods. The results showed highest bending strength for the composite containing 20 vol% TiB2 particles.

Rheological Study of Micro Particle Laden Polymeric Thermal Interface Materials: Part 2 — Modeling

2002 ◽  
Author(s):  
Ravi S. Prasher ◽  
Jim Shipley ◽  
Suzana Prstic ◽  
Paul Koning ◽  
Jin-Lin Wang
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Yield Stress ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Thermal Interface Materials ◽  
Particle Volume ◽  
Thermal Interface ◽  
Complete Set ◽  
Interface Materials

Currently there are no models to predict the thickness or the bondline thickness (BLT) of particle laden polymeric thermal interface materials (TIM) for parameters such as particle volume fraction and pressure. TIMs are used to reduce the thermal resistance. Typically this is achieved by increasing the thermal conductivity of these TIMs by increasing the particle volume fraction, however increasing the particle volume fraction also increases the BLT. Therefore, increasing the particle volume fraction may lead to an increase in the thermal resistance after certain volume fraction. This paper introduces a model for the prediction of the BLT of these particle laden TIMs. Currently thermal conductivity is the only metric for differentiating one TIM formulation from another. The model developed in this paper introduces another metric: the yield stress of these TIMs. Thermal conductivity and the yield stress together constitute the complete set of material parameters needed to define the thermal performance of particle laden TIMs.

Microstructure and Mechanical Properties of High Strength Al2O3p/6061Al Composites

2007 ◽  
Vol 353-358 ◽  
pp. 1390-1393
Author(s):  
Bai Feng Luan ◽  
Gao Hui Wu ◽  
Qing Liu ◽  
Niels Hansen ◽  
Ting Quan Lei
Keyword(s):  
Mechanical Properties ◽  
Yield Stress ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Hot Extrusion ◽  
High Strength ◽  
Dispersion Strengthening ◽  
Particle Volume ◽  
Microstructure And Mechanical Properties ◽  
Before And After

An experimental study of microstructure and mechanical properties in the Al2O3 particulate reinforced 6061 Aluminum composites has been used to determine the effect of extrusion and particle volume fraction (20, 26, 30, 40, 50, 60%Vf) in deformed metal matrix composites. The microstructure of Al2O3 /6061Al composite before and after hot extrusion is investigated by TEM and SEM. Results show that dislocation and subgrain generated after hot extrusion as well as the particle distribution of composite become more uniform with extrusion ratio of 10:1. The ultimate strength, yield strength and elongation of the composite also increase after hot extrusion. Dispersion strengthening and subgrain boundary strengthening is discussed and also the effect of precipitate introduced by heat treatment both after casting and after extrusion. The yield stress (0.2% offset) of the composites has been calculated and predicted using a standard dislocation hardening model. Whilst the correlation between this and the measured value of yield stress obtained in previous experimental test is reasonable.

scholarly journals Effect of coarse particle volume fraction on the yield stress and thixotropy of cementitious materials

2008 ◽  
Vol 38 (11) ◽  
pp. 1276-1285 ◽  
Author(s):  
Fabien Mahaut ◽  
Samir Mokéddem ◽  
Xavier Chateau ◽  
Nicolas Roussel ◽  
Guillaume Ovarlez
Keyword(s):  
Yield Stress ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Cementitious Materials ◽  
Coarse Particle ◽  
Particle Volume

scholarly journals Apparent yield stress in rigid fibre suspensions: the role of attractive colloidal interactions

2016 ◽  
Vol 802 ◽  
pp. 611-633 ◽  
Author(s):  
S. Bounoua ◽  
E. Lemaire ◽  
J. Férec ◽  
G. Ausias ◽  
A. Zubarev ◽  
...  
Keyword(s):  
Yield Stress ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Van Der Waals ◽  
Simple Shear Flow ◽  
Average Particle ◽  
Particle Volume ◽  
Friction Forces ◽  
Aspect Ratios ◽  
Fibre Suspensions

This work is focused on the modelling of the shear and normal stresses in fibre suspensions that are subjected to a simple shear flow in the presence of short-range lubrication forces, van der Waals and electrostatic forces, as well as solid friction forces between fibres. All of these forces are weighed by the contact probability. The theory is developed for attractive fibres with van der Waals interaction dominating over electrostatic repulsion. The model predicts a simple Bingham law for both the shear stress and the first normal stress difference, with the apparent shear and normal yield stresses proportional to the second and the third power of the particle volume fraction respectively. The model is applied to the experimental data of Rakatekar et al. (Adv. Mater., vol. 21, 2009, pp. 874–878) and Natale et al. (AIChE J., vol. 60, 2014, pp. 1476–1487) on suspensions of carbon nanotubes dispersed in a Newtonian epoxy resin. It reproduces well the quadratic dependence of the apparent yield stress on the particle volume fraction $(\unicode[STIX]{x1D70E}_{Y}\propto \unicode[STIX]{x1D719}^{2})$ for average particle aspect ratios of $r=160$ and 1200, while it underpredicts the power-law exponent for $r=80$ (always predicting $\unicode[STIX]{x1D719}^{2}$ behaviour instead of $\unicode[STIX]{x1D719}^{3.2}$).

Dependence of Thermal Conductivity and Mechanical Rigidity of Particle-Laden Polymeric Thermal Interface Material on Particle Volume Fraction

2003 ◽  
Vol 125 (3) ◽  
pp. 386-391 ◽  
Author(s):  
Ravi S. Prasher ◽  
Paul Koning ◽  
James Shipley ◽  
Amit Devpura
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Mechanical Response ◽  
Volume Fraction ◽  
Effective Medium Theory ◽  
Particle Volume Fraction ◽  
Thermal Interface Material ◽  
Particle Volume ◽  
Thermal Interface ◽  
Medium Theory

This paper reports the measurement of the thermal conductivity of particle-laden polymeric thermal interface materials for three different particle volume fractions. The experimental data are further compared with the percolation model and effective medium theory. We then introduce a method of obtaining the contact resistance between the particles and the polymeric matrix by a combination of percolation modeling and experimental data. We also discuss the dependence of the mechanical response of these particle-laden polymers for different filler or particle loading. A novel mechanical length scale is defined to understand the mechanical response of these materials, and is correlated to the viscosity of these materials.

scholarly journals Effect of Coarse Particle Volume Fraction on the Yield Stress of Muddy Sediments from Marennes Oléron Bay

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
A. Pantet ◽  
S. Robert ◽  
S. Jarny ◽  
S. Kervella
Keyword(s):  
Yield Stress ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Fine Fraction ◽  
General Description ◽  
Measurement Sensitivity ◽  
Particle Volume ◽  
Fine Sediments ◽  
Sandy Material ◽  
Muddy Sediments

Coastal erosion results from a combination of various factors, both natural and humaninduced, which have different time and space patterns. In addition, uncertainties still remain about the interactions of the forcing agents, as well as on the significance of non-local causes of erosion. We focused about the surface sediments in the Marennes Oléron bay, after a general description of the site that has many various activities. The superficial sediments show a mechanical behavior, mainly depends on the fine fraction for a composition that contains up to 60% of sandy material. Fine sediments fraction has a typical yield stress depending naturally of concentration or water content. This yield could be modified slightly or significantly by adding silt or sand. As a result, the rheological measurement sensitivity allows us to characterize five typical sediments that correlate with solid fraction and fine fraction.

Effect of Particle Volume Fraction on the Thermal Conductivity and Mechanical Rigidity of Particle-Laden Polymeric Thermal Interface Material

2001 ◽  
Author(s):  
Ravi S. Prasher ◽  
Paul Koning ◽  
James Shipley ◽  
Amit Devpura
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Mechanical Response ◽  
Volume Fraction ◽  
Effective Medium Theory ◽  
Particle Volume Fraction ◽  
Thermal Interface Material ◽  
Particle Volume ◽  
Thermal Interface ◽  
Medium Theory

Abstract This paper reports the measurement of the thermal conductivity of particle-laden polymeric thermal interface materials for three different particle volume fraction. The experimental data is further compared with the percolation model and effective medium theory. This paper also introduces a method of obtaining the contact resistance between the particles and the polymeric matrix by combination of percolation modeling and experimental data. We also discuss the dependence of the mechanical response of these particle-laden polymers for different filler or particle loading. A novel mechanical length scale is defined to understand the mechanical response of these materials and is correlated to the viscosity of these materials.

CHARACTERISTICS OF A YIELD STRESS SCALING FUNCTION FOR ELECTRORHEOLOGICAL FLUIDS

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2636-2642 ◽  
Author(s):  
H. J. CHOI ◽  
J. W. KIM ◽  
M. S. CHO ◽  
C. A. KIM ◽  
M. S. JHON
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Yield Stress ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Critical Evaluation ◽  
Particle Volume ◽  
Scaling Equation ◽  
Er Fluids

The electrorheological (ER) fluids exhibit a drastic change in rheological and electrical properties. Among these properties, yield stress is one of the critical evaluation parameters of the performance of ER devices. The published experimental data of yield dependence on the electric field strength and particle volume fraction are inconsistent due to the time dependence of material properties and measuring conditions. In this paper, we present a universal function, descriptive of the normalized yield stress, via scaling of the applied electric field strength. This scaling equation hybridizes both the polarization and conductivity models. Yield stress data for various ER fluids are collapsed onto a single curve for a broad range of electric field strengths, suggesting that the proposed scaling equation is adequate for predicting the ER property. Furthermore, the yield stresses, obtained from two different measuring techniques (static and dynamics methods), were also examined.

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