scholarly journals The Influence of the Microstructure of Ceramic-Elastomer Composites on Their Energy Absorption Capability

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6618
Author(s):  
Paulina Kozera ◽  
Anna Boczkowska ◽  
Rafał Kozera ◽  
Marcin Małek ◽  
Włodzimierz Idczak
Keyword(s):  
Specific Surface ◽  
Strain Rate ◽  
Volume Fraction ◽  
Alumina Ceramic ◽  
Dynamic Strain ◽  
Alumina Powder ◽  
Pressure Infiltration ◽  
Surface Fraction ◽  
Interphase Boundaries ◽  
Elastomer Composites

The paper presents the experimental results of static and dynamic compressive tests conducted on ceramic-elastomer composites. The alumina ceramic preforms were fabricated by the four-step method: ceramic mixture preparation, consolidation under pressure, presintering, and sintering under pressure, respectively. To obtain ceramic preforms with a similar volume fraction of open pores, but with different pore sizes, alumina powder with different particle size and a ceramic binder were used, as well as pore-forming agents that were evenly distributed throughout the volume of the molding mass. The composites were obtained using vacuum pressure infiltration of porous alumina ceramic by urea-urethane elastomer in liquid form. As a result, the obtained composites were characterized by two phases that interpenetrated three-dimensionally and topologically throughout the microstructure. The microstructure of the ceramic preforms was revealed by X-ray tomography, which indicated that the alumina preforms had similar porosity of approximately 40% vol. but different pore diameter in the range of 6 to 34 µm. After composite fabrication, image analysis was carried out. Due to the microstructure of the ceramic preforms, the composites differed in the specific surface fraction of the interphase boundaries (Sv). The highest value of the Sv parameter was achieved for composite fabricated by infiltration method of using ceramic preform with the smallest pore size. Static and dynamic tests were carried out using different strain rate: 1.4·10−3, 7·10−2, 1.4·10−1, and 3·103 s−1. Compressive strength, stress at plateau zone, and absorbed energy were determined. It was found that the ceramic-elastomer composites’ ability to absorb energy depended on the specific surface fraction of the interphase boundaries and achieved a value between 15.3 MJ/m3 in static test and 51.1 MJ/m3 for dynamic strain rate.

scholarly journals Fabrication and characterization of composite materials based on porous ceramic preform infiltrated by elastomer

2015 ◽  
Vol 63 (1) ◽  
pp. 193-199 ◽  
Author(s):  
P. Chabera ◽  
A. Boczkowska ◽  
A. Witek ◽  
A. Oziębło
Keyword(s):  
Volume Fraction ◽  
Split Hopkinson Pressure Bar ◽  
Porous Ceramic ◽  
Strain Curve ◽  
Sem Images ◽  
Static Compression ◽  
Pressure Infiltration ◽  
Fabrication And Characterization ◽  
Elastomer Composites

Abstract The paper presents the experimental results of fabrication and characterization of ceramic- elastomer composites. They were obtained using pressure infiltration of porous ceramics by elastomer As a result the composites in which two phases are interpenetrating three-dimensionally and topologically throughout the microstructure were obtained. In order to enhance mechanical properties of preforms a high isostatic pressure method was utilized. The obtained ceramic preforms with porosity gradient within the range of 20-40% as well as composites were characterized by X-ray tomography. The effect of volume fraction of pores on residual porosity of composites was examined. These results are in accordance with SEM images which show the microstructure of composites without any delaminations and voids. Such composites exhibit a high initial strength with the ability to sustain large deformations due to combining the ceramic stiffness and rubbery elasticity of elastomer. Static compression tests for the obtained composites were carried out and the energy dissipated during compression was calculated as the area under the stress-strain curve. The dynamic behavior of the composite was investigated using the split Hopkinson pressure bar technique. It was found that ceramic-elastomer composites effectively dissipate the energy. Moreover, a ballistic test was carried out using armor piercing bullets.

Fabrication of Ceramic-Metal Composites with Percolation of Phases Using GPI

2012 ◽  
Vol 191 ◽  
pp. 57-66 ◽  
Author(s):  
Anna Boczkowska ◽  
Paulina Chabera ◽  
Anna J. Dolata ◽  
Maciej Dyzia ◽  
R. Kozera ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Aluminium Alloy ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Gas Pressure ◽  
Image Correlation ◽  
Pressure Infiltration ◽  
Ceramic Phase ◽  
Surface Fraction ◽  
Interphase Boundaries

Al2O3/AlSi12CuMgNi composites were fabricated using gas-pressure infiltration (T=700°C, p=4 MPa) of an aluminium alloy into alumina performs. Volume fraction of the ceramic phase was up to 30%, while the pore sizes of the ceramic preforms varied from 300 to 1000 µm. Ceramic preforms were formed by method of copying the cellular structure of the polymer matrix. The results of the X-ray tomography proved very good infiltration of the pores by the aluminium alloy. Residual porosity is approximately 1 vol%. Image analysis has been used to evaluate the specific surface fraction of the interphase boundaries (Sv). The presented results of the studies show the effect of the surface fraction of the interphase boundaries of ceramic-metal on the composite compressive strength, hardness and Young’s modulus. The composites microstructure was studied using scanning electron microscopy (SEM). SEM investigations proved that the pores are almost fully filled by the aluminium alloy. The obtained microstructure with percolation of ceramic and metal phases gives the composites high mechanical properties together with the ability to absorb the strain energy. Compression tests for the obtained composites were carried out and Young’s modulus was measured by the application of the DIC (Digital Image Correlation) method. Moreover, Brinell hardness tests were performed. Gas-pressure infiltration (GPI) allowed to fabricate composites with high compressive strength and stiffness.

scholarly journals Effect of strain rate on mechanical properties and microstructure of TRIP steel

2021 ◽  
Vol 252 ◽  
pp. 02058
Author(s):  
Libo Pan ◽  
Wanjun Zhu ◽  
Zhaojun Deng ◽  
Zhijiang Zuo
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Trip Steel ◽  
Volume Fraction ◽  
Aging Effect ◽  
Tensile Tests ◽  
Total Elongation ◽  
Dynamic Strain ◽  
Soaking Time ◽  
The Difference

TRIP effect is one of the important features for TRIP steel. A Nb-Mo microalloyed TRIP steel was developed by employing two different soaking time during annealing, and tensile tests at three different strain rate for specimens after annealing were performed. The microstructures and the volume fraction of retained martensite were examined and analyzed. The result indicated that TRIP steel showed significantly different behaviour at different strain rates. The ultimate tensile strength and total elongation decreased with the strain rate increasing. The dynamic strain aging effect might occur at low strain rate. With shorter soaking time during annealing, microstructure with ultra-refined grain size could be achieved. Fracture surfaces were different at different strain rate. As strain rate increases, the fraction of retained austenite to martensite transformation at failure point decreases which leads to the difference of mechanical properties.

673K Embrittlement of Ferritic Spheroidal Graphite Cast Iron

1984 ◽  
Vol 34 ◽  
Author(s):  
O. Yanagisawa ◽  
T. S. Lui
Keyword(s):  
Strain Rate ◽  
Intergranular Fracture ◽  
Volume Fraction ◽  
Ferrite Matrix ◽  
Dynamic Strain ◽  
Spheroidal Graphite ◽  
Dynamic Strain Ageing ◽  
Cast Irons ◽  
Hydrostatic Tensile Stress

ABSTRACTIntergranular fracture had been observed in the temperature range from 573K – 673K, where the ductilit miniTum appears at 673K for the strain rate of sec−1 in ferritic spheroidal graphite cast irons.The cause of intergranular fracture at about 673K has been investigated. The following two points are emphasized. The first is the role of hydrostatic tensile stress in triaxial stress field developed in ferrite matrix among graphite nodules, relating to the effect of graphite volume fraction on the intergranular fracture. The second is the role of carbide precipitation during dynamic strain ageing, relating to the strain rate and the temperature dependence of the intergranular fracture.

Observation of dislocations in dynamically loaded Cu-SiO2

1986 ◽  
Vol 44 ◽  
pp. 424-425
Author(s):  
D. S. Pritchard
Keyword(s):  
Electron Microscope ◽  
Strain Rate ◽  
Single Crystal ◽  
Transmission Electron Microscope ◽  
Volume Fraction ◽  
Screw Dislocations ◽  
Spherical Inclusions ◽  
Transmission Electron ◽  
Crystal Dispersion ◽  
Strain Rate Loading

The effect of varying the strain rate loading conditions in compression on a copper single crystal dispersion-hardened with SiO2 particles has been examined. These particles appear as small spherical inclusions in the copper lattice and have a volume fraction of 0.6%. The structure of representative crystals was examined prior to any testing on a transmission electron microscope (TEM) to determine the nature of the dislocations initially present in the tested crystals. Only a few scattered edge and screw dislocations were viewed in those specimens.

scholarly journals A High-Strain-Rate Superplasticity of the Al-Mg-Si-Zr-Sc Alloy with Ni Addition

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2028
Author(s):  
Andrey Mochugovskiy ◽  
Anton Kotov ◽  
Majid Esmaeili Ghayoumabadi ◽  
Olga Yakovtseva ◽  
Anastasia Mikhaylovskaya
Keyword(s):  
Strain Rate ◽  
Volume Fraction ◽  
Strain Rate Range ◽  
Zener Pinning ◽  
Nucleation Effect ◽  
Pinning Effect ◽  
Ni Addition ◽  
Elongation To Failure ◽  
Mean Size ◽  
High Temperature Tensile

The current study analyzed the effect of Ni content on the microstructure and superplastic deformation behavior of the Al-Mg-Si-Cu-based alloy doped with small additions of Sc and Zr. The superplasticity was observed in the studied alloys due to a bimodal particle size distribution. The coarse particles of eutectic origin Al3Ni and Mg2Si phases with a total volume fraction of 4.0–8.0% and a mean size of 1.4–1.6 µm provided the particles with a stimulated nucleation effect. The L12– structured nanoscale dispersoids of Sc- and Zr-bearing phase inhibited recrystallization and grain growth due to a strong Zener pinning effect. The positive effect of Ni on the superplasticity was revealed and confirmed by a high-temperature tensile test in a wide strain rate and temperature limits. In the alloy with 4 wt.% Ni, the elongation-to-failure of 350–520% was observed at 460 °C, in a strain rate range of 2 × 10−3–5 × 10−2 s−1.

Microstructure and Properties of Composites Prepared by Reactive Pressure Infiltration of Aluminium into Metal and Ceramic Powder Preforms

2014 ◽  
Vol 782 ◽  
pp. 523-526
Author(s):  
Andrej Opálek ◽  
Karol Iždinský ◽  
Štefan Nagy ◽  
František Simančík ◽  
Pavol Štefánik ◽  
...  
Keyword(s):  
Ceramic Powder ◽  
Nickel Aluminides ◽  
Gas Pressure ◽  
Alumina Powder ◽  
Pressure Infiltration ◽  
X Ray ◽  
Reactive Infiltration ◽  
Melting Temperatures ◽  
Ni Powder ◽  
Properties Of Composites

Nickel aluminides exhibit very attractive high temperature properties. However, due to high melting temperatures they are difficult to prepare. Gas pressure reactive infiltration is a relatively cheap technology that provides composites where nickel aluminides are formed due to mutual reaction between Ni powder and molten aluminium forced to penetrate into powder preform. The feasibility of this concept is demonstrated in this work. Ni powder and/or Ni+25 vol. % Al2O3 powder mixture, respectively, were mechanically pressed and then infiltrated with aluminium using 5 MPa argon gas pressure at the temperature of 750 °C for 120 s. Al/Al2O3 composite using loose alumina powder was prepared in similar manner for comparison. The microstructure of composites was observed by scanning electron microscopy and newly formed intermetallic phases were analysed by energy-dispersive X-ray spectroscopy. Relative elongations during additional thermal cycling up to 800 °C had been recorded. Composites were additionally characterized by hardness measurements.

Characterization of alumina powder using multiple small-angle neutron scattering. I. Theory

1985 ◽  
Vol 18 (6) ◽  
pp. 467-472 ◽  
Author(s):  
N. F. Berk ◽  
K. A. Hardman-Rhyne
Keyword(s):  
Particle Size ◽  
Phase Shift ◽  
Neutron Scattering ◽  
Multiple Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Volume Fraction ◽  
Scattering Data ◽  
Alumina Powder ◽  
Beam Broadening

Microstructural parameters of high-purity alumina powder are determined quantitatively throughout the bulk of the material using small-angle neutron scattering techniques. A unified theoretical and experimental approach for analyzing multiple scattering data is developed to obtain values for particle size, volume fraction and surface area. It is shown how particle size and volume fraction can be measured in a practical way from SANS data totally dominated by incoherent multiple scattering (`beam broadening'). The general phase-shift dependence of single-particle scattering is incorporated into the multiple scattering formalism, and it is also shown that the diffractive limit (small phase shift) applies even for phase shifts as large as unity (particle radii of order 1 μm). The stability of the Porod law against multiple scattering and the phase-shift scale are described, a useful empirical formula for analysis of beam broadening data is exhibited, and the applicability of the formulations to polydispersed systems is discussed.

The Superplastic Properties and Microstructures Evolution of High Nb Ti3Al Based Alloy

2016 ◽  
Vol 838-839 ◽  
pp. 568-573 ◽  
Author(s):  
Xiu Quan Han ◽  
Ming Jie Fu
Keyword(s):  
Strain Rate ◽  
Work Hardening ◽  
Deformation Temperature ◽  
Volume Fraction ◽  
Alloy Sheet ◽  
Deformation Condition ◽  
Maximum Elongation ◽  
Β Phase ◽  
Superplastic Properties ◽  
Softening Stage

The superplasticity of high Nb Ti3Al based alloy - Ti-23Al-17Nb (at.%) alloy sheet under the conditions of 940~1000°C and 5.5×10-5s-1~1.7×10-3s-1are studied. The results show the elongation changes as a parabola with the deformation temperature increasing, and the maximum elongation obtained at 960°C and 5.5x10-5s-1 is 1447.5%. Work hardening stage increases much more than softening stage when strain rate is decreased due to the increasing of element Nb. Compared with primary microstructure, the lath-like α2 grains gradually disappeared, the α2 grains became more equiaxed, and the content and size of α2 grains are decreasing with increasing of deformation temperature. The volume fraction ratio of α2 and β phase at the optimum deformation condition is 50:50%. The cavities mechanism at the fracture tip was discussed; it can be defined that the cavities could be avoided when deformation temperature is higher than 940°C.

scholarly journals Behavior of Dynamic Strain Aging in Zr-1.5Nb-0.4Sn-0.2Fe-0.1Cr Alloy Strip

2021 ◽  
Vol 59 (1) ◽  
pp. 8-13
Author(s):  
Il-Hyun Kim ◽  
Myung-Ho Lee ◽  
Yang-Il Jung ◽  
Hyun-Gil Kim ◽  
Jae-Il Jang
Keyword(s):  
Tensile Test ◽  
Strain Rate ◽  
Dynamic Strain Aging ◽  
Strain Aging ◽  
Rolling Direction ◽  
Rate Sensitivity ◽  
Dynamic Strain ◽  
Alloy Strip ◽  
Lower Strain ◽  
Temperature Ranges

The behavior of dynamic strain aging (DSA) in a Zr-1.5Nb-0.4Sn-0.2Fe-0.1Cr alloy strip was investigated at temperature ranges of 25–600 °C via a tensile test. The tensile test was performed at two different strain rates 8.33 × 10<sup>-5</sup> and 1.67 × 10<sup>-2</sup> s<sup>-1</sup>. The shear stress of the alloy strip revealed a linear dependency on the test temperature when the specimens were tested under a higher strain rate (1.67 × 10<sup>-2</sup> s<sup>-1</sup>). However, the linear relationship was broken due to DSA when the samples were deformed under a lower strain rate (8.33 × 10<sup>-5</sup> s<sup>-1</sup>). The discrepancy was most significant at 400 °C. The trend in DSA behavior was similar irrespective of the orientation of the samples, i.e., rolling direction (RD) or transverse direction (TD). However, the effect of DSA was larger in the TD samples than the RD samples. The phenomena were interpreted to the variation in work hardening exponents and strain rate sensitivity. The value of the exponent decreased from 0.14 to 0.08 along a RD and from 0.1 to 0.07 along a TD, respectively. However, the smallest value was observed at 400–500 °C irrespective of the specimen orientation, which is consistent with the DSA behavior. It is suggested that the DSA was caused by an interaction of moving dislocations with solute atoms typically oxygen.

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