scholarly journals Preparation and Anodizing of SiCp/Al Composites with Relatively High Fraction of SiCp

Scanning ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Bin Wang ◽  
Shengguan Qu ◽  
Xiaoqiang Li
Keyword(s):  
Elastic Modulus ◽  
Flexural Strength ◽  
Volume Fraction ◽  
High Volume ◽  
Anodic Oxide ◽  
Infiltration Process ◽  
Oxidation Treatment ◽  
Squeeze Infiltration ◽  
High Fraction ◽  
Anodic Oxidation Treatment

By properly proportioned SiC particles with different sizes and using squeeze infiltration process, SiCp/Al composites with high volume fraction of SiC content (Vp = 60.0%, 61.2%, 63.5%, 67.4%, and 68.0%) were achieved for optical application. The flexural strength of the prepared SiCp/Al composites was higher than 483 MPa and the elastic modulus was increased from 174.2 to 206.2 GPa. With an increase in SiC volume fraction, the flexural strength and Poisson’s ratio decreased with the increase in elastic modulus. After the anodic oxidation treatment, an oxidation film with porous structure was prepared on the surface of the composite and the oxidation film was uniformly distributed. The anodic oxide growth rate of composite decreased with SiC content increased and linearly increased with anodizing time.

On Thermal Interface Materials With Polydisperse Fillers: Packing Algorithm and Effective Properties

2018 ◽  
Author(s):  
Piyas Chowdhury ◽  
Kamal Sikka ◽  
Anuja De Silva ◽  
Indira Seshadri
Keyword(s):  
Thermal Conductivity ◽  
Elastic Modulus ◽  
Volume Fraction ◽  
Effective Properties ◽  
Material Design ◽  
High Volume ◽  
Thermal Interface Materials ◽  
Thermal Interface ◽  
Packing Algorithm ◽  
Interface Materials

Thermal interface materials (TIMs), which transmit heat from semiconductor chips, are indispensable in today’s microelectronic devices. Designing superior TIMs for increasingly demanding integration requirements, especially for server-level hardware with high power density chips, remains a particularly coveted yet challenging objective. This is because achieving desired degrees of thermal-mechanical attributes (e.g. high thermal conductivity, low elastic modulus, low viscosity) poses contradictory challenges. For instance, embedding thermally conductive fillers (e.g. metallic particles) into a compliant yet considerably less conductive matrix (e.g. polymer) enhances heat transmission, however at the expense of overall compliance. This leads to extensive trial-and-error based empirical approaches for optimal material design. Specifically, high volume fraction filler loading, role of filler size distribution, mixing of various filler types are some outstanding issues that need further clarification. To that end, we first forward a generic packing algorithm with ability to simulate a variety of filler types and distributions. Secondly, by modeling the physics of heat/force flux, we predict effective thermal conductivity, elastic modulus and viscosity for various packing cases.

scholarly journals Fabrication of TiB2–Al1050 Composites with Improved Microstructural and Mechanical Properties by a Liquid Pressing Infiltration Process

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1588
Author(s):  
Seongmin Ko ◽  
Hyeonjae Park ◽  
Yeong-Hwan Lee ◽  
Sangmin Shin ◽  
Ilguk Jo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Metal Matrix ◽  
Load Transfer ◽  
Volume Fraction ◽  
High Volume ◽  
Matrix Composites ◽  
Infiltration Process ◽  
Al Composite ◽  
Al Matrix

This study was conducted on titanium diboride (TiB2) reinforced Al metal matrix composites (MMCs) with improved properties using a TiB2 and aluminum (Al) 1050 alloy. Al composites reinforced with fine TiB2 at volume ratios of more than 60% were successfully fabricated via the liquid pressing infiltration (LPI) process, which can be used to apply gas pressure at a high temperature. The microstructure of the TiB2–Al composite fabricated at 1000 °C with pressurization of 10 bar for 1 h showed that molten Al effectively infiltrated into the high volume-fraction TiB2 preform due to the improved wettability and external gas pressurization. In addition, the interface of TiB2 and Al not only had no cracks or pores but also had no brittle intermetallic compounds. In conclusion, TiB2–Al composite, which has a sound microstructure without defects, has improved mechanical properties, such as hardness and strength, due to effective load transfer from the Al matrix to the fine TiB2 reinforcement.

Novel cellular perlite–epoxy foams: Effect of density on mechanical properties

2016 ◽  
Vol 53 (4) ◽  
pp. 425-442 ◽  
Author(s):  
Haleh Allameh-Haery ◽  
Erich Kisi ◽  
Thomas Fiedler
Keyword(s):  
Elastic Modulus ◽  
Failure Modes ◽  
Shear Failure ◽  
Volume Fraction ◽  
Volcanic Glass ◽  
Effective Elastic Modulus ◽  
High Volume ◽  
Density Range ◽  
Longitudinal Splitting ◽  
Closed Cell

A novel type of economical lightweight foam with density from 0.15 to 0.45 g/cm3 was made from a high volume fraction of expanded volcanic glass (perlite) in an epoxy matrix. The compressive strength, effective elastic modulus, and modulus of toughness of the foams all increased with the foam density. The strength increased linearly, peaking at 1.7 MPa whereas the effective elastic modulus and modulus of toughness increased at parabolically increasing and decreasing rates, respectively. The specific compressive stress of the newly developed foam in the density range of 0.3–0.44 g/cm3 is comparable with foams made from alumina, aluminium–silicon carbide, closed cell phenolic resin, and closed cell polypropylene. Post-test SEM observations coupled with photogrammetry during the tests revealed three different failure modes: longitudinal splitting, shear failure, and compression failure were present over the whole density range. The material was found to be a good candidate for the stiffening cores within sandwich panels.

scholarly journals Effect of the Different High Volume Fraction of SiC Particles on the Junction of Bismuthate Glass-SiCp/Al Composite

Scanning ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Bin Wang ◽  
Shengguan Qu ◽  
Xiaoqiang Li
Keyword(s):  
Shear Strength ◽  
Volume Fraction ◽  
Coefficient Of Thermal Expansion ◽  
High Volume ◽  
Bonding Interface ◽  
Strength Testing ◽  
Infiltration Process ◽  
Sic Particles ◽  
Al Composite ◽  
Sic Particle

The in-house developed bismuthate glass and the SiCp/Al composites with different volume fractions of SiC particles (namely, 60 vol.%, 65 vol.%, 70 vol.%, and 75 vol.%) were jointed by vacuum hot-pressing process. The novel material can be used for the space mirror. The SiCp is an abbreviation for SiC particle. Firstly, the SiCp/Al composites with different vol.% of SiC particle were manufactured by using infiltration process. In order to obtain a stable bonding interface, the preoxide layers were fabricated on the surfaces of these composites for reacting with the bismuthate glass. The coefficient of thermal expansion (CTE) was carried out for characterizing the difference between the composites and bismuthate glass. The sealing quality of the composites and the bismuthate glass was quantified by using shear strength testing. The optical microstructures showed the particles were uniformly distributed in the Al matrix. The SEM image shows that a smooth oxidation layer was generated on the SiCp/Al composite. The CTE testing result indicated that the higher the vol.% of the particles in the composite, the lower the CTE value. The shear strength testing result disclosed that SiCp/Al composite with relatively low CTE value was favorable to obtain a bonding interface with high strength.

The Effects of Carbon Black on Rubber Hysteresis

1974 ◽  
Vol 47 (4) ◽  
pp. 729-757 ◽  
Author(s):  
J. D. Ulmer ◽  
W. M. Hess ◽  
V. E. Chirico
Keyword(s):  
Elastic Modulus ◽  
Carbon Black ◽  
Network Effects ◽  
Network Formation ◽  
Volume Fraction ◽  
High Volume ◽  
Network Effect ◽  
Viscoelastic Effect ◽  
Viscous Modulus ◽  
Geometrical Effect

Abstract The viscous modulus of oil-extended SBR loaded with carbon black relative to the gum stock increases with volume fraction of carbon black. This increase is much larger than predicted by the Guth-Gold equation and also greater than the increase in the elastic modulus. This behavior reflects the sum of at least three effects: geometrical (strain amplification), changes in the viscoelastic properties of the rubber, and formation of a three-dimensional network of carbon black and rubber. The geometrical effect increases with volume fraction of carbon black. Its per cent contribution to the viscous modulus decreases as the carbon black loading increases because of increased contribution of the viscoelastic effect at low loadings and of the network effect at high loading. The geometrical effect can be described reasonably well by the Guth equation with a shape factor and with the volume fraction increased by the additional immobilized rubber (bonded elastomer). The viscoelastic effect due to 60 phr black contributes at least 20 per cent to the viscous modulus and is related to structure, surface area, and volume fraction of the carbon black. It can be at least partially accounted for by rubber breakdown during mixing. At high volume fractions of carbon black (60 phr), network formation contributes about 25 to 45 per cent to the viscous modulus. It increases with decreasing interunit spacing which depends on the average volume of the carbon-black units and the amount of bonded elastomer. For a thermal black, N—990, the interpretation of the results is complicated by the distinct possibility that slippage contributes to hysteresis. We conclude, however, that at low loadings the increase of the viscous modulus is much greater than that of the elastic modulus and that network effects contribute to the viscous modulus at high loadings.

Evaluation of Mechanical Properties of Glass/Epoxy Syntactic Foams Containing Carbon Nanotubes and Nanosilica

2015 ◽  
Vol 1124 ◽  
pp. 51-56 ◽  
Author(s):  
Martina Drdlová ◽  
Michal Frank ◽  
Jaroslav Buchar ◽  
Radek Řídký
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Volume Fraction ◽  
Resin Composite ◽  
High Volume ◽  
Significant Drop ◽  
Multi Wall Carbon Nanotubes ◽  
Blast Energy

The effect of multi-wall carbon nanotubes and nanoSiO2content on physico-mechanical properties of glass microspheres-epoxy resin composite, designed for blast energy absorbing applications, was evaluated experimentally. Specific porous lightweight foam with high volume fraction of microspheres (70 vol.%) was prepared and modified by 1 to 5 vol.% of multi-wall carbon nanotubes and nanosilica (nanoSiO2). Two types of microsperes with different wall thickness and strength were used. The quality of dispersion of nanoparticles was evaluated in relation to the mixing procedure using scanning electron microscope observation. The compressive and flexural strength tests were conducted at quasi-static load. The mixtures containing nanosilica exhibited an increasing trend in both flexural and compressive strength with increasing nanoparticle content up to 4 vol.%. The addition of carbon nanotubes also increased flexural strength (again up to 4 vol%, crossing this concentration, the significant drop was observed), whereas the compressive strength was affected at lower level. Nanoparticle modification is more effective in the foams with higher thickness and thus strength. The evaluation of test results showed that the properties of glass/epoxy foams can be tailored by adding nanoscale fillers.

Properties of High Volume Fraction Fly Ash/Al Alloy Composites Produced by Infiltration Process

2015 ◽  
Vol 24 (9) ◽  
pp. 3315-3322 ◽  
Author(s):  
D. T. Kountouras ◽  
F. Stergioudi ◽  
A. Tsouknidas ◽  
C. A. Vogiatzis ◽  
S. M. Skolianos
Keyword(s):  
Fly Ash ◽  
Volume Fraction ◽  
High Volume ◽  
High Volume Fraction ◽  
Al Alloy ◽  
Infiltration Process

Morphology, Distribution and Identification of Micro-Constituents Along Grain Boundaries in Nickel-Base Alloys

1973 ◽  
Vol 31 ◽  
pp. 176-177
Author(s):  
D. E. Fornwalt ◽  
A. R. Geary ◽  
B. H. Kear
Keyword(s):  
Electron Microscope ◽  
Grain Boundaries ◽  
Volume Fraction ◽  
Rupture Life ◽  
Stress Rupture ◽  
High Volume ◽  
Precipitate Morphology ◽  
Stress Rupture Life ◽  
Nickel Base ◽  
Scanning Electron

A systematic study has been made of the effects of various heat treatments on the microstructures of several experimental high volume fraction γ’ precipitation hardened nickel-base alloys, after doping with ∼2 w/o Hf so as to improve the stress rupture life and ductility. The most significant microstructural chan§e brought about by prolonged aging at temperatures in the range 1600°-1900°F was the decoration of grain boundaries with precipitate particles.Precipitation along the grain boundaries was first detected by optical microscopy, but it was necessary to use the scanning electron microscope to reveal the details of the precipitate morphology. Figure 1(a) shows the grain boundary precipitates in relief, after partial dissolution of the surrounding γ + γ’ matrix.

HOT CORROSION OF CERIA-YTTRIA STABILIZED ZIRCONIA PLASMA SPRAYED THERMAL BARRIER COATING BY EUTECTIC VANDIUM PENTAOXIDE-SODIUM SULFATE

2018 ◽  
Vol 18 (1) ◽  
pp. 182-192 ◽  
Author(s):  
Mohammed J Kadhim ◽  
Mohammed H Hafiz ◽  
Maryam A Ali Bash
Keyword(s):  
Thermal Barrier Coating ◽  
Hot Corrosion ◽  
Monoclinic Phase ◽  
Volume Fraction ◽  
High Volume ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Plan View ◽  
Barrier Coating ◽  
Plasma Sprayed

The high temperature corrosion behavior of thermal barrier coating (TBC) systemconsisting of IN-738 LC superalloy substrate, air plasma sprayed Ni24.5Cr6Al0.4Y (wt%)bond coat and air plasma sprayed ZrO2-20 wt% ceria-3.6 wt% yttria (CYSZ) ceramic coatwere characterized. The upper surfaces of CYSZ covered with 30 mg/cm2 , mixed 45 wt%Na2SO4-55 wt% V2O5 salt were exposed at different temperatures from 800 to 1000 oC andinteraction times from 1 up to 8 h. The upper surface plan view of the coatings wereidentified for topography, roughness, chemical composition, phases and reaction productsusing scanning electron microscopy, energy dispersive spectroscopy, talysurf, and X-raydiffraction. XRD analyses of the plasma sprayed coatings after hot corrosion confirmed thephase transformation of nontransformable tetragonal (t') into monoclinic phase, presence ofYVO4 and CeVO4 products. Analysis of the hot corrosion CYSZ coating confirmed theformation of high volume fraction of YVO4, with low volume fractions of CeOV4 and CeO2.The formation of these compounds were combined with formation of monoclinic phase (m)from transformation of nontransformable tetragonal phase (t').

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