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Tribo-Surface Characteristics Of Al-B4c And Al-Sic Composites Worn Under Different Contact Pressures Sep 2006

Tribo-Surface Characteristics Of Al-B4c And Al-Sic Composites Worn Under Different Contact Pressures

A.S. Md Abdul Haseeb

Tribo-surface characteristics of two aluminium metal matrix composites (Al-MMC) of compositions Al-13 vol%B4C and Al-13 vol%SiC sliding against a commercial phenolic brake pad have been investigated under dry conditions. The wear tests were carried out using a pin-on-disc type apparatus at a linear speed of 1.62 m s-1 under contact pressures ranging from 0.75 to 3.00 MPa. The coefficient of friction was recorded on line. Wear rates were calculated from mass loss measurements. Scanning electron microscope equipped with energy dispersive X-ray spectroscopy was used to examine the tribo-surface. It is found that wear rate of both composites increases with increasing …


Velocity Imaging For The Liquid–Gas Interface In The Near Field Of An Atomizing Spray: Proof Of Concept, David L. Sedarsky, Megan E. Paciaroni, Mark A. Linne, James R. Gord, Terrence R. Meyer Mar 2006

Velocity Imaging For The Liquid–Gas Interface In The Near Field Of An Atomizing Spray: Proof Of Concept, David L. Sedarsky, Megan E. Paciaroni, Mark A. Linne, James R. Gord, Terrence R. Meyer

Terrence R Meyer

We describe adaptation of ballistic imaging for the liquid core of an atomizing spray. To describe unambiguously the forces that act to break apart the liquid core in a spray, one must directly measure the force vectors themselves. It would be invaluable, therefore, to obtain velocity and acceleration data at the liquid-gas interface. We employ double-image ballistic imaging to extract velocity information through the application of image analysis algorithms. This method is shown to be effective for liquid phase droplet features within the resolution limit of the imaging system. In light of these results, it is clear that a three- …


Relationship Between Vertical Shear Rate And Kinetic Energy Dissipation Rate In Stably Stratified Flows, Stephen De Bruyn Kops, D. Hebert Dec 2005

Relationship Between Vertical Shear Rate And Kinetic Energy Dissipation Rate In Stably Stratified Flows, Stephen De Bruyn Kops, D. Hebert

Stephen de Bruyn Kops

High resolution direct numerical simulations of strongly stratified turbulence are analyzed in order to investigate the relationship between vertical shearing of horizontal motions and the dissipation rate of kinetic energy. The relative magnitude of each component of the dissipation rate is examined as a function of the Reynolds number and of the buoyancy Reynolds number. From the simulation results, in conjunction with published laboratory results, it is concluded that (1) the simulation results are consistent with the laboratory data but span a much larger range of buoyancy Reynolds number, (2) the ratio of the square of the vertical shear rate …


Melt Dispersion Mechanism For Fast Reaction Of Nanothermites, Valery I. Levitas, Blaine W. Asay, Steven F. Son, Michelle Pantoya Dec 2005

Melt Dispersion Mechanism For Fast Reaction Of Nanothermites, Valery I. Levitas, Blaine W. Asay, Steven F. Son, Michelle Pantoya

Steven F. Son

An unexpected mechanism for fast oxidation of Alnanoparticles covered by a thin oxide shell (OS) is proposed. The volume change due to melting of Al induces pressures of 0.1–4GPa and causes spallation of the OS. A subsequent unloading wave creates high tensile pressures resulting in dispersion of liquid Al clusters, oxidation of which is not limited by diffusion (in contrast to traditional mechanisms). Physical parameters controlling this process are determined. Methods to promote this melt dispersion mechanism, and consequently, improve efficiency of energetic nanothermites are discussed.


30 Adet Pantone Rengin Ink Formulation Programi Kullanilarak Hazirlanmasi, Bilge N. Altay, Nazli Burcu Taklak Dec 2005

30 Adet Pantone Rengin Ink Formulation Programi Kullanilarak Hazirlanmasi, Bilge N. Altay, Nazli Burcu Taklak

Bilge Nazli Altay

Ink Formulation programı kullanılarak formülasyon bileşenleri bulunmak istenen renk, hedef renk olarak tanımlanır ve programa girişi spektral fotometre ile ölçülerek yapılır. Ink Formulation programı tanımlanan hedef rengin üretimi için eldeki mevcut mürekkep ve artık mürekkepleri karıştırarak, hangi mürekkepten ne kadar konulacağını gösterecek şekilde bileşenlerin formülasyon yüzdelerini hesaplayan bir masaüstü yayıncılık programıdır. Bu çalışmanın 1. bölümünde program hakkında bilgi; bölüm 2’de yazılımın kurulumu hakkında bilgi; bölüm 3’de ColorNet yazılımı hakkında bilgi; bölüm 4’de programının yapısı ve görevleri hakkında bilgi; bölüm 5’de programı başlatma hakkında bilgi; bölüm 6’da seçilen bir hedef rengin hesaplanması hakkında bilgi; bölüm 7’de formülasyonu yapılmış bir rengin ihtiyacı …


Modeling Of The Effects Of Athermal Flow Strength And Activation Energy For Dislocation Glide On The Nanoindentation Creep Of Nickel Thin Film At Room Temperature Dec 2005

Modeling Of The Effects Of Athermal Flow Strength And Activation Energy For Dislocation Glide On The Nanoindentation Creep Of Nickel Thin Film At Room Temperature

A.S. Md Abdul Haseeb

Nanoindentation creep behaviour of nickel at room temperature has been modeled based on the obstacle-controlled dislocation glide mechanism. Using the model, the effects of two important materials parameters viz. the activation free energy required by dislocation to overcome an obstacle without any aid from external stress, ΔF and the athermal flow strength, τ0, which is the flow strength of solids at 0 K are systematically studied. It has been found that ΔF plays a dominant role in room temperature creep properties of nickel. The role of ΔF is particularly dominant in determining the time dependent deformation. On the other hand, …