Abstract

Multi walled carbon nanotubes (MWCNT) were added to aluminum powder (99.97% pure) to produce a composite material. Three mixing techniques were examined

1 Low energy mixing: Using a Turbula mixer with two different speeds 48 and 67 rpm.

2 High energy mixing: Using a ball mill without adding any balls in the mixing jars with two speeds 300 and 400 rpm.

3 Ball milling: Using the ball mill (with steel balls) to mix higher CNT weight fraction samples for the electrical resistivity tests.

The mixtures were packed in copper cans and rolled in a rolling machine to compact the mixture; sintered in a vacuum furnace then in a regular sintering furnace. The resulting specimens were cut out of the cans and machined by wire EDM for physical, mechanical and electrical testing. Physical testing included inspection by SEM and TEM, and density measurements. Mechanical testing included applying tension test and measuring Young's modulus by measuring the natural frequency of a vibrating strip made from mixtures prepared by low and high energy mixing only. The electrical resistivity testing included measuring the resistivity of specimens prepared from mixtures made by high energy mixing and ball milling at both room temperature and liquid nitrogen temperature.

A set of pure aluminum specimens were compacted using the ball milling process by

utilizing the cold welding phenomenon without going through sintering. Only density measurements and SEM inspection were applied on these Al specimens. The 0.5wt.%CNT-Al specimens produced by the low energy mixing method showed enhancement in the yield strength and decrease of ductility and ultimate tensile strength. High energy mixing method achieved better dispersion of CNT inside the matrix which enhanced the strength of0.Swt.% and lwt.% CNT's specimens. Increasing mixing time and speed at high energy mixing enhanced the dispersion of the CNT's. Electrical resistivity of the high energy mixed specimens increased with the increase of CNT wt%. However, the resistivity deceased with the increase of mixing time and speed. Ball milling increased the electrical resistivity of pure ball milled aluminum. Ball milling of CNT's/Al increased the resistivity with the CNT's content till 5 wt% and it decreased at 8 wt%. CNT's.

Department

Mechanical Engineering Department

Degree Name

MS in Mechanical Engineering

Date of Award

6-1-2008

Online Submission Date

6-1-2008

First Advisor

Amal Esawi

Committee Member 1

Kamal Bedewy

Committee Member 2

Hanadi Salem

Committee Member 3

Ashraf Nassef

Document Type

Thesis

Extent

xv, 90 leaves :

Library of Congress Subject Heading 1

Aluminum strip.

Library of Congress Subject Heading 2

Metal powder rolling.

Rights

The American University in Cairo grants authors of theses and dissertations a maximum embargo period of two years from the date of submission, upon request. After the embargo elapses, these documents are made available publicly. If you are the author of this thesis or dissertation, and would like to request an exceptional extension of the embargo period, please write to thesisadmin@aucegypt.edu

Call Number

Thesis 2008/58

Location

uarch

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