Fabrication and characterization of Stepwise CU-NI functionally graded materials

Dissertant

Ghafil, Nur al-Sharif

Thesis advisor

Ataiwi, Ali Husayn
al-Zughaybi, Ala Abd al-Hasan Atiyyah Hasan

University

University of Technology

Faculty

-

Department

Department of Materials Engineering

University Country

Iraq

Degree

Master

Degree Date

2011

English Abstract

-The aim of the present research is to utilize the powder technology technique to prepare a stepwise high order functionally graded materials (FGMs) with adequate mechanical and physical characteristics for application in extreme environmental conditions.

For that purpose, five-layered stepwise Cu/Ni functionally graded materials have been successfully prepared by using pressureless sintering under vacuum conditions.

Sintering parameters, such as temperature and dwell time as well as the effect of compacting pressure were investigated.

Green density of prepared functionally graded materials compaction increases as the compaction pressure increases.

Adoption of high pressure compaction (i.e.

200psi) at high sintering temperature (850°C) for (2hrs), can give better apparent density and very low porosity percentage, in addition it can lower electrical resistivity and facilitate current flow through the materials.

Scanning electron microscopy analysis determines that all prepared functionally graded materials have good graded composition, which in turn imparts linear increasing microhardness values across the thickness.

Better increase of microhardness values across the thickness is found in C6-FGMs, (highest sintering time and temperature) compacted in 200psi and sintered at 850°C for 2hrs.

Scanning electron observations indicated also that, functionally graded materials constituents are bonded on each other as the sintering temperature and time are increased.

X-ray diffraction observations indicated that as the sintering temperature increased, set of phases have been developed like (NiCu, Cu3.8Ni and Cu0.81Ni0.19).

These phases were playing a noticeable role in enhancing thermal conductivity as well as electrical resistivity.

Finite element method used successfully in determining the contour and temperature profile across the thickness of functionally graded materials.

ANSYScode was used in the modeling of C6-FGMs sample, since it exhibits linear grading of microhardness and better physical properties.

Finite element model adopted in temperature profile determination had been extended and modified to determine thermal stress that developed when the material was subjected to a steady heat source with (1000°C).

Main Subjects

Chemistry

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Language

English

Data Type

Arab Theses

Record ID

BIM-305137