Design and sintering of Fe-Zro2 functionally graded materials

Dissertant

Aziz, Ahmad Taifor

Thesis advisor

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

2013

English Abstract

For many applications such as thermal protection systems, functionally graded materials are being developed to minimize thermal stresses which usually lead to fracture of ceramic materials.

The purpose of this research is to design, prepare and characterize the behavior of functionally graded materials through experimentation and analytical modeling.

This work involves two parts, the first part is design and the second is experimental work.

In this work a five layer metal to ceramic functionally graded materials have been prepared for high temperature applications such as jet engine using powder technology techniques.

The ceramic is represented by partially stabilized Zirconia (ZrO^) while metal is represented by iron (Fe).

The work starts with the design phase, where the FEM method has been used through the COMSOL package to find the best graded thickness (RF) that imparting low residual stresses between layers under variable volume fraction index (N).

Thermal stresses that are developed as a result of exposing of material for high temperature environments have been calculated.

Experimental part focuses on two stages; the first stage is the preparation of five layers FGMs according to the best results obtained ^om the modeling part.

Powder technology has been used extensively to prepare these materials.

Sintering practice examinations represent the second stage in practical parts.

Tuning of sintering temperature is accomplished and a model for sintering behavior is also investigated in this research.

The simulation shows that the sample (RF= 80%, N=0.

7) provides minimum residual stress (838 ^Pa) at high temperature 1000°c with good mechanical properties.

Landau theory of thermodynamics of sintering is adapted in this research.

Sintering conditions (1400°c ) for 5hr impart better graded microhardness along the thickness at modifying relative density (93.3%), lower porosity (6.7%).

Characterization of resulted sample by SEM is used to investigate the interactions between layers; these examinations could help in understanding the diffusion phenomena and its effects on the gradation of properties across the thickness of prepared materials.

Main Subjects

Civil Engineering

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-417283