Fabrication and modeling of high order functionally graded materials for space applications

Dissertant

Abd Amir, Diya Najm

Thesis advisor

Farid, Sad Badri Hassun
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

2012

English Abstract

Functionally graded materials are useful in applications, where high thermal resistance and bulk toughness are necessary.

Therefore, special and improved processing is required to produce such materials.

It is desired in this research to fabricate (Al2O3-Ti) high order stepwise functionally graded materials using Spark Plasma Sintering.

These materials combine the high fracture toughness of Ti phase and the low density of Al2O3.

For that, an extensive analysis and characterization of these materials are relevant as this material was proposed as an alternative material for shuttle space applications.

Two methods have been proposed in this research.

The first method developed inverse design procedure, which incorporates the Wakashima model and the results of COMSOL multiphysics.

The second method is the utilization of spark plasma sintering to extract the Ti powder from the Titanium hydried (TiH2).

Fabricated materials that consist of five layers, where the Al2O3 increases linearly from (0, 25, 50, 75 and 100 wt%) at the first or bottom layer to the fifth or top layer.

COMSOL multiphysics are used in simulation of fabricated materials and examination was conducted against real operation conditions (i.e.

reentry temperatures).

Simulation shows about 85% reduction in temperature profile will be achieved throughout the fabricated material model.

This reduction in temperature profile has been accompanied with 0.115mm expansion at the Al2O3 layer.

Residual stresses are also improved in acceptable manner at high reentry temperature (i.e.

1900 °C).

Spark Plasma Sintering conditions (1500°C, 30 min and 8 KN) impart graded micro hardness along the thickness at modified apparent density (4.25 g/cm3), lower porosity percentage (1.28%) and lower diametric expansion (1.58%).

Optical and scanning microscopy shows a good matching between the material constituents at the interface and obvious diffusion kinetics were monitored by EDX and EMPA techniques.

Main Subjects

Engineering & Technology Sciences (Multidisciplinary)

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-418968