Preparation and corrosion behavior of niti shape memory alloys

Dissertant

al-Husni, Imad Sadi Abd al-Karim Ahmad

University

University of Technology

Faculty

-

Department

Department of Production Engineering and Metallurgy

University Country

Iraq

Degree

Ph.D.

Degree Date

2007

English Abstract

Nickel-Titanium shape memory alloy (National or NiTi) is a fascinating material for dental applications.

In this thesis the alloy has been produced by powder metallurgy approach and the effect of Cr and Al additives studied on the ; hardness, porosity percentage, transformation temperature and corrosion rate.

A comparison made with thermal and austenitic archwhes, which produced by casting.

Master Samples (without additives) prepared using powder mixture of 55 wt % Ni and 45 wt % Ti by; mixing in a ball mill for two hours, then compacted at 300, 400: 500, 600, 700, and 800 Mpa: and then sintered at 950 °C for 9 hours under controlled atmosphere (argon).

The same approach was made for the samples with Cr and A! Additions compacted at 800 Mpa.

The additives selection depends on the melting temperature during the sintering process.

XRD test shows that the sintered samples are consisting of two phases marten site and austenitic at room temperatures (mean thermal NiTi shape memory alloy).

From the results, it was found that compaction pressure has essential effect on; increasing hardness, decreases porosity percentage and corrosion rate, but has little effect on the transformation temperatures, Results shows that Cr and Al additives increase hardness and decreases porosity percentage in all weight percentage of additives.

Compared to the master samples and the thermal dental arch wires, Cr addition has good influence in decreasing the corrosion rate at 03 wt % Cr, while the Al addition results had an increase effects in the corrosion rate.

Main Subjects

Materials Science , Minerals

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Language

English

Data Type

Arab Theses

Record ID

BIM-305645