Effect of laser surface melting on corrosion of dental alloys with harmful materials in artificial saliva medium

Dissertant

Muhsin, Ali Abd al-Karim

Thesis advisor

Atawi, Ali H.
Anani, Rana Afif

University

University of Technology

Faculty

-

Department

Department of Materials Engineering

University Country

Iraq

Degree

Master

Degree Date

2012

English Abstract

Dental alloys examined in this work were Co-Cr-Mo, Ni-Cr-Mo and Ti-Al-V alloys, classified in two groups as received alloys (untreated) and treated alloys by laser surface melting treatment.

Laser surface melting treatment (LSM) was performed by pulsed Nd-YAG laser and working conditions were laser energy 190mJ, wave length 1064nm, pulse duration 30ns and spot diameter 0.5mm.

Harmful materials included tobacco smoking (cigarette and waterpipe) yields and alcoholic beverages were studied which have side effects on human health.

Surface characterization for untreated and treated alloys was performed by optical microscope which indicates that the microstructure of untreated alloys consist of denderitic regions for Co-Cr-Mo and Ni-Cr- Mo alloys while bi phases (α+β) in Ti-Al-V alloy.

The microstructure for treated alloys indicates laser spots in alloys surface.

Hardness measurements for untreated and treated alloys were performed by Vickers microhardness which shows increasing of hardness values for treated alloys.

Surface roughness measurements show that treated alloys by LSM treatment has smooth surface as compared with alloys prior to LSM treatment.

Corrosion test was performed by (Potentiostat / Galvanostat WENKING M Lab) at 37oC and pH=4 aerated test.

OCP-time measurements show that untreated and treated Ni-Cr-Mo alloy thermodynamically offer less tendency to corrosion.

The presence of tobacco smoking yields (cigarette and waterpipe) and alcoholic beverages shift the corrosion potential values (Ecorr) either in active or in noble direction for three used dental alloys, while shift corrosion current densities (icorr) to higher values and give variation in the polarization resistance (Rp) values.

Most of corrosion potential Ecorr values for alloys shifted toward the noble direction except Ni-Cr-Mo alloy shifted toward active direction when compared with untreated alloys.

The data of corrosion rate (CR) for untreated and treated alloys in most cases follow the sequence: Ti-Al-Valloy > Co-Cr-Mo alloy > Ni-Cr-Mo alloy The cyclic polarization curves for untreated and treated alloys indicate that Co-Cr-Mo and Ni-Cr-Mo alloys were more resistant to pitting corrosion, while Ti-Al-V alloy was less resistant to pitting corrosion except for one case in the presence of ethyl alcohol.

The cyclic polarization behavior for treated Co-Cr-Mo and Ni-Cr-Mo alloys show shifting of the reverse potential Erev toward more noble direction and gave smaller hysteresis loop for treated Ti-Al-V alloy.

Main Subjects

Engineering & Technology Sciences (Multidisciplinary)

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-418692