The PhD student (Osama Abdul-Bari khuder) discussed his thesis entitled ( Improvement Some Properties of Gallium Alloy for Dental Application). The discussion was held on the discussions hall / building C / Department of Materials Engineering / University of Technology on Thursday (19/01/2020). The discussion committee was formed of the teaching staff listed:

 Abstract

  Amalgam fillings are widely used in because of the low cost, strength, high durability and ease of application, but also the most controversial of dental restorative materials because of doubts about the likelihood of toxicity of mercury.

Gallium has the second lowest melting temperature and the ability to react with metals and alloys at room temperature so the gallium base alloy was introduced as mercury-free amalgam.

The aim of this work is to prepare Galloy which consist of liquid alloy (Gallium ,Tin, and Indium) and powder alloy ( Silver, Tin, Copper )  that represent base alloy ,then adding Bismuth nano powder , Nickel-Titanium alloy nano powder prepared by powder metallurigy and then crushed into powder  and TiO₂ nano tube with different percentage (1%,2%,3%,4% and 5% wt%) to reinforced the base alloy and improve the mechanical ,physical and chemical properties.

The specimen were made according to the American Dental Association (ADA) specification No.1, with a diameter of 6 mm and 12 mm in length (cylindrical shape) , a mixture of 1:0.5 of powder alloy and liquid alloy respectively , a Teflon mould was used and a compressive stress of 14 MPa was applied by punching for 85 second , after 30 minutes the specimen was ejected from the mold and kept at 37 ᵒC  to be tested .

Hardness, compressive strength, dimetrial strength, and creep tests were done for all prepared specimens. All the three additives work to improve the mechanical properties as its percentage increases.

Scanning Electron Microscope with EDS were done for the base alloy (Galloy), 5%Bi/Galloy, 5%NiTi/Galloy, and 5%TiO₂/Galloy.to illustrate the microstructure and existing phases.

X-Ray Diffraction (XRD) test was done for the amalgam powder alloy , niti alloy powder , base alloy (Galloy ) , 5% bi/galloy , 1%bi/galloy ,3%bi/galloy ,5%niti/galloy and 5%tio2/galloy to identify the result phase during the reaction.

X-Ray Flourescence XRF test was done for Ga, Bi, In, and Sn to insure the purity of the used materials.

Chemical test like ions releas and corrosion were performe where the corrosion behavior was determined for all prepared specimen in artificial saliva with different pH (7.2 ,4.6 ,3.3) and different NaF concentration (0 ,1000,2500,5000 ppm).The ion release was done for the base alloy (Galloy), 5%Bi/Galloy, 5%NiTi/Galloy, and 5%TiO₂/Galloy where the specimen immersed in artificial saliva of pH (3.3) for one month and kept at 37ᵒC to indicate the released ions in the solution.

The dissertation was scientifically evaluated by Assist. Prof. Dr. Abdul Raheem kadhim / Babylon University / College of Engineering / Department of Materials Engineering, and linguistically by Lec. Dr. Muhaned Najah Jawad / University of Technology / Department of Materials Engineering.

The thesis discussion was conducted in a scientific atmosphere and a PhD degree with grade of pass was awarded to the student after the completion of all the corrections that have been decided by the examiners.