PhD Position in Mechanical Engineering

Tallinn University of Technology, School of Engineering, Department of Mechanical and Industrial Engineering offers a 4-year PhD position in mechanical engineering.
Proposed doctoral thesis topic: "Waste-to-resource: eggshells as a source for next generation biomaterials for bone regeneration".

Supervisors: Professor Prashanth Konda Gokuldoss and Dr. Jayaraj Jayamani

Abstract
The aim of this project is to covert egg shells and their constituents into bulk amorphous calcium phosphate for biomedical applications. The consolidation of the amorphous precursor may be carried out using powder technology and/or additive manufacturing technologies to produce micrometer sized interconnected porosity.

Description

Consolidation of amorphous calcium phosphate in to macroporous bone-like scaffolds. This involves:

• A detailed study on the crystallization kinetics using the combination of differential scanning calorimetry (DSC) and XRD to evaluate the activation energy for the crystallization process (up to 700 oC) of the ACP derived from eggshells. This information is critical for implementation of the subsequent tasks.
• Consolidation of ACP: The ACP will be consolidated into bulk form using spark plasma sintering (SPS), high pressure torsion (HPT) and selective laser sintering/melting (SLS/SLM) with selected process parameters (e.g temperature, pressure, environment) and with the knowledge gained from the crystalization kinetics. Structural (XRD) and microstructural (SEM) characterizatieeeon will be carried out of obtained specimens.
• Preparation of porous ACP: Depending on the consolidation results, the parameters used ITHfor obtaining amorphous structures will be utilized to produce porous samples using space-holder techniques (for SPS and HPT) and/or modified CAD data (for SLS/SLM) process. The goal will be to achieve the samples with 200-300 µm large interconnected porosity, which will be considered as the ideal sample in the present study. All the necessary characterizations like XRD, microscopy (including tomography), etc. will be carried out to ascertain the presence of pores and amorphous structure in the porous samples.
• Coating of porous structures with proteins from eggshell membrane: Dipping or vacuum infiltration technology will be used for coating of porous structures with proteins. The biocompatibility of all prepared materials will be further evaluated in detail.

Aim for ACP consolidated samples with density > 80% of theoretical density and 200-300 µm large interconnected porosity.