Additive Manufacturing (AM) is an emerging part production technology that offers many advantages such as high degree of customization, material savings and design of 3D highly complex structures. However, AM is a complex multiphysics process. Therefore, only a limited number of materials can already be commercially used to produce parts and a handful of others are being studied or developed for such process. Consequently, limited knowledge on this process is available, especially concerning materials that present thermomechanical challenges such as brittle materials.
The research I did during my PhD studies focuses on additive fabrication of silicon pillars on a monocrystalline silicon wafer by Direct Laser Melting (DLM) with a pulsed 1064 nm laser beam. The simple geometry of pillars allowed for the first determining steps into process understanding. Several results were achieved through this PhD work. First, crack-free silicon pillars were successfully built onto monocrystalline silicon wafers. With the help of in-situ process monitoring and sample characterization, wafer substrate temperature and laser repetition rate were found to be the main influential parameters to obtain crack-free samples, as minimum substrate temperature of 730°C and a minimum repetition rate of 100 Hz were necessary to reach this goal (for a feed rate of 15 g/min and a pulse duration of 1 ms). The influence of secondary process parameters such as feed rate and energy per pulse were also discussed. A simple Finite Element Modeling (FEM) model validated by the experiments was used to explain crack propagation in the samples. Then, process monitoring of the DLM process was realized. High-speed camera image analysis revealed that vertical stage speed and powder feed rate should match to obtain a constant pillar building rate. As all pillars presented necking at their base, estimations of the thermal characteristics of the pillar during growth were carried out by FEM simulations. They were more used to explain the pillar final shape. Finally, the microstructure of the pillars built was characterized by the Electron Back-Scattering Dif-fraction (EBSD) technique. In the conditions presented in this work, the microstructure of the pillar was found to be in the columnar growth mode. The feed rate was identified as the most influential parameter on the microstructure, followed by the stage speed, the impurity content of the powder and the crystallographic orientation of the substrate. Epitaxial growth was achieved on more than 1 mm with a feed rate of 1.0 g/min, a stage speed of 0.1 mm/s, a powder with purity of 4N and a <111> oriented wafer substrate. This work could be further continued by making improvements to the DLM setup, studying the influence of additional process parameters on the thermomechanical behavior and the microstructure control of the pillars, and/or using these results to realize more complicated shapes, either with this setup or by using a powder bed technique.
About
I was born in France and I have grown up in a little town called Beynes, in the department Yvelines, no so far from Paris and Versailles. I am the first of four kids! As a child, I wanted to be a journalist. I have always been interested in digging up into a subject in order to transforming into articles that could be read by others. I had a few friends writing a bunch of articles alongside so we could turn everything into magazines. I spent a lot of time playing with a - now old - layout software in order to make this publication look like my favorite magazines at that time – L'Hebdo, le monde des ados. I even managed to get an internship for a week there!
About
I was born in France and I have grown up in a little town called Beynes, in the department Yvelines, no so far from Paris and Versailles. I am the first of four kids! As a child, I wanted to be a journalist. I have always been interested in digging up into a subject in order to transforming into articles that could be read by others. I had a few friends writing a bunch of articles alongside so we could turn everything into magazines. I spent a lot of time playing with a - now old - layout software in order to make this publication look like my favorite magazines at that time – L'Hebdo, le monde des ados. I even managed to get an internship for a week there!
Project Gallery
Samson le Hérisson is a series of illustrated books for children placed in foster homes produced for the association Particip'Action. The series of books inform children from the age of 5 about how the placement works, promote discussions around it and support the implementation of the children's right to participate in the decisions made during their stay in the child protection system.
What I did
- Research and conceptualization of the project
- Character development
- Development and production of illustrations
- Writing of the text in collaboration with the proofreading committees and the pedagogical direction
- Graphic design and layout
Publications
- Mes premiers Pas au Foyer des Lilas, M. Le Dantec, C. Kamrath, C. Terrier, 2019
- Je vois Maman aux Tournesols, M. Le Dantec, C. Kamrath, C. Terrier, 2021
Perspectives in Foster Care
Development of an illustrated book
How to make complex subjects such as child protection accessible to a wider audience? This book uses illustration to communicate the emotions of the different people concerned by the child protection system (children, parents, professionals) in order to show their different points of view, their difficulties and their moments of joy, to understand the challenges and importance of this institution.
What I did
- Research and conceptualization of the project
- Development of the style and realization of the illustrations
- Graphic design and layout
TerrASoliBé
Logo design
TerrASoliBé is a non-profit association that promotes exchanges between France and Benin, particularly with the village of Sahou. With the actors in the field, it contributes to the improvement of living conditions such as access to water and education. Its logo transcribes the human and constructive aspect of the association, as well as the weaving of links between the two countries.
