O estudante Michel Reis Pedreira Muniz Tavares, orientado pelo Prof. Rolf Bertrand Schroeter, Dr. Eng. e coorientado por Prof. Dr.-Ing. Dirk Oberschmidt (TU Berlin)., fará seu exame de qualificação na próxima quarta-feira (25/11), às 10h, por videconferência. A defesa é vinculada ao Programa de Pós-Graduação em Engenharia Mecânica.
Título: “ANALYSIS OF THE DIAMOND CUTTING OF GALLIUM PHOSPHIDE USING ATOMISTIC MODELLING AND SIMULATION”
The present thesis proposal is part of a bigger scope from a global project. The latter aims for the development of a system for online monitoring and controlling of process variables in the diamond cutting of semiconductors materials. The former consists of the study of phenomena related to the cutting process of gallium phosphide (GaP), which lacks published studies concerning its ultra-precision diamond cutting. Semiconductors are important materials for microscope manufacturers, medicine technologies, and aerospace applications due to their optical properties, such as high refraction index in the near-infrared spectrum (IR/VIS spectrum). On the other hand, they are often complex to be machined because of their brittle behavior, and surface and form requirements for their applications in the order of nanometers. In addition, some of them, such as the GaP can be relatively expensive, limiting the number of studies. In order to fill the voids in the understanding of the machinability of GaP, the present thesis proposal aims the molecular dynamics modeling and simulation of the diamond cutting and nanoindentation of GaP using potential field equations already available in the literature and the LAMMPS® software, alongside the necessary experiments required to enhance the model’s accuracy. The main focus is the understanding of phenomena related to the GaP machining, such as minimum cutting thickness, phase transformation and the generated hydrostatic pressure during the diamond cutting, since there is no published work that explains it. In order to calibrate models, Si and SiC nano cutting and nonoindentation will be simulated first, since regardless of the voids to fill, there is a considerable amount of previously published studies to compare. The experimental phase will consist in the ultra-precision machining with force measurement and nanoindentation of GaP followed by scanning tunneling microscopy analysis and atomic force microscopy of samples in order to define the atomic structure (for comparison with the molecular dynamics simulations) and surface roughness to evaluate the surface quality. The tool wear will be evaluated through scanning electron microscopy. During the experimental phase, an additional number of experiments and simulations should be conducted in order to find optimal process parameters, such as minimal cutting thickness. The present thesis proposal is a partnership between the Laboratory of Precision Engineering (LMP) of the Federal University of Santa Catarina (UFSC) with the chair of Micro and Precision Devices (MFG) of the Institute of machine-tools and factory management of the Technische Universität Berlin (IWF/TU Berlin).
Palavras-chave: Gallium Phosphide. HPPT. Molecular Dynamics. Ultraprecision Machining.