Welcome new PhD exchange students under Chinese Scholarship Council funding
CAI Youhui
PhD Candidate
Department of Mechanical Engineering
Wuhan University of Technology
We warmly welcome the Mr. Cai, a PhD candidate from Wuhan University of Technology who will join the National University of Singapore in October as a joint PhD student funded by the Chinese Scholarship Council (CSC) to continue his research in chatter in milling of weakly rigid work materials.
New Undergraduate Students
This year we have 04 new local penultimate undergraduate students who will join our group for their ME4104A BEng Dissertation, Mr. Shannon Tan, Mr. Ryan Lim Chi Huang, Ms. Vaishnavi Harihara Venkatesan, and Mr. Tee Wee Keat. We also have 01 undergraduate student under the 3+1+1 NUS Partner Chinese Universities Education Framework between Southern University of Science and Technology (SUSTech) and NUS. Read more about our new students here!
Welcome to our new exchange PhD students
LIANG Zhenquan
PhD Candidate
School of Materials Science and Engineering
Harbin Institute of Technology
Chinese National Scholar, Outstanding Student Model
We warmly welcome the Mr. Liang, a 3rd year PhD candidate from School of Materials Science and Engineering, Harbin Institute of Technology. Mr. Liang received his bachelor’s degree in Harbin Institute of Technology in 2020 and subsequently embarked on his postgraduate doctoral program. His research interests include metal additive manufacturing and post-processing, creep and fatigue behavior of structural materials, advanced material characterization. He has authored over 20 papers and 4 Chinese invention patent applications. He is a recipient of the Chinese National Scholarship and Outstanding Student Model award. Over the next year starting in September, he will join the National University of Singapore as a joint PhD student funded by the Chinese Scholarship Council (CSC) to continue his research in post-processing for metal additive manufacturing (PP4AM).
MU Jierui
PhD Candidate
School of Materials Science & Engineering
Shanghai Jiao Tong University
We warmly welcome the Mr. Liang as a visiting PhD student to our team. His research interests include hybrid additive manufacturing and electrochemical dissolution. Starting in September, he will join our team to continue his research in electrochemical polishing of additive manufactured metals.
Visit by Assoc. Prof. Biao Cai from the School of Metallurgy and Materials, University of Birmingham
AM.NUS Center hosted Prof. Cai with a tour of the additive manufacturing facilities in NUS and graciously invited us to present our research on post-processing for additive manufacturing. He was in Singapore to attend the International Conference on Computational & Experimental Engineering and Sciences (ICCES2024) where he gave a keynote speech titled, Synchrotron and Neutron Characterization of Advanced Alloys Made by Laser Powder Bed Fusion. Prof. Cai is an expert in physical metallurgy with unique studies on micro-mechanics using in-situ synchrotron technologies to study material plasticity and mechanical properties. We were glad to share our approach toward precision surface finishing of additively manufactured materials through the systematic study of metallurgy, machinability, methodology, and support structure finishing. During the sharing session, we highlighted our latest work on the mechanochemical effect on micro-cutting of additively manufactured maraging steel where we saw some common ground in our research on field-assisted influences to material deformation characteristics. We look forward to having meaningful collaborations in the future.
Invited presentation at ICCES2024
Dr. Zhan was invited to give a presentation on Numerical Investigation on the Ductile Machining of Calcium Fluoride Single Crystal Enhanced by Laser Assistance at the International Conference on Computational & Experimental Engineering and Sciences (ICCES2024), held at Marina Bay Sands Expo & Convention Centre, Singapore, from 3–6 August.
Bruker Nanoindentation Workshops
We were blessed with the opportunity to participate in a well-organized 2-day workshop by Bruker on the 27th and 28th of August. The event was massively loaded with a wealth of information and expertise to keep both academics and industry partners on the edge of their seats throughout the sessions. The first day was hosted by Wintech Nano with the theme on Exploring Applications of Nanomechanical Technology in Material Research, Advanced Packaging and Semiconductor Failure Analysis. The second day was hosted by the Institute of Microelectronics (IME) with the sessions jointly organized by specialists from Zeiss, IME, and Bruker, Exploring Material Testing Applications for Semiconductor and Material Research. Our takeaways from this valuable workshop can be found here. Kudos to Jeffrey Teoh and the team at Bruker for organizing this highly educative and insightful event.
Overseas Researcher Invitation WRH Program
The World Research Hub (WRH) Program is driven by the International Research Frontiers Initiative (IRFI) at Tokyo Institute of Technology to host world-class researchers at Tokyo Tech for international collaborations. Assoc. Prof. Wang was warmly welcomed as an Overseas Researcher by Assoc. Prof. Sergei Manzhos to collaborate on a joint research project titled Investigation of microstructure-driven properties of functional ceramics: from large-scale atomistic calculations to experimental validation.
The collaboration with Assoc. Prof. Manzhos from the School of Materials and Chemical Technology, Tokyo Institute of Technology, was established to achieve the goal of combining the expertise of atomistic materials modeling in Ihara-Manzhos lab, and the mechanical property characterization of functional ceramics with molecular dynamics (MD) simulations and experimental micro/nano-testing in NUS, to deliver both theoretical and computational understandings on the developments of microstructural elements and material properties.
Hosting colleagues from Pen-Tung Sah Institute of Micro-Nano Science and Technology (IMNST), Xiamen University
We were honored to host an esteemed delegation from the IMNST, which included Prof. Sun Daoheng, Prof. Hou Liang, Prof. Zheng Gaofeng, Prof. Zhu Qingyuan, and other distinguished researchers. They were hosted by Guo Yunfa who showcased our lab facilities and shared insights into our latest research projects and technological achievements. We are grateful for their visit and look forward to future collaborations with IMNST toward advanced micro-/nano manufacturing science and technology.
Farewell BBQ
Over the coming weeks, we will be bidding farewell to several colleagues in the team as they end their stint at NUS, and there was no better way to celebrate their company other than a barbecue at West Coast Park. Our departing colleagues are Dr. Zhan Jiaming, Dr. Cai Yang, Zhang Baocai, and Yan Qi, while Xu Guiyin will return to NUSRI-CQ in Chongqing, China, to continue his PhD candidature.
New paper publications
This month we are proud to present new findings through 3 journal publications in Journal of the European Ceramic Society, ACS Applied Materials & Interfaces, and Tribology International.
Influence of water on the machinability of calcium fluoride crystal
J. Zhan, Y.J. Lee, S. Yang, H. Wang
Journal of the European Ceramic Society, 44(15)116738
Abstract:
Calcium fluoride (CaF2) optical components are produced by ultra-precision machining, but the often-neglected ambient water may potentially affect its processing. This work provides a systematic study on the role of water in the machinability of single-crystal CaF2. Micro-scratching experiments revealed poor machinability and reduced deformability under water adsorption. Atomic scratching simulations reproduced the mechanical deformation and identified the enhancement in dislocation nucleation with water, which led to the reduction in deformability due to dense cross-linking of dislocations. Atomic scale cutting simulations also identified easier formation of subsurface cracks under water adsorption. With the aid of mechanical schematic models based on the simplification of the scratching process, this work revealed that while water enhances the plastic flow of the material during machining, the accumulation of dislocations creates stress conditions sufficient to induce material fracture, which is a unique influence of water adsorption on the reduction in machinability of CaF2.
Triple Effects of the Physicochemical Interaction between Water and Copper and Their Influence on Microcutting
C. Zhang, Y.J. Lee, Y.F. Zhang, H. Wang
ACS Applied Materials & Interfaces, 16(28)37167–37182
Abstract:
Water has been recognized in promoting material removal, traditionally ascribed to friction reduction and thermal dissipation. However, the physicochemical interactions between water and the workpiece have often been overlooked. This work sheds light on how the physicochemical interactions that occur between water (H2O) and copper (Cu) workpiece influence material deformations during the cutting process. ReaxFF molecular dynamics simulations were employed as the primary method to study the atomistic physical and chemical interactions between the applied medium and the workpiece. Upon contact with the Cu surface, H2O dissociated into OH– ions, H+ ions, and traces of O2– ions. The OH– and O2– ions chemically reacted with Cu to form bonds that weakened the Cu–Cu bonds by elongation, while the H+ ions gained electrons and diffused into the Cu lattice as H– ions. The weakening of surface Cu bonds promoted plastic deformation and reduced the difficulty of material removal. Meanwhile, further addition of H2O molecules saw a plateau in hydrolysis and more dominance of H2O physical adsorption on Cu, which weakens the elongation of Cu–Cu bonds. While the ideal case for atomic-scale material removal was found with an optimal number of 240 H2O molecules, the presented Cu material state with more H2O molecules could account for the observations in microcutting. The constricted nature of physical adsorption and hydrogen ion diffusion in the surface layer prevented the propagation of dislocations through the surface, which subsequently caused pinning points to be closer together during chip formation as observed by smaller chip fold widths on the microscale. Theoretical and experimental analysis identified the importance of accounting for physicochemical interactions between surface media and the workpiece when considering material deformations at micronanoscale.
Modeling and analysis of surface integrity transition in cutting of Sip/Al composites based on coordination deformation effect of particle-matrix
Z. Zheng, D. Chen, K. Huang, J. Zhang, H. Wang, X. Chen, J. Xiao, J. Xu
Tribology International
Abstract:
With the wide application of Sip/Al composites in key fields, it is critical to understand the material removal behavior and surface integrity evolution mechanism of Sip/Al composites. In this paper, based on the nanoindentation and scratching experiments, the coordination deformation behavior of Si particles and the Al matrix were investigated at the micro-scale, and the mechanism and conditions of surface integrity transition (SIT) of Sip/Al composites were elucidated. Then, taking into account the feature of particle fragmentation and detachment caused by interfacial failure, an analytical model of specific cutting energy for Sip/Al composites cutting under different material removal modes was established. The competitive relationship between ductile deformation and surface defect formation was investigated, and a quantitative prediction model for the critical depth of SIT was proposed. The results show that the evolution of the material removal behavior of Sip/Al composites is a consequence of the coordination deformation the Al matrix and Si particles. The material removal mode of Sip/Al composites transitions from ductile removal to quasi-brittle removal with particle fragmentation and detachment, and there is an obvious SIT characteristic. The prediction results of critical depth are in agreement with the experimental results, with an average error of less than 9.8%. Moreover, an appropriate increase in cutting speed can effectively enhance the surface integrity of Sip/Al composites. This research contributes to a deeper understanding of the low-damage machining mechanism of Sip/Al composites.
PhD Candidature Invitation (priority for ASEAN countries)
We are looking for aspiring PhD candidates who are interested in pursuing research in the field of Artificial Intelligence for Manufacturing. A brief description on the research topic can be found in our Openings. Please contact Dr. Wang Hao (mpewhao@nus.edu.sg) if you are interested!