报告内容摘要：

The unique properties of ceramic materials such as high hardness, high strength, and high thermal and chemical stabilities are favored in aerospace, chemical, and biomedical industries. However, difficulties in machining of ceramics have limited their applications. Introducing 3D printing into ceramic materials could extensively expand their applications. Binder jetting 3D printing has demonstrated significant potential in fabricating ceramic parts due to its advantage of less geometry limitation and lower cost compared with other 3D printing technologies. Currently, the relative density of ceramic parts resultant from binder jetting additive manufacturing ranges 27%-76%, far below the requirement for load-bearing applications. The main reason comes from the contradictory requirements on the powder particle size for different steps in the manufacturing process. To deposit a smooth layer of power for binder jetting, a large particle size (10-100 µm) is preferred to offer a high flowability. To obtain a higher density by sintering, a small particle size (below 1 µm) is required to enable a high sinterability. The objective of this research is identify effective methods to address this contradiction and increase the density of 3D printed ceramics. The first approach is granulation in which ceramic nanoparticles are made into micron-sized granules with the aid of an organic binder. Therefore, the flowability is improved by the large granule size while the high sinterability is maintained due to the primary nanoscale particle size. A high density was obtained with this method, breaking the limit in the literature. The second method is particle size gradation where powders with different sizes are mixed at designed fractions. The mixed power with designed particle size gradation increased the packing density of ceramic powder and the density of ceramic after sintering. The second approach is encapsulation where coarse ceramic particles are coated with a layer of amorphous phase with the same chemical composition. The amorphous phase with high activity enhanced the sintering of the ceramic material, leading to increased material properties.

报告人简介： 

Chao Ma
Department of Engineering Technology and Industrial Distribution
Department of Mechanical Engineering (Courtesy)
Department of Materials Science and Engineering (Courtesy)
Department of Industrial and Systems Engineering (Courtesy)
Texas A&M University, College Station, TX, USA
(E-mail : cma@tamu.edu)

Dr. Chao Ma received his B.S. degree from Tsinghua University in 2010, M.S. degree from University of Wisconsin – Madison in 2012, and Ph.D. degree from the University of California, Los Angeles in 2015, all in Mechanical Engineering. Dr. Ma was a senior mechanical engineer at Cymer, LLC., San Diego, CA, from 2015 to 2016, working on laser-produced plasma as extreme ultraviolet light source for photolithography. Dr. Ma joined the faculty at Texas A&M University, College Station, TX, in 2016. He is affiliated with the Department of Engineering Technology and Industrial Distribution, the Department of Mechanical Engineering, the Department of Materials Science and Engineering, and the Department of Industrial and Systems Engineering. His teaching and research interest lies in the field of advanced manufacturing, such as additive manufacturing, laser manufacturing, nanocomposites, and modeling of manufacturing processes. His research has been supported by the National Science Foundation, the Department of Energy, and the industry. Dr. Ma has strong academic credentials with 18 journal publications in prestigious venues such as Nature Communications, Scripta Materialia, Journal of Applied Physics, Journal of Manufacturing Processes, Journal of Manufacturing Science and Engineering, Journal of Micro and Nano-Manufacturing, etc. He has published 17 peer-reviewed conference articles, two of which won the Outstanding Paper Award and the Honorable Paper Award on international manufacturing conferences.

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