MOLECULAR DYNAMICS SIMULATION OF NANOPARTICLE INFILTRATION DURING BINDER JET PRINTING ADDITIVE MANUFACTURING PROCESS: A PRELIMINARY STUDY

摘要

Binder Jetting Process involves binding layers of powder material through selective deposition of a liquid binder. Binder jetting is a fast and relatively inexpensive process which does not require a high-powered energy source for printing purpose. Additionally, the binder jetting process is capable of producing parts with extreme complexities without using any support structures. These characteristics make binder jetting an ideal choice for several applications including aerospace, biomedical, energy, and several other industries. However, a significant limitation of binder jetting process is its inability to produce printed parts with full density thereby resulting in highly porous structures. A possible solution to overcome the porosity problems is to infiltrate the printed structures with low-melting nanoparticles. The infiltrating nanoparticles help fill up the voids to densify the printed parts and also aids in the sintering of the printed green parts. In addition to increasing the density, the nanoparticle infiltration also helps improve the mechanical, thermal and electrical properties of the printed part along with bringing multi-functionality aspect. Currently, there is a lack of clarity of the nanoparticle infiltration process performed to improve the quality of parts fabricated through binder jetting. This research employs Molecular Dynamics simulation techniques to investigate the nanoparticle infiltration during binder jetting additive manufacturing process. The simulation is performed at different operating temperatures of 1400 K, 1500 K, and 1600 K. The study found that the infiltration process is significantly affected by the operating temperature. The infiltration height is found to be highest at the operating temperature of 1600 K while the porosity reduction is found to be maximum at 1500 K. The infiltration kinetics is affected by the cohesion of the nanoparticles causing blockage of channels at higher operating temperatures. The simulation model is validated by comparing with the Lucas-Washburn infiltration model. It is seen that the simulation model deviates from the theoretical prediction suggesting that multiple mechanisms are driving the infiltration process at the nanoscale.