Thermal debinding mass transfer mechanism and dynamics of copper green parts fabricated by an innovative 3D printing method

Abstract

To explore the thermal debinding mass transfer mechanism and dynamics of an innovative copper paste injection 3D printing method, the thermal behavior of the copper paste was investigated to clarify the stages of the debinding process. Furthermore, the debinding ratio, burnout ratio, shrinkage and microstructures were characterized to study the mass transfer channel and dynamics. The dynamics equation of diffusion mass transfer was analyzed. The activation energy and pre-exponential factor were calculated. The results revealed that gas phase mass transfer was the main mass transfer path and the diffusion coefficient in the carbon powder embedded environment (2.68 × 10⁻⁵ cm² s⁻¹) was higher than that in air atmosphere (1.96 × 10⁻⁵ cm² s⁻¹). Moreover, the migration of solid phase materials and the diffusion of atoms are also discussed. When combined with the sintering process, the sintered metal parts had a smooth surface flatness and excellent metallurgical bonding, the thin wall of which was only 340 μm thick.