This study aims to improve the jetting performance and low-temperature bonding strength of a sodium silicate-based inorganic binder for binder jetting (BJ) applications through silicate network structure enhancement and curing reaction control.
Silica sol, NaOH and a phosphate-based curing agent were incorporated into a sodium silicate binder system to increase the Si–O–Si network density and promote rapid curing. The developed binder was evaluated in terms of jetting suitability, bonding behavior with sand, thermal stability and practical printability. Flexural strength was measured after curing at 120, 150 and 180 °C, and the chemical network structure was analyzed using FT-IR spectroscopy.
The developed N-binder exhibited significantly improved low-temperature bonding strength compared with the conventional sodium silicate binder (S-binder). In particular, the strength increased markedly from 1.42 MPa to 6.80 MPa at 120 °C, demonstrating superior low-temperature curing behavior. At 150 °C and above, both binders showed comparable strength levels, while the N-binder maintained slightly higher mechanical performance. FT-IR analysis suggested modification of the local silicate network, including increased Na?-associated non-bridging oxygen sites, which contributed to improved curing behavior, penetration performance, and flexural strength.
This study proposes an effective strategy for improving the printability and low-temperature bonding strength of inorganic binders for BJ through control of silicate network formation and phosphate-assisted curing behavior, providing practical insights for industrial binder development.
