Binder removal via a two-stage debinding process for ceramic injection molding parts

Debinding binders in two stages is critical to maintaining the shape of injected parts; the resulting decomposition affects the strength and rigidity of a structure. This study determines the optimal debinding process on the basis of a higher binder removal rate and the production of defect-free parts. The feedstock used was a combination of alumina–zirconia powder with a binder that consists of high-density polyethylene (HDPE), paraffin wax (PW), and stearic acid (SA). During the first stage, the injected parts were immersed in an n-heptane solution at 50 °C, 60 °C, 65 °C, and 70 °C to remove PW and SA. Binder weight loss was evaluated as a function of time. In the second stage, HDPE was removed by using thermal debinding. The results show that the optimum solvent debinding process runs for 16 h at 60 °C. The weight loss of the binder reaches 41.1% and results in the formation of defect-free parts. The binders are degraded at approximately 550 °C during thermal debinding. This degradation resulted in decomposition of nearly 96.9% of the binders. Low heating rates (1 °C/min to 2 °C/min) prevent defects from forming in the injected parts.