Pretreatment Processing of Gelcast Green Body before Debinding

Abstract

Gelcasting is a novel ceramic forming technology that could be used to manufacture high-performance ceramics with complex shape. However, there are some problems in debinding of large-size green body made by gelcasting. In this paper, a new pretreatment way before binder burn-out was introduced. By means of this pretreatment processing, large-size green bodies with no defects were successfully obtained.

Sodium Bismuth Titanate‐Based Lead‐Free Piezoceramics Prepared by Aqueous Gelcasting

“…Before drying green gelcast bodies, the dipping pretreatment was applied, in which green gelcast bodies were soaked in a certain concentration of APS solution. The aim is to degrade the polymer; thereby, reticular macromolecular polymer chains (large molecules) are reduced to linear polymer chains (small molecules) 26,27 . Drying time versus linear shrinkage rate with different methods is shown in Fig.…”

“…To inhibit the propagation of flaws, drying of parts by heating needs to be handled slowly and carefully at room temperature and under an appropriate humidity condition. 24,25 A novel predrying method, i.e., dipping pretreatment was introduced in the BNBT6 gelcasting process, which has been used in other gelcast ceramics parts, 26,27 thereby reducing a time-consuming and tedious drying step as well as removing the defects due to release of residual stress. Before drying green gelcast bodies, the dipping pretreatment was applied, in which green gelcast bodies were soaked in a certain concentration of APS solution.…”

“…The aim is to degrade the polymer; thereby, reticular macromolecular polymer chains (large molecules) are reduced to linear polymer chains (small molecules). 26,27 Drying time versus linear shrinkage rate with different methods is shown in Fig. 7.…”