Ammonium citrate assisted surface modification and gel casting of YAG transparent ceramics

Isobam gelling casting system has great potential to fabricate high-quality ceramics and their composite structures or shapes for special applications. However, it is still challenging to obtain the excellent transparent ceramics by only using Isobam as dispersant and gelling agents. In this study, ammonium citrate (AC) as supplementary dispersant was used for surface modification of superfine Y2O3-Al2O3 mixture powders in Isobam system to fabricate the high-quality YAG transparent ceramics. The efficient dispersion mechanism by surface modification was systematically investigated. AC and Isobam worked together to dramatically improved the suspension's rheological behave through the complementation of different dispersion mechanisms. The high density and low shrinkage of green body with fine microstructure was obtained in the optimized composition of 0.3 wt% AC, 0.5 wt% Isobam and 76.0 wt% solid loading. The in-line transmittance of YAG ceramics (thickness 2.5 mm) at 1064 nm reached 84.4%, being close to the theoretical transmittance. Isobam combined with AC greatly promoted the industrial application of Isobam gelling system in the fabrication of high-quality optical ceramic materials.