Hydrolysis-induced aqueous gelcasting for near-net shape forming of ZTA ceramic composites

Thermal degradation of organic additives used in colloidal shaping of ceramics investigated by the coupled DTA/TG/MS analysis

“…It is based on two substances, activator (catalyst) and initiator, where due to redox reaction free radicals are created which initiate the polymerization process. In scientific literature, the most commonly used redox system in ceramic processing is N,N,N 0 ,N 0 -tetramethylethylenediamine (TEMED) and ammonium persulfate (APS) [26,27].…”

Effect of Aging Time on the Stability of Aqueous Y‐α‐SiAlON Precursor Powder Suspensions

“…These reactions predict the consumption of some water, the release of ammonia, and the concomitant pH increase of the suspension, as well as the formation of aluminum hydroxides. All these events contribute to enhance the viscosity of the suspension and might even lead to their consolidation by the well‐known Hydrolysis Assisted Solidification process 23,24,43 …”

“…The most significant changes in viscosity are observed within the low shear rate range, suggesting that they are caused by the development of some structuring forces that enhance the viscosity under near‐rest flow conditions. Such structuring forces are attributed to the hydrolysis of AlN and the concomitant formation of aluminum hydroxides () 37 that exert a cementation action, 23,24,43 accompanied by an increase of pH that tends to promote a coagulation effect upon approaching the isoelectric point of the aluminum hydroxides at about pH 9 44 . The formation of an aluminum hydroxide gel cement due to hydrolysis of AlN has been pointed out as one of the consolidation mechanisms involved in the HAS process 23,24,43 …”

“…Aqueous suspensions of the quaternary (Si 3 N 4 –Al 2 O 3 –Y 2 O 3 –AlN) system have only been used to obtain β‐SiAlON phase, therefore involving in some extent the hydrolysis of AlN, which also facilitated the consolidation process by gelcasting 22 . Later, this hydrolysis‐induced aqueous gelcasting effect was intentionally explored and reported in our recent papers 23,24 …”

Organic additives in gel-tape casting of ceramic powders – A novel approach to the problem of elasticity and cracking of thin tapes

“…Radical polymerization finds recently an important place in shaping of ceramic powders by colloidal methods [1][2][3]. Polymerization process inside ceramic suspension was first used in gelcasting [4,5].…”