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Thermal decomposition of polyhydroxy processing agents dedicated to colloidal shaping of ceramics – thermogravimetry coupled with mass spectrometry and properties of ZTA composites

Pietrzak, Emilia, Wieclaw-Midor, Anna, Wiecinska, Paulina, Poterala, Marcin, Szafran, Mikolaj
Thermochimica acta 2019
additives, aluminum oxide, ceramics, differential thermal analysis, galacturonic acid, hardness, mass spectrometry, microstructure, rheological properties, thermal degradation, thermogravimetry, zirconium oxide
The paper presents the thermal decomposition of the new, highly efficient organic additives used in colloidal shaping of ceramics, that is lactobionic acid (LAc), galacturonic acid (GAc) and diglyceryl acrylate (DGA). The sugar acids are effective deflocculants, especially for nanopowders, while DGA is the new monomer dedicated to gelcasting process. Most organic additives are indispensable in shaping step but must be then eliminated in order to obtain pure ceramic phase. The DTA/TG measurements coupled with mass spectrometry allowed to determine the thermal decomposition of organic compounds and observe type of gasses released to the atmosphere during heating. Additionally, the influence of the analyzed substances on the properties of selected ceramic suspensions and sintered bodies has been discussed. The new compounds have been examined in the preparation of ZTA (zirconia toughened alumina) composites by gelcasting, slip casting and subsequent sintering. The rheological behaviour of Al2O3-ZrO2 suspensions as well as selected properties (Vickers hardness, fracture toughness and microstructure) of sintered ZTA samples are presented.