Evaluation of APC impact on controlling precursors properties in the sol for synthesizing meso porous ZrC nanopowder through sol-gel process

Abstract

In this research, the dispersion characteristics of the suspension containing precursors were investigated in terms of charge, particle size, and rheological properties. Zirconium carbide nanopowder was prepared in the four-component system of alkoxide-resin-dispersant-catalyst based on the sol-gel chemical process under acidic conditions. Ammonium polycarboxylate (APC) was manipulated as a sol-dispersing agent to reach a particle size of less than 5 nm. Results depicted that the amount of surface charge of precursors was changed in the presence of ammonium polycarboxylate agent, and the PZC point was shifted towards acidic pHs less than 6.1. According to electrokinetic data, the interaction of surface sites and APC cause alteration of free specific energy for surface adsorption with a negative value. With regard to DLS analysis, the presence of APC stabilizes particles in the sol with precise control over their sizes in less than 10 nm. At intermediate pHs, the viscosity of the sol containing precursor increases which leads to a decrease in the particles stability. FTIR analysis of gel powder confirmed the proper formation of Zr–O–C bonds through hydrolysis and condensation reactions. The surface of the synthesized nanopowders is porous and in the meso range, so that their specific surface area is 165 m2/g. DTA analysis indicated that initial nuclei of ZrC were formed at around 1320 °C, which XRD patterns confirm this. SEM microstructure images showed that ZrC particles were created in the nanometer dimensions, and particle size distribution were reported in a narrow range with uniform morphology. TEM images and their diffraction patterns represented the synthesis of crystalline ZrC particles less than 50 nm.