Síntese de zircônia estabilizada com ítria via método sustentável usando clara de ovo

Abstract

This work proposes the synthesis of ultrafine yttria-stabilized zirconia (𝑍𝑟􀔽 ) with 2 yttria (􀕇 ) powders using the egg white method as a complexing agent, aiming at a 2􀔽3 sustainable and economical route for the production of advanced ceramics. Zirconia exhibits polymorphism, presenting monoclinic, tetragonal, and cubic phases. Stabilization of the tetragonal and cubic phases is fundamental to ensure mechanical strength and durability at ambient temperature. The egg white method which employs the ovalbumin protein, allows for the substitution of conventional synthetic reagents, thereby reducing the environmental impact of traditional processes such as sol-gel, Pechini, and hydrothermal methods. Zirconia powders with additions of 3 mol% and 8 mol% yttria were synthesized using egg white in solution as the complexing agent. The precursors were initially calcined at 600 ºC and subsequently at 900 ºC and 1100 ºC. Structural and morphological characterization of the calcined powders was performed using Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), and X-ray Diffraction (XRD). The powders were then shaped and uniaxially pressed into pallets to evaluate their green density. The characterization results of the calcined powders indicate the formation of powders in irregular micrometric aggregates composed of nanometric and rounded primary particles (<100 nm), with the stabilization of the tetragonal and cubic phases in the yttria-containing samples. The powder calcined at 1100 ºC with an 8 mol% yttria addition exhibited a higher degree of agglomeration, differentiating it from the other samples. The evaluation of the geometric density of the pressed pellets indicated low packing efficiency, suggesting that subsequent milling and agglomerate size reduction processes are necessary to enable their use in high-density components.