Densification and microstructure of spark plasma sintered 7YSZ–Gd₂O₃ceramic nano-composites

Abstract

Spark plasma sintering (SPS) technique was used to densify 7 mol% yttria-stabilized zirconia (7YSZ) powder with Gd 2 O 3 -particles, at temperatures ranging between 1000 and 1200 • C. Fine dispersion of Gd 2 O 3 -particles into a full-densified matrix was achieved. Shrinkage and microstructure, as well as porosity were investigated. The fine Gd 2 O 3 -particles distributed into 7YSZ matrix have influence over the sintering consolidation and final microstructure. An increment in the spark plasma sintering temperature around 70 • C is detected when Gd 2 O 3 particles are present. The thermal characterization was performed using the photothermal infrared radiometry technique. Both thermal diffusivity and thermal conductivity display a similar sigmoidal (Boltzmann type) behavior with the Gd 2 O 3 concentration in the samples.

Chemical and microstructural characterisation of HfO2-Y2O3 ceramics with high amount of Y2O3 (33, 40 and 50 mol. %) manufactured using spark plasma sintering

“…This difference leads to possible micropores in place of the initial Y 3+ location, which may limit sintering as they become closed pores remaining after elaboration. This "Kirkendall effect", has previously been observed in the literature, for HfO2-Y2O3 compositions [51] and for 7YSZ-Gd2O3 composites [52]. In consequence, for low sintering temperatures, the increase in the amount of Y2O3 could limit the shrinkage and thus slowing down the diffusion mechanisms between the species and finally, leading to a low amount of the foreseen Y2Hf2O7 phase.…”

Combustion flame spray of 7YSZ powders followed by corrosion in molten salts of the coating

“…For YSZ coatings that work at high temperature up to 1000°C to increase their properties, it has been needed to develop new characteristics to be able to work in extreme conditions [6][7][8][9]. 7YSZ-based TBC systems have been used extensively in gas turbine industry, although the manufacture processes are associated with complex dispositive to build up a coating [1][2][3][4][5][6][7][8][9][10]. Thus, Electron Beam Plasma Vapor deposition (EB-PVD) could be used to deposit a dense and enhanced tolerance capacity coating from the vapor phase [11][12][13], but with lower deposition rate and higher operating cost restrict its application to small surfaces.…”

Sintering and hot corrosion of yttria silicate tablets in molten salts prepared by spark plasma sintering

“…Many studies have been performed on the preparation process of Si-based ceramics; nevertheless, the problems of a high synthesis temperature, long production period, and low yield still need to be solved. Under these perspectives, many plausible studies indicate that ceramics prepared via spark plasma sintering (SPS) can reach theoretical high densities and a fine grain size can be retained after the SPS process due to much lower sintering temperatures than those typically used (Omori, 2000;Bangchao et al, 2004;Dahl et al, 2007;Serrano Pérez et al, 2017). However, there is a lack of literature on the sintering of yttria silicate by SPS (Wu et al, 2016).…”