Compositionally graded YSZ–NiO composites by surface laser melting

Abstract

Laser surface melting has been applied to near eutectic NiO-YSZ sintered ceramics. The objective is to generate a functional gradient composite material with graded microstructure and composition. At low solidification rates the resultant material has a graded composition, with a severe NiO segregation towards the surface. A thick NiO layer whose thickness depends on the travelling speed is formed. Below this layer the microstructure is eutectic like with composition varying with depth. In contact with the ceramic, excess YSZ coming from the hypereutectic composition forms an almost continuous YSZ layer. The thickness of both segregated layers, NiO and YSZ can be controlled by traverse speed. Thickness decreases as travelling speed increases until a limiting travelling rate of 110 mm/h, at which no more segregation is found. Possible causes to explain the relevant NiO segregation towards the surface are discussed.

Growth of a Plate-Shaped SrTiO3–TiO2 Eutectic

“…Eutectics may also find application in energy generation and storage systems, such as solid oxide fuel cells (SOFC). − To our knowledge, eutectics have not yet been implemented in any other type of energy system. However they seem to have much potential, since (i) hybrid semiconducting materials of various component phases can be obtained, (ii) component phases are characterized by high crystallinity, and (iii) micro/nanostructure refinement can be controlled by varying the growth rate.…”

Directionally solidified CeO2 (or GDC)/CoO eutectic ceramics as cermet precursors for SOFCs anodes: Microstructure cross-over

“…32 The change of microstructure with the growth rate is poorly documented and, in the few systems where some changes have been observed, the results are contradictory. In the oxide system MgO-MgAl 2 O 4 , 29,33 and in the alloy systems Al-Al 4 Ce and Al-Al 3 Y, 34 the change was the inverse: a lamellar to fibrous microstructure change is observed with increasing the growth rates.…”

Optimization of Ni–YSZ solid oxide fuel cell anodes by surface laser melting

“…All laser parameters were controlled using the Easy Mark 2009 software. Additional details about laser surface melting of similar samples can be found in [17,24].…”

“…Garcia zirconia) eutectics [16]. In a similar approach, Merino et al [17] proved that applying surface laser melting to YSZ rich hypereutectic of YSZ-NiO ceramics, it is feasible to obtain layered material consisting of different layers: primary zirconia, eutectic with graded composition and single NiO phase. Once more, the fabrication of a SOFC cell by this procedure is still challenging.…”