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In-situ spark plasma sintering behavior of La2O3-Y2O3 co-doped AlON ceramics: An attempt to prevent carbon contamination

2023    Aydogmus, Demet; Duygulu, Ozgur; Sahin, Filiz Cinar

Un-doped and La2O3-Y2O3 co-doped Aluminum oxynitride (AlON) ceramics were fabricated by reactive spark plasma sintering method (R-SPS) by using Al2O3 and AlN as starting powders with a composition of 70 mol% and 30 mol%, respectively. The effects of co doping system on densification, microstructure, mechanical properties and optical transmittance of AlON ceramics were investigated. X-ray analysis confirmed the fully transformation of g-AlON phase for all compositions prepared at 1650 degrees C in 30 min under 40 MPa under nitrogen. The results indicated that 0.02 wt% La2O3 thorn 0.08 wt% Y2O3 added composition had the optimal combination of sintering additives. In an attempt to reduce the graphite contamination, the powder mixture was encapsulated in a Nb-coated graphite foil before subjecting to SPS. Nb-coated graphite foil encapsulated sample was found to reduce carbon contamination leading to high densification (99.6 %) and high transmission (-81 % at 2500 nm). This study demonstrated that optical transmittance of R-SPSed AlON ceramics is significantly improved without any post-heat treatment by using Nb-coated graphite foil during SPS processing.(c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).