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


Aydoğmuş D., Duygulu O., Şahin F.

Journal of Materials Research and Technology, vol.27, pp.2323-2335, 2023 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 27
  • Publication Date: 2023
  • Doi Number: 10.1016/j.jmrt.2023.10.047
  • Journal Name: Journal of Materials Research and Technology
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Compendex, INSPEC, Directory of Open Access Journals
  • Page Numbers: pp.2323-2335
  • Keywords: Aluminum oxynitride, Carbon contamination, Spark plasma sintering, Transparent ceramics
  • Istanbul Technical University Affiliated: Yes

Abstract

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 γ-AlON phase for all compositions prepared at 1650 °C in 30 min under 40 MPa under nitrogen. The results indicated that 0.02 wt% La2O3+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.