In-situ synthesis and densification of Ce1-xGdxB6 ceramics by spark plasma sintering

Koroglu L., AĞIL A. A., Ayas E.

Ceramics International, cilt.48, sa.20, ss.30960-30966, 2022 (SCI-Expanded) identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 48 Sayı: 20
  • Basım Tarihi: 2022
  • Doi Numarası: 10.1016/j.ceramint.2022.07.054
  • Dergi Adı: Ceramics International
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Chemical Abstracts Core, Communication Abstracts, INSPEC, Metadex, Civil Engineering Abstracts
  • Sayfa Sayıları: ss.30960-30966
  • Anahtar Kelimeler: Electrical resistivity, Mechanical properties, Microstructure, Rare earth hexaborides, Solid solutions, Spark plasma sintering
  • Hakkari Üniversitesi Adresli: Evet

Özet

The study aims to investigate the effect of Gd doping on phase evolution, microstructural development, sintering behavior, mechanical and electrical properties of polycrystalline bulk Ce1-xGdxB6 ceramics (x = 0, 0.2, 0.4, 0.6). For this purpose, in-situ synthesis and densification of Ce1-xGdxB6 ceramics were carried out via spark plasma sintering by applying a two-step-heating schedule (1000°C-10min & 1950°C-30min) under 50 MPa using CeO2, Gd2O3, and B starting powders. XRD, SEM, and image analysis results showed that all ceramics mainly composed of Ce1-xGdxB6 (>97 vol%); however, the total volume of secondary phases (B2O3 and B4C) slightly increased from 1 to 2.7% with Gd content, which reduced relative density from 98 to 93%. Temperature-displacement curves obtained through SPS referred to the condensation of B2O3 gases and the reduction of densification rate because of the heavier Gd cations. Vickers hardness values were in the range of 16.3–19.9 GPa. Ce0.8Gd0.2B6 exhibited the highest fracture toughness (4.5 MPa.m1/2) through toughening mechanisms. The electrical resistivity values, found between 100 - 10−2 ohm.m, enhanced with Gd content by reason of imperfections. Briefly, 20% Gd doped CeB6, having 95% relative density, 98.3% matrix volume, 16 GPa Vickers hardness, 4.5 MPa.m1/2 fracture toughness, and 9.3 × 10−2 ohm.m electrical resistivity, carries a potential to be used as an electron-emitter.