Mechanical Evaluation of Plasma-Sprayed Ceramic/Metal Composites for Functionally Graded Coatings by Means of Small Punch Tests

Jing Feng Li, Nobuyuki Shimoda, Akira Kawasaki, Ryuzo Watanabe

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

To attain fundamental information needed for designing functionally graded thermal barrier coatings, the strength and deformation properties of plasma-sprayed ZrO2-8wt%Y2O3/Ni-20wt%Cr composits with various compositions (0, 25, 50, 75, 100% Ni-20wt%Cr) were investigated from room temperature to 1200°C by means of small punch tests. The room temperature strength decreased rapidly with increasing ceramic content, from > 1400MPa for metal to ∼ 100MPa for ceramic. The monolithic ceramic and ceramic-rich (75%) composites retained their strength up to 1200°C, whereas the compostions with > 50 vol% metal showed lower strength at temperature above 800°C. All the plasma-sprayed materials showed low Young's moduli, being about 20-60% (lower bound for ceramic and upper bound for metal) of the theoretical data for fully dense composites, because of the microstructural features, such as high porosity and microcracks. Connection and propagation of microcracks (process-related defects) were found to occur before the eventual macrofracture of materials, consequently plasma-sprayed materials showed specific fracture behavior; nonlinear load-deflection curves were obtained in spite of brittle nature of the fracture.

Original languageEnglish
Pages (from-to)237-241
Number of pages5
JournalFuntai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy
Volume45
Issue number3
DOIs
Publication statusPublished - 1998 Mar

Keywords

  • Functionally graded materials
  • High-temperature deformation
  • NiCr alloy
  • Partially stabilized zirconia
  • Plasma spraying
  • Small punch testing
  • Thermal barrier coating

ASJC Scopus subject areas

  • Mechanical Engineering
  • Industrial and Manufacturing Engineering
  • Metals and Alloys
  • Materials Chemistry

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