Synthesis, structure and mechanical properties of ice-templated tungsten foams

André Röthlisberger, Sandra Häberli, Ralph Spolenak, David C. Dunand*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

Tungsten foams with directional, controlled porosity were created by directional freeze-casting of aqueous WO3 powder slurries, subsequent freeze-drying by ice sublimation, followed by reduction and sintering under flowing hydrogen gas to form metallic tungsten. Addition of 0.51 wt% NiO to the WO3 slurry improved the densification of tungsten cell walls significantly at sintering temperatures above 1250 °C, yielding densely sintered W-0.5 wt% Ni walls with a small fraction of closed porosity (<5%). Slurries with powder volume fractions of 15-35 vol% were solidified and upon reduction and sintering the open porosity ranges from 27-66% following a linear relation with slurry solid volume fraction. By varying casting temperature and powder volume fraction, the wall thickness of the tungsten foams was controlled in the range of 10-50 m. Uniaxial compressive testing at 25 and 400 °C, below and above the brittle-to-ductile-transition temperature of W, yields compressive strength values of 70-96 MPa (25 °C) and 92-130 MPa (400 °C).

Original languageEnglish (US)
Pages (from-to)753-764
Number of pages12
JournalJournal of Materials Research
Volume31
Issue number6
DOIs
StatePublished - Mar 28 2016

Keywords

  • freeze-casting
  • freeze-drying
  • porous material
  • refractory metals

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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