Accession Number:

ADA244985

Title:

Processing of a Mullite Matrix, Molybdenum Disilicide Reinforced Composite

Descriptive Note:

Master's thesis

Corporate Author:

WASHINGTON UNIV SEATTLE DEPT OF MATERIALS SCIENCE AND ENGINEERING

Personal Author(s):

Report Date:

1991-01-01

Pagination or Media Count:

113.0

Abstract:

A mullite matrix reinforced with molybdenum disilicide particles was investigated as a potential high temperature composite material. Mullite is well known for its high temperature strength, creep resistance, corrosion resistance and ability to withstand oxidizing environments. MoSi2 has the potential to be a good reinforcement because it forms a protective silica layer during oxidation, undergoes a brittle to ductile transformation at 900-1000C which would increase high temperature composite toughness, and is thermodynamically stable with mullite. Samples containing 2.5 to 20 vol MoSi2 were processed using both hot pressing and pressureless sintering techniques. Low temperature mechanical testing was performed both in the as sintered state and after oxidation at 1400 C for 96 hours. Densities of greater than 93 of theoretical were attained for composites containing up to 20 vol MoSi2 via pressureless sintering. K sub Ic and strength values of the as-sintered composite were up to two times that of monolithic mullite. After oxidation at 1400 C for 96 hours, strength improved by 1.5 times over the as-sintered strength, and fracture toughness improved by 2.5 times over the as-sintered toughness indicating that the composite is self-healing during oxidation.

Subject Categories:

  • Ceramics, Refractories and Glass
  • Laminates and Composite Materials
  • Properties of Metals and Alloys

Distribution Statement:

APPROVED FOR PUBLIC RELEASE