Effect of water vapor on the mechanical behaviors of hot isostatically pressed silicon nitride containing Y2O3

The effect of water vapor on the mechanical behavior of Si3N4 ceramics was studied. Strength measurements by flexural dynamic fatigue tests were made at temperatures from 1038°C to 1350°C and at actuator speeds of 8.4 × 10−2 and 8.4 × 10−5 mm/s (∼200 and ∼0.2 MPa/s). Step stress rupture tests were a...

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Bibliographic Details
Published in:Journal of materials science 2000-07, Vol.35 (13), p.3415-3423
Main Authors: HONGSANG RHO, HECHT, N. L, GRAVES, G. A
Format: Article
Language:English
Subjects:
Actuators
Applied sciences
Building materials. Ceramics. Glasses
Ceramic industries
Chemical industry and chemicals
Coalescing
Crack propagation
Crack tips
Creep (materials)
Exact sciences and technology
Fatigue tests
Loading rate
Materials fatigue
Materials science
Mean time to failure
Mechanical properties
Oxidation
Rupture tests
Silicon nitride
Structural ceramics
Technical ceramics
Water vapor
Yttrium oxide
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Summary:The effect of water vapor on the mechanical behavior of Si3N4 ceramics was studied. Strength measurements by flexural dynamic fatigue tests were made at temperatures from 1038°C to 1350°C and at actuator speeds of 8.4 × 10−2 and 8.4 × 10−5 mm/s (∼200 and ∼0.2 MPa/s). Step stress rupture tests were also performed at 1288°C and 1150°C. Water vapor had a beneficial effect on the flexural strength due to flaw healing, and/or blunting mechanisms. Dynamic fatigue results demonstrated that the beneficial effects of water vapor on the strength increases as temperature increases and/or loading rate decreases. Time-to-failure was always longer in wet air during step stress rupture testing. Creep crack growth by formation and coalescence of cavities ahead of the crack tip generated from the oxidation pits or subsurface pores were the primary mechanism for slow crack growth for NT 164 Si3N4.
ISSN:0022-2461
1573-4803
DOI:10.1023/A:1004845421543