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Mechanical Properties, Thermal Shock Resistance, and Thermal Stability of Zirconia‐Toughened Alumina‐10 vol% Silicon Carbide Whisker Ceramic Matrix Composite
Author(s) -
Solomah Ahmad C.,
Reichert Wolfgang,
Rondinella Vincenzo,
Esposito Leonardo,
Toscano Enrique
Publication year - 1990
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1990.tb06583.x
Subject(s) - materials science , composite material , thermal shock , flexural strength , whisker , ceramic matrix composite , composite number , fracture toughness , ceramic , silicon carbide , cubic zirconia , whiskers
Zirconia‐toughened alumina (Al 2 O 3 –15 vol% Y‐PSZ (3 mol% Y 2 O 3 )) reinforced with 10 vol% silicon carbide whiskers (ZTA‐10SiC w ) ceramic matrix composite has been characterized with respect to its room‐temperature mechanical properties, thermal shock resistance, and thermal stability at temperatures above 1073 K. The current ceramic composite has a flexural strength of ∽550 to 610 MPa and a fracture toughness, K IC , of ∽5.6 to 5.9 MPa·m 1/2 at room temperature. Increases in surface fracture toughness, ∽30%, of thermally shocked samples were observed because of thermal‐stress‐induced tetragonal‐to‐monoclinic phase transformation of tetragonal ZrO 2 grains dispersed in the matrix. The residual flexural strength of ZTA–10 SiC w ceramic composite, after single thermal shock quenches from 1373–1573 to 373 K, was ∽10% higher than that of the unshocked material. The composite retained ∽80% of its original flexural strength after 10 thermal shock quenches from 1373–1573 to 373K. Surface degradation was observed after thermal shock and isothermal heat treatments as a result of SiC whisker oxidation and surface blistering and swelling due to the release of CO gas bubbles. The oxidation rate of SiC whiskers in ZTA‐10SiC w composite was found to increase with temperature, with calculated rates of ∽8.3×10 −8 and ∽3.3×10 −7 kg/(m 2 ·s) at 1373 and 1573 K, respectively. It is concluded that this ZTA‐10SiC w composite is not suitable for high‐temperature applications above 1300 K in oxidizing atmosphere because of severe surface degradation.