Premium
Oxidation Behavior and Flexural Strength of Aluminum Nitride Exposed to Air at Elevated Temperatures
Author(s) -
Kim HyounEe,
J. Moorhead Arthur
Publication year - 1994
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.1151-2916.1994.tb07264.x
Subject(s) - flexural strength , materials science , sintering , nitride , oxide , humidity , substrate (aquarium) , composite material , layer (electronics) , aluminium , thermal oxidation , relative humidity , analytical chemistry (journal) , chemistry , metallurgy , environmental chemistry , oceanography , physics , thermodynamics , geology
The oxidation behavior of a sintered aluminum nitride containing 3 wt% Y 2 O 3 as a sintering aid was investigated. Samples were exposed to air at elevated temperatures for times up to 100 h. The weights of the samples were continuously monitored during exposure at various temperatures and humidity levels. The effects of oxidation on room‐temperature flexural strength were also determined, and correlated to the observed weight changes of the samples. At temperatures 1200°C, linear weight gains were observed. However, at temperatures above 1200°C, the weight gains became parabolic with respect to exposure time. The oxidation rates were significantly increased by water vapor in the air. The oxidation products were found by X‐ray analysis to be a mixture of Al 2 O 3 and 5A1 2 O 3 ·3Y 2 O 3 . The oxide layer formed on the surface was severely cracked because of the thermal expansion mismatch between the oxide layer and the substrate. The cracks initiated in the oxide layer and propagated into the substrate, resulting in severe reduction in the room‐temperature flexural strength of the material. When exposed to ambient air for more than 50 h at temperatures greater than 1100°C, the strengths of the samples decreased to less than half that of the as‐received material.