The Characteristics of Acoustic Emission of <TEX>$Al_2O_3$</TEX> Ceramics by an Amount of Additive <TEX>$Y_2O_3$</TEX>

J. Ocean Eng. Technol. 2008;22(3):71-75.

The Characteristics of Acoustic Emission of $Al_2O_3$ Ceramics by an Amount of Additive $Y_2O_3$

Kim Jin-Wook,Ahn Seok-Hwan,Nam Ki-Woo

Korea Institute of Materials Science,School of Mechanical Engineering Pukyong National University,Division of Materials Science and Engineering Pukyong National University

소결조제 $Y_2O_3$ 함유량에 따른 $Al_2O_3$ 세라믹스의 음향방출 특성

김진욱,안석환,남기우

재료연구소,부경대학교 기계공학부,부경대학교 신소재공학부

Keywords: Alumina ceramics, Additive, Crack healing, Acoustic emission, Wavelet analysis, Dominant frequency

핵심용어: 알루미나 세라믹수, 첨가제, 균열치유, 음향방출, 웨이브릿 해석, 탁월주파수

Abstract

This paper illustrates haw $Y_2O_3$ contributes to crack-healing strengths as a function of crack-healing temperature and the additive amount. In investigating mechanical properties, the indentation fracture method is very simple and useful, but careful attention must be paid to the statistical data processing because data may be scattered excessively, especially for brittle materials. To estimate accurate AE signal properties we applied the useful time-frequency method with a discrete wavelet analysis algorithm. In experiments, three kinds of specimens were prepared. After the specimens were indented by a Vickers indentor, they were heat-treated and crack-healed to evaluate bending strength and the AE signal. With higher amounts of the additive powder, as 1, 3, or 5% wt. of $Y_2O_3$, the concentrative tendency of dominant frequency trended toward lower frequency groups. The $Al_2O_3$ ceramic with 3% wt. of $Y_2O_3$ was judged most suitable because it demonstrated superior crack-healing ability and relative concentration on the highest frequency group.