J. Korean Ceram. Soc. > Volume 29(4); 1992 > Article
 Journal of the Korean Ceramic Society 1992;29(4): 312.
 알루미나의 방탄특성에 대한 입경의 영향 백용기, 강을손, 정동익, 최원봉 국방과학연구소 Effect of Grain Size on the Ballistic Performance of Alumina Ceramics ABSTRACT Two kinds of alumina specimens with different grain size (1 and 51 $mutextrm{m}$) but same density were prepared by hot-pressing. Fracture strength and fracture toughness of these specimens at low strain rate, sonic velocity, and elastic property were evaluated. Ballistic performance against Cal. 50 AP projectile was characterized by thick-backing method by using A16061-T6 reference block. Mechanical properties measured at low strain rate showed that the specimen with samll grain (SG) were better than specimen with large grain (LG). Fracture strength and fracture toughness of LG specimen were 131 MPa and 3.01 MPa{{{{ SQRT { m} }}, but those of SG specimen were 349 and 4.23, respectively. Sonic velocity and elastic properties of these specimen were similar, but bulk velocity and bulk modulus were different at amount of 4 and 9%. The tendency of ballistic performance was not consistent with the mechnaical properties at low strain rate. The ballistic performance based on quantitative efficiency revealed that the LG specimen (5.13) was ballistically better than the SG specimen (4.00) in spite of their lower mechanical properties.
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