Porosity dependence of elastic constants in aluminum nitride ceramics

• Main Authors: Humberto Naoyuki Yoshimura, André Luiz Molisani, Nilson Eiji Narita, Paulo Francisco Cesar, Hélio Goldenstein
• Format: Article
• Language: English
• Published: Associação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol) 2007-06-01
• Series: Materials Research
• Subjects: aluminum nitride; porous material; elastic behavior; sintering
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392007000200006

Aluminum nitride is a relatively new engineering ceramic and its mechanical properties have not been extensively studied. In this work, the effects of porosity (~0 to 38%) on sonic velocities, Poisson's ratio, and elastic moduli of partially sintered A1N, both pure and with additives, were investigated. The elastic constants, determined by the ultrasonic pulse-echo method, were significantly influenced by the porosity, but not by the different types of additives used (2 wt. (%) of CaCO3, CaO, and Y2O3). All elastic constants evaluated decreased with increasing porosity, but the rates of decrease were higher for elastic moduli compared do sonic velocities and Poisson's ratio. The results were analyzed in the light of stress concentration and loading bearing area models proposed in the literature.