Relationship between elastic and mechanical properties of dental ceramics and their index of brittleness

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• 作者：Humberto Naoyuki Yoshimura^a ; ^{humberto.yoshimura@ufabc.edu.br} ; Carla Castiglia Gonzaga^b ; ^c ; Paulo Francisco Cesar^b ; Walter Gomes Miranda Jr.^b
• 关键词：C. Mechanical properties ; C. Fracture ; C. Toughness ; E. Biomedical applications ; Ceramics
• 刊名：Ceramics International
• 出版年：2012
• 期刊代码：13_02728842
• 类别：ms
• 出版时间：August, 2012
• 卷：38
• 期：6
• 页码：4715-4722
• 文件大小：634 K

摘要

The purpose of the study was to verify the effects of a number of materials鈥?parameters (crystalline content; Young's modulus, E; biaxial flexure strength, 蟽_i; Vickers hardness, VH; fracture toughness, K_Ic; fracture surface energy, 纬_f; and index of brittleness, B) on the brittleness of dental ceramics. Five commercial dental ceramics with different contents of glass phase and crystalline particles were studied: a vitreous porcelain (VM7/V), a porcelain with 16 vol%leucite particles (d.Sign/D), a glass-ceramic with 29 vol%leucite particles (Empress/E1), a glass-ceramic with 58 vol%lithium-disilicate needle-like particles (Empress 2/E2), and a glass-infiltrated alumina composite with 65 vol%crystals (In-Ceram Alumina/IC). Discs were constructed according to manufacturers鈥?instructions, ground and polished to final dimensions (12 mm 脳 1.1 mm). Elastic constants were determined by ultrasonic pulse-echo method. 蟽_i was determined by piston-on-3-balls method in inert condition. VH was determined using 19.6 N load and K_Ic was determined by indentation strength method. 纬_f was calculated from the Griffith-Irwin relation and B by the ratio of HV to K_Ic. IC and E2 showed higher values of 蟽_i, E, K_Ic and 纬_f, and lower values of B compared to leucite-based glass-ceramic and porcelains. Positive correlations were observed for 蟽_i versus K_Ic, and K_Ic versus E^1/2, however, E did not show relationship with HV and B. The increase of crystalline phase content is beneficial to decrease the brittleness of dental ceramics by means of both an increase in fracture surface energy and a lowering in index of brittleness.