Contact damage resistance and strength degradation of glass-infiltrated alumina and spinel ceramics
Contact damage resistance and strength degradation of glass-infiltrated alumina and spinel ceramics
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DOI：
10.1177/00220345990780031401
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发表时间：
1999-03-01
影响因子：
7.6
通讯作者：
Lawn, BR
中科院分区：
文献类型：
--
作者：
Jung, YG;Peterson, IM;Lawn, BR
全瓷冠因其卓越的美观性和化学惰性而得到广泛应用。本研究检验了这样的假设：玻璃渗透的氧化铝和尖晶石芯陶瓷在代表性口腔接触条件下能够抵抗损伤累积和强度下降。因此，使用硬球进行赫兹压痕测试来评估具有不同预成型晶粒形态和孔隙率的氧化铝和尖晶石陶瓷中的损伤累积。在完全渗透的材料上测量的压痕应力-应变曲线显示出对起始预成型状态的明显不敏感性。研究表明，玻璃相在为陶瓷结构提供机械刚性和强度方面发挥着至关重要的作用。所有渗透陶瓷均显示出表面下锥体断裂和高于临界载荷 Pc（开裂）和 Py（屈服）的准塑性变形，具体取决于球体半径，且 P-Y < P-C。高于这些临界载荷的赫兹接触中损伤累积导致的强度下降明显很小，这表明渗透材料对于咀嚼过程中遇到的“钝”接触应该具有高度的损伤耐受性。强度测试中的失效源于锥体裂纹（“脆性模式”）或屈服区（“准塑性模式”），脆性模式在尖晶石中更占主导地位，而准塑性模式在氧化铝中更占主导地位。研究发现，较低负载但仍高于口腔功能典型负载的多循环接触在空气和水中最多 10(5) 次循环是无害的，尽管在水中 10(6) 次循环的接触确实会导致强度显着下降。相比之下，与维氏压头的接触在低负载下会产生大量的强度损失，这表明这些材料的机械完整性可能会因无意的“尖锐”接触而受到损害。
All-ceramic crowns are coming into widespread use because of their superior esthetics and chemical inertness. This study examines the hypothesis that glass-infiltrated alumina and spinel core ceramics are resistant to damage accumulation and strength degradation under representative oral contact conditions. Accordingly, Hertzian indentation testing with hard spheres is used to evaluate damage accumulation in alumina and spinel ceramics with different pre-form grain morphologies and porosities. Indentation stress-strain curves measured on fully infiltrated materials reveal a marked insensitivity to the starting pre-form state. The glass phase is shown to play a vital role in providing mechanical rigidity and strength to the ceramic structures. All the infiltrated ceramics show subsurface cone fracture and quasi-plastic deformation above critical loads Pc (cracking) and Py (yield), depending on sphere radius, with P-Y < P-C. Strength degradation from accumulation of damage in Hertzian contacts above these critical loads is conspicuously small, suggesting that the infiltrated materials should be highly damage-tolerant to the "blunt" contacts encountered during mastication. Failure in the strength tests originates from either cone cracks ("brittle mode") or yield zones ("quasi-plastic mode"), with the brittle mode more dominant in the spinels and the quasi-plastic mode more dominant in the aluminas. Multi-cycle contacts at lower loads, but still above loads typical of oral function, are found to be innocuous up to 10(5) cycles in air and water, although contacts at 10(6) cycles in water do cause significant strength degradation. By contrast, contacts with Vickers indenters produce substantial strength losses at low loads, suggesting that the mechanical integrity of these materials may be compromised by inadvertent "sharp" contacts.