Gradients in elastic modulus for improved contact-damage resistance. Part I: The silicon nitride-oxynitride glass system
Gradients in elastic modulus for improved contact-damage resistance. Part I: The silicon nitride-oxynitride glass system
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DOI：
10.1016/s1359-6454(01)00200-2
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发表时间：
2001-09-20
期刊：
影响因子：
9.4
通讯作者：
Suresh, S
中科院分区：
文献类型：
--
作者：
Pender, DC;Padture, NP;Suresh, S
制备了氮化硅（Si3N4）基梯度材料，其弹性模量从表面到内部具有可控的单向梯度。这是通过将低模量的氧化氮化硅玻璃渗透到致密的、高模量的氮化硅陶瓷中来实现的，在梯度氮化硅和单片氮化硅上进行了弹性赫兹压痕（球面压痕）实验。虽然单片陶瓷的赫兹压痕导致了经典的锥形裂纹，但在相当的载荷水平下，这种裂纹在梯度材料中被完全抑制，尽管包含玻璃的表层的强度和韧性较低。研究人员还对压痕相关应力进行了有限元分析（FEA），以深入了解梯度材料抗接触损伤能力增强的机制。计算分析表明，与单片氮化硅相比，赫兹接触圈外驱动锥裂纹的最大拉伸应力降低了约30%。相对于单片Si3N4，这种拉应力的降低弥补了梯度材料表面较低的韧性。有限元分析还使我们能够制定一些弹性模量梯度的策略，这些策略将进一步改善梯度材料的锥裂抑制特性。(C) 2001材料学报Elsevier Science Ltd.出版。版权所有。
Silicon nitride (Si3N4)-based graded materials were fabricated with controlled, unidirectional gradients in elastic modulus from the surface to the interior. This was accomplished by infiltrating a low modulus silicon oxynitride glass into a dense, higher modulus, Si3N4 ceramic, Elastic Hertzian indentation (spherical indenter) experiments were performed on both the graded and the monolithic Si3N4. While Hertzian indentation of the monolithic ceramic resulted in classical cone cracks, such cracks were completely suppressed in the graded materials at comparable load levels, despite the lower strength and lower toughness of the surface layer comprising glass. Finite element analysis (FEA) of the stresses associated with the indentation was also performed to gain insight into the mechanism for the enhanced contact damage resistance in the graded materials, The computational analysis revealed that the maximum tensile stresses outside the Hertzian contact circle, which drive the cone-cracks, are reduced by approximately 30% relative to those present in the monolithic silicon nitride. This reduction in the tensile stresses more than compensates for the lower toughness at the graded material surfaces, relative to the monolithic Si3N4. The FEA also allowed us to develop some strategies for elastic-modulus-gradients that would lead to further improvements in the cone-crack suppression characteristics of graded materials in general. (C) 2001 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.