Spark Plasma‐Sintered WC–ZrO2–Co Nanocomposites with High Fracture Toughness and Strength
Spark Plasma‐Sintered WC–ZrO2–Co Nanocomposites with High Fracture Toughness and Strength
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DOI：
10.1111/j.1551-2916.2010.03685.x
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发表时间：
2010-06
影响因子：
3.9
通讯作者：
A. Mukhopadhyay;D. Chakravarty;B. Basu
中科院分区：
文献类型：
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作者：
A. Mukhopadhyay;D. Chakravarty;B. Basu
在本文中，我们首次证明了如何部分/全部取代钴（金属相）与ZrO 2（陶瓷相）在WC-Co系统，沿着放电等离子烧结，可以导致高性能的WC基陶瓷纳米复合材料的发展。会聚束电子衍射分析，结合透射电子显微镜，揭示了纳米t-ZrO 2颗粒的分散，以及Co相，在致密的WC-ZrO 2-Co纳米复合材料。为了获得可靠的措施的强度和断裂韧性性能，四点弯曲配置，和单边V型切口梁技术，分别使用。在所研究的纳米复合材料中，WC-6wt%ZrO2晶间/晶内纳米复合材料表现出最佳的机械性能组合，如高硬度（~ 20 GPa），弯曲强度（~ 1.3 GPa）和断裂韧性（~ 10 MPa·m1/2）。抗弯强度比参照WC-6wt%Co金属陶瓷的抗弯强度高上级18%，而断裂韧性仅略低16%。理论估计，残余应力诱导增韧的基础上，被认为是微不足道的解释高韧性的纳米复合材料。保持相当高的断裂韧性的能力已部分归因于由t-ZrO 2相的转变增韧。来自其他增韧机制的额外贡献源自在纳米尺寸的ZrO 2颗粒、裂纹桥接和由ZrO 2颗粒引起的裂纹偏转的存在下从沿晶（WC-6重量% Co金属陶瓷）到穿晶的断裂模式的变化。基于更精细的微观结构分析以及力学性能的测量，已作出努力，以建立在所研究的陶瓷纳米复合系统的结构-性能关系。
In this paper, we demonstrate for the first time how partial/full replacement of Co (metallic phase) with ZrO2 (ceramic phase) in WC–Co system, along with spark plasma sintering, can lead to the development of high-performance WC-based ceramic nanocomposites. Convergent beam electron diffraction analysis, in combination with transmission electron microscopy, reveal the dispersion of nanosized t-ZrO2 particles, as well as the Co phase, in the dense WC–ZrO2–Co nanocomposites. In order to obtain reliable measures of strength and fracture toughness properties, four-point bending configuration, and single-edge V-notch beam techniques, respectively, were used. Among the investigated nanocomposites, WC–6 wt% ZrO2 inter/intragranular nanocomposite exhibited the optimum combination of mechanical properties such as high hardness (∼20 GPa), flexural strength (∼1.3 GPa), and fracture toughness (∼10 MPa·m1/2). The flexural strength was superior by ∼18% to that measured with the reference WC–6 wt % Co cermet, while the fracture toughness was only modestly lower by ∼16%. Theoretical estimates, based on residual stress-induced toughening, were found to be insignificant to explain the high toughness of the nanocomposites. The ability to maintain considerably high fracture toughness has been attributed partly to the transformation toughening by the t-ZrO2 phase. Additional contributions from other toughening mechanisms originate from the change in fracture mode from intergranular (WC–6 wt% Co cermet) to transgranular in the presence of nanosized ZrO2 particles, crack bridging, and crack deflection by the ZrO2 particles. Based on finer scale microstructural analysis as well as mechanical property measurement, an effort has been made to establish the structure–property relationship in the investigated ceramic nanocomposite system.