Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10400986 | Diamond and Related Materials | 2005 | 4 Pages |
Abstract
Disparities prevail among the reported hardness and fracture toughness values for hard and brittle materials. A better understanding of the physical nature of hardness and fracture toughness and a standardized technique for reliable measurements of these quantities is urgently needed. We strongly recommend the use of the measured hardness after the bend in the hardness versus load (HâFLoad) curve, when the hardness approaches its asymptotic value. The present work reports a systematic study of hardness and fracture toughness on moissanite (single crystal hexagonal silicon carbide, 6H-SiC) samples. The measurements were performed over a broad load range from 0.49 to 294 N with the direct indentation method. Asymptotic values of Knoop hardness of HK = 19 GPa and Vickers hardness of HV = 22 GPa were reached at a high load between 50 N and 100 N. A consistent fracture toughness of KIC = 1.8 MPa·m1/2 was obtained across the entire load range. Our study presents experimental results for the hardness and fracture toughness of moissanite in the asymptotic-hardness region, and it raises concern regarding the application of moissanite single crystals as anvil material under shear/fracture conditions.
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Authors
J. Qian, L.L. Daemen, Y. Zhao,