Experimental determination of the fracture toughness via microscratch tests: Application to polymers, ceramics, and meta
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Citation
Akono, Ange-Therese, Nicholas X. Randall, and Franz-Josef Ulm. “Experimental Determination of the Fracture Toughness via Microscratch Tests: Application to Polymers, Ceramics, and Metals.” Journal of Materials Research 27.02 (2012): 485–493. ©Cambridge University Press 2012
As Published
http://dx.doi.org/10.1557/jmr.2011.402
Publisher
Cambridge University Press (Materials Research Society)
Version
Final published version
Accessed
Sun Jun 07 22:43:13 EDT 2015
Citable Link
http://hdl.handle.net/1721.1/77996
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Detailed Terms
Experimental determination of the fracture toughness via microscratch tests: Application to polymers, ceramics, and metals Ange-Therese Akono Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
Nicholas X. Randall CSM Instruments, Needham, Massachusetts 02494
Franz-Josef Ulma) Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (Received 28 July 2011; accepted 27 October 2011)
This article presents a novel microscratch technique for the determination of the fracture toughness of materials from scratch data. While acoustic emission and optical imaging devices provide quantitative evidence of fracture processes during scratch tests, the technique proposed here provides a quantitative means to assess the fracture toughness from the recorded forces and depth of penetration. We apply the proposed method to a large range of materials, from soft (polymers) to hard (metal), spanning fracture toughness values over more than two orders of magnitude. The fracture toughness values so obtained are in excellent agreement with toughness values obtained for the same materials by conventional fracture tests. The fact that the proposed microscratch technique is highly reproducible, almost nondestructive, and requires only small material volumes makes this technique a powerful tool for the assessment of fracture properties for microscale materials science and engineering applications. I. INTRODUCTION
The fast development of microelectromechanical systems in the past decades has given rise to a high demand for mechanical testing procedures at the microscale, including fracture toughness testing techniques. Several methods have been proposed that evaluate the fracture toughness through microindentation with a sharp probe. Most popular is the Vickers Indentation Fracture Test where the fracture toughness, Kc, is determined using a Vickers probe and according to Eq. (1)1: # 12 " E P Kc ¼ a ; ð1Þ H c1=2 o where P is the indentation load, E is the Young’s modulus, H is the hardness, co is the average length of the radial cracks generated by the indentation, and a is
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