Bonding force determination at AFB interfaces of single crystal sapphire composites

Huai-Chuan Lee; Helmuth Meissner; Xiaodong Mu; Chao Liu; Wei Qiu

doi:10.1117/12.817337

27 April 2009 Bonding force determination at AFB interfaces of single crystal sapphire composites

Huai-Chuan Lee, Helmuth Meissner, Xiaodong Mu, Chao Liu, Wei Qiu

Proceedings Volume 7302, Window and Dome Technologies and Materials XI; 73020A (2009) https://doi.org/10.1117/12.817337
Event: SPIE Defense, Security, and Sensing, 2009, Orlando, Florida, United States

Abstract

We report on the bond strength at the interfaces of Adhesive-Free-Bonded (AFB®) single crystal sapphire composite bars as deduced from the fracture toughness. Fracture toughness (K_IC) characterizes the resistance of a bulk brittle material to fractural failure caused by unstable crack propagation. Correlation between the well-defined initial flaw size and the apparent failure strength gives the fracture toughness that is a function of the average bond strength at the fractured interfaces. To ensure that the fracture interface coincides with the AFB® interface, we make a pre-notch at the AFB® interface to be the initial surface flaw using a 532 nm wavelength marking laser. The measured failure strength yields the fracture toughness of the AFB® composites. We have found in this study that the average fracture toughness of AFB composite samples is 2.51 MPa*√m and that of non-composite control samples is 2.39 MPa*√m. The correlating fracture energy is 13.1 J/m² and 11.9 J/m², respectively. The apparently greater fracture toughness of composite samples compared to that of non-composite samples conforms with the hypothesis that attributes the origin of the bonding forces at the AFB interfaces to the Lodon-Van der Waals interaction between two solid bodies.

Citation Download Citation

Huai-Chuan Lee, Helmuth Meissner, Xiaodong Mu, Chao Liu, and Wei Qiu "Bonding force determination at AFB interfaces of single crystal sapphire composites", Proc. SPIE 7302, Window and Dome Technologies and Materials XI, 73020A (27 April 2009); https://doi.org/10.1117/12.817337

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