An Investigation of the Mechanical Properties and Fracture Characteristic of Hot-Pressed Boron Nitride Ceramics

Abstract:

The overall mechanical characterization of hot-pressed hexagonal boron nitride (h-BN) based ceramics was performed. Hardness, flexure strength and fracture toughness (KIC) measurements were carried out using Vickers indentations, 3-point bending tests and SEVNB method, respectively. The fracture characteristics of hot-pressed h-BN ceramics were investigated by analyzing fracture surfaces using scanning electron microscope (SEM). The hardness, ranged from HV = 0.20GPa to HV = 0.25GPa, which was higher in the surfaces parallel to the hot-press direction due to the perpendicular alignment of the basal planes of the h-BN platelets to the hotpress direction. The fracture toughness and flexure strength values were determined to be 2.6 MPa.m1/2 and 0.14 GPa, respectively. A single KIC value was obtained since a slight variation of the fracture toughness was observed with the orientation of h-BN. The microstructural observations of h-BN grains indicated completely brittle fracture with intergranular voids and microcracks revealing a mixed mode of fracture.

• Periodical: Materials Science Forum (Volume 554)
• Pages: 201-205
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.554.201
• Online since: August 2007
• Authors: B. Ertug, T. Boyraz, O. Addemir
• Keywords: Fracture Characteristic, Fracture Toughness, Hexagonal Boron Nitride (HBN), Hot-Pressing

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