Fracture toughness measurements of LPS-SiC: a comparison of the indentation technique and the SEVNB method

• Main Author: Strecker,Kurt
• Publication Date: 2005
• Other Authors: Ribeiro,Sebastião, Hoffmann,Michael-Johannes
• Format: Article
• Language: eng
• Source: Materials research (São Carlos. Online)
• Download full: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392005000200004
• topic: fracture toughness measurement; indentation technique; SENVB method

Many methods are currently used to measure the fracture toughness of ceramic materials. Methods based on crack-length measurements of cracks introduced into the sample surface by the Vicker's indentor have the advantage that they are easy to use, but are very unreliable due to subcritical crack growth and the difficulty in determining the exact length of the cracks. Furthermore, depending on the crack shape there are many equations to calculate K Ic. Other methods like the Chevron Notch or Single Edge Pre-cracked Beam (SEPB) are often difficult to execute or expensive. The simple and inexpensive Single-Edge-V-Notched Beam (SEVNB) on the other hand gives reliable values of fracture toughness of ceramic materials. In this method a saw cut is tapered to a sharp V-notch using a razor blade sprinkled with diamond paste. Thus, it is possible to introduce a sharp crack with a notch width of less than 20 micrometers, necessary to conduct valid tests. In this investigation, fracture toughness measurements on LPS-SiC materials carried out by the indentation technique and the SEVNB method have been compared.