Identifying of Transition from Ductile to Brittle Groove Formation in Scratching Fine Ceramics by Using Acoustic Emission Method

Abstract

This paper deals with an acoustic emission signal analysis for identifying the transition from ductile to brittle groove formation in scratching fine ceramics. A series of scratching tests of representative fine ceramics with a conical diamond indenter have been conducted to investigate the characteristics of the acoustic emission signals generated in different scratching modes. Main results obtained in this paper are as follows I (1) The scratching process may be classifided into following three types ',1) ductile scratching mode in which no cracking is observed, 2) brittle scratching mode I in which the brittle cracks occur and 3) brittle scratching mode II in which extensive cracking and chipping along the grooves occur. (2) When the scratching process changes from ductile to brittle mode with an increase of scratching load, a sudden incresing in AE event count rate takes places. Therefore, the identifying of ductile/brittle transition in scratching may be performed by using this phenomenon. (3) The AE signals generated during ductile scratching have the frequency components lower than 0.35 MHz, while the AE signals during brittle scratching have high frequency components between 0.4-0.9 MHz as well as the frequency components lower than 0.35 MHz. Consequently, the ductile/brittle transition in scratching may be identified by recognizing the pattern of the power spectra of AE signals. © 1992, The Japan Society for Precision Engineering. All rights reserved.