Availableonlineatwww.sciencedirect.com SCIENCE MACHINE TOOLS MANUFACTURe ELSEVIER Intemational Journal of Machine Tools Manufacture 45(2005)1393-1401 Failure mechanisms of TiB2 particle and Sic whisker reinforced Al2O3 ceramic cutting tools when machining nickel-based alloys Deng jianxin Liu Lili. Liu jianhua. Zhao jinlo Department of Mechanical Engineering, Shandong University of Technology, Jinan, Shandong Province 250061, Peoples Republic of China Received 20 November 2004; accepted 28 January 2005 Available online 4 March 2005 Abstract In this paper, Al2O,/TiBy/SiCw ceramic cutting tools with different volume fraction of TiB2 particles and SiC whiskers were produced by hot pressing. The fundamental properties of these composite tool materials were examined. Machining tests with these ceramic tools were carried out on the Inconel718 nickel-based alloys. The tool wear rates and the cutting temperature were measured. The failure mechanisms of these ceramic tools were investigated and correlated to their mechanical properties. Results showed that the fracture toughness and hardness of the composite tool materials continuously increased with increasing Sic whisker content up to 30 vol %. The relative density decreased ith increasing SiC whisker content, the trend of the flexural strength being the same as that of the relative density. Cutting speeds were found to have a profound effect on the wear behaviors of these ceramic tools. The ceramic tools exhibited relative small flank and crater wea at cutting speed lower than 100 m/min, within further increasing of the cutting speed the fank and crater wear increased greatly. Cutting speeds less than 100 m/min were proved to be the best range for this kind of ceramic tool when machining Inconel718 nickel-based alloys. The composite tool materials with higher SiC whisker content showed more wear resistance. Abrasive wear was found to be the predominant far nk wear mechanism. While the mechanisms responsible for the crater wear were determined to be adhesion and diffusion due to the high utting temperatu C 2005 Elsevier Ltd. All rights reserved Keywords: Ceramic cutting tools; Wear mechanisms; Cutting performance; Ceramic composites Ceramic cutting tools usually perform better in high speed machining and in the machining of high hardness Ceramics have intrinsic characteristics, such as high work piece materials as compared to high-speed steel and melting point, high hardness, good chemical inertness and carbide tools. However, the use of single-phase ceramic tool high wear resistance, that make them promising candidates materials, even fully densified, has been limited by their for high-temperature structural and wear resistance com- properties, such as their low strength and fracture toughness ponents, where metallic components achieve only unsatis and poor thermal shock resistance. Furthermore, ceramics factory service lives, owing to inadequate heat, corrosive or are very sensitive to microscopic flaws, thus ceramic cutting wear resistance. Components made of advanced ceramics tools often crack at the tool edge, leading to unpredictable can survive and perform well at higher operating tempera and catastrophic gross fracture of the tool. The low fracture ture, and improve the wear resistance. Nowadays the toughness leads to brittle fracture, and the low thermal advanced ceramics are widely used in cutting tools, drawing conductivity and high anisotropy thermal expansion of or extrusion, seal rings, valve seats, bearing parts, and a ceramics lead to large temperature gradients and thermal variety of high-temperature engine parts, etc. [1-3 micro-cracks at the cutting edge and the tool tip. Therefore, fracture toughness and thermal shock resistance are the most Corresponding author. Tel: +86531295 5081x2047; fax: +86 531 especially for monolithic alumina tool. Improveme s, parameters 955999 mechanical properties must be achieved before the potenti E-mailaddress:jxdeng(@sdu.edu.cn(D.Jianxin) of ceramics can be fully realized. Since, about 1970, 0890-6955/S- see front matter o 2005 Elsevier Ltd. All rights reserved ceramic tools have improved remarkably [4, 5]. These doi: 10. 1016/j.jmachtools. 2005.01.033 improvements are mainly due to: (1)microstructures haveFailure mechanisms of TiB2 particle and SiC whisker reinforced Al2O3 ceramic cutting tools when machining nickel-based alloys Deng Jianxin*, Liu Lili, Liu Jianhua, Zhao Jinlong, Yang Xuefeng Department of Mechanical Engineering, Shandong University of Technology, Jinan, Shandong Province 250061, People’s Republic of China Received 20 November 2004; accepted 28 January 2005 Available online 4 March 2005 Abstract In this paper, Al2O3/TiB2/SiCw ceramic cutting tools with different volume fraction of TiB2 particles and SiC whiskers were produced by hot pressing. The fundamental properties of these composite tool materials were examined. Machining tests with these ceramic tools were carried out on the Inconel718 nickel-based alloys. The tool wear rates and the cutting temperature were measured. The failure mechanisms of these ceramic tools were investigated and correlated to their mechanical properties. Results showed that the fracture toughness and hardness of the composite tool materials continuously increased with increasing SiC whisker content up to 30 vol.%. The relative density decreased with increasing SiC whisker content, the trend of the flexural strength being the same as that of the relative density. Cutting speeds were found to have a profound effect on the wear behaviors of these ceramic tools. The ceramic tools exhibited relative small flank and crater wear at cutting speed lower than 100 m/min, within further increasing of the cutting speed the flank and crater wear increased greatly. Cutting speeds less than 100 m/min were proved to be the best range for this kind of ceramic tool when machining Inconel718 nickel-based alloys. The composite tool materials with higher SiC whisker content showed more wear resistance. Abrasive wear was found to be the predominant flank wear mechanism. While the mechanisms responsible for the crater wear were determined to be adhesion and diffusion due to the high cutting temperature. q 2005 Elsevier Ltd. All rights reserved. Keywords: Ceramic cutting tools; Wear mechanisms; Cutting performance; Ceramic composites 1. Introduction Ceramics have intrinsic characteristics, such as high melting point, high hardness, good chemical inertness and high wear resistance, that make them promising candidates for high-temperature structural and wear resistance com￾ponents, where metallic components achieve only unsatis￾factory service lives, owing to inadequate heat, corrosive or wear resistance. Components made of advanced ceramics can survive and perform well at higher operating tempera￾ture, and improve the wear resistance. Nowadays the advanced ceramics are widely used in cutting tools, drawing or extrusion, seal rings, valve seats, bearing parts, and a variety of high-temperature engine parts, etc. [1–3]. Ceramic cutting tools usually perform better in high speed machining and in the machining of high hardness work piece materials as compared to high-speed steel and carbide tools. However, the use of single-phase ceramic tool materials, even fully densified, has been limited by their properties, such as their low strength and fracture toughness and poor thermal shock resistance. Furthermore, ceramics are very sensitive to microscopic flaws, thus ceramic cutting tools often crack at the tool edge, leading to unpredictable and catastrophic gross fracture of the tool. The low fracture toughness leads to brittle fracture, and the low thermal conductivity and high anisotropy thermal expansion of ceramics lead to large temperature gradients and thermal micro-cracks at the cutting edge and the tool tip. Therefore, fracture toughness and thermal shock resistance are the most limiting parameters in ceramic cutting tool applications, especially for monolithic alumina tool. Improvement in mechanical properties must be achieved before the potential of ceramics can be fully realized. Since, about 1970, ceramic tools have improved remarkably [4,5]. These improvements are mainly due to: (1) microstructures have International Journal of Machine Tools & Manufacture 45 (2005) 1393–1401 www.elsevier.com/locate/ijmactool 0890-6955/$ - see front matter q 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijmachtools.2005.01.033 * Corresponding author. Tel.: C86 531 295 5081x2047; fax: C86 531 295 5999. E-mail address: jxdeng@sdu.edu.cn (D. Jianxin)