Chemical wear mechanisms of innovative ceramic cutting tools in the machining of steel

It is commonly known that commercially available uncoated hardmetals, cerme ts and Si3N4-based inserts are not suitable for high speed and dry machinin g of steel because of the chemical incompatibility of the above mentioned m aterials at elevated temperatures. Based on thermodynamic equilibrium solub ility calculations, a number of potentially suitable ZrO2- and sialon-based ceramic composites with 30 vol.% of TiB2, TiC0.5N0.5 or TiN were selected and manufactured by means of uniaxial hot pressing. The calculated chemical stability was verified by means of static steel-ceramic interaction couple experiments at elevated temperatures. Actual turning tests were performed and the: predictive capabilities of the chemical stability calculations and interaction couple results were evaluated. In this paper, thermodynamic st ability calculations, abrasive wear susceptibility estimates and interactio n couple experiments are used in order to elucidate the chemical compatibil ity of novel ceramic composites and steel and to predict the actual relativ e wear behaviour under those conditions in which chemical wear is the predo minant mode of tool wear. (C) 1999 Elsevier Science S.A. All rights reserve d.