Manufacturing Tool-Grade Cermet Cr2O3–22Cr by Spark Plasma Sintering at Pressures up to 800 MPa

Abstract

The study reveals that the structure of Cr₂O₃–22 wt % Cr cermet, obtained from a mixture of chromium oxide and chromium by spark plasma sintering at a temperature of 1520°C and a pressure range of 40–300 MPa, consists of a chromium oxide matrix with globular 0.5- to 20-μm Cr inclusions, comparable in size to the particles of the initial mixture. At pressures ranging from 300 to 800 MPa, elongated inclusions appear in the structure, the concentration of which increases with the rise in pressure during spark plasma sintering, leading to a decrease in globular grain size. The cermet exhibits maximum Vickers hardness and crack resistance values, determined by the Palmqvist method at 20.2 GPa and 7.6 MPa m^1/2, respectively. Its stability under intermittent dry cutting with 9Kh12F steel (HRC 58–60) is comparable to ceramics based on Al₂O₃–TiC from Sandvik Coromant (Sweden).