Sintering of BN Based Composites with ZrC and Al under High Temperatures and Pressures
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UCTION, STRUCTURE, PROPERTIES
Sintering of BN Based Composites with ZrC and Al under High Temperatures and Pressures K. V. Slipchenkoa, c, *, D. A. Stratiichuka, V. Z. Turkevicha, N. M. Bilyavynab, V. M. Bushlyac, and J.-E. Ståhlc aBakul
Institute for Superhard Materials, National Academy of Science of Ukraine, Kyiv, 04074 Ukraine b Taras Shevchenko National University of Kyiv, Kyiv, 01601 Ukraine c Lund University, Lund, SE-22100 Sweden *e-mail: [email protected] Received June 11, 2019; revised September 30, 2019; accepted October 1, 2019
Abstract—The sintering of cubic boron nitride (cBN) based ceramic matrix materials with zirconium carbide and aluminum has been carried out under high pressures and temperatures. The performed study has revealed that the interaction between mixture components with the formation of a new phase, namely, zirconium diboride (ZrB2) occurs at sintering temperatures above 1750°C and an applied pressure of 7.7 GPa. A further increase in the sintering temperature leads to a growth in the volume ZrB2 content and reduces the microhardness and crack toughness of the studied materials. The flank wear of specimens under the conditions used for the processing of AISI316L stainless steel (vc = 300 m/min, t = 300 s) grows with an increase in the sintering temperature to attain the critical value VB = 325 μm, when the specimen sintered at temperature of 2300°C is used, and VB = 200 μm for the specimen sintered at 1750°C. Keywords: zirconium carbide, cubic boron nitride, zirconium diboride, microhardness, high pressure DOI: 10.3103/S1063457620040103
INTRODUCTION Materials based on cubic boron nitride (cBN) are widely used for the high-speed machining of iron and its alloys due to its physicochemical properties, among which it is necessary to pay attention to unordinary chemical inertness and high hardness [1]. Cutting cBN based tools are manufactured by sintering under high pressures (5–8 GPa) and temperatures (1200–2300°C) [2, 3]. Cubic boron nitride is a synthetic compound with covalent bonds [4], which additionally complicate the manufacturing of cutting tools even under the above described conditions, so some binder phases are used to promote the process of sintering [5]. The type and content of a binder phase predetermine the further application of tools. Thus, the materials with a cBN content of 80–90% and binders in the form of pure W, Co, Al, and Ti metals or their compounds are classified in the BH group. One of the main application spheres of the materials belonging to the BH group is the lining of white cast irons under high dynamic loads [6]. The materials with a cBN content of 45–65% are classified in the BL group. The properties of BL group materials can be controlled to a certain extent via the use of different binder phases [7]. A high chemical stability of the binder phase [8] provides the possibility to increase the performance of BL group materials [9], but the materials belonging to this group are inferior to the BH group in their mechanical properties, so their applica
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