Evolution of the Microstructure and Mechanical Properties of cBN-Based Cutting Tools with Silicides Compounds as Binder Phase

Silicide based compounds are widely used for coatings due to their high melting temperature, oxidation resistance and moderate density. Employment of binders based on silicides of transitional metals can provide cBN-based cutting tools with higher chemical stability and better performance. The relationship between phase composition, microstructure and mechanical properties of novel polycrystalline cubic boron nitride (PcBN) materials were investigated. Three series of PcBN samples were made by high pressure high temperature (HPHT) sintering. Silicides of chromium-CrSi2, vanadium-VSi2 and molybdenum MoSi2 were used as a binder phase in each case, while aluminum was introduced to the mixture as an oxygen getter. During HPHT sintering at temperatures above 1850 C the formation of borides of binder phase were observed in cases with VSi2 and MoSi2. For system with CrSi2 binder, temperature of boride formation was found to be lower-1600 C. Materials with MoSi2 binder phase demonstrated the highest level of microhardness. Performance of materials were investigated in conditions of machining of stainless steel AISI 316L and Inconel 718

Characterization by SEM, TEM and Quantum-Chemical Simulations of the Spherical Carbon with Nitrogen (SCN) Active Carbon Produced by Thermal Decomposition of Poly(vinylpyridine-divinylbenzene) Copolymer

Amorphous Spherical Carbon with Nitrogen (SCN) active carbon has been prepared by carbonization of poly(vinylpyridine-divinylbenzene) (PVPDVB) copolymer. The PVPDVB dehydrogenation copolymer has been quantum chemically (QC) simulated using cluster and periodic models. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) studies of the resulting product have conformed the QC computation results. Great structural similarity is found both at the nano- and micro-levels between the N-doped SCN carbon and its pure carbonic SKS analog

Multicomponent binders for PcBN performance enhancement in cutting tool applications

This study proposes a novel design of binders for polycrystalline cubic boron nitride (PcBN) cutting tool materials. Well-known binder phases TiC and TiN were combined with transitional metal nitrides ZrN, VN, and HfN. Performance screenings of longitudinal turning Inconel 718 and AISI 316 L highlighted the superior performance of PcBN materials with mixed TiC-ZrN and TiC-VN binders. These two systems were further sintered in a wider range of temperatures. XRD and STEM-XEDS analysis confirmed mutual dissolution of both TiC and ZrN, and TiC and VN, thus forming two types of solid solutions (Ti,Zr)(C,N) and (Ti,V)(C,N). Extended performance tests showed that tools with TiC-ZrN binder outperform reference PcBN with TiC binder by up to 20% when machining Inconel 718. When machining hardened Caldie tool steel, the performance of tools with TiC-ZrN and TiC-VN binders were 80–90% higher than the reference tools