Pavel Loginov

Nanocomposites for Machining Tools

Machining tools are used in many areas of production. To a considerable extent, the performance characteristics of the tools determine the quality and cost of obtained products. The main materials used for producing machining tools are steel, cemented carbides, ceramics and superhard materials. A promising way to improve the performance characteristics of these materials is to design new nanocomposites based on them. The application of micromechanical modeling during the elaboration of composite materials for machining tools can reduce the financial and time costs for development of new tools, with enhanced performance. This article reviews the main groups of nanocomposites for machining tools and their performance.

Development of a Next Generation of Diamond Tools Based on Superhard Materials with a Nanomodified Binder for Steel and Cast Iron Machining

The possibility of using binders of the Next100 type alloyed with nickel and modified with WC, ZrO2, and hBN nanoparticles for fabricating a cutting tool based on superhard materials and intended for steel and cast iron machining is shown. It is established that alloying the binder with nickel makes it possible to increase its impact viscosity by a factor of 2.5 and substantially improve the resistance of tool segments during operation. An increase in binder strength by 100–150 MPa and hardness by 5–7 HRB is provided due to the introduction of WC, ZrO2, and hBN into it. The adhesion of cubic boron nitride to a binder increases in the presence of WC nanoparticles. The optimal ratio of diamond single crystals and cubic boron nitride in a working layer, at which maximal service characteristics of the tool are attained, is determined to be 75: 25. The formation of nanoclusters of amorphous boron at the interface of cubic boron nitride and a binder and dissolution of a small amount of nitrogen in binder components during hot compaction are revealed.

Interfaces between Model Co-W-C Alloys with Various Carbon Contents and Tungsten Carbide

Interfaces between alloys simulating binders in WC-Co cemented carbides and tungsten carbide were examined on the micro-, nano-, and atomic-scale. The precipitation of fine WC grains and η-phase occurs at the interface of the alloy with the low carbon content. The precipitation of such grains almost does not occur in the alloy with the medium-low carbon content and does not take place in the alloy with the high carbon content. The formation of Co nanoparticles in the binder alloy with the medium-low carbon content was established. Interfaces in the alloy with the medium-low carbon content characterized by complete wetting with respect to WC and with the high carbon content characterized by incomplete wetting were examined at an atomic scale. The absence of any additional phases or carbon segregations at both of the interfaces was established. Thus, the phenomenon of incomplete wetting of WC by liquid binders with high carbon contents is presumably related to special features of the Co-based binder alloys oversaturated with carbon at sintering temperatures.