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The results of experimental studies show that the use of composite powders (WC-Co) in combination with the modification by the additives of ceramic nanoparticles allows controlling the parameters of the microstructure and increasing the strength of the binder and the level of physical and mechanical properties of the hard metal in general. The coating of carbide particles with a layer of a binder is an effective starting method that allows to obtain a bulk compound that preserves the unique properties of the initial nanopowders and ensures a uniform distribution of the phases (WC, Co, Al2O3). Such multiphase fragmentary nanostructured composite is characterized by additional heterogeneity, determined by the differences in size and elastic properties of the phases. By combining the sizes and properties of the phase components in such heterogeneous composite, it is possible to increase the fracture energy (i.e. Palmqvist fracture toughness) up to 20 - 22 MPa∙m1/2 as a result of inhibition on inclusions of nanoparticles the stress relaxation and change in the trajectory of the intergranular crack. Based on the proposed stereological models and experimentally established relationships between composition and microstructure parameters, the required volume concentrations of nanoparticles’ additives and composite powders (WC-Co) were determined.

This paper introduces a new concept of coated fine carbides modified by nanoparticles Al2O3, ZrO2 (inhibitors) as the starting method for improved hardmetals. The study involved computational and experimental methods to determine functional relationships between the parameters of microstructure, sizes, volume content of additives of nanoparticles and properties (transverse rupture toughness, hardness, fracture toughness) of the heterophase hardmetal composites. Factors having a positive influence on the structure of hardmetals are the decrease in the average size and contiguity of carbide grains due to SPS-consolidation and ultrasonic activation during mixing. The study of microstructural parameters by scanning electron microscopy in a combination with x-ray phase analysis indicates high statistical homogeneity of the relative distribution of nanoparticles (inhibitors) in the cobalt binder between carbide grains and the formation of nanostructured inclusions in hardmetal composites.

The influence of nanoparticles additives on the hard metals properties has been investigated. Nanoparticles introduced into a binder of average size decrease the metal interlayer and therefore increase the strength of binder and composite as a whole. The reduction of the carbide grain average size was found as well (owing to nanoparticles blocking influence on re-crystallization). Besides, the internal thermotension and adhesion wear decrease at high speed cutting (especially for stainless steel) in comparision with base hard metals. The test results display that the modification through ultrafme particles enables to improve the main properties: wear resistance – 1.6 - 2 - fold; fracture toughness – 1.8 - 2 - fold; transverse rupture toughness - at 25 - 50%; tool life – 1.3 - 4 - fold.

New data on the effect of technological modes (depth cutting, a m f, longitudinal feed, fn ; azimuthal feed, faz ; cutting speed, Vr ) and constructive factors (geometric and kinematic parameters of the tool) on cutting forces have been obtained. On this basis, semiempirical computational formulas Pz = f (amf , fn , faz , Vr ) for the assignment of rational modes of processing by the method of rotational turning multifaceted cutter (RTMC) are proposed. The obtained numerical values of the cutting forces for PTMC (up to 900N) are much lower than for conventional turning (up to 4000N) at similar values of amf and fn .

Effect of geometrical and technological parameters of method rotary turning by multifaceted cutters (RTMC) on the quality of machining was investigated. Using the numerical, analytical and experimental methods the effect of cutting conditions on roughness was determed. The resulting semiempirical dependences allow to appoint the cutting conditions with predict roughness parameters Ra, Rz, R max.

The influences of conditions of rotational turning by multifaceted cutters (RTMC) on the cutting point temperature under the intermittent cutting operation are examined. By employing a different geometry of the tool and selecting an appropriate tool peripheral speed so as to reduce the tool-workpiece contact time and frictions, tool temperatures and failures are suppressed. The morphology of the different types of chips generated during RTMC confirms the theoretical position of the intense fragmentation and removal of chips from the cutting zone.