International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

It is known that the formation of oxide nanopowders takes place in the complex process including as non-isothermal and isothermal stages. In case of powders isothermal heat treatment led to realization of sequential process at transition from amorphous state to crystalline state, in particular, dehydration, crystallization, disintegration of linked nanoparticles in amorphous matrix and ensuing growth of crystals. In this work the questions of forming of particles and ceramic based on these nanoparticles are discussed. The influence of particles characteristics which synthesized at different temperatures on kinetics of isothermal sintering is estimated. It was shown that particles size and surface characteristics influence on kind of diffusion which is realized at ceramic sintering. The possible mechanisms of isothermal stage of nanoparticles and ceramics forming are discussed.

A new approach to design of oxide ceramic-ceramic nanocomposites instead of industrial technical ceramics has been proposed. The use of mixing of liquid solutions of reagents instead of powders mixing allows entering in the matrix material the oxide dopants in supersaturated concentrations. The synthesized nanoparticles contain a potential for the formation of various structures. By the controlling of heating regimes during nanopowders sintering processes we can control the diffusion processes on the particles volume and boundaries. The decomposition of initial supersaturated solid solution during heat treatment (especially at fast sintering) can lead to formation of multilevel nanocomposite structure in the ceramic matrix with enhancing mechanical, electrical, optical and magnetic properties. It is established on the example of zirconia that even a slight amount of aluminum oxide, nickel oxide, zinc oxide leads to a significant change of the nanopowders and ceramics properties.

The results of studies on the application of complex boron coating powder method on hard alloys. Defined phase and chemical composition, thickness and microhardness of the coating on alloys.

It was established that after diffusion saturation of hard alloy in boron mixture for 4 hours formed coating with boride phases TiB, WB, CoB and WC, TiC, whose thickness is 50-60 microns. At complex saturation with boron and copper for 4 hours diffusion saturation formed coating with boride phases TiB, WB, CoB and WC, TiC and separate inclusions of copper with a thickness of the diffusion layer up to 70-80 microns.

Boriding and complex saturation with boron and copper allows in 2 – 2.5 times increase the microhardness of the surface layers of hard alloys, that in turn leads to increased wear resistance.

The results of studies wear resistance of boron coatings alloyed with Сu, V, Nb, Cr or Ti under dry friction – slip in the air, and it was determined that the best coatings are the boride layers alloyed with copper. Alloying with copper inereases wear resistance of boride layers in 3 times. When alloying of boride layers with niobium wear resistance increases in 2,8 times, with titanium – in 2,4 times, with chromium and vanadium – in 1,5 times. Wear resistance of boride coatings alloyed with copper under dry friction – slip 14 times higher than wear resistance of bronze of Cu – Al – Mn system and wear resistance increases when applying boride layers alloyed with copper.