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

The effect of metal phase composition in the Fe-based + (2 % glass) powdered composites on the basic mechanical and tribological properties of the composites, made by means of sintering and hot forging, have been investigated. As a basis for the metallic phase of the composite the mixtures of iron powders with additives of graphite, B₄C, BN and Cu at different ratio were used. It was shown that at sintering of metal-glass material the reaction of glass phase with oxides on the surface of iron powder particles takes place, resulting in a change of glass phase chemical composition. The results of materials mechanical properties investigations had shown that the highest strength properties and hardness have the composites with the content of the initial powder mixture of 5% Cu and 2% B₄C, while the best tribological properties have the composites with 2% B₄C, 5% Cu and 1% BN.

In the present study the influence of the monitored type iron powder, and the process of sintering in the presence of a liquid phase on the tensile strength of the powder metallurgical samples of the system Fe-C-Cu . Research samples are subjected made of three types of iron powders – ASC 100.29, SC 100.26 and NC 100.24. Thereto is added of 0,2 to 0,8% carbon and 2,5% copper. After sintering the measured density of the samples in the range of 6,20÷7,00g/cm³. Are presented graphics, amending the tensile strength of the samples depending on their density and the concentration of copper and carbon in the iron matrix.

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 capabilities of powder hot forging for manufacturing of Fe₃Al intermetallics and effect of forging and following thermal treatment routines on their structure and properties had been investigated. Fe₃Al intermetallic powders were produced by means of thermal synthesis at 1000°С in vacuum from a mixture of Fe and Al elemental powders. Hot forging of consolidated preforms had been carried out from 1000, 1050, 1100 and 1150°С and afterwards the hot forged preforms were subjected to supplementary sintering in vacuum at 1100÷1450°С. It is foud, that thermal synthesis of Fe + 14% Al powder mixture results in formation of Fe₃Al phase. Sintering of hot forged specimens result in increasing of strength and crack growth resistance, which values enhance with increasing of sintering temperature. Otherwise the hardness of hot forged intermetallics decreases after their sintering. The influence of modes of treatment on the structure and properties of the materials was investigated. It has been established that the strength and fracture toughness of the intermetallics obtained from milled blend after hot forging had the higher values as compared with the alloy made from the batch without its milling.