Ilya Zhukov

Thermal Shock-Resistant Ceramic Composites Based on Zirconium Dioxide1

Changes in structure, phase composition and crystal structure parameters are studied for materials of the ZrO2–MgO system after cyclic thermal shock effects. Features are revealed for formation of ceramic structure and phase condition with implementation of internal stresses connected with a sharp change in temperature. Optimum compositions are established for refractory materials based on ZrO2 answering high specifications for thermal shock resistance and refractoriness.

Self-propagating high-temperature synthesis of energetic borides

A promising way to synthesize new energy materials based on refactory inorganic compounds is self-propagating high-temperature synthesis of compositions based on boron compounds. This paper describes a laboratory technology of production of aluminum borides. The experimental results of thermogravimetric analysis and particle size analysis obtained for synthesized powders are given. According to thermogravimetric analysis data the degree of oxidation of obtained powders exceeds 95 %. The experimental data have shown that the development of new compositions of high-energy fuel cells using borides can yield high-quality results in the sphere of solid hypersonic engines.

Plasma-chemical method for producing metal oxide powders and their application

Structure and properties of ZrO2 and Al2O3 powders produced using plasma chemical technique were studied in the framework of this research. Obtained Al2O3 powder was used for reinforcement of Al alloy. Improvement of mechanical properties of Al alloy associated with introduction of alumina particles into the melt was demonstrated.

Synthesis and Properties of Energetics Metal Borides for Hybrid Solid-Propellant Rocket Engines

In this paper, the problems of production and characterization of microsized metal borides (including aluminum, titanium, magnesium) are discussed. The preferences of application for high-energy materials are presented. The problems of chemical stability and chemical compatibility are discussed. A technique for production of metal borides is also described which is known as self-propagating high-temperature synthesis (SHS) and the subsequent mechanical treatment. The result is microsized borides which have an average size of around 5 microns with a sharp curve for distribution sizes. The purity is enough for use as fuel of high-energy materials hybrid solid-propellant rocket engines. The results of SEM, X-Ray, DSC, and TG analyses are also presented and discussed.

Regularities in the structure and properties formation of aluminum-based composites during hot pressing

The purpose of this study is to investigate the phase composition, parameters of fine crystalline structure and mechanical properties of aluminum-based composites, produced by hot pressing with different synthesis temperatures and isothermal times. For synthesis of composites we used powder mixture of aluminum (particles size 700 nm) and carbon powder in a form of nanodiamonds (size 4 nm). It has been shown that after hot press processing a nanophase (crystallites size 25 nm) of aluminum carbide was formed. Regardless of the synthesis temperature for the maximum holding time of powder mixtures, the density of hot-pressed compacts is about 2.2-2.37 g/cm3. In particular, the value of bending strength of composite samples with a density of 2.37 g/cm3 ranges from 350 to 480 MPa. In the nonporous state, the bending strength of the composites may reach 920 MPa.

On the possibility to fabricate ceramics using fused deposition modeling

The paper presents a uniquely designed device that enables controlled manufacturing of semi-fabricated products from thermoplastic ceramic suspensions by fused deposition modeling. Sintering of the products yields ceramics with high strength and hardness. We use ceramic aluminum oxide (Al2O3) as an example to prove that additive ceramic structures can be produced without noticeable boundaries between layers of the material.

Structure and deformation characteristics in magnesium alloy ZK51A reinforced with AlN nanoparticles

The aim of this work was to study the influence of nanoparticles of aluminum nitride on the structure and mechanical properties of magnesium alloy. We examine the resulting magnesium alloys. The experiment consisted in the introduction into the melt of magnesium aluminum nitride powder in an amount of 0.75 and 1.5%. Introduction of nanoparticles into the molten metal was carried out by external vibration exposure. Studies were carried out of aluminum nitride powder, comprising X-ray diffraction analysis to study the morphology using electron microscopy. Introduction of nanoparticles in the alloy increases the pore volume space from 5 to 15% and increased average pore size from 8 to 30 µm. It was shown that the presence of the nanoparticles in an amount of 1.5% increases the alloy properties by more than 30% compared with the reference (non-particulate) alloy. We were obtained diagrams such as stress - strain. It was also carried out studies of the structure and X-ray analysis of the alloys obtained.

The Use of Alumina and Zirconia Nanopowders for Optimization of the Al-Based Light Alloys

The paper presents data on the structure, phase composition and other properties of zirconia and alumina powders obtained by electric explosion of wire and plasma-chemical deposition methods. Scanning and transmission electron microscopy reveal that the nanoscale powders are composed of spherical particles and aggregates formed by these particles. X-ray diffraction is used to identify the parameters of the crystal structure of these powders. Specific surface area is determined for all powders by BET method. Powders are used to improve the mechanical properties of aluminum alloys. For the optimization of introduction reinforcement nanoparticles used ultrasonic treatment of the melt.

Influence of Wood Flour Additive on Porous Structure and Strength Properties of Moulded Alumina

The moulded Al2O3 materials prepared by mixing of thermochemically activated aluminum trihydroxide (TCA ATH) with wood flour were proposed to be used as promising porous catalyst support for various processes. A series of Al2O3 supports with different wood flour loading (0, 2 and 5 %wt.) were studied by SEM, low-temperature N2 sorption, XRD, granule strength and water-absorbing capacity. It was shown that supports were characterized by porous structure with mesopore sizes of 2-20 nm and specific surface area of 159-186 m2/g. The increase of the amount of wood flour leads to increase of the share of pore volume with wider than 10 nm and the decrease of the strength of alumina granules. Thus, optimization of preparation conditions allows obtaining alumina materials with desired porous structure.