R. A. Apakashev

Utilization of Alumina Calcining Furnace Dust Containing Nanoparticles

A rational method is considered for utilizing alumina calcining furnace dust containing nanoparticles based on using technogenic alumina dust as a basic abrasive material component for decorative treatment of a natural stone surface.

Formation of Aluminum Matrix Composite Material with High-Temperature Reaction of Al–SiO2 System Components

Results are presented for a study of aluminum chemical composition and structure after reaction with silicon dioxide refractory material. It is established that high-temperature reaction of Al–SiO2 system components is accompanied by refractory working surface breakdown and formation of aluminum matrix composite material containing silicon microparticles.

Use of Economic Mineral Hydraulic Mining Technology for Expanding the Raw Material Base for Refractory Manufacture

The problem is considered of including in the raw material base for manufacturing the main refractory products hydraulically mined economic minerals (quartzite, sandstone, refractory clay, kaolin, bauxite, sillimanite, serpentinite, bischofite, etc.). It is noted that the specific nature of hydraulic mining gives rise to the possibility of comprehensive use of natural raw material components and simplified preliminary preparation technology for use within the composition of refractory objects. A mechanized hydraulic device is proposed for mining economic minerals, effective for enriching and classifying sand and clay mixtures in flooded sand, and sand and gravel deposits.

Capturing Nanoparticles in Alumina Production

The movement of charged dust particles of different sizes in an electrostatic precipitator is studied. It is found that such particles acquire different velocities before they are deposited in the precipitator. They differ significantly from one another in the curvature of their trajectories, which makes it easier to precipitate nanoparticles from the general dust-air flow. A unit is proposed for capturing the nanosized fraction of dust particles in the upward pneumatic transport of bulk materials during alumina production.

Results from Study of a Pneumatic System for Transporting Nanoparticle-Bearing Lime Dust at the Serov Ferroalloys Plant

A description is presented of the system used by the Serov Ferroalloys plant for the pneumatic transport of lime dust that contains nanoparticles. The morphology of the particles of well-burnt lime is discussed. Recommendations are given on ensuring stable operation of the system and subjecting the dust to additional comminution.

Study of the Interaction of Molten Aluminum with the Contact Surface of a Quartz Refractory

Results are presented from studies of the kinetics of the reaction in which silicon is reduced from silica by molten aluminum. The micro- and nano-structure of molten aluminum in contact with the surface of a quartz refractory were also investigated. It was established that at 985 K the contact reaction between the components of the heterogeneous system Al-SiO2 takes place at an average rate of 5.7 × 10–1 moles/(m2·sec). It is shown that the aluminum matrix structure which crystallizes in this system is characterized by the presence of micro- and nano-particles of silicon.

Energy-Saving Synthesis of Very Fine Tungsten Carbide Powder

An energy-saving method is proposed for synthesizing very fine tungsten carbide powder within which the starting tungsten-containing raw material used is ammonium paratungstate, pressed with carbon-containing material. The tungsten carbide preparation method proposed provides marked energy saving as a result of reducing temperature and starting reagent heating duration. Predominance of tungsten carbide particles in synthesized material is demonstrated, corresponding to two main size ranges: 100 – 200 nm and 2.0 – 8.0 μm. Clear facets are typical for particles of the micron range, missing from nanosize particles.

The Effect of Nanostructuring on Physical and Mechanical Properties of Metallic Materials

The effect of nanostructuring on physical and mechanical properties of metallic materials is studied. It has been established that the tested samples of nanostructured metal materials exhibit the specific strength and durability enhanced by 11-32 % which at the corrosion rate less than about 11 %. In the example of titanium at 1000 K is shown that the thermal diffusivity of nanostructured metal is 1,2 times lower than in conventional polycrystalline state.

The Effect of Directional Flow of Metallic Melt on the Structure of Cast Metal

There was studied the effect of directional flow of metallic melt on the forming of the structure of an ingot. Authors found out the possibility of the forming of micro- and nanostructures of solid metal by treatment in a molten state without the use of alloying elements and with negligible energy consumption on the deformation.