Viktor Mironov

Hybrid Syntactic Foams of Metal – Fly Ash Cenosphere – Clay

This paper addresses an innovative syntactic foam produced out of metal powder (Fe), fly ash cenospheres (CS) and clay ceramic syntactic foams composite material (CM). Due to the low density of CS (bulk density - 0.38 g/cm3), the average density of these foams is about 2.6-2.9 g/cm3. It was found that CS undergoes phase transformation during thermal treatment at a temperature of 1200°C. Microstructural observations reveal a uniform distribution of CS and Fe particles in the composite. Compressive strength, and friction coefficient of obtained Fe/CS CM are in the range between 149 - 344 MPa and 0.15 - 1.1, respectively. Dependence of compressive strength on firing temperature is demonstrated exhibiting the maximum at 344 MPa; however, dependence of coefficient of friction on a material properties, obtained at different firing temperature exhibits the minimum value of 0.15 at the firing temperature of 1150 °C. The obtained syntactic form was shown to be a candidate for wear resistant applications.

Ferromagnetic Sorbents for Collection and Utilization of Oil Products

This Current paper reports the research conducted at Riga Technical University and Rezekne Higher Education Institution on the development of sorbent material, which is made of closed hollow microspheres possesses ferromagnetic properties, with a large specific surface. A review and comparison of existing sorbents for oil products collection are presented. The manufacturing process of proposed sorbent are described. The structure and morphology of obtained composite sorbent are discussed. It was found that proposed sorbent allows an efficient and safe way for surface water cleaning contaminated by spilled oil products. In particular, it shows a storing effect on a thin oil film (1-2 mm). Adsorption capacity to motor oil is investigated and compared with other magnetic sorbents on metal powders base. Newly proposed sorbent demonstrates a significantly higher adsorption capacity comparing to iron powders. Sorbent saturated by spilled oil can be evacuated by means of magnetic (or electromagnetic) captures.

Illite Clay Ceramic Hollow Sphere - Obtaining and Properties

This work focuses on clay ceramic hollow spheres (CCHS) preparation using Liepa clay and sacrificial template method in a lab scale device and testing of their properties. Water retention and compression strength were investigated in order to found out if obtained CCHS can be used as an additive for improving soil resilience.The synthesis and characterization of CCHS using expanded polystyrene spheres (EPS) as sacrificial template is presented. CCHS were fired at five different temperatures and their compressive strength, water retention, bulk density, material density, water absorption, phase composition, surface morphology, porosity using hydrostaticweighing and BET nitrogen adsorption methods, were determined.Study of clay ceramic hollow sphere structure and surface morphology revealed that all samples have spherical shape. These spheres have several pronounced protrusions from the granulation process. Clay ceramic hollow spheres have porosity rate of 21 - 36% and a water absorption rate of 15 -33%. The highest rate of porosity and water absorption was observed for hollow spheres fired at 1050°C.The increase of clayceramic hollow spheresfiringtemperature led to decrease of specific surface area-thehighestvaluewas observed at950°C and the lowest at 1150°C. The bulk density increased at 1150°C.Mechanicalstrength test of ceramic hollowspheres(HS)revealedthat with the increase of scorchingtemperature the compression strength of the spheres increasedas well.The sphere hollowshadpractically globular shape with the averagewallthickness of0,6 mm, whichcomprises10-13% ofthe outer diameter.The obtained clay ceramic hollow spheres are proposed as water retention agent.

Combined Magnetic Pulsed Compaction of Oxide Ceramic Powder Materials

The paper discusses the basic methods of combined magnetic pulse compaction of ceramic powder materials. One important direction is a method that combines axial compaction of the powder, carried out with the help of a hydraulic press, and magnetic pulse compaction (MPC). Experimental studies were carried out on materials such as Al203-Si02. The influence of compaction of specific energy on the compressibility of materials has been shown. It has been established that the combined compaction allows to increase the density of the material, to improve the uniformity of properties in the bulk of the product and to reduce shrinkage during sintering.

Screen Elements Made of Perforated Steel Tape and their Application for Shielding Electromagnetic Fields

In the present work the methods for producing flat and three-dimensional shielding screens from the perforated steel tape are proposed. The possible application variants of mentioned screens are offered and analyzed. Main attention is given for producing one-layer and multi-layer screens with cellular structure due to its relatively low weight and technological elasticity – complex three-dimensional structures could be done successfully.Examples of produced shielding screens from the perforated steel tape for protection from electromagnetic fields in different frequency range are offered and tested. The efficiency of a shielding material was determined by measuring the magnetic field before and after applying the shielding material. Distribution of the magnetic field behind the shielding screen was determined by software vector mapping. Shielding efficiency was measured for 1) a three-layer perforated steel screen; 2) an one-layer perforated steel screen - shielding screen was placed in between the magnetic field source and the measurement point forming a two dimensional screen; 3) copper composite sprayed screen. During experimental investigation it was established, that a three-layer perforated steel screen application allowed the 27% reduction in the magnetic field, while one-layer perforated steel screen gave only 12% reduction. Copper composite sprayed screen reduced magnetic field by 15%.Recommendations for producing the multi-layer perforated steel screen accordingly to shielding efficiency are elaborated and laid down. The discussed material carries also ecological significance, since the material is produced by waste products (after stumping etc.). Therefore the production of such materials comes with reduced cost both in light of capital expenditures and ecological footprint.

Investigation of Hydration Features of the Special Concrete with Aggregates of Various Metal Particles

This study presents an analysis of various size metal particle waste (MP) influences on Portland cement (PC) paste hydration course, concrete sample structure densification during hardening and physical-mechanical properties. Investigations have shown that MP filler accelerates maximum heat release rate in PC pastes. MP intensifies structure development in the early phase, but slows it down in later PC hydration period. After 28-days of hardening the compressive strength of the concrete samples without MP filler is about 20% higher than of samples with MP. When in concrete composition microsilica and MP fillers are used together, compressive strength of concrete sample composition is up to 50% higher than of samples with MP filler only.

Recycling of Al-W-B Composite Material

A waste of composite material (CM), containing boron-tungsten fibre and aluminium matrix (CM Al-W-B) is investigated. A method of grinding has been used for processing of Al-W-B CM waste. This method has been carried out in several stages in order to obtain a powder with determined particle size. The milled material contains aluminium matrix alloy, boron and tungsten. The morphology of CM Al-W-B particles is described. The mechanism of disintegration and relationship between energy spent for disintegration, and a degree of milling of CM Al-W-B powder, are described. Possible applications of Al-W-B composite powder as a source material for obtaining a new composite ceramics by self-propagating high-temperature synthesis (SHS) are noted.

Non-Destructive Testing of Joints of Antifriction Parts Crimped by Pulsed Magnetic Deformation

Possibilities of non-destructive testing (NDT) methods to assess the quality of permanent joints of powder metal parts were evaluated. Antifriction bushing-bushing couples used in transport braking systems were investigated. The parts made of bronze graphite were crimped by pulsed magnetic deformation by means of electromagnetic equipment with a maximum discharge energy of 30 kJ. The gap between joint parts in the couples was assessed by ultrasonic and radiographic methods. A standard ultrasonic flaw detector Krautkramer USM-25 with an Olympus 4MHz dual-element echo transducer and an industrial x-ray apparatus YXLON EVO 200D were used, correspondingly. In first trial, both methods were equally sensitive to tight and weak connection of joints.

Combined Magnetic Pulsed Compaction of Powder Materials

Upgrading the quality of compaction of powder materials is achieved by the use of hybrid technologies when the powders are acted upon by two or more sources of loading. The present paper describes compaction of a powder under the action of static and dynamic loads. A pulse-magnetic field is used as a dynamic load. The procedure and technique of experimental researches are described. Porosity (compactness) and structure of the material are evaluated for various combinations of loads, geometrical sizes and shapes of products. The conclusion is made about significant upgrading of quality of the powder material when used the hybrid technology compared to the static compaction.

Research of Laser Cladding of the Powder Materials for Die Repair

The study of laser cladding of powder materials (H13, A11 and M2) onto the tool steel 41Cr4 and C80U was conducted with the aim to establish the influence of overlap ratio, scanning speed and powder feed rate as well as appliance of post-heat treatment on the coating quality and mechanical properties. The highest hardness was achieved for A11 and M2 cladding materials, lowest coefficient of friction – for H13 and M2 coatings. It could be recommended to apply the laser cladding at larger percentage of overlap (50%).