A. K. Radchenko

Process Approaches for Producing Complex Composite Inoculants by Rolling of Powder Mixtures. I. Inoculant Powder Mixtures. Composition, Structure, and Properties

This series of papers are devoted to the development of process approaches for producing complex composite inoculants to manufacture agricultural machines from spheroidal graphite cast iron. Complex composite inoculants as strips and their fragments can be produced by rolling of powder mixtures. The first paper justifies the choice of inoculants and characterizes the starting powders they consist of. Weight and volume correlations between the brittle and ductile components for different compositions of inoculants are calculated. It is established that all powder compositions belong to critical systems that have approximately 50 vol.% of both brittle and ductile components. Such systems require special process approaches to make high-quality products. Process characteristics of the powders that influence the quality of the rolling strips are determined. These are apparent density of the starting powders and their mixtures, friction index (Hausner ratio), and shear angle and its tangent.

Process Approaches for Producing Complex Composite Inoculants by Rolling of Powder Mixtures. II. Compacting Conditions, Structure, and Properties of Two-Component Model Systems Fe–FeSi and Al–FeSi

The optimization of compacting processes for two-component model systems consisting of brittle and plastic components is discussed. Fe–FeSi and Al–FeSi compositions with different volume content of the plastic component are tested. The compaction is conducted by pressing with different compacting force. Mechanical properties of cylindrical compacts are determined by axial compression test and the Brazilian test. It is established that the content of brittle component must be ≤ 60% and the compaction force must be ≥ 400 MPa. With increasing compaction force, the strength of the compacts increases significantly. It is established that the application of both iron and aluminum as binder is acceptable. However, iron and aluminum compositions are the best for low and high content of the brittle component, respectively.

Optimizing the Thermomechanical Processing of Spray-Formed Corrosion-Resistant Steel

The structure and properties of spray-formed corrosion-resistant steel 95Kh18 with subsequent thermomechanical processing are investigated. The optimal conditions for steel deformation and heat treatment are established. With increasing temperature of the rolled hot forming from 800 ± ± 20°C to 1100 ± 20°C, the steel impact strength increases from 80 to 260 kJ/m2.

PROCESS APPROACHES FOR PRODUCING COMPLEX COMPOSITE INOCULANTS BY ROLLING OF POWDER MIXTURES. III. PRODUCTION AND PROPERTIES OF MULTI-COMPONENT COMPACTS AND ROLLED STRIPS OF POWDER INOCULANTS WITH DIFFERENT COMPOSITIONS

The formation of inoculants by pressing and rolling is studied. To obtain process-strong inoculant billets (moldings), optimal routes for the formation of mixtures containing brittle materials that the complex inoculants consist of (up to 60 wt.%) are worked out. It is established that the decrease in the apparent relative density of the powders of ductile components allows decreasing the total content of the latter. The application of large diameter rolls allows obtaining thicker strips, whose strength and density greatly exceeds the required processing strength of the moldings. The increase in the final strip thickness allows increasing the weight of the billet and, therefore, increasing the process efficiency. The powder rolling ensures the production of 5–6 tons of inoculants per month using a 500 mm roller mill.

Socially-parasitic Myrmica species (Hymenoptera, Formicidae) of Himalaya, with the description of a new species

Abstract A new socially-parasitic species, Myrmica latra sp. n. is described based on a queen and male from Indian Himalaya. Its queen differs from other species by the distinctly narrower petiole and postpetiole, blunt and non-divergent propodeal spines, and a darker body colour. The taxonomic position of the three known Himalayan socially-parasitic Myrmica species is discussed, and Myrmica ereptrix Bolton 1988 is transferred to the smythiesii species-group. It is supposed that Myrmica nefaria Bharti 2012 is a temporary social parasite, but Myrmica ereptrix and Myrmica latra sp. n. are permanent social parasites, and a key for their identification is provided.

Multilayer Steel Composite Prepared by Rolling

Two types of multilayer material have been studied: a self-sharpening composite with a wear-resistant layer in the middle and soft outer layers, and a layered macrocomposite made by alternating two layers with a different graphite content. It is established that the powder rolling method and appropriate thermomechanical treatment make it possible to prepare materials with markedly different layer-by-layer hardness and high hardness for the pearlitic component. These materials may be used for preparing cutting tools with a self-sharpening effect and high operating life.

Behavior of multilayer steel-bronze composites on frictional loading

Tribological aspects are examined for layered composites made by consolidation. Dry friction tests at sliding speeds of 1.6–4.3 m/sec show that this multilayer antifriction material is better by 1–2 orders of magnitude in wear resistance than the initial material. The multilayer composite can withstand a load increased by an order of magnitude without losing its viability under the conditions of surface-structure adaptation.