A. M. Stolin

Manufacture of multipurpose composite and ceramic materials in the combustion regime and high-temperature deformation (SHS extrusion)

The results of developing the process of SHS extrusion in order to produce long dimensional products of brittle and hardly deformed powders of refractory inorganic compounds are presented. In this process, the synthesis of material and the formation of billets takes few seconds in a single technological cycle. The experimental study of the rheological behavior of SHS materials and their ability to plastic deformation at high temperature region are discussed. A review of the experimental studies concerning the issue of the structure formation and properties of extruded SHS materials is presented. The main aspects of the mathematical simulation of SHS extrusion and pressing are highlighted, which were the key to correctly understanding the regularities of the high-temperature compression and molding final products from the combustion products. There are examples of the practical application of the developed SHS extrusion method for manufacturing the long-dimensional products using new multifunctional materials, including composite ceramic materials with nanosized structural elements; materials based on the MAX phase of the titanium system, i.e., aluminum-carbon; and intermetallides based materials.

SHS extrusion: An overview

Overviewed is the state-of-art in the science and technology for extrusion of still hot SHS products (also termed SHS extrusion). Addressed are the experimental and theoretical studies on rheological behavior of materials with a limited duration of their ductility. The structures/properties of extruded materials and items are also presented and discussed. Presented are the examples of practical implementation of the process to production of rod-like electrodes for electrospark alloying from new multifunctional materials, such as nanograined cermets, MAX compounds, and intermetallics.

Hot forging of MAX compounds SHS-produced in the Ti-Al-C system

Investigated was the forgeability (extent of compression) of still hot SHS products (MAX phases) formed in the Ti-Al-C system at relatively low applied pressures (1.5–15.0 MPa in a press punch) in conditions of free SHS compression. The extent of compression was measured as a function of time delay (between the end of reaction and compression) and applied pressure. Characterized were the microstructure and phase composition of thus obtained MAX compounds.

Mathematical modeling of SHS compaction/extrusion: An autoreview

Overviewed are general approaches to mathematical modeling of SHS compaction/extrusion. Presented are some examples of successful implementation of modeling predictions in technological practice.

Nonisothermal method for calculating the mold equipment of an apparatus for compacting the hot products of self-propagating high-temperature synthesis

The existing methods for calculating molding equipment are discussed. Their common disadvantage lies in the fact that they do not reflect the unsteady-state state and the gradient nature of heat exchange during self-propagating high-temperature synthesis (SHS) inside a mold. The results of the application of mathematical modeling in the study of the temperature fields that appear in mold equipment during SHS compaction are described. It is recommended that the thermal method be used for calculating the mold equipment, and a theoretical rationale is given to justify the application of this method. The paper cites examples of calculating the wall thickness of the mold by the standard and proposed methods. It is shown that a nonisothermal calculation allows for a significant decrease in the wall thickness and, accordingly, the mass of the mold.

SHS Extrusion of Thick Rods: A Numerical Simulation

Numerically modeled are thermal conditions during the process of SHS extrusion of thick (above 3 mm in diameter) and relatively long (above 100 mm in length) rods.

Dynamics of solid-state extrusion of viscoelastic cross-linked polymeric materials

A mathematical model for the solid-state extrusion of a compressible polymeric material is developed. The novel feature of the model is the consideration of the actual rheologic behavior of the material and crosslink formation kinetics. Two types of boundary conditions at the press plunger are considered. The system of the governing equations is solved using Lagrangian coordinates. The generalized Maxwell model is used to describe the viscoelastic behavior of the material. The results of numerical experiments discussed in the study show that an unstable material flow can be observed both for high and low extrusion velocities.

Mathematical modeling of solid-phase plunger extrusion with two-stage compression of composite materials

The proposed model of solid-phase plunger extrusion with two-stage material compression is used as a basis to study the effect of process parameters and thermal conditions on the length and density of manufactured long-sized materials. It is shown that two-stage compression increases the length of an extruded material part, and there are optimal intermediate die radii for attaining the maximum length of an extruded material part. Self-propagating high-temperature synthesis extrusion is studied by the method of mathematical modeling.

Influence of Ti doping on the moldability of hot MoSi2-based composites

102 Due to rich combination of valued properties [1, 2], MoSi2 based materials are being widely used in production of high temperature electric heaters effec tive at temperatures up to 1700°C [3, 4]. In order to improve creep resistance, these materials are doped with Nb, W, and B [5, 6], but this diminishes their crack resistance [7]. Optimal balance can be reached upon alloying with various silicides, refractory metal oxides [8], and other alloying agents. In SHS extru sion, an alternative method for production of high temperature heaters, of key importance is the mold ability of still hot combustion products [9–11].

Structurally Inhomogeneous Regimes of Spreading of Film‐Forming Polymer Solutions

Results of mathematical modeling of the process of spreading of polymer materials are discussed. Viscosimetric data obtained in the experiments have been analyzed and processed with the aim of determining the rheological properties of the polymer compositions used.