Porous Structures and their Effect on Thermophysical Properties of Thermal Protection Elements

Abstract

The improvement of the thermal insulating material thermophysical characteristics of the thermal protection elements by studying the porous structure is a promising direction of research. The article describes the effects of the porosity and coupling of the porous structure on the thermophysical characteristics of thermal insulating materials. The article uses standard systematized techniques and instruments of scientific research applied in thermophysics. The research methodology of highly-porous material thermophysical properties is based on performance of empirical laboratory investigations of the samples obtained. It was found that for the pore structure effect on the material characteristics it is rational to use the following complex indices: porosity, number of pores, pore position in space, the pore form, pore formation energy. The article shows the effect of the porous structure on the thermophysical characteristics of the material. The complex parameters of the porous structure, which will allow to develop a new method of control of the porous structure, are proposed. As a result of the experiment planning method, the regression equation of an effective coefficient of thermal conductivity for porous thermal protection structures was developed. It was established that for a more even distribution of the mixture in a volume it is necessary to minimize the size of the dispersed components, thereby increasing the area of their contacts. The experimental method revealed that the moisture evaporation caused the formation of pores inside the clay. The shape of the pores was determined using electron microscope MMP-2P, both on the sample section and surface. The clearest clay has the greatest porosity (no iron oxide and calcium oxide). The pores have a spherical shape in it. The presence of impurities reduces the material porosity due to the increased clay viscosity.

The research thermoplastic deformation modes of dual-phase special alloys for obtaining rational intermetallic structure

“…High-temperature synthesis of the intermetallic compound γ-TiAl in a powder mixture of pure elements in the conditions of thermochemical pressing at a thermal explosion at a minimum external pressure on the mixture allows obtaining an intermetallic synthesis product with an average grain size of ~ 30 μm. An increase in the degree of plastic deformation of the intermetallic product synthesized under pressure in the conditions of the thermochemical pressing allows to reduce the size of the grain in the final product by an order of magnitude and even to form a sub-microcrystalline granular structure in the intermetallic alloy [12,15]. The graphical interpretation of calculated results is shown on Figure 3.…”

“…On the basis of the results of the above papers [5][6][7][8][9][10][11][12][13][14][15] and the earlier self-study results of the thermochemical pressing process [5,6,14], an attempt was made to determine the basic patterns of deformation and structure formation, to determine the ways and methods of controlling the processes of forming the structure and properties of compressed articles under conditions SHS In order to solve the problem, the method of mathematical modeling is used, in the implementation of which can be conditionally distinguished the following main stages: the idealization of internal properties of the given process (object) and external influences (construction of the physical model); mathematical formulation of the behavior of a physical model (construction of a mathematical model); choice of method for studying a mathematical model and conducting this research; analysis of the obtained mathematical result.…”

Minimization of Energy Consumption of Vortex Devices for Granulation of Materials

“…An important issue in the study of the processes of creating granular materials in vortex devices is the formation of symmetry of the vortex flow, which is usually achieved by increasing the number of outlets (Koshlak & Pavlenko 2019). Work (Pavlenko & Koshlak 2015) investigated the formation of an axisymmetric vortex ring by pulsed liquid pushing through a cyclone chamber. An idealised model of circulation, momentum, and energy was developed that ensures the symmetry of the forces of a multicomponent mixture.…”

“…Considering that the main kinetic energy of turbulence belongs to large vortices (Pavlenko & Koshlak 2015) and that disperse impurity significantly reduces the turbulence energy, the turbulence energy of large vortices can be accounted for through the vortex drag.…”

Production of Titanium-Based Alloys by Metallothermic Reduction of Oxide Titanium-Containing Raw Materials

“…In this case, the titanium waste reaches 45 -65% [5]. Ti-Al alloys are widely used in alloying and modifying aluminum and its alloys [6], in production of valves in automobile engines [7,8], as heat-resistant, corrosion-resistant and wear-resistant coatings [9,10], and as a filler material for arc welding [11], since titanium aluminides are easily crushed to a powdery state. Titanium aluminides are also used for the manufacture of catalysts [12], getters and Raschig rings for rectification columns [13], as a reducing agent in metallothermic processes in the preparation of ligatures for titanium alloys [2], as additives to carbon-graphite materials to improve the crystal structure and so on.…”