Isayev K. Thermophysical properties of composite materials in wide ranges of temperatures and heating rates.

In dissertation the complex approach for determination of a thermal conductivity of different materials on the basis of experimental temperature field in samples of these materials and two methods for solving of inverse heat conduction problems is designed. The mathematical model of heat transfer in heat-shielding materials with an organic matrix is designed, in which one the process of destruction of resin and heat absorption by gas products of this process is allowed. The density of a material in a zone of resin destruction is represented by a quadratic function of temperature. The effect of heating rate is taken into account by introducing of temperatures of a beginning and ending of resin destruction, which are functions of this rate. For a quasistationary regime of heating for materials (the constancy of a surface temperature of a sample and speed of its move) an analytical solution of a straight non-linear problem of heat conduction in an implicit aspect in an integrated form with allowance of internal sinks (sources) of heat is obtained . On the basis of this solution the method for determination of a thermal conductivity of materials is designed. For its realization a measuring of temperature variation in one cross-section of a sample is necessary. The constructions of a heat-receiver which is sample of an investigated material with thermocouples and applicable heat-insulation for determination of one-dimensional temperature fields in samples of compact, superhard, heat-shielding, powdered and other materials are designed. These constructions are protected by the patents. Influence of different factors on the thermophysical properties more than three tens composites is investigated. Samples of these composites are tested in different conditions of one-way heating (convection, radiation, contact) at different heating rates in wide range of temperatures. On the basis of complex approach of materials thermal conductivity determination the automated system is designed. The Database of the thermophysical properties of heat-shielding materials and temperature fields in their samples is created.