STUDY OF THERMOMECHANICAL PROPERTIES OF UHMWPE

The paper presents comparative studies of the thermomechanical properties of ultra-high molecular weight polyethylene (UHMWPE) and its composite containing 0.5% coke-graphite powder (CGP). It was found that explosive pressing with a pressure of 0.25-0.6 GPa provides high heat resistance of UHMWPE and the investigated composite (154-156 ° C). The heat resistance of the composite decreases to 143-145 ° C, but it is higher than that of a similar material after static pressing (128 ° C).

Studies of the Influence of High Temperatures and Aggressive Media on the Performance Properties of O-Rings Used in the Automotive Industry

The paper provides the results of the studies on the influence of high temperatures and aggressive media on the performance properties of O-rings having one name but made by different manufacturers. O-rings by supplier No. 1 are made from fluorosilicone rubber, and O-rings by supplier No. 2 are made from fluororubber. The analysis of O-rings showed that the color of O-rings made from fluorosilicone rubber changed and their physical mechanical properties decreased after operation when subjected to G-energy Si-OAT and G-energy SNF coolants. The comparative analysis of TGA curves of O-rings showed that O-rings made from fluororubber were more heat stable than O-rings made from fluorosilicone rubber, i.e. they can withstand higher operating temperatures in an air atmosphere. Fluoroelastomers can recover quickly and are used to manufacture products which should have a high heat resistance during operation and high resistance to aggressive coolants.

Heat Resistance of Steel N8G6M3FTB Obtained by Surfacing Cored Wire

The operational reliability of rolling production tools depends on the heat resistance of the steel from which they are made. To increase the performance of the rolls, a hardening surfacing with wear-resistant alloys is used. The effectiveness of the applied hardening technology depends on the functional characteristics of the deposited metal. The aim of the work is to study the tempering resistance in the state after heat treatment of the deposited steel (Fe-C-Ni-Mn-Mo-V-Ti-Nb system). It was established that the thermal resistance coefficient of steel 15N8G6M3FTB at temperatures from 650 to 800 °C varies from 0.76 to 0.66, which exceeds the heat resistance of steel 30Kh2V8F by 1.5 times. It is shown that in the fine structure of such a metal after tempering at 800 °C, large amounts of finely dispersed precipitates are observed. These precipitates have a rounded shape up to 100 nm in size and belong to the Laves phases - Fe2Mo, Fe2Nb, and Fe2Ti. The obtained high heat resistance values of 15N8G6M3FTB steel make it possible to recommend it for creating surfacing materials. Flux-cored wire based on this steel can be used for hardfacing hardening of tools operating at temperatures up to 800 °C inclusive.

CURING OF DIGLYCIDAL ESTERS OF BISPHENOLS WITH AMINE HARDENERS

The effect of hardeners on the properties of cured epoxy polymers is studied. For the purpose of synthesis of polymers with increased thermal properties. Theglycide esters of polycyclic bisphenols synthesized by us were used as a diol component. Since the thermal and heat resistance of polymers, in addition to the chemical structure of bisphenols, also depend on the structure of the hardener used, amine hardeners of different chemical structure are used to improve the thermal parameters of polymers, both heat resistance and heat resistance. The influence of the chemical structure of these hardeners on the properties of epoxy polymers is studied. Cured epoxy polymers are characterized by high heat resistance. High heat resistance results are obtained by 4,4′-diaminodiphenylsulfone, benzidine, 4,4′-diaminodiphenyloxide and other aromatic diamines. Polymers obtained by curing with these hardeners are deformed in the temperature range of 220-245°C. The use of the above hardeners gives high results in terms of heat resistance. In all cases, the polymers obtained on the basis of these hardeners decrease in weight by 10% in the temperature range of 340-400°C.

GEOMETRICAL–TOPOLOGICAL CHARACTERISTICS OF THE SUBSOLIDUS STRUCTURE IN THE MgO – Al2O3 – TiO2 SYSTEM

Among the materials that attract attention from the point of view of creating refractory products with increased heat resistance, one can single out materials based on compositions of the MgO – Al2O3 – TiO2 system. As a result of the thermodynamic analysis of the MgO – Al2O3 – TiO2 system, it was found that the partition of the system into elementary triangles will change in three temperature ranges: I – up to 1537 K, II – in the temperature range 1537 – 2076 K and above 2076 K. It has been established that up to a temperature of 2076 K there is a concentration range of spinel phases: magnesium aluminate spinel – quandylite. Above 1537 K, there is a concentration range: tialite – karroite, which meets the requirements for materials with high heat resistance. The elementary triangle TiO2 – Al2TiO5 – MgTi2O5 can be used to obtain heat–resistant materials based on Al2TiO5 stabilized by MgTi2O5. To obtain heat–resistant periclase–spinel materials, an elementary triangle Mg2TiO4 – MgAl2O4 – MgO is recommended, in which only compounds with a cubic crystal lattice are present. Thus, the division of the MgO – Al2O3 – TiO2 system into elementary triangles and the analysis of the geometrical–topological characteristics of the phases of the system made it possible to select in the system under study the regions of compositions that have optimal properties for obtaining materials with the specified optimal properties.