Вестник СГАСУ. Градостроительство и архитектура | 2015 | № 4 (21) 108 Ресурсоэнергосбережение Подробно рассмотрены состав, структура и свойства мальтеновой составляющей дорожных битумов. Показано влияние природы сырья и способов его переработки на деформативные свойства вяжущего, а также количественное соотношение углеводородов мальтеновой фракции на его структурные характеристики.The paper thoroughly investigates the composition, structure and properties of road bitumen malthenes. It describes the infl uence of the nature of raw materials and ways of their processing on the deformation properties of the binderm and the infl uence of quantitative relation of malthenes faction hydrocarbons of their structural characteristics.Ключевые слова: битум, мальтены, углеводородные масла, смолы, ресурсо-и энергосберегающие технологии.

Many production operations in machine building and metallurgy involve the service of heating equipment operating in a broad temperature range and in various aggressive media. For example, metal billets are heated for forging at 1150-1200~ in an oxidizing atmosphere. Heat treatment is done in salt baths in molten salts of alkaline and alkaline-earth metals (NaC1, KC1, CaC12, BaC12) at 800-950~ In furnaces for chemicothermal treatment of metal a carbon-containing protective reducing atmosphere is used. The heat treatment temperature in an atmosphere of protective gases reaches 900-950~ Melting and casting equipment operates in the t100-1150~ range. The lining of such furnaces is constantly in contact with various molten metal alloys, fluxes, and slags.Failure of the linings of salt baths and melting and casting furnaces occurs in contact with molten salts and nonferrous metals, which, having a low viscosity, penetrate easily into the pores of refractories and attack them. In gas heating furnaces the hearth of the lining is subjected to intense wear as the result of the mechanical action of metal billets, variable temperatures, and scale. The scale, accumulating on the hearth surface, forms low-melting eutectics with the constituent oxides of the refractories and gradually causes failure of them.In a gaseous reducing atmosphere soot carbon, which is formed at high temperatures according to the Bell reaction[1]2CO -* CO2 + C soot has an aggressive destructive action on the lining. During service of a lining, it, crystallizing in the pores of the refractories, increases in volume, causing internal stresses, which leads to destruction of the material. It should be noted that the catalyst of the Bell reaction is iron oxides (FeO, Fe203) contained in the refractories.The "weak link" in any lining is the joints. Penetration of the liquid phase (molten material, scale) into the lining joints leads to formation of zonal structures with different physicomechanical properties, which causes spalling of material from the lining joints. The use of large refractory parts reducing the number of joints and the addition of compacting additions to such parts increase the service life of the lining but do not solve the problem as a whole.One of the promising directions making it possible to increase lining life taking into consideration the specifics of heating equipment service is the use of heat-resistant concretes. At present in heat-resistant concrete tecin~ologay increasing attention is being devoted to compositions based on phosphate binders and water glass, which are distinguished by improved production properties and high chemical resistance [2, 3]. Certain difficulties in their use have been observed, including a shortage of highly refractory raw material, the high cost of it, complexity in control of the forming process of the phosphate cement stone, and the necessity of high-temperature firing of it to obtain material with the specified properties.The authors have developed compositions of heat-resistant concretes using com...

There is a sufficiently reliable correlation between the critical coefficient of stress intensity (the main criteiron for crack resistance of materials in linear mechanics for damage to solid bodies) and the other parameters of crack resistance, in particular, the microbrittleness and the microstrength, determined by the micropressure method and simpler methods K~c=--0,297+4,26 (R=0,968), KI~=1,57~+0,40 (R=0,912).Thus, the density of the hot-pressed alumina specimens critically affects their micromechanical properties. With increase in density, the microhardness increases, and the crack resistance tends to fall. A reduction in the crack resistance is clearly connected with the reduction in the number of pores in the microvolumes of the material, which in brittle damage conditions, within the local microvolumes, are "traps" for the growing cracks.

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