The article is devoted to ranking of quality criteria for multiparameter, multicriteria production technology of lightweight concrete depending on their significancy using fractal formalism. The proposed approach allows to determine the operation area of stability of the physicomechanical properties of expanded clay concrete with preset technology parameters depending on the size of their self-similarity area and to control the technological process relative to the determine parameter - watertightness. For concrete thin-walled hydraulic structures watertightness is one of the main indicators of quality, ensuring the durability of structures. In the experiment conducted on 15 points optimal plan, 3 factors of the composition varied: sulfate-resistant portland cement, silica fume, water reducing admixture. Possibility of ranking the indicators of W/C and physicomechanical properties of expanded clay concrete depending on the variation of concrete mixture components is shown. Stability of physical and mechanical properties of expanded clay concrete is necessary to ensure its durability and accordance with design requirements. Expanded clay concrete similar to those described in this article can be used in reinforced concrete shipbuilding to reduce weight of structures.

The development of modern technology requires a constant increase in reliability and durability of products. Widely used in the practice of domestic and foreign engineering coatings from electrolytic chromium for several hundred hours are triggered, they are unsatisfactorily working on friction and wear at high temperatures. The subject of the study were powder materials based on nickel PG-SR3 and PG-SR4. The work is devoted to the study of the formation of gas-plasma coatings on parts of the cylinder-piston group of internal combustion engines using self-fluxing powders based on nickel, as well as the structure and properties change after coating sputtering, its reflow, subsequent hardening. The purpose of this work is to study powder materials applied to the working surfaces of piston rings by gas-thermal spraying. The object of the study are processes of formation of the structure and properties of coatings from powder materials. The presence in the deposited layer of a solid solution based on nickel, carbide phase, borides of chromium and nickel, chromium silicides is established. The greatest macro- and microhardness is possessed by fused layers containing the greatest number of strengthening phases. The conducted researches and industrial tests allowed to introduce the coating into production.

For the manufacture of parts and assemblies of the turbopump unit of details of power equipment, welded joints with corrosion resistant steels and heat-resistant alloys are used, requiring various modes heat treatment to achieve the required level of mechanical properties. In the manufacture of parts and assemblies of details of power equipment at the machine-building enterprises of Ukraine, it became necessary to replace semi-finished products. It is necessary to replace sheet products from high-alloy alloys ХН67МВТЮ and 06Х15Н6МВФБ with one alloy with a high complex of physical and mechanical characteristics. In the work, as a replacement for the applied heat-resistant alloys, Inconel 718 alloy welded to 316L steel. Samples of welded joints, processed according to the recommended mode, showed increased corrosion resistance.

Feasibility of application of multifractal theory for evaluation of materials mechanical properties, cast iron in particular, has been considered. The proposed method enables evaluation of mechanical properties of materials based on determination of their sensitivity to dimensions of structure elements from the multifractal Renyi spectrum. Sensitivity of cast iron ultimate strength to informational dimension of carbides, ultimate bending strength to fractal dimension of carbides, impact strength to correlation dimension of carbides and hardness to fractal dimension of graphite have been determined. Fractal prediction models of quality characteristics of cast iron based on the analysis of the following its structure elements (carbides and graphite) have been received.

Ключевые слова: чугунные валки, механические свойства, микрострук-тура, область самоподобия, фрактальный формализм.У роботі проведено оцінку критеріїв якости багатопараметричних техно-логій. Запропонований підхід уможливлює, залежно від величини облас-ти самоподібности визначального параметра, оцінювати ступінь значу-щости критеріїв на прикладі визначення їх для сортопрокатних чавунних валків.Ключові слова: чавунні валки, механічні властивості, мікроструктура, область самоподібности, фрактальний формалізм.In the article, the quality criteria of multiparametric technologies are analysed. An approach allowing estimating a significance of the criteria depending on the size of the area of key parameters' self-similarity is proposed. As an illustrative example, this approach for the case of cast-iron rolls is used.