Vol 76, No 1-2 (2019)

The process of forming, by means of a proposed technology, the transitional layer between a dispersed medium and a dispersed phase of a ceramic matrix composite is investigated and a method of fabricating multilayer samples modeling at the macro level the interface between phases in the direction matrix–core of the composite material is presented. A qualitative and semiquantitative analysis is presented of new phases which are products of an interaction, occuring during firing, of a core made from sludgy iron-ore wastes and a matrix made from clayey raw material.

Methods of obtaining metal nitrides are examined. The main advantages and disadvantages are highlighted for each method. The possibilities of using these materials in different industries are briefly discussed.

The influence of SnO on the physicochemical properties of low-melting glasses in the system Li₂O–SnO–P₂O₅(LSP), intended for use in compositions for vacuum-tight low-temperature bonding of different materials, was studied. The low values of T_g promoted high spreadability of LSP-glass powders at temperatures below 450°C (typical for gluing electronic articles). The mass losses upon boiling of LSP-glasses varied over a wide range (0.19 – 4.55%), and in terms of chemical resistance the glasses characterized by mass losses below about 3% surpass the lead-borate glasses widely used in solders. The values of ñ_v for LSP-glasses were raised to values characteristic for lead-borate glasses by optimizing the alkali-content ratio.

The influence of the synthesis temperature on the phase composition, size distribution, and morphology of AlMgB₁₄ particles, obtained by direct interaction of powders of elementary Al, Mg, and B with the addition of free carbon in vacuum 10 – 2 Pa at 1200 – 1400°C, was studied. The synthesized powders were analyzed by means of x-ray diffraction, SEM, EDX, and laser diffraction. The highest mass content of the main phase AlMgB₁₄ (94%) was obtained at synthesis temperature 1200 – 1300°C with 1 h soaking. Impurity MgAl₂O₄ as well as magnesium-depleted spinel and AlB₁₂ were recorded at soaking temperature above 1300°C.

It is shown that the tribological characteristics of structural steels under different conditions of rubbing can be significantly increased by depositing a layer of composite chemical coatings with nickel-phosphorus alloy with inclusions of disperse particles of the chromium, aluminum, titanium, and zirconium oxides as well as boron carbide, titanium nitride, diamond, and copper phthalocyanine. The influence of the nature, size, and content of disperse particles in composite coatings on the wear resistance of the tribo-contact was studied. The optimal conditions for depositing composite coatings with heightened wear resistance were determined.

An aluminum-graphite composite was obtained by spark plasma sintering. The graphite particle size, compaction temperature, and soaking time were shown to influence the aluminum carbide formation process. It is demonstrated that the use of larger graphite plates decreases Al₄C₃ formation by almost a factor of two. The influence of the graphite content on the density, CLTE, and thermal conductivity of the composite was studied. It was found that for graphite weight content above 70% the thermophysical properties of compacts degrade significantly because large numbers of pores are formed.

It is shown that the fabrication of large glass-fiber reinforced plastic parts by means of transfer molding technologies makes it possible to solve technical problems that cannot be solved by using other materials. The development of accessible technologies and equipment for efficient recycling of such parts will make glass-fiber reinforced plastic a sixth technological paradigm material.

Mathematical modeling is used to perform a computational and theoretical study of thermal processes occurring in regenerative heat-exchangers of glass furnaces. Recommendations for increasing the efficiency and operating life of the heat-exchangers of this type are developed on the basis of the obtained data. These recommendations can be used in designing new glass furnaces as well as in modernizing currently operating melting complexes in the glass industry.

The process of removing an organic component from composites (photopolymer/calcium phosphate) with complex architecture, which are obtained by 3D-printing in order to create personalized bioceramic implants, was studied. Ceramic materials with complex pore-space organization were obtained by stereolithographic printing. It is shown that the degree of polymerization of the composite influences the final density of the calcium phosphate ceramic materials with complex architecture.