Vol 2017, No 13 (2017)

Various products (sheets, sections, etc.) manufactured by metal forming (rolled products, forged pieces, etc.) from semi-continuous castings are widely used in the aerospace industry. The so-called pool, which is the conical volume of a liquid metal, exists at the top of the liquid metal. Experience demonstrates that the geometry, the depth, and the shape of the pool substantially affect the structure formation in a casting and its quality. The application of a titanium nitride nanopowder, which is introduced in a melt in the volume of a rod, as a modifier allowed us to find the exact geometry of the pool.

The results of experimental studies, which are related to the regulation of the fractional composition of refractory compounds by roll milling in using controlled roll opening and unbalanced peripheral speeds of rollers, are reported. The content of prepared fine, middle, and coarse fractions is within 50–80%; in this case, the milling time of synthesis products is less than the time of ball milling by an order of magnitude. The application of roll milling for refining the products of self-propagating high-temperature synthesis can be most efficient in using together with heat-generating reactor to solve the main problem of self-propagating synthesis (SHS), which is a problem for recent several decades (the problem is the creation of intense automated production of refractory compounds in using continuous manufacturing cycle within a energotechnological system with the recovery of a great quantity of heat released during SHS).

The problem of the recycling of plastic wastes is discussed. The polypropylene needs of the modern Russian market are analyzed. The necessity of recycling of plastic wastes is revealed, and its advantages over reclamation are substantiated. The problems of a real enterprise regarding the recycling of polypropylene—polyethylene raw materials for increasing the properties of the end product and optimizing its production are considered, and methods for their solution are proposed.

The results of rheological studies of the suspensions of polyimide particles in a polydimethylsiloxane fluid are presented. The viscosity of the suspensions decreases in an applied electric field by 10–20%. This property is called a negative electrorheological responce.

This paper considers the main tendencies of development and ways of introduction of new technological solutions and alloys in the production of industrial gas-turbine unit (GTU) blades and presents a review of modern corrosion-resistant alloys, casting units for high-gradient directional solidification, and the techniques providing the preparation of a single-crystal structure in the blades of stationary turbine plants.

Aluminum alloys, the composition of which is close to the matrix alloy of a composite antifriction materials, are deposited onto a steel substrate with a 10-μm-thick zinc coating. An aluminum coating on a steel substrate is formed by manual argon-arc facing with a nonconsumable electrode, arc facing using the cold metal transfer technology, and the technology that combined these methods with remelting of the first layer. The influence of the rate of energy input in facing and the alloying elements in a filler material (silicon is used as an example) on the kinetics of formation and growth of an intermetallic layer at the interface during the deposition of an aluminum layer onto a steel substrate is studied.

The strip tension conditions that provide the possibility of transition to one-zone rolling are considered. The energy-force parameters are compared for some particular cases, and a nomogram is proposed to choose the tensions to create one-zone rolling with one forward region in the deformation zone.

The machining of the machine elements that are made of polymer composite materials (PCMs) or are repaired using them is considered. Turning, milling, and drilling are shown to be most widely used among all methods of cutting PCMs. Cutting conditions for the machining of PCMs are presented. The factors that most strongly affect the roughness parameters and the accuracy of cutting PCMs are considered.

It is shown that depth-sensing indentation can be used to perform express control of the mechanical properties of high-strength and hard-to-machine materials. This control can be performed at various stages of a technological cycle of processing materials and parts without preparing and testing tensile specimens, which will significantly reduce the consumption of materials, time, and labor.

The conditions of using a software package for studying the state of stress in the cutting element intended for cold milling of a road coating are considered. The mechanism of designing a 3D model for the cutting element and the choice of failure criteria for the cutting element are described. The state of stress is subjected to graphical analysis at various loads.

The following two methods of formation of threaded surfaces on FDM components are considered: cutting with a hand-guided threading tool in a workpiece fabricated by 3D printing and 3D printing of components with initially simulated threaded surfaces in inner and outer cylindrical surfaces. The fabrication of threaded surfaces by 3D is found to be promising as compared to cutting. Printing is shown to be adjusted so that threaded components are produced under specific conditions, which differ from the printing conditions of the base material.

Some aspects of biological sewage treatment are considered. A method for sorption purification using carbon fibrous materials is proposed to remove oil products and heavy metal ions from sewage and to improve the quality of biological sewage treatment.

A mathematical model is proposed to calculate the growth rate of the thin-film coating thickness at various points in a flat substrate surface during planetary motion of the substrate, which makes it possible to calculate an expected coating thickness distribution. Proper software package is developed. The coefficients used for computer simulation are experimentally determined.

Technologies for repairing worn abrasive tools via their modification for other sizes are described.

The mechanical and service properties of the composite materials intended for sliding bearings, which are prepared by liquid-phase impregnation of foam aluminum with B16 babbit, are tested. The alloying of aluminum with nickel, iron, and titanium is found to affect the mechanical properties of the composite materials and their wear resistance.

An analysis of the behavior of nanosized colloidal particles in a supersaturated solution made it possible to substantiate the possibility of increasing the heat-transfer efficiency in a heat exchanger during magnetic treatment of a heat-transfer agent. A model is proposed to weaken the scale during magnetic treatment of a water stream. A colloidal solution is shown to decrease its stability—the coagulation of colloidal particles begins—because of the deformation of the double electrical layer. As a result of increasing the effective radius of curvature of nanoparticles, the solution becomes strongly supersaturated with respect to forming aggregates, which accelerates the solidification of dissolved salts on them. The influence of the interfacial layer of nanoobjects decreases the energy of formation of critical nuclei (size effect) and their sizes. Since coagulation tends to decrease the concentration of critical nuclei in the solution, their loss should be compensated via the homogeneous generation of new nuclei. As a result, the concentration of suspended particles increases additionally and the antiscale effect is enhanced. The solidification flux of dissolved salts is shown to deposit mainly on suspended nanoparticles due to an increase in their total surface area and to the fact that the coefficient of mass transfer to suspension is higher than that to the wall by four orders of magnitude. The mathematical model constructed on the basis of the detected set of physical processes can be used to perform quantitative estimates of the antiscale effect in real power plants.

An alternative method for producing aluminum cast iron in a mold using the recycling of fine machine-building wastes without an external power supply is proposed. Unlike the charge used in traditional energy- and material-consumption furnace methods, the charge for the self-propagating high-temperature synthesis is a mixture of an iron scale, granulated aluminum, spilled sand, and graphite chips.