Vol 2018, No 13 (2018)

The physicochemical and technological properties of the liquid media based on sodium, boron, and silicon oxides and containing other components are studied. The properties of the liquid media, the surface quality, and the corrosion rates of various steels and alloys to be processed in these media are found to be interrelated.

The distribution of reinforcing particles in metal-matrix composite materials is studied by different methods. The particle distributions in cast rods and coatings formed by surfacing with a nonconsumable electrode, which have different particle sizes and contents, are compared.

Two technologies of metallization of carbon ribbons in vacuum deposition and magnetron sputtering setups are considered. Titanium is used as a metallic coating. Carbon fiber reinforced plastic samples with a coupling agent based on aminopropyl triethoxysilane are prepared for comparison. The coupling agent is also applied using the following two technologies: in the first technology, it is applied onto a ribbon and is then dried; in the second technology, it is introduced into the composition of a binder. A LUP carbon ribbon and an epoxy binder are used for investigations. The carbon fiber reinforced plastics for all technologies under study are prepared using vacuum infusion. The increase in the interlayer shear strength is found to be maximal for the metallization of the carbon on a Bulat-6 setup.

A principle is proposed to form a heat-exchange developed structure with the required thermohydraulic characteristics by deformational cutting using end-to-end computer simulation. Several simulation stages, including the finite element simulation of deformational cutting, are considered using the formation of an acicular pin as an example. The discrepancy between the main geometric parameters of the pin model and a real sample does not exceed 10%.

The methods of thermal cyclic tests used for determining the thermal fatigue resistance of materials are analyzed using thermal cyclic maps (TC maps). These methods are based on the construction of the dependence of life time N on plastic strain in a cycle ε_p. An analysis showed that the dependence of N on ε_p does not give complete information on the thermal fatigue of materials, since it is built without consideration of the peculiarities of developing deformation related to their physicomechanical properties during a thermal cycle of tests. This is observed, for example, in the studies of single-crystal turbine blade materials, in which many conflicting data are obtained according to the results of testing VKNA-1V and ZhC6F alloys.

The process of casting carbonless VZhM4 nickel superalloy cooled blades with a single-crystal 〈001〉 structure on UVNK plants is developed. Model blade units with seed parts for the formation of a single-crystal structure in a turbine blade are designed, the structure of the alloy is studied, and experimental batches of single-crystal blade ingots are cast. The influence of the directional solidification conditions on the structure of the carbonless alloy and the susceptibility of the single-crystal structure of the ingots to defect formation are investigated.

The effect of refining a metal structure caused by the addition of refractory nanopowders into a liquid metal during casting and welding is described. Refinement enhances the mechanical properties of both cast and welded products made of various alloys.

The service properties of thermoplastic materials (molten adhesives) are studied to estimate the possibility of their application for repairing road-building machines. The swelling resistance of molten adhesives in working media, namely, water, motor oil, and antifreeze, is investigated. Dynamomechanical analysis is used to analyze the deformation properties of the molten adhesives. The adhesion strengths of the epoxy adhesives traditionally used in repairing machines and the thermoplastic molten adhesives are compared.

The methods of the magnetic water treatment for scale control are considered as an alternative to chemical methods.

The problems of functionality of pipelines are considered. Algorithms are proposed to calculate the functionality indices of a pipeline, which are the most important characteristics to be quantitatively estimated. The functionality of a pipeline is estimated by engineering methods, which are directly related to the main indices of erecting the pipeline with allowance for a failure flow, and this is the basis of designing a building structure.

The peculiarities of processing of the workpiece surface by a loose polishing material in the areas of small cutting depth not exceeding 1 μm are considered, and mathematical models for the impact of abrasive grain microrelief on processed workpiece surface are presented. It is demonstrated that the fracture of the surface metal layer is more brittle in comparison with microcutting of the workpiece surface by the top of an abrasive grain at a preset force and working parameters of workpiece processing by the surface protrusions of abrasive grains. This intensifies chip formation and promotes the achievement of a given surface quality.

The influence of the parameters of feeding and heating of an additional flux-cored electrode during machine hidden arc welding with an additional hot additive on the process is considered. Beads are deposited onto a 10-mm-thick steel (St3sp steel, GOST 380) plate, and the addition conditions, namely, the distance between the flux-cored electrode and the filler wire and the filler wire feed rate, are varied. The filler wire feed rate is found to depend on the electric current used for heating and to be independent of the distance between the point of introduction of the additional hot additive and the main arc. The limiting amount of the filler wire additive at which the transition from a deposited metal to the base metal is not sharp is determined.

The modern laying technologies of molding parts made of polymer composite materials are analyzed and compared, and the advantages and disadvantages of sewed fabric fillers are considered. The state of stress in carbon fiber reinforced plastic made of sewed fabric is calculated as a function of the filament thickness and step. Several stacks of carbon fabric consisting of various numbers of sewed layers are considered.

The methods of laser cementation of low-alloy tool steels by laser radiation are discussed. The results of experimental investigation of various cementation methods are presented, and the optimum cementation method providing reproducible results and commercial use is determined.

The influence of modification by ultradispersed materials on the structure and physicomechanical properties of alloys is considered. Nanostructured boron nitride and aluminum hydroxide monohydrate (boehmite) are chosen as modifying additions to study their influence on the structure formation in a zinc–aluminum–copper antifriction alloy. Scanning electron microscopy and electron-probe microanalysis are used to identify high-hardness phases in the alloy structure. Modifying particles are found to affect the hardness of the alloy, which increases significantly with the number of particles. The strength of the alloy depends on both the number and the size of introduced particles, and powders with small grain sizes are more effective to increase the strength of the alloy. Moreover, silicon carbide is shown to exert a stronger effect on the strength of silumins than alumina does.

The kinematics of the deformation zone during lengthwise rolling is considered, and the slip, retardation, and gathering region lengths are studied. The condition of absent retardation region and passage to a four-region deformation zone is determined.

Silicon is one of the most harmful impurities in nickel superalloys used for casting aviation turbines: it decreases the high-temperature strength and the ductility. The reduction of silicon from a ceramic mold is experimentally studied during the directional solidification of a single-crystal nickel superalloy.

The abrasive wear resistance of tool steel samples hardened with a multichannel CO₂ laser are tested. Laser hardening is shown to increase the abrasive wear resistance by a factor of 2.5–6. No cracks, pores, and blowholes in the laser-hardened zones are observed.

The technologies of repairing the worn parts of metallurgical equipment using plastic deformation methods, namely, expansion, swaging, upsetting, pressing, knurling, and forge-rolling, are described. Recommendations are given to choose temperature conditions in repairing the parts and determining the deformation forces.