Physicochemical modification of heat-shrinkable epoxy polymers

An approach to the physicochemical modification of heat-shrinkable epoxy-diane polymers was considered, these polymers being used as couplings for the repair of polymer pipelines for various functional purposes. The purpose of the modification is to stabilize and improve the performance of the end couplings that are heat-shrinkable. We assessed the prospects of preparation of the products of various profiles by forming cross-linked polymers in a highly elastic state by plunger extrusion via creating favorable conditions for the orientation of interstitial fragments in epoxy-diane polymers. The starting epoxy-diane composition contained rigid and elastic components. The polymers fabricated by hardening of these compositions have both a glass transition temperature, which is convenient for operation, and high deformability in glassy and highly elastic states. We investigated the tensile strength, the elastic modulus, the failure deformation and the flaring deformation of the inner diameter of the preform of epoxy-diane polymers. Physical modification of a liquid filled epoxy-diane composition before mixing with a hardener was performed by using low-frequency ultrasonic treatment. We analyzed the results associated with the effect of combined ultrasonic treatment on the physical-mechanical and service properties of heat-shrinkable epoxy-diane polymers filled with short glass fibers.

Machinability of Heat-Resistant Titanium Alloys during Turning

The article discusses the properties and features of heat-resistant titanium alloys. The microstructure of a new titanium alloy VT41, its mechanical and service properties after various processing modes are presented. The main problems in the machining of difficult-to-machine titanium alloys are considered. The developed mathematical model of the formation of errors in turning titanium alloys, taking into account thermal deformations and dimensional wear of the cutting tool, elastic deformations of the technological system, is described. The paper presents the results of experimental research on turning of heat-resistant titanium alloy VT41 on a multi-parameter stand.

Study of the Combined Severe Plastic Deformation Techniques Applied to Produce Contact Wire for High-Speed Railway Lines

This work considers the development and the application of combined severe plastic deformation (SPD) techniques to produce contact wire with an enhanced complex of physical, mechanical, and service properties used for high-speed railway lines. This type of processing can be used as an alternative to most conventional production methods, including rolling and drawing. The proposed technique is based on the combination of radial swaging and equal-channel angular pressing, bundled with the wire-forming process. Laboratory contact wire samples with an enhanced complex of physical, mechanical, and service properties were produced during physical experiments. The composition of processed alloy samples meets modern requirements for contact wires for high-speed railways. Ultimate tensile strength of 560 ± 20 MPa, electrical conductivity of 76 ± 2% IACS, and relative tensile elongation of 20 ± 2% are achieved through the formation of a band structure. Fragments of 300 ± 20 nm were formed inside strips with the precipitation of secondary phase particles of 20–100 nm along the fragment boundaries, mainly during the aging process.

Determination of Thermo-Physical and Physical Properties of Complex Alloyed Brass

At present time complex alloyed brasses are widely used for manufacturing of parts worked in fray conditions. The mechanical and service properties of this alloys are provided by presence of different structural constituents in the structure of alloys. The wear resistance is a basic property of complex alloyed brasses. The information on actual problems in the industrial production of cast bars, semi-finished products and [ pfrts]-непонятно] of complex alloyed brasses is presented in the article. In accordance with the increasing requirements of consumers to reliability and service life of parts the complex alloyed brass Cu62Zn31.6Mn3Al2Si0.8Ni0.4Cr0.2 was proposed as a material for production of parts. The development of technology of melting and semi-continuous casting of complex alloyed brass is an important problem. Moreover, for estimation of thermal contition of ingot and simulation of the process of solidification of the ingot, it is necessary to know thermal physic and physical characteristics of an alloy. Therefore, the research on determination of heat conductivity, heat capacity and density of complex alloyed brass, depending on temperature, was carried out. The obtained experimental data can be used to thermos-technical calculation of thermal contition of ingot and simulation of the process of solidification of ingot during semi-continuous casting for the purpose of determination of technological parameters of casting.

Porous permeable metal-ceramic materials on base of iron oxides with addition of the ground complex ores

The self-propagating high-temperature synthesis (SHS) was used to obtain the heat-resistant porous permeable metal-ceramic material (PPMM) on base of the mixture composed of the alloyed steel's scale powder and the oxides of both metals and complex ore (monazite). The prepared SHS-material can be used as the catalytic agent for the diesel's exhaust gas purifcation. However, instead of the expensive rare-earth elements (REE) cerium and thorium the ground complex ores containing these REE can be used. The influence of the monazite's content up to 18 wt. percents on the physical, mechanical and service properties of the prepared materials were regarded in the article.Ill.8. Ref. 17. Tab. 2.

THE INFLUENCE OF TECHNOLOGICAL PARAMETERS OF LASER SURFACING ON THE PROPERTIES OF NiCrBSiC-WC COMPOSITES

It was investigated the influence of technological parameters of laser cladding on the thickness of the carbide composite coatings with similar composition and properties of matrix and different types of reinforcing inclusions (spherical tungsten carbides (WC) and recycled carbides). Special attention is paid to physical-mechanical and service properties of the composites such as hardness and resistance to abrasive wear. It is established that the thickness of the carbide composite coatings increases with increasing laser power and flow rate of the carrier gas, and with decreasing speed of the laser and the step of cladding. The study showed that at the addition of 50 wt.% WC matrix has smaller hardness values 540-560 HV, which allows to obtain the structure of the carbide composite coatings without cracks. At the same time, at addition of 80 wt.% WC matrix has higher hardness 670 HV, which does not provide the structure without cracks. Resistance of composites NiCrBSiC-WC to cracking, as well as their wear resistance, increases with increasing content of tungsten carbide. The wear resistance of the coatings received from powder Technicord 655-SL, with a reinforcement by recycled carbide, comparable to that for coatings from spherical tungsten carbide Tekmat WC-125. Coatings NiCrBSiCWC, obtained by laser cladding, are used to increase the service life of the equipment telemetering systems, in particular, it is possible to prevent of abrasion and provide of increasing the service life of the contact pads of the equipment for measurement while drilling.

Fatigue Behaviour of S235JR Steel after Surface Frictional-Mechanical Treatment in Corrosive Environment

In the paper low (LCF) and high cycle fatigue (HCF) behavior of the S235JR low alloyed steel after surface frictional-mechanical treatment in a corrosive environment (3.5 % NaCl ) has been presented. The treatment was used in order to improve mechanical and fatigue properties of the steel Obtained research results indicate an insignificant improvement of mechanical and service properties of the strengthened steel under the conditions of corrosion at constant load. Under variable loads and operating corrosion, fatigue strength results of the steel do not unequivocally confirm a favourable effect of the applied treatment. It is particularly noticeable in the range of low-cycle fatigue.

Influence of Intermetallic Phases on Fracture Resistance of Silumins

In secondary aluminium alloys iron is the main detrimental impurity. It forms intermetallic phases which have lamellar shape, high brittleness and weak crystallographic conformity with the matrix. In the work the influence of intermetallic phases on the initiation and propagation of microcracks, mechanical and service properties of aluminium alloys has been investigated.