Explosive Pressing Research Articles

МИКРОСТРУКТУРА И ФАЗОВЫЙ СОСТАВ МАТЕРИАЛОВ СИСТЕМЫ «ТИТАН-ЖЕЛЕЗО», ПОЛУЧЕННЫХ ВЗРЫВНЫМ ПРЕССОВАНИЕМ И РЕАКЦИОННЫМ СПЕКАНИЕМ

The results of a study of the influence of modes of explosive pressing of powder mixtures of titanium and iron and reaction sintering of compacts on the phase composition and structure of materials of the Fe-Ti system are presented. It has been shown that the use of 71 at. % Ti and accelerated cooling after sintering makes it possible to obtain a material consisting almost entirely of the intermetallic compound Ti2Fe.

МЕТАЛЛОКЕРАМИЧЕСКИЕ МАТЕРИАЛЫ, ПОЛУЧАЕМЫЕ ВЗРЫВНЫМ ПРЕССОВАНИЕМ СМЕСЕЙ ПОРОШКОВ КАРБИДОВ С ТИТАНОМ

The main principles of the formation of metal-ceramic materials of the Cr3C2-Ti and SiC-Ti systems during explosive pressing of powder mixtures on a steel base are considered. It has been established that the formation of strong interfaces between carbide (Cr3C2 or SiC) and titanium occurs at the temperature of heating the powder mixture as a result of shock wave compression to (0.35...0.4)Tm of the carbide phase. In this case, the chemical composition of the alloy components does not undergo changes, the redistribution of elements between phases in macrovolumes does not occur, and the hardness reaches its maximum level.

ВЛИЯНИЕ ВЗРЫВНОЙ ОБРАБОТКИ НА ТЕРМОМЕХАНИЧЕСКИЕ СВОЙСТВА И СТРУКТУРУ ВТОРИЧНОГО ФТОРОПЛАСТА-4

In order to develop a technology for processing hard-to-recycle F-4, the thermomechanical properties and crystal structure of secondary fluoroplast-4 (F-4), obtained by explosive pressing of waste in the form of industrial chips, were studied. The heat-deformation properties, phase transition temperature, and fine structure parameters in different compaction zones are determined.

Structure of the Aluminum-Fluoroplastic Framed Composites Produced by Explosive Pressing

Structure of the Aluminum-Fluoroplastic Framed Composites Produced by Explosive Pressing

Study of Structure Formation in Polytetrafluoroethylene Filled with Aluminum after Explosive Pressing

Study of Structure Formation in Polytetrafluoroethylene Filled with Aluminum after Explosive Pressing

Влияние взрывной обработки на структуру и свойства сверхвысокомолекулярного полиэтилена

With the aim of developing a technology for the explosive pressing of ultra-high molecular weight polyethylene (UHMWPE), the influence of pressure on the characteristics of the fine structure, the thermal and thermodeformation properties of the polymer has been investigated. It was established that a change in pressure when using this pressing method led to the implementation of various compaction mechanisms for UHMWPE and affected the characteristics of the polymer.

RESEARCH OF THE KINETICS OF THE FIRST HYDRATION OF MATERIAL TIFE + TI<sub>2</sub>FE, OBTAINED BY EXPLOSIVE LOADING OF MIXTURES OF TITANIUM AND IRON POWDERS

The kinetics of the processes of primary hydrogenation of material based on TiFe obtained by explosive pressing of titanium and iron powders with subsequent heat treatment has been investigated. Using the results obtained and mathematical processing of the curves using the Avraami-Erofeev equation, it was revealed that the mechanism of their saturation with hydrogen corresponds to the classical concepts of reaction diffusion. The process begins with the formation of a layer of solid solutions of hydrogen on the surface of the material in the initial phases of the material and after the latent period continues with the formation of a layer of hydride phases. t is shown that the hydrogen storage material TiFe + TiFe has a significantly higher hydrogen capacity than single-phase TiFe.

RESEARCH OF THERMAL PROPERTIES OF UHMWPE BASED COMPOSITES AFTER EXPLOSIVE PRESSING

The thermal characteristics of the initial UHMWPE and its composites with QGP and MDF, as well as those obtained by explosive pressing (VP), have been investigated. It has been established that explosive pressing leads to hindering the processes of melting and thermal destruction, which may be associated with chemical interaction, the formation of inter- and intramolecular cross-links characteristic of this polymer. UHMWPE and its compositions with 3% CHP after VP have higher melting points of the crystalline phase, thermal oxidation and thermal destruction in comparison with the starting materials of similar composition. In the UHMWPE composition with 10% MDF, no increase in thermal properties after VP was observed, similar to the original fluoroplastic.

RESEARCH OF THERMAL PROPERTIES OF UHMWPE BASED COMPOSITES AFTER EXPLOSIVE PRESSING

The thermal characteristics of the initial UHMWPE and its composites with QGP and MDF, as well as those obtained by explosive pressing (VP), have been investigated. It has been established that explosive pressing leads to hindering the processes of melting and thermal destruction, which may be associated with chemical interaction, the formation of inter- and intramolecular cross-links characteristic of this polymer. UHMWPE and its compositions with 3% CHP after VP have higher melting points of the crystalline phase, thermal oxidation and thermal destruction in comparison with the starting materials of similar composition. In the UHMWPE composition with 10% MDF, no increase in thermal properties after VP was observed, similar to the original fluoroplastic.

RESEARCH OF THERMOMECHANICAL PROPERTIES OF UHMWPE AND ITS COMPOSITE WITH QGP AFTER EXPLOSIVE COMPRESSION

To develop the technology of explosive pressing of ultrahigh molecular weight polyethylene (UHMWPE) and its powder composite mixtures with inorganic fillers, the thermomechanical properties of an unfilled polymer and a composite containing 3% coke graphite powder (KGP) after explosive pressing were studied. It was found that explosive pressing with a pressure of 0.25-1.3 gpa provides high heat resistance of UHMWPE and the studied composite (154-156 °C), and the filler restrains the thermal deformation expansion of the polymer, which is associated with increased intermolecular and adhesive interaction at the phase boundary. Thus, the method of explosive pressing can be recommended for industrial processing of UHMWPE and its composite mixture with 3 % KGP.

Thermal processes under explosive loading of amorphous alloy powders

The article deals with the state of production of bulk amorphous and nanocrystalline materials. Conditions for the preservation of the “X-ray” amorphous state in compact materials obtained by explosive pressing of amorphous alloy powders are formulated. The two-front Stefan problem is solved and it is shown that the cooling rate of liquid layers on the contact surfaces of powder particles under explosive loading corresponds to the critical quenching rate of the formation of amorphous structures in metal alloys.

OBTAINING COATINGS FROM HARD ALLOYS BY EXPLOSIVE LOADING OF MIXTURES OF CHROME CARBIDE AND TITANIUM CARBIDE POWDERS ON METAL BASES

The principal features of the mechanism of formation of coatings from hard alloys during their production by explosive pressing of mixtures of CrC and Ti powders on metal substrates are described. The phase composition and structure of coatings deposited using loading by a plane normally incident detonation wave and sliding loading are considered.

RESEARCH OF THERMAL PROPERTIES AND STRUCTURE OF UHMWPE COMPOSITES WITH β-SIALON AFTER EXPLOSIVE PRESSING

With the aim of developing a technology for explosive pressing of powder composite mixtures of ultra-high molecular weight polyethylene (UHMWPE) with inorganic fillers, the thermomechanical properties and structure of a composite containing 5% β-sialon after static and explosive pressing were investigated. It was found that explosive pressing with a pressure of 0.75 GPa provides a composite heat resistance close to that of the initial UHMWPE (142-148 °C), reducing its thermal deformation expansion, which is associated with an increase in intermolecular as well as adhesive interaction at the phase boundary. During sintering, the polymer matrix is monolithized, and higher heat resistance is achieved after sintering under pressure. The research results allow us to recommend a method of explosive pressing for industrial processing of a composite mixture of UHMWPE + 5% β-sialon.

STUDY OF THE STRUCTURE OF HIGHLY FILLED FLUOROPLAST-ALUMINUM COMPOSITES

Structure formation in fluoroplastic-aluminum composites obtained by static and explosive pressing has been investigated. The concentration of dispersed aluminum was 50 and 70% vol. In fluoroplastic-aluminum composites, after static pressing, spalling of metal particles, formed during the preparation of a microsection, was found, which indicates low adhesion of the polymer and metal. The production of fluoroplastic-aluminum composites using explosive pressing leads to the formation of a monolithic material with a high adhesive interaction of the components and the formation of a metal frame.

Structure Formation in Nickel-Polytetrafluorethylene Composite Materials upon Explosive Pressing of Powders

In this paper, we study the features of structure formation in composite materials based on polytetrafluoroethylene containing from 50 to 90 vol % of nickel that results from the explosive pressing of powder mixtures in a cylindrical ampoule. It is revealed that, at an increase in parameters of explosive pressing, a change in the structure along the pressing radius that characterized by increased deformation of the components up to their grinding and remelting in the center of the pressing with a simultaneous increase in the physicochemical interaction of the components of the composite mixture is observed.

Chemical composition and structure of interfacial boundaries in Cr<sub>3</sub>C<sub>2</sub>-Ti powder hard alloys after explosive pressing and subsequent heating

The paper presents the results of studies of the fine structure, chemical and phase composition of boundaries between the components of the Cr 3 C 2 -Ti hard alloy containing 40 wt.% of titanium bond in the state after explosive pressing, as well as after heat treatment. The powder mixture was subjected to shock-wave loading at a heating temperature of 730 °C and pressure of 14 GPa to ensure the maximum compaction and consolidation of the powder mixture without sintering. Compact specimens were heat-treated by heating from 400 to 700 ° С and holding in the oven for 1 hour followed by still air cooling. The equilibrium phase composition was calculated by numerical thermodynamic modeling using Thermo-Calc software. The structure and elemental composition were studied using FEI Quanta 3D and Versa 3D electron microscopes with an integrated focused ion beam system for foil fabrication, as well as FEI Tecnai G2 20F and Titan 80-300 transmission electron microscopes with foil transmission scanning mode. The Bruker D8 Advance diffractometer was used for X-ray phase analysis. It was shown that the formation of strong interfacial boundaries under explosive pressing of titanium and chromium carbide powder mixtures is accompanied by chemical interaction between the components with the formation of boundary layers having a total thickness of about 90 nm. There is a continuous monotonic change in the Cr and Ti content within the transition layer at the almost constant carbon content. The phase composition of layers corresponds to the equilibrium one calculated at the shock-wave compression pressure but it is thermodynamically nonequilibrium under normal conditions. When heated to 400 °C, boundary layers dissolve with the transition of Cr 3 C 2 -Ti hard alloys into a two-phase state. When heated to 700 °C, alternating layers of carbon-depleted chromium carbides (Cr 7 C 3 , Cr 23 C 6 ) and titanium carbide (TiC) form along the interfacial boundaries by carbon diffusion from the original chromium carbide (Cr 3 C 2 ) to titanium.

Technology of Production of Diamond-Abrasive Composites with Metal Matrix

The prospects of using the method of explosive pressing for solving urgent problems of creating high-performance diamond composites for instrumental purposes on binders of powders of fairly cheap materials are substantiated. Purpose of this work is to develop the technology of diamond-abrasive composites synthesis from powders mixtures of natural diamond and widespread low-cost iron-carbon alloys which combines explosive pressing and subsequent short-term high-temperature heating. The processes of varying the compositions of diamond-metal powder mixtures, the parameters of their explosive pressing and the modes of subsequent heat treatment of the resulting compacts are studied. It is shown that the use of explosion energy at the stage of powder briquetting opens up new opportunities for the production of high-performance diamond-containing materials with a matrix of iron-carbon alloy powders. This is due to the specifics of the explosive action which results in the activation of the bonding material which becomes obvious with further high-temperature heating in its intensive hardening and acceleration of diffusion processes. It is revealed that the shock waves create thermobaric conditions that allow for better preservation of the diamond component than with traditional methods of sintering. Samples of abrasive diamond composites with wear resistance corresponding to the level of wear resistance of industrial diamond dressers but with half the consumption of diamond raw materials were obtained.

Investigation of the Structure and Distribution of Chemical Elements between the Phases of Hard Alloys of the Cr<sub>3</sub>C<sub>2</sub>-Ti System, Obtained at Various Modes of Explosive Compaction

The Article presents the findings of the studies of the microstructure, chemical and phase composition of the Cr3C2-Ti system alloys obtained by the explosion. Scanning electron microscopy, energy dispersive and x-ray diffraction analyses were used. The program Thermo-Calc software was used to calculate the equilibrium phases. The phase composition of the compact was shown to fully correspond to that of the initial powder mixture during explosive pressing in the modes of heating from 300 ̊С to 600 ̊С. When heated above 600 ̊С, the chemical interaction of the initial components begins with the formation of new boundary phases. Meanwhile, there is a change in the sample destruction nature and a significant increase in hardness, which points to the hard alloy consolidation. The increase in the powder mixture heating in shock waves to 1000 ̊С leads to intensive macrochemical interaction of the powder mixture components and to formation of an equilibrium phase composition. The established temperature limits determine the most appropriate parameters of shock-wave loading when producing hard alloys by explosive pressing.

RESEARCH OF THE CRYSTALLINE STRUCTURE OF POLYMERIC COMPOSITE MIXTURES AFTER EXPLOSIVE PRESSING

The method of X-ray diffraction analysis was used to study polymer composites based on thermoplastic polymers of ultra-high molecular weight polyethylene UHMWPE with β-sialon and polytetrafluoroethylene PTFE with aluminum oxide Al2O3 after static and explosive pressing. The studies were carried out with the aim of developing explosive pressing technology for polymer composite materials with enhanced strength and antifriction properties.

RESEARCH OF STRUCTURAL CHANGES IN EXPLOSIVE PRESSING OF POLYMERIC COMPOSITE BLENDS

The method of X-ray diffraction analysis was used to study polymer composite materials with a hybrid matrix in the form of blends of thermoplastic polymers of polytetrafluoroethylene PTFE with rigid high-temperature resistant polyarylate PA filled with molybdenum disulfide after explosive pressing with a pressure of 0.9-4.6 GPa. The studies were carried out with the aim of developing the technology of explosive pressing of polymer composite materials with a hybrid matrix, filled with molybdenum disulfide, with increased strength and antifriction properties.