Mechanochemical method of preparing polymer-silicate nanostructures

In this paper the advantages of application of the nanocomposite track membranes (NCTM) with TiN coating as the substrates for sample preparation for their investigation by methods of electron microscopy are discussed. This membrane material was obtained by the ion-plasma sputtering of TiN coating on the polymer track-etched membrane. The physicochemical properties of NCTM were researched. Preparation technique allows to separate nanoand microdimensional samples from dry, liquid and gas mixtures for their investigation by methods of scanning and transmission electron microscopy.

TiNb coatings were obtained by the electro-explosive doping on the surface of a titanium dental implant (VT6 alloy). The elemental and phase composition was determined by the methods of scanning and transmission electron microscopy and by X-ray structural analysis. The morphology and defective substructure of the coating were studied. Hardness and Young's modulus, friction coefficient and wear resistance of the formed coating were determined. It has been established that the electro-explosive coating is multi-element and multi-phase and possesses submicro-and nanocrystalline structure, high strength and tribological properties. It was found, that the formation of TiNb coating is accompanied by a multiple (more than 2 times) decrease in the wear parameter, i.e. wear resistance increase of the surface layer, an increase in the friction coefficient by 1.5 times, significant increase in hardness (1.5 times) and Young's modulus (1.3 times).

The elemental and phase composition, the state of the defective substructure of eutectic silumin used for engineering were studied by the methods of scanning and transmission electron microscopy. The findings of the study show that silumin is a multiphase material and comprises, along with phases based on solid solutions of aluminum and silicon, intermetallic compounds of different composition. Particles of silicon and intermetallics have diverse forms and as a consequence they can both reinforce the material or cause microcracks in the process of product operation.

A β-titanium alloy, obtained by cooling a melt at a rate of ∼ 800°C/s, has been studied by the methods of scanning and transmission electron microscopy, short-duration and long-duration macroindentation, as well as uniaxial compression in a temperature range of 20–1000°C. The alloy in the solid state contains ultrafine dendritic crystals, in the interstices between which are nanosized particles of minor phases. The alloy may be regarded as heat-resistant alloy: it possesses a high thermal stability of mechanical properties, higher values of high-temperature strength and creep resistance.

Methods of scanning and transmission electron microscopy are used to perform a comparative analysis of the structur evolution of ultrafine-grained molybdenum subjected to nickel-free annealing and to diffusion annealing accompanied by nickel penetration from the surface into the bulk of Mo(Ni) specimens. The kinetics of nickel diffusion-induced recrystallization of ultrafine-grained molybdenum in the temperature interval 1123–1223 K is investigated and the recrystallization activation energy is determined. Plausible reasons for a decrease in the nickel diffusion-induced recrystallization temperature of ultrafine-grained molybdenum as compared to its fine-grained cousin are discussed. The nickel diffusivity in ultrafine-grained molybdenum along grain boundaries is estimated on the basis of the results obtained.

The changes in the structure-phase state of the surface layer of molybdenum caused by the action of a soft-X-ray beam of energy density E<9 J/cm/sup 2/ and pulse duration 0.1 /spl mu/s were investigated by the methods of optical metallography, scanning and transmission electron microscopy. It has been found that the action of a soft X-ray beam causes the surface under irradiation to melt, produces thin films of complex-composition amorphous phases, and increases (almost doubles) the microhardness of the surface layer. The irradiation with soft X-rays has been demonstrated to be highly efficient method for enhancing the performance of materials and article. This method allows surface modification modes which, preserving the surface condition, preclude, in particular, crater formation, surface melting, etc.

The article considers laser alloying technologies of surface layers of samples made of structural steel using powder filler add-on materials based on tungsten carbide and chromium. Structural transformations, concentration changes of chemical elements, grain and subgrain structures, dislocation density, size and volume fraction of phase precipitates, causes of crack formation in treated surface layers under various alloying regimes have been studied by the methods of optical, analytical scanning, and transmission electron microscopy. It was found that the tendency to crack formation of samples after laser alloying is due to structural (crystallite size, shape factor) and concentration changes associated with redistribution of elements, in particular, chromium. Noticeable changes in the structural-phase state of the treated surfaces are observed for an optimal mode of laser alloying. This laser alloying regime is characterized by a uniform distribution of dislocations with a general decrease in their density. The sizes of phase precipitates in the surface layers are more dispersed and evenly distributed in the internal volumes of grains. These are nanoparticles with a size of 40...100 nm and larger phase precipitates (up to 1 μm).

Results of structural-morphological studies of platinum-rhodium alloy nanosized powders obtained by method of conductor electric explosion in argon are shown in the paper. Investigation results of specific surface, morphology and structure are given in the article. Optimal modes of explosion are found and described. Methods of transmission electron microscopy, scanning electron microscopy, X-ray phase analysis and BET-method were used to investigate properties.

A method to obtain films of hexane-insoluble asphaltenes from a toluene solution of medium-temperature coaltar pitch is discussed. To describe topographic, morphological and structural features of the obtained films of asphaltene associates they were studied by scanning and transmission electron microscopy methods. The surface morphology and structure of the samples were studied by scanning and transmission electron microscopy (SEM JEOL JSM 6390 LV and TEM JEOL JEM 2100). Heat treatment of the films was carried out in the presence of air in an electric chamber furnace (EСPS-10V). Elemental analysis of the samples was performed using an inductively coupled plasma emission spectrometer (iCAP 6500 Duo). Structural changes of substances and transformations were investigated by mean of IR spectroscopy (IR-Fourier spectrometer INFRALUM) in couple with synchronous thermal analysis (STA NETZSCH 409 PG Luxx). The crystal structure of the samples was investigated by X-ray diffraction. The process of thermal decomposition of hexane-insoluble asphaltenes in the temperature range from 20 to 800°C was investigated. It was found that at 495°C a process of the film substance structuring occurred. The formation of graphite-like structures during annealing of the films was observed using IR spectroscopy and X-ray diffraction.

A new transmission electron microscopic (TEM) method to determine differences between cationic polymers in solution

Influence of the nanostructure of Ti-TiN-(Ti,Al,Cr)N multilayer composite coating on tribological properties and cutting tool life

Morphology control of titanium oxides by tetramethylammonium cations in hydrothermal conditions

Methods of transmission and scanning electron microscopy and chemical microanalysis, electron diffraction, and X-ray diffraction were used to systematically study the structure and the chemical and phase composition of the Ni50Ti38Hf12 alloy synthesized by rapid quenching from the melt and subjected to various heat treatments. The critical temperatures of the devitrification of the initially amorphous rapidly quenched alloy and the B2 ↔ B19′ thermoelastic martensitic transformations have been determined. The lattice parameters of the B2 austenite and thermoelastic B19′ martensite have been measured. The main features of the formation of an ultrafine-grained structure in the alloy and the subsequent phase transformations (martensitic transformation and the decomposition with the formation of an intermetallic phase of the (Ti,Hf)2Ni type) have been studied depending on the regimes of heat treatment. Based on the results of measurements of mechanical properties upon tension (σM, σu, and δ) and the shape-memory effects (degree of shape recovery depending on the deformation by bending; and magnitude of the reversible strain erev), regimes for obtaining high-strength and plastic states of the alloy with a shape-memory effect have been established.

Data have shown that on the internal surface of reused haemodialysis membranes complement elements of plasma proteins, cells and cellular debris from the patient's blood are deposited. The aim of our study was to identify the effect of reuse on the haemodialysis membrane surface. Original and reused haemodialysis membranes were studied by the methods of light, transmission and scanning electron microscopy, immuno-histochemistry and X-ray spectrum element analysis. With reuse the membrane surface becomes uneven, and its continuity may break. Plasma protein and cellular elements are deposited on the damaged surface following continued reuse. Presence of IgM deposists were confirmed by immunohistochemical observation. Moreover, following reuse the X-ray spectrum analysis verified structural changes in the haemodialysis tube compared to the control material; accumulated aluminium, silicon, phosphorus, sulphur and chlorine were detected on the wall of the dialysis membrane.

Methods of X-ray diffraction, transmission and scanning electron microscopy, and electron diffraction have been used to study phase and chemical compositions and structure of Ti2NiCu alloys. The alloys of the quasi-binary section TiNi–TiCu, which exhibit in the initial as-cast state thermoelastic martensitic transformations B2↔B19 and related shape memory effects, have been produced by rapid quenching of the melt (melt spinning technique). The chemical composition of the Ti2NiCu alloys was varied with respect to titanium and nickel within x ≤ ±1 at. %. The mechanical properties of the alloys have been measured in the initial state and after subsequent heat treatment. The kinetics of the crystallization from the amorphous state, devitrification processes and the forward and reverse thermoelastic martensitic transformations were investigated. Their characteristic temperatures have been determined by measuring temperature dependences of the electrical resistivity of the alloys. The diagram of the dependence of the critical temperatures on the chemical composition has been constructed.