CONTENTS

 

Effect of energy fluxes on materials

 

E.V. Morozov, A.S. Demin, V.N. Pimenov, V.A. Gribkov, V.V. Roshchupkin, S.A. Maslyaev,

S.V. Latyshev, E.V. Demina, E.E. Kazilin, A.G. Koltsov, G.G. Bondarenko, A.I. Gaydar

Features of damage and structural changes in the surface layer of tungsten under the pulsed action

of laser radiation, ion and plasma fluxes......................................................................................................................................5

The main features of degradation of W surface layer under pulsed laser irradiation in a free-running

mode (power density q=105-5106 W/cm2, pulse duration t=0.7 ms) and Q-switched mode

(q=109-1010 W/cm2, t=80 ns) as well as under plasma beam irradiation in Plasma Focus (PF) device

(q=108-1012 W/cm2, t=10-100 ns) have been investigated. It is shown that there are common and

dissimilar features in W surface damages under Q-switched laser irradiation and ion PF-irradiation.

In both cases, a wavelike and droplet structures as well as thermal stress induced microcracks are

found to be formed on the irradiated surfaces and the crack propagation is promoted with the number

of influential impulses increasing. But the micropore containing areas formation was observed on

irradiated W surface only after PF-irradiation, but there are no craters occurring, while the craters

containing the areas with a micro- and submicrosized columnar structure are appeared after

free-running mode laser irradiation. It was found that Q-switched laser irradiation is accompanied

by the formation of two zones on the W surface: a central zone with the maximum density of

absorbed energy and material damage level, and a zone of weaker thermal influence. The central

zone is characterized by the surface layer intense evaporation and melting, formation of a wavelike

relief and drip structure, and craters formation with the size of up to several tens of micrometers.

In both zones, no microcrack formation is observed in the surface layer, while the effect of

deuterium ion and deuterium plasma fluxes on W in PF device is manifested in the fusion of the

surface layer and formation of microcrack network. Both types of irradiation leads to the shock

wave formation and propagation in the bulk of W. Shock wave pressure amplitude after PF plasma

impact is approximately twice as much after pulsed laser irradiation at comparable irradiation

conditions. It has been established that the process of erosion of W under the action of laser

radiation in the free-running regime proceeds more intensively than under plasma PF-irradiation.

The difference observed is due to the difference in the mechanisms of energy absorption and

transfer to the solid. When the laser radiation is exposed to tungsten in Q-switched mode, the

erosion becomes approximately the same as under PF-irradiation. It is shown that the use of PF

devices in combination with laser equipment is promising for simulation of extreme radiation-

thermal effects in materials that are typical for thermonuclear fusion devices with magnetic and

inertial plasma confinement.

 

Keywords: pulsed laser irradiation, plasma focus, surface damage, structural changes.

 

Functional coatings and surface treatment

 

N.N. Nazarenko, A.G. Knyazeva, E.G. Komarova, M.B. Sedelnikova, Yu.P. Sharkeev

Relationship of the structure and effective diffusion properties of porous zinc- or copper-bearing

calcium phosphate coatings........................................................................................................................................................19

Morphology and structure of zinc- or copper-bearing calcium phosphate coatings deposited by

Micro-Arc Oxidation (MAO) method at different voltage on Ti and low-modulus Ti-40 wt.% Nb

alloy substrates were investigated. Morphology of the MAO coatings is composed of globe-shaped

structure elements of 8-42 mm in size and pores with size of 1-15 mm. When the process voltage

is increased from 200 to 300 V, the structural elements are grown and partially destructed. It was

ascertained that the MAO voltage increasing leads to a linear increase of the surface porosity of

the coatings from 14 to 24%. Analysis of the structure led to the conclusion that the effective

diffusion coefficients of a model biological fluid in porous coatings are varied from 0.851010

to 9.01010 m2/s. With increasing of the structure element size, the coating effective diffusion

coefficient is found to be increased in coatings deposited on Ti substrate and to be decreased

for ones deposited on Ti-40 wt.% Nb alloy. The difference observed is connected with different

amount of crystalline phase in different coatings.

 

Keywords: effective diffusion coefficient, porosity, micro arc oxidation, calcium phosphate coating,

commercial pure titanium, Ti-40 wt.% Nb alloy.

 

Yu.A. Zheleznov, T.V. Malinsky, Yu.V. Khomich, V. A.Yamshchikov

Effect of nanosecond laser pulse scanning beam on the microtopography of Al2O3 ceramic coatings.....................................31

The possibility of changes in Al2O3 ceramics surface microtopography under the action of

nanosecond laser pulses has been investigated. Results of the surface modification are presented

for lasers operated in a pulse-periodic mode (10 ns pulse duration, 100 Hz repetition frequency):

ArF-excimer laser (193 nm wavelength) and solid-state Nd:YAG laser (355 nm wavelength, third

harmonic). Ceramic specimens were irradiated in air by series of laser beam (350 mm in diameter)

pulses with fluences from 0.2 to 0.7 J/cm2 with scanning speed up to 1 mm/s. Formation of new

laser-induced periodic surface structures was is to be ascertained. The surface microstructure shape

and size parameters were studied with the help of atomic force microscopy. Effects of absorbed

energy density and laser radiation wavelength on the characteristic dimensions of the structures

formed have been studied. The laser pulse fluence and wavelength were found to be the key

parameters determining the resulting surface structure dimensions. Laser treatment with a shorter

wavelength results in a decrease in the characteristic period of the microstructures.

 

Keywords: laser machining, surface, topography, ceramics

 

Composite materials

 

A.G. Meilakh, Yu.V. Kontsevoy, A.B. Shubin, E.A. Pastukhov, I.S. Sipatov

Activated sintering of Cu-Al2O3 powders....................................................................................................................................37

A technique for production of high-density composite material (Cu-1 wt.% Al2O3) by one-fold

cold compacting and sintering was developed. It is known that presence of gases in ductile metals,

e.g. copper, inhibits consolidation of powder metal products. The technique is able to succeed in

degassing of the composite material during heating in hydrogen atmosphere. The technique is based

on addition of cobalt and copper oxalates in a mixture of Cu and Al2O3. Efficiency of the technique

was estimated by the relative density and hardness values of produced Cu-Al2O3 composite materials.

Mechanism of impact of activated sintering on compaction of composite materials has been

investigated. It was established that decomposition of cobalt and copper oxalates at heating in

hydrogen atmosphere synchronizes activated reduction of copper oxides and degassing of products,

supporting permeability of composite materials. Composition of active admixture 0.5 wt.% CoC2O4

+ (2-2.5) wt.% CuC2O4 is optimized. It has been found experimentally that addition of oxalates

produces a positive impact on consolidation processes and properties of composite materials on

the base of copper and Al2O3 micro- and nanoparticles irrespective of preparation techniques:

electrolysis, evaporation-condensation, salt decomposition, precipitation and coprecipitation of

hydroxides with further reducing heat treatment and milling. Application of activated sintering of

powders obtained by hydroxides coprecipitation and compacted at 700 MPa enables the formation

of Cu-1% Al2O3 composite material with improved properties. As a result, composite material with

homogeneous structure (grain size 2-10 μm), increased values of density (8.4 g/cm3), and Brinell

hardness up to 780 MPa was produced.

 

Keywords: composite materials, dispersion hardening, activated sintering, refining, structure,

physical-mechanical properties.

 

A.G. Zholnin, E.A. Klyatskina, E.G. Grigoriev, M.M.D. Salvador, A.A. Misochenko,

P.L. Dobrokhotov, M.G. Isaenkova, M.A. Sinaysky, V.V. Stolyarov

Spark-plasma sintering of Al2O3grapheme nanocomposite......................................................................................................47

Effect of the addition of 0.5-2.0 wt.% graphene on the properties of Al2O3 nanocomposite produced

by spark-plasma sintering has been investigated. Density, microhardness, friction coefficient, wear

rate were measured on the composite specimens with different content of graphene. Fractography

investigations of the surface of wear tracks, X-ray diffraction analysis, and the temperature

dependence of the composite electroconductivity with 2% graphene measurements were carried out,

too. It is ascertained that graphene addition reduces the composite density down to 96.6% from

corundum that. Microhardness value for graphene doped composite is increased from 22.1 to

23.4 GPa. Simultaneously, the rate of wear under friction is decreased by two orders of magnitude

due to the lack of pitting of grains. Increasing the microhardness of corundum-graphene composite

as well as wear rate decreasing can be attributed to the reinforcing effect due to graphene flakes

embedding in corundum grains, especially when the single flake belongs to two or more grains.

Electrical conductivity of the sintered compacts without and with graphene is manifold increased

during heating up to almost the same values at the temperatures above 1000C. The rise of

electroconductivity of specimen without graphene begins at 500C, and at 850 conductivity

reaches the maximum value 3103 Sm/m which is by two orders of magnitude more then initial

one (2105 Sm/m). At higher temperatures the conductivity is not increased. Specific conductivity

of the composite with graphene at room temperature is an order of magnitude lower than that for

compact without graphene (1106 Sm/m), but its growth begins at 300C and the maximum is

achieved at 800C (1102 Sm/m), that is increment of conductivity is four orders of magnitude.

 

Keywords: nanopowder, alumina, graphene, spark plasma sintering.

 

A.A. Aushev, A.N. Balandina, E.N. Grishin, O.B. Drennov, A.M. Podurets, M.I. Tkachenko

Peculiarities of uniaxial and biaxial deformation of interface between metals under explosive welding.................................55

Behavior of uniaxial and biaxial deformation of a pair of metals (Cu-Ti, Cu-Al) was experimentally

studied. A process of deformation took place in a mode of explosion welding of initial samples.

Uniaxial deformation is occurred under the plates collision at an angle when the metals are bent

jointly at a point of contact. Biaxial deformation was put into effect under explosion welding of

cylindrical samples when bending deformation and radial tension of specimens takes place at a

point of its collision. Most attention was concentrated on a state of a contact boundary (weld seam).

Investigations were carried out with the help of metallographic analysis, X-ray structural analysis,

and scanning electron microscopy methods. Formation of Al2Cu (solidus temperature 548)

intermetallide precipitations was to be found is occurred under uniaxial deformation of Cu-Al pair

in the process of welding and no other compounds besides the initial materials were presented in

the seam after Cu-Ti pair welding at the same conditions. After biaxial deformation during welding,

Al2Cu, AlCu and Al4Cu9 (solidus temperature 873C) intermetallides are presented in the welding

zone for Cu-Al pair as well as TiCu2 (solidus temperature 880C) intermetallide formation takes

place for Cu-Ti pair welding. Appearance of intermetallides with high temperatures of formation

(Al4Cu9, TiCu2) is caused by a higher level of deformation of the metal plates welded under the

biaxial geometry induced by higher heating of a contact zone. It is possible to estimate the contact

zone temperature by means of analysis of composition of intermetallides formed. On the contrary,

level of plastic deformation in the weld seam can be determined by the value of crystallization

temperature of present intermetallides.

 

Keywords: explosion welding, plastic deformation, contact boundary, intermetallide,

solidus temperature.

 

A.S. Mostovoy, A.N. Ledenev

Modification of epoxy polymers by nanosized silicon................................................................................................................61

Mechanical and thermophysical properties of epoxy composition modified with nanodisperse silicon

have been investigated. It is shown that doping with nanosized Si leads to increasing the tensile,

compression, and bending strength values, rise the toughness value by a factor of five as well as

modulus of elasticity and hardness increasing. The structure formation of the epoxy composition

when in use condensation is found to be modified by the addition of the fine Si particles, which

manifests itself in an increase of the gelling time from 45 to 58 min and the condensation time from

53 to 75 min while the maximum condensation temperature does not change. Coefficient of thermal

conductivity of the modified epoxy composition increases the by a factor of 2 whereas the heat of

the polymer is reduced. An optimal content of nanostructuring Si addition is ascertained as 0.1

party by weight.

 

Keywords: epoxy resin, modification addition, nanodispersed silicon, mechanical and

thermophysical properties.

 

New methods of treatment and production of materials with required properties

 

G.N. Kozhemyakin, Yu.S. Belov, B.M. Loginov, A.N. Parashchenko, S.S. Romanenko

Microstructure peculiarities of the extruded crystals of bismuth and antimony khalcogenides................................................67

The microstructures of thermoelectric solid solution materials of p-type (Bi2Te3)x-(Sb2Te3)1x

(x≈0.26 mol.%) and n-type (Bi2Se3)x-(Bi2Te3)1x (x≈0.06 mol.%) produced by a hot extrusion

method have been investigated. The bulk crystals with diameter of 30 mm were cut parallel to

the axis using an electrical discharge machine. One cut surface of these crystal specimens with

size of 4×3×15 mm was ground abrasive with 40 μm Al2O3 and polished with 1-2 μm Cr2O3.

Polished surface was etched in a 50% HNO3 solution. Specimens structure was studied with the

use of Polyvar Met optical microscope. Crystallites with size of 1-50 μm in a p-type specimen

and size of 1-30 μm in a n-type one extended along the bulk axis were observed in the solid

solution microstructures. Intellectual program complex for more careful analysis of microstructure

photos has been developed. It was found that the larger amount of the crystallites had an identical

intensity of gray color and it indicates on their close orientation. Such crystallites orientation is

formed during the hot extrusion process. It is ascertained that these polycrystalline materials have

a high thermoelectric and mechanical properties. Crystallite size and its number on the area of

the microstructure photos were determined with the help of development intellectual program.

It was observed that the most of the crystallites have the size of 1-10 μm in p-type material and

1-20 μm in n-type one. The intellectual program complex can be used for a microstructure

analysis in the crystals and technological process improvement.

 

Keywords: microstructure, crystals, thermoelectric materials, extrusion, intellectual analysis program.

 

P.Yu. Gulyaev, M.K. Kotvanova, A.I. Omelchenko

Nanotechnologies of the treatment and preparation of transition metals complex oxides

with a high photothermal effect..................................................................................................................................................74

The results of the treatment of SHS-product of complex transition metal oxides with a high

photothermal effect have been presented which were carried out in the frame of the problem of

production of bio-functional nanomaterials on the base of nanoparticles of metal oxide bronzes

AOBy (A=K, , Na; B=Ti, Mo, W; 0<x<2; y=2, 3). By means of powder fragmentation, size

separation, magnetic separation, and functionalizing with bio-compatible gels (starch, poly-(vinyl)

-pyrrolydon), the nanoparticles (5-10 nm in size) with desired physicochemical properties as well

as the stable colloid solutions of this particles in water were prepared. Optical methods for monitoring

of the nanoparticles size in aqueous solution is developed. Optical absorption spectra of the colloidal

solutions containing the potassium-tungsten bronze nanoparticles have been measured. Monochromatic

absorption coefficients of bronze nanoparticle solutions with different concentrations of colloid (from

10 to 35 mg/ml) were defined on the wavelength of l=1.45 and 1.56 mm. The values of photothermal

effect in different bronze nanoparticles of transition metals (Ti, Mo, W) were ascertained, and it was

found the maximal effect under laser irradiation (l=1.45 mm) in K0.4WO3 nanoparticles. After

mechanical treatment of SHS product of K- and Na-bronzes of oxides of Ti, W, and Mo, magnetization

of the powder produced occurred. Temperature dependency of electroconductivity of the powder of

titanium bronze nanoparticles in the temperature range 25-270 was measured. Electroconductivity

is found to be increased by an order of magnitude at the specimen heating up to ~200C. The results

obtained are expected to be used in nanotechnology of making of bio-functional nanoparticles with a

high photothermal effect for use in biophotonics, e.g. for laser irradiation of frozen biological tissues.

 

Keywords: nanotechnology, SHS, mechanical treatment, transition metal complex oxides,

bio-functional nanoparticles, photothermal effect, laser radiation.

 

Yu.V. Sokolova, A.M. Ayzenshtadt

Evaluation of dispersion interaction in aluminum silicate system under the influence of organic additive..............................83

Dispersion interaction in aluminum silicate system (clay soil) under the influence of organic additive

(glyoxal) has been investigated with the use of the value of the surface tension at the solidsolution

interface determined by Owens-Wendt-Rabel-Kaelble method. Clay soil saponite containing (60-63%,

mean size of particles is 591 nm, specific surface is 35280 m2/kg) waste was used as a model material

extracted from the circulating water suspension of an industrial ore dressing of the diamond deposit.

Measured sizing characteristics of the model system of clay soil were compared with the literature

data and the results obtained prove conformity of the model system to real materials. An optimal

composition of organic additive for strengthening of the natural aluminum silicate systems (clay soils)

is determined. It was ascertained that a complete stabilization of organic additiveclay soil system

occurs when the content of glyoxal is 0.52% of clay soil mass. Structure SEM investigations show

that when the clay soil is stabilized by organic additive a homogeneous periodic colloidal structure

is formed due to the synthesis of a sealing layer from the organic polymer. It increases the dispersion

interaction between the soil particles.

 

Keywords: aluminum silicate system, clay soil, organic additive, glyoxal, saponite containing material,

surface tension,homogeneous periodic colloidal structure.