Композиты и наноструктуры COMPOSITES and NANOSTRUCTURES

V 9 #1 2017

A.V. Baikov, R.A. Korokhin, V.I.Solodilov, A.Ya.Gorenberg, V.G.Ivanova-Mumjieva, U.G.Zvereva, AM.Kuperman

EFFECT OF GLASS MICROSPHERE FRACTIONATION ON ELASTIC AND STRENGTH

PROPERTIES OF SYNTACTICS........................................................................................................................................... 1

Considered are the potentials for improving elastic and strength characteristics of syntactics by the way of diameter fractionation of glass microspheres. The sieve fractionation method was used, while the second way included the action of hydraulic pressure of varying intensity on the microspheres. Dispersion of microsphere diameters was investigated as well as compressive and shear strength of the specimens. It was shown that syntactic strength increased with decreasing glass microsphere diameter, while the density decreased with increasing diameter (p. 3-13; fig. 9).

E.A. Bogachev

HIGH TEMPERATURE STRUCTURAL COMPOSITES WITH A MINIMAL STRUCTURE CELL...................................... 12

The process to obtain high-temperature carbon-carbon and carbon-ceramic composites envisages the void(pore) filling of reinforcing preforms using matrix material. The preform pores are, usually, interfilament (not less than 1 pm) and intertow or inter-rod ones (up to 1 mm and more), which is impossible in the cases that the size of material non-homogeneities can be compared to typical part dimensions (sharp edges, thin electrodes and so on). There exist pore nonwoven base-carbon materials wherein carbon fibers have been split into filaments; however, the densities of such preforms (no more than 0.2 g/cm³) are too low for structural composites. Compacting of the nonwoven spunlaced and needle-punched preforms based on the oxidized polyacrylonitrile followed by carbonization results in carbon preform densities up to 0.55-0.65 g/cm³ and equivalent pore diameter from several microns to 30-40 pm. The preforms obtained called Ipresskon allow for producing structures out ofhigh-temperature composites having up- to-date maximum structural homogeneities. (p. 14-25; fig. 8).

Smolyanskii A.S., Biryukov Yu.G., Maslenkova E.V, Zheltova A.V., Ryndya S.M., Shvedov A.S., Minashkin V.M.

MORPHOLOGY OF THE METAL PRECIPITATIONS SYNTHESIZED BY EVAPORATION

OF MICRO-DROPS OF COLLOIDAL SOLUTIONS............................................................................................................. 24

Morphology of the metal precipitations formed by silver nano-/micro-particles, synthesized by evaporation of micro-drops of colloidal solutions of the metal nano-/micro-particles in ethanol, which were obtained as a result of controlled deposition on a silicon substrate aerosols of silver with an average particle diameter of45-50 nm in the atmosphere of ethanol vapor, has been studied by scanning electron and atomic force microscopy. It was found that the formed precipitates have a characteristic oval shape, which differs significantly from the structure of the precipitation formed during the aerosol deposition of metal particles in air. It was suggested that during the deposition of metal particles in the alcohol vapors the adsorption of ethanol molecules on the surface of silver, as well as joint condensation of the aerosol particles and the ethanol molecules have been occurred simultaneously. The result is a mist of droplets of colloidal solution of silver nanoparticles in alcohol, which are deposited on the surface of a silicon substrate followed by the evaporation process to form the clusters of 2-5 silver nanoparticles having the specific sickle shape, the totality of which had an oval structure in the scale from one to 10 pm. It was concluded that the nature of the observed phenomenon can be related to the processes of dealcoholation self-organization of metal nanoparticles, developing during the evaporation of droplets of colloidal solutions (p. 26-36; fig. 5).

Yu.A.Svirskiy, Yu.P.Trunin, A.V.Pankov, M.D.Zaytsev, V.F.Fagalov

HEALTH MONITORING SYSTEMS (HMS) AND PERSPECTIVES TO USE FIBER BRAGG

STRAIN GAGES IN HMS..................................................................................................................................................... 35

Basic approaches are proposed for HMS usage at primary PCM aircraft structure monitoring, when service life is assigned using «safe life», «damage tolerance» or both «damage tolerance» and «safe damage» rules. Test results concerning damage identification based on tensometry data and properties of fiber Bragg strain gages under cyclic loading are presented (p. 37-46; fig. 3).

V.T.Sapunov

STABILITY ANALYSIS OF COMPOSITE STRUCTURAL COMPONENTS USING A SAFETY APPROACH..................... 45

To compute the stability of bars in compression with reduction factor for longitudinal bending, we choose the one parameter Rankin’s formula. The stability lost is considered as a failure criterion. The probability of failure is then computed for bars and plates of composite (p. 47-53).

A.Yu. Sergeev, R.A.Turusov, N.I. Baurova

THE DETERMINATION OF ADHESIVE BOND STRENGTH OF JOINTS ON EXAMPLE

OF TESTING SPECIMENS USING PULL-OUT METHOD ................................................................................................. 52

The experimental results of the shear strength of adhesive binder modified with dispersed fillers are obtained. The results of samples microscopy after pull-out testing are given. It is shown that the adhesive interaction model describes experiment satisfactorily and allows to get the parameters of adhesive compound, specific to the selected pair of adhesive - substrate. The possibility of using the experimental results of the determination of adhesive bond strength by means of pull-out method in relation to repair of cylindrical machine parts is investigated (p. 52-62; fig. 7).