Ion nitriding in glow discharge with hollow cathode effect

The process of ion nitriding in the plasma of glow discharge under the conditions of occurrence of hollow cathode effect (HCE) is studied. The action of the HCE on the parameters of the glow discharge and on the structure and distribution of microhardness over the thickness of nitrided layers on steel 38KhMYuA and on titanium alloy VT22 is determined. Nitriding in glow discharge without HCE is performed for comparison. __________ Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 33–36, July, 2007.     

Analytical Investigation of the Dynamics of a Hydraulic Fracture Using the Principle of Incomplete Coupling

An investigation of a self-similar solution of a coupled problem on the creeping flows of a viscous fluid in a hydraulic fracture and the strain and flow in the external poroelastic medium induced by them. The process is governed by injection fluid into a well. The flow in the fracture is described by the Stokes hydrodynamic equations in the approximation of the lubricant layer. The external problem is described by the equations of poroelasticity. The variant of a uniform pressure in the fracture is considered for three-dimensional and two-dimensional cases. In the second case, a self-similar solution can be obtained in an analytical form.     

Application of TOPSIS Method in Support of Decisions Made in Staff Management Issues

Evaluation model was proposed which refers to fuzzy formalism of the personnel management issues taking account their specific characteristics. Application of TOPSIS （technique for order Performance by similarity to ideal solution） method for evaluation and regulation of alternatives based on hierarchically structured criteria of qualitative character by multiple experts to intellectually support decisions made in staff management issues is reviewed in the article. Candidate selection experiment based on criteria system formed using TOPSIS method for evaluation of candidates during solution of hiring problems reviewed and obtained results were compared with results obtained using Matlab program package.     

Atomic Layer Deposition of Aluminum Nitride Using Tris(diethylamido)aluminum and Hydrazine or Ammonia

Aluminum nitride (AlN _x ) films were obtained by atomic layer deposition (ALD) using tris(diethylamido) aluminum(III) (TDEAA) and hydrazine (N₂H₄) or ammonia (NH₃). The quartz crystal microbalance (QCM) data showed that the surface reactions of TDEAA and N2H4 (or NH₃) at temperatures from 150 to 225°C were self-limiting. The rates of deposition of the nitride film at 200°C for systems with N₂H₄ and NH₃ coincided: ~1.1 Å/cycle. The ALD AlN films obtained at 200°C using hydrazine had higher density (2.36 g/cm³, 72.4% of bulk density) than those obtained with ammonia (2.22 g/cm³, 68%). The elemental analysis of the film deposited using TDEAA/N2H4 at 200°C showed the presence of carbon (~1.4 at %), oxygen (~3.2 at %), and hydrogen (22.6 at %) impurities. The N/Al atomic concentration ratio was ~1.3. The residual impurity content in the case of N₂H₄ was lower than for NH₃. In general, it was confirmed that hydrazine has a more preferable surface thermochemistry than ammonia.     

Effect of sublimation epitaxy conditions on the properties of (SiC)<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>(AlN)<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> solid solutions

We have studied the effect of growth conditions on the growth rate, chemical composition, and conductivity type of films of (SiC)_{1 ? x} (AlN) _x semiconductor solid solutions produced by sublimation epitaxy on 6H-SiC substrates in an argon + nitrogen atmosphere.     

A microscopic study of the effect of γ-radiation on Pb1 − x Mn x Se epitaxial films

The surface morphology of n- and p-type epitaxial films of lead manganese selenide (Pb_1?x Mn _x Se (x = 0.01)) on barium fluoride substrates of the (111) orientation in the initial state and after exposure to gamma-radiation is studied by atomic force microscopy. It is shown that the surface relief undergoes modification in the absorbed dose region of 5 ≤ D _γ ≤ 35 kGy. The p?n conductivity inversion at 10 ≤ D _γ ≤ 25 kGy is found from the characteristics of the surface structures and confirmed by the electrophysical measurements. It is revealed that the radiation resistance of these films is violated at a dose above 35 kGy.     

A study of the structure and dielectric properties of nanocomposites based on polypropylene and zirconia nanoparticles

New nanocomposite structures based on isotactic polypropylene and zirconia nanoparticles are developed; the distribution of the zirconia nanoparticles is studied by optical (Motic AE 30/31) and scanning electron microscopy (Carl Zeiss). It is shown that, during the direct introduction of nanopowders into the polymer matrix, the powder nanoparticles form cluster-like fractal structures in the form of dendrites even at the first stage of mixing of the components. The electron microscopy study of the samples shows that the developed technique for preparing nanocomposites makes it possible to obtain a homogeneous distribution of zirconia nanoparticles in the matrix of polypropylene. The dielectric characteristics of nanocomposites based on polypropylene and zirconia are studied. It is found that the dielectric permeability in PP + ZrO₂ nanocomposites varies as a function of the frequency owing to the low-frequency polarization.     

Using two-stage clustering of acoustic-emission signals for the detection of weld flaws

A two-stage method for the clustering of acoustic-emission (AE) signals using their parameters and digitized shapes was considered. AE signals were initially clustered according to a set of their informative parameters; the primary clusters that were obtained using these parameters were then subjected to clustering using their digitized AE signal shape. The use of two-stage clustering for the processing of AE signals that were recorded at the moment of welding allowed the calculation time to be reduced without loss of localization accuracy.     

Effect of the structure of piezoceramics on the dielectric and strength properties of composites based on polyvinylidene fluoride

The effect of the structure of the piezoceramics on the dielectric and strength properties of a composite based on polyvinylidene fluoride was studied. It is shown that the dielectric strength ?, tanδ, and logρ_v correlate as dependent on the electric field intensity during the electric treatment. It is assumed that the correlation between the electric and mechanical strength is related to a change in the physical structure of the polymer matrix and the boundary layer of the composite components. The causes for a change in the charge value as dependent on the filler’s structure are found.