Preparation of nanostructured TiC x O y

Nonstoichiometric titanium oxycarbide, TiC _x O _y , nanopowder consisting of isolated stable nanoparticles with an average size of 40 ± 10 nm has been prepared by two-step synthesis from metallic titanium and oxalic acid. The nanostructured precipitate obtained by reacting titanium and oxalic acid was reduced by carbon in the process of solid-state sintering in vacuum. We examine the capabilities of this approach, which allows one to control the average particle size and composition of titanium oxycarbide.     

Dilaton-scalar models in the context of generalized affine gravity theories: Their properties and integrability

Nowadays it is widely accepted that the evolution of the Universe was driven by some scalar degrees of freedom both on its early stage and at present. The corresponding cosmological models often involve some scalar fields introduced ad hoc. In this paper we cultivate a different approach, based on a derivation of new scalar degrees of freedom from fundamental modifications of Einstein’s gravity. In elaboration of our previous work, we here investigate the properties of dilaton-scalar gravity obtained by dimensional reductions of a recently proposed affine generalized gravity theory. We show that these models possess the same symmetries as the related models of GR with ordinary scalar fields. As a result, for rather a general class of dilaton-scalar gravity models, we construct additional first integrals and formulate an integral equation well suited for solving by iterations.     

Experience in the ultrasonic testing of fastening studs in the covers of hydraulic units at hydroelectric power plants

The criteria for evaluation of the admissibility of discontinuity flaws under the threads of studs during their inspection from the end face without unscrewing them from their seat in a hydraulic unit frame are experimentally substantiated. A transducer with the optimal parameters that allows one to reveal cracks of minimal depths is selected. Ultrasonic inspection of studs with a hexahedron at the end face is used as an example and the results of the ultrasonic testing of studs with detected cracks are presented.     

Pitting Corrosion of Carbon Steel in Chloride-Containing Saturated Ca(OH)2 Solutions

Protection of Metals and Physical Chemistry of Surfaces - Pitting formation in carbon steel in saturated Ca(OH)2 solutions containing different concentrations of added NaCl is studied...     

Active Monitoring of Thermal Insulation Protection Status of Pipelines

Refractories and Industrial Ceramics - The article discusses the temperature regimes of transit pipelines for steam and hot water movement. A new device for thermal insulation of high-temperature...     

Solution to the Problem of Cleaning Autoclaves for Growing Synthetic Quartz

Refractories and Industrial Ceramics - An experimental study was performed to break down a sample of a by-product of the autoclave production of artificial quartz crystals using a pilot...     

Calculation of the variation in the work function caused by adsorption of metal atoms on semiconductors

A simple model is suggested for calculating the variation of the work function Δφ, which is caused by the adsorption of metal atoms on semiconductor surfaces. The model accounts for both the dipole-dipole repulsion of adatoms and metallization of the adsorbed layer for large coverages. The results of calculating Δφ for the adsorption of alkali metals on the Si(001) surface are in good agreement with the experimental data.     

Acoustic inspection of materials and welded joints

Processing features of a d.c. arc in helium and its mixtures with argon are considered, using non-consumable electrodes of three types, i.e. with conic grinding of the working area, butt end cavity, and bi-metal composite. Influence of the electrode working area construction and shielding gas composition on the depth, width, and penetration shape ratio, as well as on the weld seam formation quality, is investigated.     

Effect of the Sapphire-Nitridation Level and Nucleation-Layer Enrichment with Aluminum on the Structural Properties of AlN Layers

The effect of atomic aluminum deposited onto sapphire substrates with different nitridation levels on the quality of AlN layers grown by ammonia molecular-beam epitaxy is investigated. The nitridation of sapphire with the formation of ~1 monolayer of AlN is shown to ensure the growth of layers with a smoother surface and better crystal quality than in the case of the formation of a nitrided AlN layer with a thickness of ~2 monolayers. It is demonstrated that the change in the duration of exposure of nitrided substrates to the atomic aluminum flux does not significantly affect the parameters of subsequent AlN layers.