Wear Mechanism and Failure of Carbide Cutting Tools with Nanostructured Multilayered Composite Coatings

The aim of this work is to study physical and chemical properties of nanostructured multi-layered composite coating based on three-layered architecture, deposited to a carbide substrate, as well as to study the mechanism of wear and failure of coated carbide tools under the conditions of stationary cutting. The coating were obtained by the method of filtered cathodic vacuum arc deposition (FCVAD). Here, the microstructure of coating as well as its hardness, strength of the adhesive bond to the substrate, chemical composition and phase composition were investigated on a transverse cross-section of experimental samples. The studies of cutting properties of the carbide inserts with developed coatings was conducted on a lathe in longitudinal turning of steel C45 (HB 200). The analysis of mechanisms of wear and failure of coated tool was carried out, including the processes of diffusion and oxidation in the surface layers of the coated substrate. Tools with harder and less ductile coatings showed less steady kinetics of wear, characterized by sharp intensification of wear and failure in transition from “steady” to drastic wear, i.e., at the end of the tool life. The X-ray microanalysis showed a considerable increase in oxygen content in the transverse cracks in the coating

ВПЛИВ АКСІАЛЬНОГО МАГНІТНОГО ПОЛЯ НА ПРОПЛАВЛЯЮЧУ ЗДАТНІСТЬ ДУГ З ВОЛЬФРАМОВИМ КАТОДОМ У АРГОНІ

The paper presents data on the effect of the axial magnetic field on the melting ability of the direct polarity arc that may be used in welding using tungsten electrode in argon.Приведены сведения о влиянии аксиального магнитного поля на проплавляющую способность дуги прямой полярности которые могут быть использованы при сварке вольфрамовым электродом в аргоне.Наведено відомості про вплив аксіального магнітного поля на проплавляючу здатність дуги прямої полярності які можуть бути використані при зварюванні вольфрамовим електродом в аргоні

Specific features of the study and maintenance of a potato collection threatened by viruses and virus-like diseases

Background. The article deals with the problems faced while studying and maintaining a collection of plant genetic resources against a strong virus infection background.Materials and methods. The data obtained during 8 years of monitoring over 1000 potato accessions for the incidence of virus diseases are presented. The work was carried out at Pushkin and Pavlovsk Laboratories of VIR and at the Polar Experiment Station of VIR (Khibiny, Arctic Circle). Visual control of the symptoms of the infection was combined with an enzyme-linked immunosorbent assay (ELISA) for potato mosaic viruses Х, S, M and Y.Results and conclusions. For many years, the global collection of VIR has been studied and maintained under a threat of strong virus infections. Among the viruses that have the widest distribution and cause significant damage to potato, there are viruses M and Y in Pushkin, and Х in Khibiny. Among the infected plant material, accessions with a latent virus infection, manifesting tolerance to the pathogens, have constantly been observed. The conventional point-based principle of scoring field resistance of potato cultivars and hybrids to viruses requires a significant revision. A new alternative approach is proposed for virus resistance assessment, when the clonal reproduction type of the tested accessions is taken into account

Specific features of g ≈\approx 4.3 EPR line behavior in magnetic nanogranular composites

Films of metal-insulator nanogranular composites M$_x$D$_{100-x}$ with different composition and percentage of metal and dielectric phases (M = Fe, Co, CoFeB; D = Al$_2$O$_3$, SiO$_2$, LiNbO$_3$; x $\approx$ 15-70 at.%) are investigated by magnetic resonance in a wide range of frequencies (f = 7-37 GHz) and temperatures (T = 4.2-360 K). In addition to the usual ferromagnetic resonance signal from an array of nanogranules, the experimental spectra contain an additional absorption peak, which we associate with the electron paramagnetic resonance (EPR) of Fe and Co ions dispersed in the insulating space between the granules. In contrast to the traditional EPR of Fe and Co ions in weakly doped non-magnetic matrices, the observed peak demonstrates a number of unusual properties, which we explain by the presence of magnetic interactions between ions and granules

A topological central point theorem

In this paper a generalized topological central point theorem is proved for maps of a simplex to finite-dimensional metric spaces. Similar generalizations of the Tverberg theorem are considered.Comment: In this version some typos were corrected after the official publicatio

A numerical study of tropical cross-tropopause transport by convective overshoots during the TROCCINOX golden day

International audienceObservations obtained during the Tropical Convection, Cirrus and Nitrogen Oxides (TROCCINOX) golden day have revealed the presence of ice particles up to 410 K (18.2 km) 2 km above the local tropopause. The case is investigated using a three-dimensional quadruply nested non-hydrostatic simulation and Meteosat Second Generation (MSG) observations. The simulation fairly well reproduces the measurements along the flight track. A reasonable agreement with MSG observations is also achieved: the 10.8-µm brightness temperature (BT) minimum of 187 K is reproduced (a value 6 K colder than the environmental cold-point temperature) as well as the positive BT difference between the 6.2- and 10.8-µm bands, an overshoot signature. The simulation produces several overshooting plumes up to 410 K yielding an upward transport of water vapour of a few tons per second across the tropical tropopause. The estimated mass flux agree with those derived from over tracer budgets indicating that convection transport mass across the tropopause

First airborne water vapor lidar measurements in the tropical upper troposphere and mid-latitudes lower stratosphere: accuracy evaluation and intercomparisons with other instruments

In the tropics, deep convection is the major source of uncertainty in water vapor transport to the upper troposphere and into the stratosphere. Although accurate measurements in this region would be of first order importance to better understand the processes that govern stratospheric water vapor concentrations and trends in the context of a changing climate, they are sparse because of instrumental shortcomings and observational challenges. Therefore, the Falcon research aircraft of the Deutsches Zentrum für Luft- und Raumfahrt (DLR) flew a zenith-viewing water vapor differential absorption lidar (DIAL) during the Tropical Convection, Cirrus and Nitrogen Oxides Experiment (TROCCINOX) in 2004 and 2005 in Brazil. The measurements were performed alternatively on three water vapor absorption lines of different strength around 940 nm. These are the first aircraft DIAL measurements in the tropical upper troposphere and in the mid-latitudes lower stratosphere. Sensitivity analyses reveal an accuracy of 5% between altitudes of 8 and 16 km. This is confirmed by intercomparisons with the Fast In-situ Stratospheric Hygrometer (FISH) and the Fluorescent Advanced Stratospheric Hygrometer (FLASH) onboard the Russian M-55 Geophysica research aircraft during five coordinated flights. The average relative differences between FISH and DIAL amount to −3%±8% and between FLASH and DIAL to −8%±14%, negative meaning DIAL is more humid. The average distance between the probed air masses was 129 km. The DIAL is found to have no altitude- or latitude-dependent bias. A comparison with the balloon ascent of a laser absorption spectrometer gives an average difference of 0%±19% at a distance of 75 km. Six tropical DIAL under-flights of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board ENVISAT reveal a mean difference of −8%±49% at an average distance of 315 km. While the comparison with MIPAS is somewhat less significant due to poorer comparison conditions, the agreement with the in-situ hygrometers provides evidence of the excellent quality of FISH, FLASH and DIAL. Most DIAL profiles exhibit a smooth exponential decrease of water vapor mixing ratio in the tropical upper troposphere to lower stratosphere transition. The hygropause with a minimum mixing ratio of 2.5 µmol/mol is found between 15 and 17 km. A high-resolution (2 km horizontal, 0.2 km vertical) DIAL cross section through the anvil outflow of tropical convection shows that the ambient humidity is increased by a factor of three across 100 km

Scientific visualization as a possible component of the imaginative part of academic drawing and painting in a process of industrial design teaching

The article raises the question of the conscious possibility of scientific visualization usage in a context of designers' education. The article considers the problem of mixing creativity (such as academic drawing) and computer technologies in the process of design students' education. This article underlines the priority of impressions and the secondariness of constructive specifications of images that may appear in the very beginning during the process of work with material. The material of the article covers such things like the nature of image appearance and presumable results of original ideas realization. The actual ideas of image appearance are given as a singularity of a gouache painting technique. According to the tradition of school of academic painting, aspiration to stand out by originality of smear, tone and color of stretch marks, relief, pasty painting are welcome