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The studies of the structure, hardness and wear resistance of coatings obtained by electron-beam surfacing of "titanium monoboride – titanium carbide – titanium binder" composite powders synthesized from mixtures of titanium boron and carbon in the wave combustion mode were carried out. The ratio effect of titanium borides and carbides on the structure, hardness and abrasive wear of electron-beam coatings based on the synthesized hybrid TiB-TiC-Ti powders was analyzed. [ABSTRACT FROM AUTHOR]

Samples of FeTi + 7.5 wt % C reaction powder mixtures were subjected to mechanical activation (MA) in a planetary ball mill with a variation of the intensity and duration. "Titanium carbide – ferrite binder" metal-matrix composite was synthesized in thermal explosion mode from mechanically activated powder mixtures. Impact of MA parameters on synthesis temperature, phase composition and carbide inclusions dispersion were traced. [ABSTRACT FROM AUTHOR]

This paper shows the effect of silicon on structural and phase transformations in aluminum-chromium powder compacts during heating in the ambient air at 500°C. Samples were obtained by pressing from a mixture of the powders. The studies were carried out by using X-ray diffraction and metallographic analysis, and measuring the weight gain of the samples. It was found that silicon additives (10–20 at %) block the reaction interaction of aluminum and chromium, that occurred in two-component mixtures (Al-Cr) at 500°C and prevent a significant volume growth of the compacts. [ABSTRACT FROM AUTHOR]

In this study, structural changes in aluminum-chromium powder compacts were considered during exposure in the air at 500 °C. The samples were obtained by pressing the mixture of aluminum and chromium powders. The studies were carried out with using the X-ray diffraction and the metallographic analysis and by measuring the weight gain of the samples. It was established that the value of the specific mass gain has a complex and ambiguous dependence on the initial porosity of Al-Cr compacts due to phase transformations in powder mixtures. At short-term (up to 30 minutes) 500 °C air heating of the porous compacts significant oxidation does not occur. However, at the long-term exposure at 500 °C the reaction diffusion between aluminum and chromium occurs resulting in Al13Cr2 intermetallic formation and compacts swelling. [ABSTRACT FROM AUTHOR]

The paper describes the structure, hardness and wear resistance of electron beam coatings cladded by using of “TiB–titanium binder” composite powders. The powders have been synthesized from titanium and boron powder mixtures by self-propagating high temperature synthesis (SHS) at wave burning mode. The SHS powders were cladded on titanium substrate VT1-0 by electron beam surfacing. A phase composition and a structure of the SHS powders and of the cladded coatings were investigated by X-ray diffraction and optical microscopy. According to structure investigation and hardness measurement in the “coating–titanium base plate” transition zone an adhesion between the coating and the substrate was high. The maximum hardness increase of the coatings strengthened by needle-like titanium monoboride inclusions was 2.2 times and abrasive wear resistance—3.7 times as compared with V􀉌􀀔-0 titanium. [ABSTRACT FROM AUTHOR]

The volume changes and structure of the sintered powder compacts Ti + TinAm were studied, where A is one of the elements forming a refractory compound with titanium (Si, C or B). The comparative results of porosity changes in sintered composites of Ti + TinAm powder compositions obtained by different technological methods were presented. It is shown that various methods of combining the components have a significant effect on the macrostructure formation of the metal matrix composite including grain size and porosity while maintaining the basic phase composition. The use of synthesized powders leads to reduce in a porosity of the sintered composites. [ABSTRACT FROM AUTHOR]

Tunka-Rex, the Tunka radio extension, is an array of 20 antennas at the Tunka experiment close to Lake Baikal in Siberia. It started operation on 08 October 2012. The antennas are connected directly to the data acquisition of the Tunka main detector, a 1km2 large array of 133 non-imaging photomultipliers observing the Cherenkov light of air showers in dark and clear nights. This allows to cross-calibrate the radio signal with the air-Cherenkov signal of the same air showers - in particular with respect to the energy and the atmospheric depth of the shower maximum, Xmax. Consequently, we can test whether in rural regions with low radio background the practically achievable radio precision comes close to the precision of the established fluorescence and air-Cherenkov techniques. At a mid-term perspective, due to its higher duty-cycle, Tunka-Rex can enhance the effective observing time of Tunka by an order of magnitude, at least in the interesting energy range above 100PeV. Moreover, Tunka-Rex is very cost-effective, e.g., by using economic Short Aperiodic Loaded Loop Antennas (SALLAs). Thus, the results of Tunka-Rex and the comparison to other sophisticated radio arrays will provide crucial input for future large-scale cosmic-ray observatories, for which measurement precision as well as costs per area have to be optimized. In this paper we shortly describe the Tunka-Rex setup and discuss the technical and scientific goals of Tunka-Rex. [ABSTRACT FROM AUTHOR]

Addressing the mysteries of cosmic rays requires a comprehensive observational approach, including information on mass composition and spectrum (from CR nuclei) as well as directional information (gamma-rays or neutrinos). HiSCORE covers both approaches using indirect air-shower observations of cosmic rays from 100 TeV to 1 EeV and gamma-rays in the so far poorly covered energy range from 10 TeV to several PeV. Among other questions of astroparticle and particle physics, HiSCORE will allow cosmic ray composition and spectral measurements in the transition range between Galactic and Extragalactic origin. Searching for gamma-rays from the PeV-accelerators, the pevatrons, will consititute a crucial building-block for solving the question of the origin of Galactic cosmic rays. HiSCORE is an array of non-imaging light-collecting stations for Cherenkov light-front sampling. The lateral Cherenkov photon density and arrival-time distribution are measured, allowing the reconstruction of the direction, the energy, and the particle type (mainly shower depth) of the primary particle. A prototype detector station was developed and first air-shower measurements were performed in the Tunka valley (Siberia). The deployment of an engineering array of up to 1 square-km is planned on the Tunka cosmic ray experiment site in Siberia for 2012/2013. [ABSTRACT FROM AUTHOR]