International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

An experimental study was carried out to develop a technique for manufacturing a high silicon Al-Si-Ni sintered alloy with a coefficient of thermal expansion close to steels. A stage of hot forging was added to overcome porosity and improve silicon inclusions morphology to obtain better mechanical properties. Liquid and solid phase regimes of sintering were studied for the material made of the elemental components powders mixture as well as of a pre-alloyed powder. The impracticality of liquid-phase sintering modes is shown for this type of material primarily because of the tendency to liquid-phase exudation. It was proposed to carry out a solid-state vacuum sintering with subsequent hot deformation. Only the pre-alloyed powder is suitable for the technique; the other way, it leads to the course and sometimes, not equilibrium intermetallic inclusions will form in place of nickel particles because of the insolubility of Ni in solid Al. It is shown the possibility of successful plastic deformation of this material after sintering despite its extremely low ductility, which helps successfully overcome porosity and improve the characteristics of the microstructure of the material.

This paper analyses the oxidation resistance of ductile irons containing 2.11, 3, 4.28, 4.49 and 4.81 wt.% Si that were held at 850 °C for 32 hours. A scale was formed on all the samples and their weight increased. The scale thickness and increase in weight were decreased with increase of the silicon content, especially when the silicon content > 4 wt.%. The compactness of the scale on the sample surface is significantly higher at higher silicon contents. The results obtained indicate that the resistance of ductile iron to high-temperature oxidation increases with increasing silicon content.

Semiconductor silicon diodes are used widely as detectors in oncology radiation centers for In Vivo Dosimetry (IVD). IVD is the ultimate method used in cancer treatment centers to detect possible errors in dose delivery. Diode dosimetry is based on the linearity of diode current with dose. Number of carriers taking part in diode current, is proportional to dose received for practical dose range. However, carrier lifetime and mobility are temperature dependent. In addition dark current increases with temperature. Correction factors are therefore needed in order to offset dark current influence, whenever dose is measured at a temperature different from calibration or reference temperature. We investigate the effect on signal for three PTW diodes in a 18 MV photon beam generated by Elekta Synergy Accelerator and find correction factors for clinical range of temperatures.

The results of research coatings coatings obtained after complex saturation boron and silicon in the powder environment on steel 45. Determine the thickness and microhardness of the resulting coatings, their phase and chemical composition. It has been established that the coatings obtained after complex saturation boron and silicon more plastic and have a 1.8 times higher fracture toughness (K_1c) and 1.5 times higher than the wear resistance as compared with coatings obtained by borating.