Influence of Obtaining Conditions on Microstructure, Phase Composition and Properties of Eutectic Alloy of WC–W2C System

The influence of the obtaining conditions on microstructure, phase composition and proper ties of eutectic alloy of the WC–W2C system (relit), which is widely used as a surfacing material to strengthen the wearing parts, was installed. Using scanning electron microscopy, X ray diffraction and durometric analyzes, it was found that the increase in mechanical properties is satisfactorily correlated with a decrease in the ratio between the number of phases of W2C, WC and WC1–x, the thickness of the phase layers in the grains, and the elongation of the latter

Justification of choice of the spectral range for the study of combustion processes with the use of thermography in the middle IR range

The paper presents the emission spectra of flame formed during combustion of different fuels and gives the grounds for application of various narrow spectral ranges in the mid-infrared region to record the temperature fields in flame and flame screened objects

Effect of Molybdenum Additions on the Microstructure and Properties of WC-W2C Alloys

Translated from Poroshkovaya Metallurgiya, Vol. 53, No. 3–4 (496), pp. 121–128, March-April, 2014.The paper examines how additions of 5, 10, and 20 wt.% molybdenum influence the structure, stress–strain state, phase composition, and size of phase components in WC–W2C alloys. It is found that 5 wt.% molybdenum leads to 30% increase in the microhardness and twofold to threefold increase in the wear resistance of cast tungsten carbide compared to the alloy without additions. Higher molybdenum content of the WC–W2C alloys changes the phase composition and increases compressive stresses in the W2C matrix phase and tensile stresses in WC, (Mo, W)2C, and Mo2C inclusions

DYSLIPIDEMIA IN PATIENTS WITH CHRONIC KIDNEY DISEASE

Summury. Data about lipid disorders at different stages of chronic kidney disease (CKD), including those on dialysis are presented in the review. The possible influence of dyslipidemia on the progression of CKD, as well as the onset and progression of cardiovascular complications in patients with CKD are discussed. The questions of lipid-lowering therapy use, including statins, in patients with CKD on dialysis and predialysis, are disclosed

Modeling of wood surface ignition by wildland firebrands

The probability of structural ignition is dependent both on physical properties of materials and the fire exposure conditions. In this study, the effect of firebrand characteristics (i.e., firebrand size, number of firebrands) on wood ignition behavior was considered. Mathematical modeling and laboratory experiment were conducted to better understand the conditions of wood ignition by a single or group of firebrands with different geometry. This model considers the heat exchange between the firebrands, wood layer and the gas phase, moisture evaporation in the firebrands and the diffusion gases of water vapor in the pyrolysis zone. In order to test and verify the model, a series of experiments to determine probability and conditions for ignition of wood-based materials (plywood, oriented strand board, chipboard) caused by wildland firebrands (pine twigs with a diameter of 6–8 mm and a length of 40 ± 2 mm) were conducted. The experiments investigated the firebrand impact on the wood layer under different parameters, such as firebrand size and quantity, wind speed, and type of wood. The results of experiments showed that the increase in wind speed leads to the increase in probability of wood ignition. Based on the received results, it can be concluded that the ignition curve of wood samples by firebrands is nonlinear and depends on the wind speed and firebrand size as well as their quantity. At the same time, there is no ignition of wood samples in the range of wind speed of 0–1 m/s. The ignition of wood is possible with a decrease in the distance between the firebrands with a decrease in the firebrand length. This result agrees more closely with the model

The structure and properties of the molybdenum-doped WC–W2C eutectic alloy depending on the production method

Translated from Poroshkova Metallurgiya, Vol. 58, Nos. 1–2 (525), pp. 48–56, 2019. Original article submitted July 9, 2018.Scanning and transmission electron microscopy and X-ray diffraction have revealed that the eutectic 5 wt.% Mo-doped WC–W2C alloy changes its cooling rate in the melt crystallization process when produced in the Tammann furnace, by electron-beam evaporation, and by centrifugal sputtering. This increases the size of phase components by a factor of 2 to 2.5, decreases the number of phases, and reduces compressive stresses (in the W2C matrix) and tensile stresses (in the WC, Mo2C, and (W, Mo)2C inclusions) to 50% and more. These changes result in one and a half times higher hardness and two times higher strength of doped relit, which is widely used for surfacing machine parts and mechanisms operating in conditions of abrasive wear and high dynamic loads