Structural‑phase composition of a gas‑thermal coating of Fe‑Cr‑Ni‑Al pseudo alloy subjected to annealing

The structural‑phase state of the gas‑thermal coating made of Fe‑Cr‑Ni‑Al pseudo‑alloy in the initial state, as well as after annealing in the temperature range 550–650 °C for 20–60 minutes, has been investigated. It has been established that the phase composition of the Fe‑Cr‑Ni‑Al pseudo‑alloy in the initial state includes mainly Al and α‑Fe, and its porosity does not exceed 3–5 vol.%. Annealing of a thermal spray coating from a pseudo‑alloy at temperatures of 550–650˚C for 20–60 minutes leads to the release of iron‑aluminum intermetallic compounds Fe3Al, Al13Fe4 and Al5Fe2, an increase in hardness and porosity.

CFD-analysis of the interaction of particles with a surface in the conditions of suspension plasma spraying

Gas-thermal coating using suspensions and solutions of precursors allows to obtain promising functional coatings based on oxide ceramics with a controlled microstructure. CFD modeling of air plasma flows generated by the PNK-50 plasmatron in subsonic and supersonic operating modes (diameter of the nozzle 6, 8, 10 mm, gas flow rate of a plasma-forming gas 1 - 7 g / s, flow rate 500 - 2100 m / s). The interaction of single particles of the sprayed material with a size of 0.1 - 5 m with the boundary layer of gas on the surface of the substrate (base) in the process of coating formation was studied, the values ​​of the speed of collision of particles with the base in various spraying modes were obtained. It is shown that the minimum particle size involved in coating formation is 0.5 - 1 m.

TiC coatings on an alloyed steel produced by thermal diffusion

In this study, an alloyed steel surface was coated by thermal diffusion with titanium carbide powder at different temperatures (900, 1000 and 1100 °C) and times (1, 2 and 3 h) to determine their effect on the coating microstructure. The thermal coating was carried out by tube cementation designed and manufactured by us for the purpose of thermal coating. Coating thickness, element distribution and phase composition were analyzed by optical microscope, scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction (XRD) methods, respectively. Microhardness tests were performed to determine mechanical properties. The influence of different temperatures and production times on the coating thickness and microstructure were determined. The results illustrated that titanium carbide particles adhere almost completely and are diffused to the substrate during production. Thus, coating thickness increased through increasing time and temperatures. Moreover, microhardness increased with increasing temperature more than time did. The highest microhardness value achieved was 1301 HV for 3 hours. Temperatures of 1000 °C were reached due to the diffusion of TiC to the surface of the substrate, thus forming an extremely hard and protective layer.

Development of Technological Bases for Manufacturing Blanks of Friction Disks with Molybdenum Gas-Thermal Coating for Working in Oil in Units of Transport Machines

This article is dedicated to the questions of development of technological bases for the manufacturing blanks of friction disks with molybdenum gas-thermal coating applied by plasma spraying, for working in oil in the transmission units of transport machines. For ensure high performance indicators, there is has been offered a technological scheme for manufacturing friction disk blanks: short blasting preparation of the surface of the disk’s steel base, applying a molybdenum coating, that characterized by high adhesion to the ferrous metals, mechanical processing of the coating by grinding, monitoring the coating’s quality. The developed technological bases for manufacturing blanks of friction disks with molybdenum gas-thermal coating, applied by plasma spraying, for working in oil in transmission units of transport machines are contributed to the creation of efficient products with enhanced performance indicators for friction coefficient, wear resistance, reliability in modern conditions at the enterprises.