PSI - Issue 40

Vladimir Arkhipov et al. / Procedia Structural Integrity 40 (2022) 27–31 Vladimir Arkhipov et al. / Structural Integrity Procedia 00 (2022) 000 – 000

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from 270˚C to 450˚C. The electronic compound of the γ phase r educed CSR from 200 to 62 nm with temperature increase from 360˚C to 450˚C. The copper particles microstrain applied at temperature of 270˚C was not influenced by the amount of overlap. The further temperature increase led to the decrease in microdeformations of copper particles from 0.187% to 0.119% with overlap of 64% and the decrease from 0.187% to 0.129% with overlap of 55%. Microstrains of the ε - phase increased with the temperature increase from 0.1% to 0.2% at both overlaps, the γ - phase, on the c ontrary, decreased from 0.307% to 0.17% with the spraying temperature increase from 360°C to 450°C, but only at 64% overlap. There are practically no microdeformations of zinc particles. The copper lattice parameters study showed that its period was slightly increased from 0.36074 to 0.3620 at all processing options. The zinc "c" lattice parameter was 0.4947 nm and varied depending on the technological modes of sputtering. With 64% overlap, it increased with temperature increase and only at 450°C it decr eased to its initial value. At 55% overlap, the zinc "c" lattice parameter decreased below the initial value and amounted to 0.4944 nm. The microspectral analysis revealed the presence of two areas in the coating with different copper and zinc content. The area with a low copper content between 8% and 92% zinc, as well as the area with a high copper content of 19% and 81% zinc. Thus, during the diffusion of copper into zinc, two compounds of the electronic type of the ε -phase were formed, and their lattice period depended on the overlap value and the air flow temperature. At the maximum temperature of coating application, the diffusion was complete and the electronic type compound was formed with a copper content of 20 at.%, and zinc content of 80 at.% by Efremov (2016). The lattice parameter of the γ -phase did not depend on the spraying temperature and was 0.8888 nm. The corundum content in the coating with 64% overlap decreased from 5.4% to 2.2% and increased with 55% overlap from 5.9% to 8.0% with the increase in the spraying temperature to the maximum. At the spraying temperature of 450°C, phase analysis revealed zinc oxide with a mass fraction of 4.3 at.%. 4. Test results discussion The coating structure and properties were affected by two factors: deformation and crushing of the initial powder particles, which occurred due to their collision with the sprayed surface, corundum and with each other, as well as heating. The calculations performed earlier revealed that the particle during the spraying did not heat up above 80˚C, therefore, it was heated after spraying on the surface, when the temperature in the coating formation zone was 90% of the air flow initial temperature Arkhipov et al. (2017). The deformation and heating of the particles occurred with a minimal time difference; therefore, minor changes in the process led to significant changes in the resulting coating properties. With the overlap of 55%, a more dispersed structure was formed, since exposure time had less effect on heating. The air flow temperature increase led to the particles energy flow increase, which in turn increased their deformation. The microdeformations decrease occurred due to the subsequent heating by the air flow and the return (rest) processes course. A large amount of deformation contributed to the lower heating for triggering the processes of the boundaries rearrangement and migration of atoms by Mirkin (1981). The results of CSR study and microdeformations revealed that during gas-dynamic spraying of coatings, the metals deformation took place at the low coating heating temperature, while zinc under the impact of corundum was destroyed into small parts without significant microdeformations along the crystallographic planes. The change in the "c" zinc parameter occurred due to the implanted atom with its increase and because of vacancies with its decrease, under the action of diffusion processes on it. The change in the corundum content in the coating with increasing temperature is associated with the increase in the coating thickness up to two times and the corresponding increase in the angle of coating spraying depending on the overlap, which led to a greater reflection of corundum particles and less fixation of its fragments in the coating.