PSI - Issue 20

Vladimir Arkhipov et al. / Procedia Structural Integrity 20 (2019) 124–129 Vladimir Arkhipov et al./ Structural Integrity Procedia 00 (2019) 000–000

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al. (2017). At this temperature, zinc is in a state close to melting; the number of vacancies increases significantly, which stimulates the diffusion process by the vacancy mechanism. The mechanical properties are very low, for example, the tensile strength is close to zero, and corundum particles passing through zinc with sharp protrusions capture it and transfer it – they are embedded in copper particles. An abnormal change in the concentration of components is observed in copper particles, when at a distance of ≈ 3 μ m the concentration of copper varies from 39.11 at.% up to 98.45 at.% Fig. 3, point 10 and point 11.

Fig. 3. Analysis of the chemical composition of the surface area of the coating after deposition at a temperature of 450°C (areas of elemental analysis are highlighted).

In copper, the tensile strength at a temperature of ≈ 400 °C decreases almost twice and is ≈ 220 MPa. In by Arkhipov et al. (2010), the study of the “package” of a metal composed of aluminum rolled with a thickness of 100 μ m, after gas-dynamic treatment with corundum particles, revealed traces of deformation (well) up to 230 μ m in depth. In this case, under the influence of corundum particles, copper particles can deform, which will lead to a change in the boundaries between the metals; however, this process cannot be accompanied by the formation of phases, since this requires diffusion and restructuring of the lattice. But, if the deformation of particles is accompanied by the formation of stresses, then their relaxation will take place due to the cooperative displacement of atoms, which will significantly increase the rate of diffusion of copper into zinc. In this case, a high value of the diffusion coefficient for gas-dynamic deposition of a coating based on copper and zinc particles should be attributed to a significant increase in point defects (vacancies) in zinc, as well as the onset and relaxation of deformation – stresses in copper particles. The brass coating applied by means of gas spraying using the mechanical mixture of copper, zinc and aluminum oxide particles has a promising future of tribological application, since its phase composition differs from standard brasses: in addition to copper solid solution it includes two electron compounds, Cu 5 Zn 8 and CuZn 3 , which shall ensure specific tribological properties of this coating. 4. Conclusions During the gas-dynamic deposition of a mechanical mixture of the particles of copper, zinc and corundum with an overlap ratio of 55%, a coating based on copper, zinc and solid copper solution in zinc ( η phase) is formed, with the mass fraction of 58%, 23% and 19%, respectively. An increase in the overlap ratio (62%) reduces the zinc content in the coating till 9% and is accompanied by the formation of intermetallic (electronic) compounds based on CuZn 3 ( ε phase) and Cu 5 Zn 8 ( γ phase), whose mass fraction does not exceed 11% and 33%.