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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3

Fig. 1. Schematic diagram of the coating deposition on the sample surface when the nozzle is displaced by l = 2 mm: 1 – nozzle projection, 2 – sample, 3 – areas of the sample surface exposed to particles 2 times and 4 – three times. 3. Research results X-ray fluorescence analysis shows that when the nozzle is displaced by 2 mm and 3 mm, the chemical composition of the coating practically does not change; in the first case, the mass fraction of copper and zinc is – 62.5%: 35.3%, and in the second – 64.8%: 35.0% (the rest is aluminium oxide). X-ray structural phase analysis reveals significant differences in the structure and phase composition of the coating applied when the nozzle is displaced by 2 mm and 3 mm Table 1. Copper is present in the amount of 58% and zinc, the mass fraction of which significantly increases with increasing nozzle displacement during deposition. The lattice distance of metals is significantly increased as compared with pure metals, which may be due to deformation and/or diffusion processes (interdiffusion) and the formation of solid solutions. The size of the coherent scattering region (CSR) in copper and zinc with a nozzle offset of 2 mm is much smaller (89.8 nm and 63.7 nm) than when sprayed with an overlap factor of 55% (216 nm and 218 nm), which is due to an increase in exposure time (42 s and 24 s) of particle stream to the surface.

Table 1. X-ray analysis results.

Nozzle offset, mm

Phases

2

3

d, nm

CSR, nm

Mass content, %

d, nm

CSR, nm

Mass content, %

Copper

0.3617

89.8 63.7

58

0.3615

>216 >218 >135

58 23 19

Zinc

0.2666/0.4946

9

0.2664/0.4944 0.2750/0.4293

Phase η Phase ε Phase γ

-

-

-

0.2754/0.4296

96.5 62.0

11 33

- -

- -

- -

0.8900

At a larger displacement step in the deposited metal layer, a zinc-based solid solution is detected ( η -phase); the coating applied with an overlap factor of ≈ 62% contains intermetallic (electronic) compounds based on CuZn 3 ( ε phase) and Cu5Zn 8 ( γ -phase) in the structure. In accordance with the copper-zinc state diagram, these phases form when the zinc content is ≥ 55 at.% by Efremov (2016).