PSI - Issue 33

Pietro Tonolini et al. / Procedia Structural Integrity 33 (2021) 1152–1161 / Structural Integrity Procedia 00 (2019) 000–000

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(composed principally by the coarse iron fibers present in the friction material) and of the “secondary plateau” derived from the densification of the wear debris (Fig. 8). The white arrows in Fig. 8 put in evidence the tungsten micro particles embedded in the secondary plateau on the pin worn surface coupled with the WC coatings (R-SS and HVOF). Due to the presence of Fe and Cr elements into the friction material it is hard to highlight these elements, by EDS analysis, derived from disc wear debris into the secondary plateau of the pin tested against GCI and SS samples.

Fig. 7 SEM images of the worn surfaces at the end of PoD test for a-b) GCI; c-d) SS coating; e-f) R-SS coating; g-h) HVOF coating.

Table 4 Summary of EDS analysis of the spectrums numbered in Fig. 7. Spectrum C O Mg Al Si S Ca

Cr

Mn

Fe

Ba

Sn

Ni

W

Other

1 2 3 4

15.05

30.62

1.36 0.84 0.95 0.81

-

0.46

0.42 48.39

- -

1.09 - 0.21 -

- -

Bal. Bal. Bal. Bal.

2.87 5.54

4.02

0.39 - 4.07 -

- -

0.14 -

12.45

- - -

79.92 39.91

37.07 14.72

1.43 0.54 2.63

2.65 1.51 -

11.63 42.37

19.06

1.20 0.57 -

0.36 -

6.27

2.06

-

-

13.39