PSI - Issue 33

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

1159

8

Fig. 8 SEM images of the pin wear surface at the end of PoD test for a) R-SS coating and b) HVOF coating.

Table 5 Summary of EDS analysis of the spectrums numbered in Fig. 8. Spectrum C O Mg Al Si S Ca

Cr

Fe

Zn

Sn

Ni

W

Other

1 2

N/A N/A

44.33 36.60

5.69 4.49

1.78 2.85

-

2.73 3.47

1.76 0.63

2.6

29.42 18.80

2.52

4.04 2.66

-

4.24

Bal. Bal.

5.13

7.56

-

1.96

14.90

Fig. 9 shows the SEM micrographs of the worn surface at the end of the BoR test for GCI (Fig. 8a and 8b), SS coating (Fig. 8c and 8d) and R-SS coating (Fig. 8e and 8f). As well as for PoD tests, the primary wear mechanism appears to be abrasive wear; in fact, grooves are observed in the wear surfaces of all the tested samples. Material transfer from the block to the ring is very limited and hardly detectable also for the SS coating sample, justifying the reduction of CoF respect to the PoD test (Fig. 4 and Fig. 5).

Fig. 9 SEM images of the worn surfaces at the end of BoR test for a-b) GCI; c-d) SS coating; e-f) R-SS coating.