PSI - Issue 5

Pavol Hvizdoš et al. / Procedia Structural Integrity 5 (2017) 1385–1392 Pavol Hvizdoš et al. / Structural Integrity Procedia 00 (2017) 000 – 000

1390

6

a)

b)

c)

20 µm

Fig. 6 Wear tracks of all materials at 400 °C against WC-Co ball - significant surface oxidation, smearing of tribofilm. a) 0% C, b) 1.8 % C, c) 2.2 % C.

At medium temperature 200 °C wear rate values (1.10 -7 mm 3 /N.m for steel ball and 1.10 -6 mm 3 /N.m for WC-Co ball) are slightly higher in comparison to wear rate values at room temperature. As at room temperature, abrasion and microcracking were the dominant damage mechanisms, but surface titanium oxidation also occurred, Fig. 8. Sample with 2.2 wt.% C addition shows higher wear rate values and suffered more surface damage in comparison to worn surfaces for the reference material and the one with 1.8 wt.% of graphite, which can be connected to soft nature of the metallic α -cobalt binder.

Ti

O

10 µm

C

Ta

Co

C

Fig. 7 EDX analysis inside wear track of 2.2% C material worn at room temperature against the steel ball - abrasion, microcracking..

Ti

O

50 µm