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

5

1389

1,0

1,0

200 °C

200 °C

0,9

0,9

0,8

0,8

0,7

0,7

0,6

0,6

0,5

0,5

0,4

0,4

0,3

0,3

Friction cofficient [-]

0,2 Friction coefficient [-]

0 wt.% C 1,8 wt.% C 2,2 wt.% C

0 wt.% C 1,8 wt.% C 2,2 wt.% C

0,2

0,1

0,1

WC-Co ball

Steel (100Cr6) ball

0 25 50 75 100 125 150 175 200 225 250 275 300 0,0

0 25 50 75 100 125 150 175 200 225 250 275 300 0,0

Sliding distance [m]

Sliding distance [m]

Fig. 3 a) Friction coefficients at 200 °C with WC-Co ball. b) Friction coefficients at 200 °C with steel (100Cr6) ball

The wear tracks of the reference and composite materials samples worn at the experimental temperatures are shown in Figs. 4 – 6, respectively. Room temperature wear tests show the lowest values of wear rates, around 5.10 -8 mm 3 /N.m for steel ball and around 5.10 -7 mm 3 /N.m for WC-Co mm 3 /N.m ball. Main damage mechanisms at room temperature was abrasion, occasionally microcracking also took place. Surface oxidation does not seem to be important, Fig. 7.

a)

b)

c)

20 µm

Fig. 4 Wear tracks of all materials at room temperature against WC-Co ball - abrasion. a) 0% C, b) 1.8 % C, c) 2.2 % C.

a)

b)

c)

20 µm

Fig. 5 Wear tracks of all materials at 200 °C against steel ball - abrasion, microcracking and debris production, beginning of formation of oxidic tribofilm. a) 0% C, b) 1.8 % C, c) 2.2 % C.