Tribological studies of monolithic chromium diboride against cemented tungsten carbide (WC–Co) under dry condition

• Wear of bulk monolithic CrB2 has been studied in reciprocative sliding mode.
• Wear tests were carried out at 3, 5 and 10 N loads using 10 and 15 Hz frequencies.
• Abrasive wear to tribo-oxidation wear is evident at 5 N load and 15 Hz frequency.
• EDS and micro XRD analysis of debris revealed the presence of oxides in wear zone.
• Cr2O3, a product of tribo-oxidation, acts as solid lubricant and thus reduce wear.
• Wear mechanisms include abrasive wear, tribo-oxidation wear and delamination wear.

Friction and wear behaviour of the hot pressed monolithic chromium diboride (CrB2) of 94% theoretical density were studied at different loads (3, 5 and 10 N) and frequencies (10 and 15 Hz) under dry reciprocative sliding condition against cemented tungsten carbide (WC–Co) ball. Coefficient of friction and wear rate were calculated. While the value of coefficient of friction (COF) is decreased from 0.50 to 0.36 with increasing load from 3 N to 10 N; it is observed to be nearly independent with respect to sliding frequency. The measured wear volume is in the range of 0.67××10−3–2.24 ××10−3 mm3 for the investigated regime. The lowest specific wear rate of 4.63××1010−7 mm3/N m was observed at 10 N load and 15 Hz frequency. Abrasive and tribo-oxidative wear with delamination were the active mechanisms manifested in both flat and counter body materials.