Wear characteristics of dual-phase high-entropy ceramics: Influence of the testing method

Wear behavior of a fine-grained dual-phase high-entropy carbide/boride ceramics was investigated using ball-on-flat dry sliding methods in air, applying rotational and linear reciprocation motion with SiC counterpart. The investigated system showed very high nanohardness of the carbide and boride grains with mean values of 37.4 +/- 2.3 and 43.0 +/- 2.9 GPa, respectively, with the microhardness of dual system HV1 29.4 +/- 2.0 GPa. The stabilized friction coefficient values during the circular tests changing from .62 to .77. During the reciprocal test, the frictional coefficient values are very similar with an average value of .53. The specific wear rates during the circular motion were similar in the range from 4.65 x 10-7 to 1.68 x 10-7 mm3/N m. During the reciprocal test, the wear rates at 5 and 25 N were similar as in the case of circular motion, but at 50 N load, the wear rate increased significantly to the value of 9.11 x 10-6 mm3/N m. The dominant wear mechanisms in all cases were oxidation driven tribochemical reaction and tribolayer formation in boride grains and mechanical wear in carbide grains. During the linear reciprocation test, the loading mode created conditions resulted in relatively low coefficient of friction and very high specific wear rate.