CoCrNi matrix high-temperature wear resistant composites with micro- and nano-Al2O3 reinforcement

The high-temperature wear resistant CoCrNi matrix composites containing micro-Al2O3 and nano-Al2O3 ceramic particles were prepared by powder metallurgy technology. The high-temperature wear mechanisms of the composites reinforced with nano-Al2O3 and micro-Al2O3 were systematically studied. The tribological performance of CoCrNi matrix composites were evaluated from 23 degrees C to 1000 degrees C sliding against Si3N4 ceramic ball. The results revealed that the CoCrNi matrix composite reinforced by nano-Al2O3 had high hardness and compactness. The wear rates of CoCrNi matrix composite with nano-Al2O3 were 0.5-5 times lower than those of the composite with micro-Al2O3 and Al2O3-free alloy. Above 800 degrees C, the nano-Al2O3 particles reacted with CoO and formed the high temperature solid lubricant Co(AlO2)(2), resulting in low wear rate and friction coefficient. The excellent wear resistance of CoCrNi matrix composites reinforced with nano-Al2O3 was attributed to the high hardness and compactness as well as the solid lubricant oxide film on the worn surfaces, which consisted of metal oxides, NiCr2O4, Co2CrO4 and Co(AlO2)(2). The wear mechanisms of CoCrNi matrix composites were established at elevated temperatures.