Tribological behavior of HVOF-sprayed Cr3C2-NiCr and TiC-based coatings under hightemperature dry sliding conditions

摘要

In the current study, the tribological properties of TiC-based coatings paired with polycrystalline alumina underunlubricated sliding conditions were investigated in order to demonstrate the technological and engineeringpotential of such coatings. (Ti,Mo)(C,N)-Co coatings were prepared from an agglomerated and sintered spraypowder by HVOF spraying using JP-5000 equipment. Cr3C2-NiCr coatings were studied for comparison. Slidingwear tests were performed over the temperature range from 23°C to 800°C with sliding speeds in the range 0.3-3m/s, a wear distance of 5000 m and a normal force of 10 N. Wear rates of coatings and sintered aluminacounterparts were measured separately. Compared with Cr3C2-NiCr coatings, (Ti,Mo)(C,N)-Co coatings showedsignificantly lower total wear rates, corresponding to those found in the region of mixed/boundary lubrication. Withfew exceptions, the coefficients of friction were found to be lower for (Ti,Mo)(C,N)-Co coatings than for Cr3C2-NiCrcoatings. After tests were performed, the coating microstructures were studied by optical microscopy and SEM.The oxide scales formed on the coating surfaces were investigated by SEM and X-ray diffraction. Comparison ofthe total wear rates of the couples consisting of sintered alumina and a (Ti,Mo)(C,N)-Co coating with those of otheralumina-ceramic and hardmetal-hardmetal tribological systems demonstrates the immense potential of TiC-basedcoatings for sliding wear applications.