Tribological behavior of diamond-like carbon in-situ formed on Fe ₃ C-containing carburized layer by plasma carburizing

The previous article reported a valuable finding of diamond-like carbon (DLC) in-situ formed on Fe ₃ C-containing carburized layer by plasma carburizing. The formation mechanism of DLC film was revealed with aid of first-principles calculations. However, the tribological behaviors of the duplex layer combining DLC film and carburized layer were not presented. In the present paper, the microstructure of the duplex layer was systematically analyzed by means of optical microscope and atomic force microscopy. The DLC film was characterized by scanning electron microscopy and high-resolution transmission electron microscopy. DLC film gradually forms on the carburized layer of specimen treated at 400 °C and 450 °C with treatment duration increasing. The tribological tests demonstrate that the DLC film coated carburized layer has lower coefficient of friction (less than 0.3) and wear rate due to the self-lubricating property. The predominant wear mechanism of DLC film coated carburized layer is transformed into micro cutting wear compared with the slight adhesive wear and abrasive wear for traditional carburized layer. The excellent tribological properties of the DLC film coated carburized layer exhibits great potential to modify ferrous alloys by plasma carburizing.