Formation mechanism and single abrasive wear of TaC dense ceramic layer on surface of gray cast iron

Abstract TaC dense ceramic layer on the surface of gray cast iron was prepared in situ using casting-heat treatment process. Phase composition, morphology, and element distribution of TaC dense ceramics were analyzed and determined using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS). The microstructure and crystal structure of Ta–TaC interface and TaC–Fe interface were studied using transmission electron microscopy (TEM), and TEM samples were prepared using focused ion beam (FIB) technique. Scratch test with progressively increasing load of 0–50 N was conducted on the surface of TaC dense ceramic layer. Single abrasive wear behavior of TaC dense ceramic layer was evaluated using microscopic morphology of scratch, friction curve, and acoustic emission curve. Results show that TaC dense ceramic layer on gray cast iron surface was obtained via in situ reaction of C atoms in gray cast iron with Ta atoms in tantalum plate. Dominant mechanism for TaC particle growth is the diffusion of C atoms into the octahedral gap of Ta, and growth direction of TaC particles is the normal direction of Ta plate. TaC dense ceramic layer with a thickness of 20 μm can carry critical load of 48.7 N. The critical compressive stress of TaC dense ceramic layer on the gray cast iron matrix is estimated to be 302.08 MPa by theoretical calculation. The plastic deformation of TaC dense ceramic occurs before critical load of 48.7 N, and brittle fracture occurs after critical load of 48.7 N. The single abrasive wear form of TaC dense ceramic is the cutting wear.