Improving the performance characteristics of grey cast iron parts via ion implantation

Introduction. Cast iron is a material that is widely used in various industries. It possesses high heat capacity, relatively high hardness, and a number of other physical, mechanical and technological properties. Due to the significant operational stress experienced by the working surfaces of cast iron parts and its frequent exposure to aggressive environments, additional surface treatment is required to enhance wear resistance, corrosion resistance, and other properties. There are many different methods of surface modification. One of the most promising and modern ones is ion implantation with various ions. The purpose of the work is thus to study the effect of ion implantation on the surface of cast iron and the resulting changes in its mechanical properties. Methods. Cast iron samples were implanted with nitrogen ions of different doses (optimal dose of implanted nitrogen ions as a nitride-forming element). The surface microstructure of cast iron samples was investigated using a scanning electron microscope Stereoscan S-180 at a magnification of ×2,900 and ×5,000. Microdurometry analysis of the samples was carried out using a Neophot-2 metallographic microscope equipped with an attachment for measuring microhardness, at a load of 10 g after implantation of cast iron samples with various doses of nitrogen ions. In addition, X-ray diffraction analysis was performed on a DRON-3 diffractometer to determine the phase composition and fine structure of modified cast iron samples. Results and Discussion. Ion implantation of cast iron samples significantly increases microhardness. Thus, the conducted study reveals that the best mechanical properties (specifically microhardness) are observed in cast iron samples after implantation by N+ ions with a dose of 5×1017 ions/cm2 with energy of 40 KeV. X-ray diffraction analysis demonstrated that the ion implantation with nitrogen results in the formation of Fe2N and Fe2N nitrites, and also revealed changes in fine structure (average dislocation density and size of mosaic blocks).