Analysis on microstructure and friction wear performance of chromium carbide/Ni 3Al composite surfacing layer

Artikel i vetenskaplig tidskrift, 2012

Microstructure of chromium carbide reinforced Ni 3Al-based matrix composite coating prepared by argon tungsten-arc welding was investigated with optical microscope, scanning electron microscopy (SEM), electron probe micro-analysis (EPMA) and X-ray diffraction (XRD). The wear performance of the coating and cast iron of piston ring were tested by a Pin-on-Disc tribometer. The results indicated that the Ni 3Al-based matrix was formed during welding, a large number of fine carbide particles such as Cr 3C 2 and Cr 7C 3 dispersed in it; The particle of Cr 3C 2 in welding wire was dissolved and re-precipitated during hardfacing. The re-precipitation of chromium carbide particle contains Fe, Ni elements and forms strong metallurgically bond with Ni 3Al-based matrix. Diffuse distribution of chromium carbide particles and Cr solid-solution in Ni 3Al-based matrix, makes the surfacing layer with higher hardness. The hardfaceing layer shows excellent dry friction wear resistance and its friction coefficient is 0.23, lower than 0.39 which is the friction coefficient of piston material of vermicular graphite cast iron. The wear rate of hardfaceing layer is only 43 percent of vermicular graphite cast iron.