Microstructure and intermediate–temperature tribological properties of laser cladded NiCoCrAlY–xTiC coatings

Abstract

Temperature had a significant effect on the wear resistance of metallic components, NiCoCrAlY thermal barrier coating was used to improve high–temperature tribological properties. In this work, TiC reinforced NiCoCrAlY coatings were prepared on H13 steel by laser cladding to further improve its intermediate–temperature tribological properties. The morphologies, chemical elements and phases of obtained coatings were analyzed using a scanning electron microscope, energy dispersive spectrometer, and X − ray diffraction, respectively, and the effect of TiC mass fraction on the tribological properties at 500 °C was investigated using a ball–on–disc wear tester The results show that there are no pores and cracks on the NiCoCrAlY–xTiC coating cross–sections, which form metallurgical bonding with the substrates. The hardness of NiCoCrAlY–5%TiC, −10%TiC, −15%TiC and − 20%TiC coatings is increased compared with the NiCoCrAlY–0%TiC coating by 4.2 %, 18.5 %, 30.4 %, and 43.8 %, respectively, showing that the coating hardness is increased with the TiC mass fraction. The average coefficients of friction of NiCoCrAlY–5%TiC, −10%TiC, −15%TiC and − 20%TiC coatings in the stable wear period are decreased compared with the NiCoCrAlY–0%TiC coating by 6.7 %, 10.3 %, 20.7 %, and 34.5 %, respectively, and the corresponding wear rates are decreased by 8.6 %, 22.9 %, 42.0 %, and 62.7 %, respectively,exhibiting that the NiCoCrAlY–20%TiC coating presents the best friction reduction and wear resistance. The intermediate–temperature wear resistance and self–lubricity of NiCoCrAlY–xTiC coatings are improved with the increase of TiC mass fraction, and the wear mechanism is adhesive wear, accompanied by oxidative wear.