Abstract:
Taking Cr
3C
2 powder, h-BN powder and Ni60 powder as raw materials, BN-reinforced Ni60–Cr
3C
2 composite coatings were fabricated on the surface of quenched and tempered 40Cr cylindrical bars via ultra-high-speed laser cladding technology. The effects of BN on the microstructure and properties of Ni60–Cr
3C
2 coatings were systematically investigated by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), Vickers microhardness test, friction and wear test, and electrochemical measurement. The results show that the Ni60–Cr
3C
2 coating is mainly composed of Cr
3Ni
2, Cr
1.12Ni
2.88, Cr
7C
3 and Fe
3C phases. After the addition of BN, in-situ synthesized Fe
2B, Cr
2N and Cr
2B
3 phases are formed in the coating. BN can promote the decomposition of residual Cr
7C
3 and the formation of Cr-rich dendritic networks within the coating. The microstructure uniformity and wear resistance of the BN-reinforced Ni60–Cr
3C
2 coating are significantly improved. Compared with the pure Ni60–Cr
3C
2 coating, its volume wear loss is reduced by 53.3%. In addition, the BN-reinforced coating exhibits an enhanced corrosion resistance, with a corrosion current density of 1.28×10
−6 A·cm
−2, which is 81.0% lower than that of the Ni60–Cr
3C
2 coating. Its charge transfer resistance reaches
5562 Ω·cm
2, 2.2 times that of the original Ni60–Cr
3C
2 coating.