Study on salt spray corrosion resistance of tin bronze based WC-20Cr ₃ C ₂ -7Ni ceramic coating prepared by HVOF

Coating technologies play a crucial role in protecting ship components exposed to seawater from corrosion. Oxide coatings produced by thermal spraying are widely used for corrosion protection; however, their mechanical toughness is often insufficient. Tungsten carbide (WC) coatings, known for excellent toughness, gain industry attention. This study prepared them via atmospheric plasma spraying (APS) and high-velocity oxygen fuel (HVOF) spraying, comparing with Al 2 O 3 -40 % TiO 2 coatings on tin bronze substrates. The fracture toughness of APS-sprayed oxide and WC-based coatings was 1.10 and 1.37 MPa m 1/2 , respectively, whereas that of the HVOF-sprayed WC-based coating reached 3.83 MPa m 1/2 . The HVOF-sprayed coatings exhibited significantly fewer pores and microcracks than those produced by APS. In salt spray corrosion tests conducted for 10 and 20 days, the HVOF-sprayed WC-based coating showed the best corrosion resistance, followed by the APS-sprayed oxide coating, while the APS-sprayed WC-based coating exhibited the poorest performance. Microstructural observations and energy-dispersive spectroscopy analyses indicate that the dense microstructure of the HVOF-sprayed WC-based coating effectively inhibited the penetration of corrosive media during salt spray exposure, which is directly related to its superior coating quality.