SiCw strengthened WC-Y2O3 composite and its electrochemical corrosion in aggressive medium

The mechanical properties and corrosion resistance of binderless tungsten carbide largely determine its performance and lifespan in complex industrial environments. Herein, WC-1Y ₂O ₃-xSiC _w (x = 0, 0.5, 1, and 2 wt%) was prepared using the hot-press sintering. The mechanical properties of the composite, as well as the corrosion resistance of optimized mechanical properties in an aggressive medium (0.05 M H ₂SO ₄ and 1 M NaOH) were investigated. Results showed that SiC _w could significantly increase mechanical properties of the composite, but excessive content (2 wt%) leads to whiskers aggregation and lower properties. The flexural strength and fracture toughness are all increased to varying degrees with whisker content. WC-1Y ₂O ₃-0.5SiC _w possesses the optimal mechanical properties. The Vickers hardness, fracture toughness, and flexural strength are 2331.24 HV ₃₀, 8.59 MPa·m ^1/2, and 1727 MPa, respectively. Electrochemical tests show that the corrosion resistance of the WC-1Y ₂O ₃-0.5SiC _w in H ₂SO ₄ is higher than that in NaOH solution, and its corrosion resistance in H ₂SO ₄ solution increases, but that of the NaOH solution decreases with exposure time. Detailed characterization demonstrated that a dense WO ₃ film forms in the H ₂SO ₄ solution, resulting in a flatter corrosion surface. In contrast, the WC phase in NaOH solution dissolves, thus leading to the accelerated corrosion rate.