Study on microstructures and properties of Ni-based WC ceramic coating on screw drilling rotor surface

In order to improve the wear resistance and corrosion resistance of screw drill rotors, a Ni+50% WC cladding layer was fabricated on the surface of 45^# steel using laser cladding technology. The microstructure and morphology of WC ceramic particles in the cladding layer were analyzed using scanning electron microscopy. Surface properties were tested using a hardness tester, mechanical property analyzer, and an electrochemical testing system to assess the effects of adding 50% WC particles on the microhardness distribution, wear resistance, and corrosion resistance of the Ni-based alloy layer. The results showed that the Ni+50% WC cladding layer had a thickness of approximately 1.35 mm, and featured metallurgical bonding with a low dilution rate. The WC particles in the cladding layer were uniformly distributed, along with the precipitation of polygonal carbides and grain boundary reticular carbides. Due to the combined effect of solid solution strengthening and precipitation strengthening, the hardness of the Ni+50% WC cladding layer reached 577.2 HV_0.2. Although the weight loss slightly increased with increasing rotational speed, the wear loss of the Ni+50%WC cladding layer remained significantly lower than that of 45^# steel, accounting for only 3.5% of the latter. The wear scar width was also considerably reduced, and the wear mechanism transitioned to abrasive wear. Corrosion resistance tests in a 3.5% NaCl solution confirmed that the self-corrosion current density of the Ni+50% WC cladding layer was only 0.034603 μA/cm², which was 0.565% that of 45^# steel. Therefore, the laser-clad Ni+50%WC composite layer can significantly enhance the wear and corrosion resistance of 45^# steel, which is of great significance for prolonging the service life of screw drill rotors and reducing maintenance costs.