Preparation Of WC-composited Wear-resistant Coating By Thermal Spray Methods

WC composite wear-resistant coating were coated on the surface of 45# steel by means of the improved arc spraying technology, and then remelted by argon shielded arc remelting technology.The microstructure of the composite coating was investigated by means of metallographic microscope, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The microhardness of composite coatings was measured by the microhardness instrument. And changes in microhardness of the cladding layer were analyzed.The wear resistance of the composite was tested by an MM-200 friction wear testing machine under unlubricated condition. The friction surface morphology was observed by means of scanning electron microscopy (SEM), and the wear mechanism was investigated.The results show that the method of the improved arc spraying technology feasible in laboratory. Some WC composite coating samples with different WC content were prepared. The microstructures of composite coatings after argon shielded arc remelted are more homogeneous and refine than WC-steel composite coatings after arc sprayed. And in the coatings, the lamellar character of the microstructure disappeared, defects eliminated, the cladding layer and the substrate transition zone between the relatively has a gentle microhardness gradient. The composite coatings are mechanically bond after arc spraying, but metallurgical bond after argon shielded arc remelted to the base metal. The hardness and wear resistance of the WC composite wear-resistant coat can be greatly improved as a result of the generation of amounts of finer particles with appropriate WC content. As the WC content increased, the hardness of the coating will increase, but the wear properties to deteriorate after the first changed for the better. There is a best content of WC in WC-composite coating in order to improve wear resistance of materials. There are different wear mechanisms, with different WC content in composite coating. The dominant wear mechanism is adhesion and slight cutting for that with 10wt%WC content, heavy cutting for the clad with 15wt%WC content, slight cutting and spalling with 20wt%WC content, and spalling with 25wt%WC content.