Abstract
To further improve the hardness of the laser cladding layer on the surface of the vermicular graphite cast iron, the structural parameters of the laser cladding Co-base were designed and optimized, and the properties of the clad layer were evaluated using optical microscopy (OM), scanning electron microscopy (SEM), energy spectroscopy (EDS), X-ray diffractometer (XRD), electrochemical workstation, and friction wear equipment. The results show that the average hardness of the molten layer of Ni and Co-based composite cladding layer is 504 HV0.5, which is 0.64 times that of the Co-based cladding layer due to the combined factors of Ni-Cr-Fe equivalent to the dilution of the Ni-based cladding layer to the Co-based cladding layer. Due to the potential difference of the Ni, Cr, and Co elements on the surface of the cladding layer, the self-corrosion potential of the Ni and Co-based composite cladding layer is 1.08 times that of the Co-based cladding layer, and the self-corrosion current density is 0.51 times. Laser cladding Co-based cladding layer has high corrosion resistance. Under the influence of plastic deformation and oxidative wear of the cladding layer of the Ni and Co-based composite cladding layer, the wear amount of the cladding layer of the Ni and Co-based composite cladding layer is less.
Highlights
In order to improve the durability of the valve seat in the service process, the new power is integrated with a cylinder head and a valve seat
The use of high-frequency induction phase hardening, which requires the development of special induction coils for the shape of the valve seat, a method that primarily involves heating ductile iron above the phase hardening hardness and using rapid cooling in phase change hardening regions to form martensite tissue
When the protective coating is prepared by laser cladding, the material design of the cladding layer can be made according to the service conditions of the valve seat, combining the advantages of the high-power density of the laser and fast scanning speed of the laser cladding, the organization of the formed cladding layer is relatively small and the cladding layer and the substrate can be metallurgically bonded
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. When the protective coating is prepared by laser cladding, the material design of the cladding layer can be made according to the service conditions of the valve seat, combining the advantages of the high-power density of the laser and fast scanning speed of the laser cladding, the organization of the formed cladding layer is relatively small and the cladding layer and the substrate can be metallurgically bonded. Paczkowska et al [15] evaluated the possibility of laser melting of cobalt-based cladding on the surface of ductile cast iron, and carried out the surface modification of ductile cast iron valve seats to study the organization and hardness of the clad layer by varying different cooling rates and obtaining a clad layer with high hardness, fine organization, and high-temperature resistance. The research results provide support for the optimization of process parameters in engineering
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