| Submicron TiC and WC reinforced metal matrix composite (MMC) coatings on a ductile iron were fabricated by laser surface alloying (LSA) using CO2 laser. Microstructure and phase of the LSA coatings with different content of TiC were investigated by SEM and XRD. The microhardness and wear resistance of the coatings were tested. The results showed that, when the content of TiC was increased to 30% the white small particles began to appear in the LSA coating and the white particles were ceramic hard phase. While the TiC content increased to 40%, the white particles become even more. The microstructures of the LSA coating with 40% TiC were refine, homogeneous and compact, and the properties of the coating was better than that of low content of TiC. The coating with 40% TiC has a average hardness of 1097 HV0.2. The wear mass loss of the coating is just one ninth of that of the ductile iron and the worn surface is relatively smooth, which indicated that the wear resistance of ductile iron was improved by LSA with submicron TiC and WC. |
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