IN SITU SYNTHESIS OF TiC–TiB2 REINFORCED FeCrSiB COMPOSITE COATING BY LASER CLADDING

TiC and TiB2 reinforced iron based metal matrix composite (MMC) coating was synthesized on mild carbon steel by laser cladding employing B4C, ferrotitanium, and FeCrSiB mixed powders. The microstructure and chemical composition were analyzed by means of SEM, EPMA, and XRD. Results show that the coating mainly consists of α–Fe(Ni), TiB2, TiC, B6Fe23, Cr2B, and M23C6. TiB2, and TiC reinforcements are formed in situ through the reaction between B4C and ferrotitanium. Hardness and wear measurement results show that the hardness and wear resistance of the composites are much higher than that of the as-received sample.Composite materials, coating, in situ synthesized, laser cladding, TiC–TiB2

PHASE COMPOSITION, MICROSTRUCTURE, AND TRIBOLOGICAL PROPERTY OF PLASMA-SPRAYED TiC-BASED COATING

TiC-based wear resistant coating was prepared by plasma spraying using reconstituted composite powders doped with ultra-fine carbide. Phase composition and microstructure of as-sprayed coating were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) utilizing backscattered imaging mode (BSE), and electron probe micro-analysis. Wear test was performed by using a ring-on-block tester under dry sliding condition. Results show that the coating adheres well to the substrate and no delamination appears. TiC content underwent pronounced reduction because of oxidation, reaction, and physical loss. Reactions between TiC and Mo and probably between dissociated C and Mo lead to the formation of Mo2C. Wear resistance of NiCrMo–TiC coating is about 4–8 times higher than that of substrate under different applied force. This work shed light on the reconstitution of spraying powder doped with ultra-fine reinforce phase particles, and the present results are important for the preparation of nano-doped TiC-based coatings.Coating, microstructure, X-ray diffraction, wear