In-situ synthesis of TiN coating prepared by laser cladding

The TiN coating were developed on Q235 steel surface by laser cladding using mechanical milling Ti powder.The microstructure of the TiN coating were analyzed by using SEM, XRD EDS and BSE methods. Meanwhile, the hardness, high temperature stability and corrosion resistance of the cladded layers were also measured. The results showed that the TiN coating was composed of TiN, TiO₂ and Fe and a metallurgical bonding was formed. Global particles can be seen in the fusion zone.However, two phases in the form of dendrites and needle platelets were found in the dilution zone. Ti powders can be refined and activated by mechanical milling process. Therefore, finer grain could be easily formed in the coatings by using milled powders. Furthermore, the microhardness and the high temperature stability were excellent. The highest microhardness of the coating was 951.5 MPa under the conditions of laser power 1 000 W and scanning speed 600 mm/min. The corrosion resistance of coating was not good because of the defect like porosity presented in the coating.