In-situ synthesis of Nb(C, N) ceramic particulates reinforced Fe-based composite coatings by laser cladding

The Nb(C, N) ceramic particulates reinforced Fe-based composite coatings have been successfully synthesized in situ by prior pasting laser cladding on steel 42CrMo. The phase constituents and microstructure of the composite coatings were investigated using X-ray diffraction, and scanning electron micrography. The results indicate that the coatings consist mainly of Fe-Cr fine phases with good resistance to oxidation and corrosion and a few of -Fe phases. In-situ synthesized Nb(C, N) particulates are uniformly distributed with blocky morphology in the composite coatings. The wear test shows that these reinforcement particulates improves wear resistance of the coatings significantly. The wear mass loss of the substrate with coating is about one ninth of that of the substrate without coatings. The coatings have better oxidation resistance through 750 ℃ constant temperature oxidation, and the oxide scale mainly consists of NbO1.1 and Cr2O3. The oxidation products of the substrate are Fe2O3 , and easy to spall off, resulting in a poor effect in substrate protection. The oxide scale of the coatings is one fifth as thick as that of raw substrate