Microstructure and Mechanical Properties of Two-Layer Laser-Cladded Co-Based Coatings

Two-layer Co-based cladded coatings with high-temperature wear resistance were fabricated on the surface of Q235 steel by using laser cladding process. The microstructure and phase constitution of the cladded coatings were observed by SEM, EDS, XRD and TEM. The microhardness and high-temperature wear behaviors of the cladded coatings were evaluated by friction wear equipment. The microstructure of the upper region of the first-layer cladded coatings showed a uniformly dendrite formation, while amorphous phase existed in the upper region of the second-layer cladded coatings because of the comparatively lower dilution in the upper layer. The microhardness of the second-layer cladded coatings was up to over 1200 HV_0.2 which was six times of the substrate. The wear loss of the second-layer cladded coating was 18.3% less than that of the first-layer cladded coating. The second-layer cladded coating possessed excellent comprehensive mechanical properties due to the existence of amorphous phase.