NiAl composite coating strengthened by ZrC and ZrB2 phases is synthesized by the plasma cladding process. The influence of cladding speed on microstructrue and properties of coatings is studied. The main phases of coatings are NiAl, γ-(Fe,Ni), ZrC and ZrB2 phases. ZrC is in the shape of points and small blocks, ZrB2 shows long strips and needle bar. The slower the cladding speed, the larger the size of the reinforcing phases. With the increase of cladding speed, the wear resistance of the coatings improves. Coating with the cladding speed of 10mm/s has excellent wear-resistance property owing to high hardness and low friction coefficient. ZrC and ZrB2 strengthening phases play an important role. The main wear mechanism of NiAl composite coating is adhesive wear.

The ZrC-ZrB2/Ni metal matrix composite coatings were in-situ synthesized from a mixture of Ni, Zr and B4C by plasma transferred arc (PTA) cladding process. Microstructures and phase constituents of the coatings were characterized by electron probe micro-analyzer (EPMA) and X-ray diffraction (XRD). Microhardness and wear resistance of the coatings were systematically investigated by means of vickers hardness tester and wear tester. The results showed that the main phases of the composite coatings were ZrB2 and ZrC. The coatings had a sound metallurgical bonding to the SA-283C steel substrate. Microhardness and wear resistance of the substrate were greatly improved by the composite coatings, and both of them showed a tendency to increase first and then decrease with the increase of the Ni content. As the content of Ni was 30 wt.%, the hardness of the coating reached the maximum value, 1522 HV, and the wear resistance was about 15 times that of the substrate.