Characterisation of Cr3C2–NiCr Cermet Powder for High Velocity Oxyfuel Spraying

The structural characteristics of a commercial high velocity oxyfuel thermal spraying powder containing chromium carbides and a Ni–Cr metallic matrix have been determined using a variety of experimental techniques including X-ray diffraction, SEM, and electron probe microanalysis. The powders were prepared in such a way that a liquid phase was formed. In some cases the liquid phase surrounded the original carbides but in other cases the liquid did not surround the carbide particles, giving rise to a mixture of both spherical and irregular granules. Apart from the original Cr3C2, secondary Cr3C2 has been found together with Cr7C3 and Cr23C6 with some nickel replacement for chromium in these carbides. The results have been interpreted in relation to the C–Cr equilibrium diagram with appropriate modifications for the presence of nickel. PM/0642