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

Abstract

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