Ti2AlC coatings deposited by High Velocity Oxy-Fuel spraying

High Velocity Oxy-Fuel has been utilized to spray coatings from Ti2AlC (MAXTHAL 211 (R)) powders. X-ray diffraction showed that the coatings consist predominantly of Ti2AlC with inclusions of the phases Ti3AlC2, TiC, and Al-Ti alloys. The fraction of Ti2AlC in coatings sprayed with a powder size of 38 mu m was found to increase with decreasing power of the spraying flame as controlled by the total gas flow of H-2 and O-2. A more coarse powder (56 mu m) is less sensitive to the total gas flow and retains higher volume fraction of MAX-phase in the coatings, however, at the expense of increasing porosity. X-ray pole figure measurements showed a preferred crystal orientation in the coatings with the Ti2AlC (0001) planes aligned to the substrate surface. Bending tests show a good adhesion to stainless steel substrates and indentation yields a hardness of 3-5 GPa for the coatings sprayed with a powder size of 38 mu m. (c) 2008 Elsevier B.V. All rights reserved.