In-situ synthesis of nanostructured NiAl-Al2O3 composite coatings on cast iron substrates by spark plasma sintering of mechanically activated powders

The SPS process is analyzed by FEM-simulations using a homogeneous reaction model where the properties are given by linear combinations of reactants and products. Melting enthalpies of all compounds are taken into consideration when calculating the maximum reaction temperatures for various combustion times and gap conductivities between powder and graphite parts of the SPS apparatus. The maximum reaction temperatures are calculated for pellets and for coatings on cast iron substrates and also for mixtures of activated and already reacted powder. The results are shown as isotherms. Comparison to experiments suggests a reaction time exceeding 1 s and a gap conductivity of less than 10 kW.m− 2.K− 1. For ignition at 500 °C, the adiabatic temperature is estimated to 2056 °C.