Sintering Study of NiCrAlY

In ceramics TBC s (thermal barrier coating) the MCrAlY layer is used like a bond coat between nickel superalloys and zirconia ceramics used in aeronautical turbine blades. However the oxidation of this layer is an important step to obtain an Al2O3 as TGO (thermally grown oxide), on which the zirconia ceramics is placed on to protect the turbine blades from high temperatures and oxidizers and corrosive gases generated during the burning of the fuel. To understand the oxidation process, parallel and flat surface samples are required. These surfaces will allow characterization, especially the tribologic ones. The samples were prepared through different process and sintering routes. Powders of NiCrAlY with and without binder were uniaxially pressed from 100 MPa to 250 MPa. Isostatically pressed samples at 300 MPA were also prepared. The samples were sintered in the air, at 10-7 Torr and hot uniaxially pressed at 10 MPa. The sintering temperature started at 800 °C up to 1200 °C during one hour. The best result was from the hot pressed samples between 1000 °C and 1150 °C. Above this temperature the process became complicated and started melting at 1200 oC. Mainly due to the spherical shape of NiCrAlY particles, it was not possible to get good samples when sintering in the air.