Microstructures, mechanical and oxidation behaviors ofC/C composites modified by NiAl alloy
(State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China)
Abstract: Carbon/carbon composites modified by NiAl alloy were prepared using vacuum reactive melt infiltration methods with NiAl and titanium mixed powders as raw materials. The microstructures were investigated by scanning electron microscopy. The fracture behavior, infiltration and oxidation mechanism were further discussed. The results indicated that NiAl alloy exhibited good wettability on the C/C preform because a TiC reaction layer formed at the interface. Multi-layer (PyC/TiC/NiAl+TiC) coating evenly and compactly distributed on the surface of the carbon fiber in tubular form. The penetration depth of molten NiAl alloys depended on the reaction between the PyC and titanium. The impact fracture was inclined to along the interface between the NiAl permeability layer and C/C matrix. Al2TiO5 and TiO2 formed on the surface, while the interior multi-layer tubular structure partially remained after oxidation at 1773 K for 30 min.
Key words: carbon/carbon composites; interface; NiAl; multilayer structure; oxidation