Abstract
The molten aluminum resistance of arc-ion plated TiN coating was evaluated in pure molten aluminum by immersion tests at 715, 765 and 800°C. The interfacial reaction between TiN and molten aluminum was studied by micro beam x-ray diffraction and cross-sectional TEM. After immersion tests, a compound layer containing hexagonal wruzite AlN and Al3Ti was observed at the interface. We assume that a TiN+4Al→AlN+Al3Ti reaction took place. The compound layer thickness was increased as the testing temperature and time was increased. The compound layer growth ratio at 765°C was 2.5μm/ks significantly larger than that of CrN coating previously reported. This difference in reactivity may depend on the protectivity of the AlN compound layer formed at the interface. The microstructure of the compound layer is discussed in connection with that of the CrN and TiN coating.
