Abstract: By static combustion synthesis tests, Ti-B₄C-C+5wt%Al was chosen as the reactive system to prepare the Ti(C_0.7, N_0.3)-TiB₂- Al₂O₃ multiphased ceramic coatings on the metal substrate with a reactive flame spray technology. It is found that the coatings have the multiphased heterogeneous metastable structure, which consists of TiC_0.7N_0.3, TiB₂, Al₂O₃, titanium oxide and some pores. The structure of the coatings can be divided into three kinds: the Tistructure with the cluster-shaped TiB₂ in micron-nanometer size, the structure with mass-shaped 1--2μm Ti(C_0.7, N_0.3) particle surrounded by the needle-shaped or strip-shaped TiB₂ and the black phase of anomalous pores. The forming causes of the three kinds of structure are the same as those of the coatings with no additive Al. However the additive Al raises the reaction velocity, so the amount of ceramic phase increases, the structure becomes fine, the pores reduce and the micro-hardness of the coatings is increased.

Key words: reactive flame spray, TiC-TiB2-Al2O3, multiphase ceramic coatings, structure