Synthesis and characterization of oxidation-resistant TiB2 coating on molybdenum substrate by chemical vapor deposition

Practical applications of molybdenum (Mo) and Mo-based alloy have been limited for their weak oxidation resistance properties under oxidizing environments. Anti-oxidation coating technology is a major solution for the improvement of oxidation resistance of Mo. In this study, titanium diboride (TiB2) was deposited as an anti-oxidation coating on pure molybdenum substrate from a gas mixture of TiCl4, BCl3 and H2 at 1000 °C by chemical vapor deposition (CVD). The result shows that good quality TiB2 thin coating has been grown on pure molybdenum and the thickness of the coating deposited at 1000 °C for 2 h reached 13 μm. The TiB2 coating was found to have a typically columnar particle structure and the length of the columnar particle is 1-2 μm. Meanwhile, TiB2 crystal has a preferential orientation growth in the (0 0 1) direction. The results of oxidation test reveal TiB2 coating formed on Mo substrate exhibits better oxidation resistance in air at 900 °C.