Two phases α2-TiAlγ-TiAI intermetalic alloy is developed for high temperature operation in oxidation enviroments. Its oxidation is relatively high due to the formation of TiO2 oxide scale which is not protective. Utilization of this material in a gas turbine engine can result in cracking and spelling of the oxide scale. The halide activated pack cementation method was used to deposit aluminize coatings on α2-TiAlγ-TiAI intermetalic alloy to enhance the oxidation resistance of α2-TiAlγ-TiAI intermetalic alloy. The aluminizes were deposited from a pack of aluminum powder, NH4CI, and alumna powder, the composition of the pack used variation was 10, 15, 20 wt % Al, 1, 1,5 2 wt % NH4C1, and Al2O3 as inert balance. All coatings were deposited tested at 900°C during 10 hours an argon atmosphere. Both coatings were subsequently at 1100°C under cyclic condition. X-ray diffraction (XRD), energy dispersive analysis of x-ray (EDAX), scanning electron microscopy (SEM) and optical microscopy were used to evaluate the coating deposition, morphology and oxidation behavior. The aluminide coating deposited in this study was of a compact duplex structure, the processes formed two layers, they are TiAl2 and TiAl3. During cyclic oxidation testing the aluminide coating at two phases α2-TiAlγ-TiAI intermetalic alloy substrate form by oxide scale is α-Al2O3 and TiO2. Forming And growth of TiO2 oxide faster by increasing cycle at temperature 1100°C. Substrate which is coated will give better oxidation resilience if is thick of coating above 48,66 gm with TiAl3 phases.
Ganda Putra (Bandung Institute of Tecnology, Indonesia
