Effect of NiCrAl/YSZ/NiCrAl-B. e composite coating on combustion products of high-temperature α+β titanium alloys

Abstract

NiCrAl/YSZ/NiCrAl-B. e composite coating on TC11 titanium alloy was combusted by friction in oxygen-enriched atmosphere. The combustion products were studied by XRD, SEM, EDS and EPMA. The effect of the composite coating on the combustion behavior of TC11 titanium alloy was discussed. The results show that there is regional microstructural evolution along radial direction in the substrate of the combusted specimen. The substrate near the central hole is the ignition source. When the combustion degree is low, the effect of the YSZ intermediate layer on the combustion behavior of titanium alloys can be ignored. However, when the combustion degree is high, the YSZ intermediate layer dissolves greatly in the titanium alloy melt through decomposition reaction, which provides O and Zr for the titanium alloy melt and accelerates the interaction between Ti and O. Furthermore, the ZrTiO4 combustion product has a worse ability to block oxygen diffusion than TiO2. As a result, NiCrAl/YSZ/NiCrAl-B. e composite coating, especially the YSZ layer, promotes the ext-ended combustion of TC11 titanium alloy.

Keywords

• high-temperature titanium alloy
• NiCrAl/YSZ/NiCrAl-B. e composite coating
• microstruc-ture
• combustion behavior
• mechanism