High Temperature Erosion- Oxidation Behavior of Nickel- Based Alloys Containing Mo in Fluidized Bed Waste Incineration

Abstract

High-temperature erosion-oxidation behavior of nickel-based alloys containing 0-7 wt.% Mo in fluidized bed waste incineration conditions was studied. A stream of hot condensed air with a flow rate of 25 L/min caused hot silica sand (700 °C) mixed with 0.5 wt.% of chloride salts to hit the specimens for 250 h. By removing the erosive factor, the high-temperature oxidation behavior of the alloys in air and air-chlorine atmospheres was studied at 520 and 560 °C for 100 h. Mass gain measurement due to oxidation followed by thickness loss measurement in the erosion-oxidation tests showed that an increased Mo content led to improved oxidation resistance as a result of reduced scaling rate. However, under simultaneous oxidation and erosion conditions, the lower oxidation rate of the alloy with 7 wt.% Mo caused rapid removal of the protective scale and a reduction in erosion-oxidation resistance of the alloy. Under these conditions, the alloy with 3 wt.% Mo showed the smallest removal rate. Microscopic observations and XRD analysis confirmed formation of Cr2O3/NiCr2O4 scales on the surface. Mo-free alloy with lowest oxidation resistance showed a higher erosion-oxidation resistance. However, the high oxidation rate of this alloy led to a severe Cr-depletion and internal oxidation in subsurface region.

Keywords

• high-temperature erosion-oxidation
• ni-based alloy
• element molybdenum
• fluidized bed incineration.