Abstract
In order to obtain high cost-effective coating materials working in chlorine-containing environment at high temperature, a 904L super austenitic alloy modified by an AlFeNiMoNb alloy (904L:AlFeNiMoNb) was obtained by vacuum arc melting process. The 904L:AlFeNiMoNb high-entropy alloy has a similar phase component with the AlFeNiMoNb alloy, but a more homogenous microstructure than that of the AlFeNiMoNb alloy. High-temperature chloride corrosion tests for 904L, AlFeNiMoNb, and 904L:AlFeNiMoNb high-entropy alloy were carried out under N2–2.6 vol.% CO2–1.3 vol.% O2–2,700 vppm HCl gaseous environment at 700°C and 800°C for 55 h, respectively. Due to the volatilization of FeCl2, weight change curves of the 904L alloy at 700°C and 800°C showed obvious weight loss. Especially at 800°C, the weight loss of the corroded 904L sample was 10 times that of the corroded sample at 700°C. Different from the weight loss situation of the 904L sample, both AlFeNiMoNb and 904L:AlFeNiMoNb high-entropy alloy showed small weight gains under the corrosion temperature of 700°C, while the latter gained half as much weight as the former. When the corrosion temperature was raised to 800°C, the AlFeNiMoNb and 904L:AlFeNiMoNb high-entropy alloy showed flat weight change curves with little weight loss. Weight loss for the AlFeNiMoNb and 904L:AlFeNiMoNb high-entropy alloy were 1.35138 and 0.0118 mg/cm2, respectively. The high temperature chloride corrosion resistance of 904L:AlFeNiMoNb high-entropy alloy is higher than that of 904L and AlFeNiMoNb at both 700°C and 800°C. Meanwhile, on the basis of the morphology and composition results of the corroded samples, combined with thermodynamic calculation, the high-temperature chloride corrosion mechanics of the tested alloys were discussed.
Highlights
Nowadays, more and more municipal wastes are made with the improvement in the living standards of the people and the acceleration of urbanization construction
The purpose of this study is to reduce the cost of the protective coating materials used in high-temperature chloride corrosion environment and expand the selection range of corrosion-resistant coating materials
The AlFeNiMoNb plate had several different phase compositions as shown in Figure 3, which were obtained by the analysis of its x-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) results
Summary
More and more municipal wastes are made with the improvement in the living standards of the people and the acceleration of urbanization construction. Among these corrosive gaseous corrosion processes, chlorine-induced high-temperature corrosion results in the most serious failures of materials used in municipal waste incinerators (Zahs et al, 1999) This is because the metal chlorides, which are the corrosion products of alloy matrix under the high-temperature chloride corrosion condition, have low boiling point and high vapor pressure. The volatilization of these corrosion products makes it easier for the base material to be exposed to the corrosive atmosphere, directly accelerating the corrosion progress (Galetz, 2017; Ma et al, 2020). In order to develop materials with excellent corrosion resistance, chlorine-induced corrosion behavior of alloys has been widely studied (Bender and Schütze, 2003; Galetz et al, 2015; Lequien and Moine, 2018; Izzuddin et al, 2020)
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