Biomass fuel is effective renewable energy and being used for replacing fossil fuel energy. It can be produced from synthesis gas containing a high percentage of carbon monoxide (CO) and hydrogen (H2) in biomass-to-liquid plants. Austenitic stainless steel AISI 316L (Cr17% Ni 10% Mo 2%) is used for equipment parts in chemical and petrochemical industries due to good corrosion resistance at various operating conditions. The corrosion resistance of stainless steel may be degraded by the reduction reaction of the passive film and carbide formation from carbon diffusion, which leads to the intergranular corrosion on the steel surface. This research aims to study the degradation of stainless steel AISI 316L in a simulated carbon monoxide containing atmosphere at 15-45%CO and a sensitizing temperature of 800 °C. Before the test, the samples were preoxidized in the air at 800 °C for 6 hours. An electrochemical reactivation (EPR) technique was used to analyze for detecting sensitization. The mass change of AISI 316L slightly increased after the reduction test. Besides, the high carbon diffusion was shown on the steel surfaces as chromium carbides at the high percentage of carbon monoxide.
This work reveals the high-temperature oxidation resistance of WC-Co coated on SA213-T22 by High-Velocity Oxy-Fuel (HVOF) technique in simulated molten salt atmospheres and compare that with the uncoated Cr-containing steel. The corrosion behaviors of SA213-T22 coated and uncoated with WC-Co alloys were studied by immersion test under simulated molten salt atmospheres at 600 °C for 3 hours and investigated their corrosion current densities by electrochemical test. Scanning electron microscope equipped with EDS technique and X-ray diffraction were used to evaluate the surface morphology and phase constitution. The oxidation rate of the coated and uncoated steels was observed under simulated atmospheres at 750 °C for 120 hours before the immersion test. The mass gain scale increase with increasing the oxidation time and the oxidation rate of scale are limited by the WC-Co alloys coating layer, which acted as a protective layer. The low corrosion current density of the WC-Co self-fluxing coated steel after oxidation was shown 5 – 10 μA/cm 2 after the corrosion test in molten salt for 3 hours. After the immersion, the scale layer on the uncoated specimen was disappeared, but one-half of the oxidized coating layer on the coated specimen has remained.
Stainless steel is widely used for many components and parts in coal-fired thermal power plants. AISI 430 ferritic stainless steel (FSS) is one common grade to combat the degradation at high temperatures in coal combustion atmospheres containing flue gas, coal ash, and soot (impure solid carbon particles). However, the effect of the solid carbon particles on the degradation of FSS needs to be clarified. Graphite powder was used to simulate solid carbon atmospheres for investigating the degradation of AISI 430 at high temperatures of 1150℃ to 1350℃ in coal-fired boilers. After the carbothermic reduction, the mass gain of a pre-oxidized sample at 750℃ was approximately 0.0793 mg⸳cm-2 and increased when increasing the reduction temperature. The peak of Fe2O3 and Cr7C3 were detected by X˗ray diffraction (XRD) after the oxidation and reduction test, respectively. Besides, the degree of sensitivity (%DoS) of the samples was measured by double loop electrochemical potentiokinetic reactivation (DL-EPR) technique and increased around 30 times after heating the pre-oxidized sample to 1150℃.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.