The high temperature corrosion of stainless steels (SUS316L and SUS310S) in the presence of molten carbonate [(Li0.62K0.8)2CO3 and (Li0.52Na0.48)2CO3] has been studied in a CO2-O2 atmosphere by measuring the weight gain of the specimens.The corrosion of SUS316L significantly depended on the reaction conditions. With the carbonate coating (both Li/Na and Li/K carbonates), severe corrosion occurred during the initial period of the corrosion test below 923 K, especially around 823 K. The initial severe corrosion was a local corrosion which produced through holes in the metal specimens and occurred more clearly at low Pco2 with the Li/Na coating than with the Li/K coating. The corrosion became more severe at higher CO2 pressures and lower O2 pressures. In a pure CO2 atmosphere (without O2), the corrosion rate significantly increased at 823 K. The steel was corroded uniformly at that time.

With increase in pulverized coal injection rate to blast furnace, renewal behavior of deadman has been attracting much interests. This paper focuses on the renewal rate of the deadman induced by the sink-float motion of hearth coke bed, and it is discussed through cold-model experiments using half-cut model of blast furnace. Trajectories of packed particles in the deadman zone are converted into the transient velocity field, and further to the distribution of time required for particle transferring to the raceway zone. With this distribution the renewal rate of the deadman is quantitatively discussed. As the results, it is revealed that increase in the amount of accumulated water in the hearth, shallower hearth depth, and increase in gas flow rate make the discharging time of particles in the deadman zone shorter, and this tendency is explained by the height of sink-float motion of the hearth packed bed. About ten percent of particles that are discharged from the raceway passes through the deadman zone in the standard condition of this study. The particle movement induced by the sink-float motion of hearth packed bed is indispensable mechanism in the evaluation of deadman renewal.

The high-temperature corrosion of stainless steels (SUS316L and SUS310S) in the presence of lithium-potassium eutectic carbonate and lithium-sodium eutectic carbonate has been studied by thermogravimetry and the metal consumption method under a carbon dioxide–oxygen atmosphere in the temperature range of 773–1123 K. Although the corrosion of SUS310S obeyed the parabolic rate law for all reaction conditions, the corrosion of SUS316L significantly depended on the reaction conditions. At or above 923 K, the corrosion of SUS316L obeyed the parabolic rate law, even with a carbonate coating. The corrosion rates were accelerated during the initial period of corrosion tests below 923 K, especially around 823 K with a lithium-sodium carbonates coating. The initial accelerated corrosion was a local corrosion, which produced through holes in the metal specimens, and occurred more clearly at higher carbon dioxide partial pressures with the lithium-sodium carbonate coating than with the lithium-potassium carbonate coating.

<p>Corrosion of reinforcing bars causes serious damages to concrete structures, for example, initiation and growth of cracks, exfoliation, and losing their durability. In concrete structural integrity assessment and repair, it is very important and difficult to know when the defects will be appeared and where the priority points should be repaired. In this paper, the accuracy of the two prediction methods of concrete deterioration, the electrochemical methods and the probability model, are assessed using experimental data. It is concluded that electrochemical method is useful for the concrete parts and the probability model methods are useful for maintenance planning of many concrete structures.</p>

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