Influence of impurity and alloying elements on high temperature oxidation resistance of E110 type zirconium alloys

The structural-phase state has been investigated and content of oxygen and hydrogen in the E110 type alloy after high-temperature oxidation simulating an accident of the LOCA type has been determined. Tubular samples with a diameter of 9.13 mm and a wall thickness of 0.7 mm from the Zr—1% Nb alloy obtained on the electrolytic zirconium basis (E110), the zirconium sponge basis (E110G), and from a modified alloy Zr—1% Nb—0.12% Fe—0.13% O (E110M) were selected for the study. The samples were subjected to a steam oxidation at a temperature of 1100 °C to 18% local oxidation depth. It was found that the E110G alloy based on a zirconium sponge absorbed oxygen and hydrogen less under LOCA conditions.

Oxidation Behavior of Ta–Al Multilayer Coatings

Ta–Al multilayer coatings were fabricated through cyclical gradient concentration deposition by direct current magnetron co-sputtering. The as-deposited coatings presented a multilayer structure in the growth direction. The oxidation behavior of the Ta–Al multilayer coatings was explored. The results specified that Ta-rich Ta–Al multilayer coatings demonstrated a restricted oxidation depth after annealing at 600 °C in 1% O2–99% Ar for up to 100 h. This was attributed to the preferential oxidation of Al, the formation of amorphous Al-oxide sublayers, and the maintenance of a multilayer structure. By contrast, Ta2O5 formed after exhausting Al in the oxidation process in an ambient atmosphere at 600 °C which exhibited a crystalline Ta2O5-amorphous Al-oxide multilayer structure.

Effect of PAN Oxidation on the Electrochemical Lithium Insertion/Deinsertion Behavior of Resultant Carbons

The effect of polyacrylonitrile (PAN) oxidation on the properties and electrochemical lithium insertion/deinsertion behavior of carbons produced in the temperature range of 1000–1150°C has been assessed. Air-treatment at 220 and 240°C modifies essentially the carbonization behavior of polymer leading to materials with developed microporosity and enhanced oxygen content in contrast to practically nonporous pristine PAN-based carbon. The extent of the modification increases with the oxidation depth and decreases with HTT. Galvanostatic charge/discharge reveals typical hard carbons characteristics of all the materials. PAN-based carbon heat-treated at 1050°C represents most promising anodic performance. It gives reversible capacity (Crev) near 420 mAh g−1with a reasonable coulombic efficiency during cycling of ~99% and a moderate low voltage capacity of 100 mAh g−1. Extensive oxidation enhances overall 1st discharge cycle capacity to 870 mAh g−1andCrevto 560 mAh g−1; however, large irreversible capacity (Cirr) and poor cycleability are serious drawbacks of all carbons from oxidized PAN. Pyrolytic carbon coating using methane CVD at 830°C is effective in suppressingCirrby about 30% but the cycleability remains nonacceptable.