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Thin wall cladding tubes of yttrium-bearing 9Cr ferritic-martensitic steel have been fabricated by cold-rolling process, with the final dimensions of 6 mm outer diameter, 0.5 mm thickness and 3 m length. The changes of microstructure of hot-rolled plate, forged rod and the final tubes were attributed to the cold-rolling process and the intermediate heat treatment. Mechanical properties were tested from room temperature to 600 °C. The final tubes showed the strength level between the traditional ferritic-martensitic steel and the metallurgy alloyed oxide dispersion strengthened steel. It was also found that the degradation of ductility at 400 °C was related to the dynamic strain ageing (DSA) effect. At last, ultra-sound test, flattening test and flaring test were carried out to evaluated the qualities of the final tubes.

Van der Waals (vdW) screening or Faraday-cage-like screening of vdW interaction by monolayer crystals has recently been observed in experiments and understood from first-principles theories. Here, we investigate the vdW screening by a bulky dielectric layer using the Lifshitz theory. The ratio of vdW screening is found to depend on not only the interobject distance but also the thicknesses of the separated layers. Surprisingly, the screening ratio exhibits a nonmonotonous distance dependence, first increasing, but beyond a critical distance reducing, toward zero. The short-range trend coincides with that predicted for graphene-like trilayers by the random phase approximation, while the long-range trend poses a contrast to the increasing screening with distance by graphene predicted by the many-body dispersion approach. The positive correlation between the screening ratio and the dielectric constant revealed for atomistic layers is reproduced for the bulky dielectric layers.

A kind of Y-bearing ferritic/martensitic fuel cladding tube with qualified dimensions, acceptable mechanical properties as well as good flattening and flaring performance was manufactured recently by our group. In this paper, to improve and further evaluate its oxidation resistance, the cladding tube was aluminized firstly and then subjected to high temperature steam oxidation at 1200°C for 8 h. The results indicated that aluminizing coating with gradient content of Al was prepared on the tube successfully. And the matrix microstructure was transformed from tempered martensite into ferrite during aluminizing. Weight gains after high temperature steam oxidation were 72.7 and 1.48 mg cm −2 for the bare and aluminized tubes, respectively. The latter one exhibited better oxidation resistance due to the generated dense aluminum oxide film. Meanwhile, Kirkendall pores were formed near oxidation surface and should be eliminated for the real application of the aluminized tube in the future.

Electron–hole interaction has an exceptionally large effect on the long-range van der Waals energy between two-dimensional semiconductors.