Tadaoki Morimoto

Fabrication of Ag-Sheathed Ba-Y-Cu Oxide Superconductor Tape

Ba2YCu3O7-δ tapes were fabricated by cold rolling. The critical current density Jc apparently depended on the thickness of the tape and increased markedly with decreasing tape thickness. The maximum Jc of 3330 A/cm2 at 77 K in a zero magnetic field was achieved in an Ag-sheathed BYCO tape, 0.06 mm in thickness. The presence of a 20 mT magnetic field reduced the Jc value by 1/100.

The Effects of Small Additions of Yttrium on the High-Temperature Oxidation Resistance of a Si-Containing Austenitic Stainless Steel

The oxidation characteristics of a 19Cr–10Ni–1.5Si alloy with and without 0.03Y have been examined using scanning-electron microscopy, secondary-ion mass spectroscopy and transmission-electron microscopy. Y has been found to segregate to oxide grain boundaries and thereby to inhibit outward-cation diffusion and promote the internal oxidation of Si. The synergism between the beneficial effects of Y and Si is described, and the results are discussed in relation to the de-oxygenating and de-sulphurizing influences of Y in steel production.

A microscopic study of ash deposits in a two-stage entrained-bed coal gasifier

Deposits adhering to the wall of a 50 t d−1 two-stage entrained-bed coal gasifier were analysed for morphology, structure, composition and sintering strength. Deposits were classified into three types: powder, lump, and fused slag. Of these, the powdery deposit consisted of melted ash particles, soot and char. Char considered as unmelted particles was produced at a lower oxygen/coal ratio. It served as a dispersive material in the deposit and prevented complete sintering even at high temperature. Because the two-stage gasifier operates with a lower oxygen/coal ratio at the gas exit zone and a higher oxygen/coal ratio at the molten slag exit zone, the slagging problem at the gas exit zone was decreased by the production of an adequate amount of char during gasification.