Glass fibres of pure and erbium- or neodymium-doped yttria-alumina compositions

Article Abstract:

Containerless liquid-phase processing can be used to achieve deep undercooling of molten oxides to temperatures where the viscosity is sufficient for fibre-pulling operations. It was possible to pull glass fibres up to 0.5 m long at rates of 1 m s-1 to 1.5 m s-1 before crystallization of the melt stopped the process. The fibre-pulling behaviour seen for pure yttrium aluminium garnet and doped compositions may be the result of the greater sensitivity of undercooling behaviour in general for the pure composition.

Yttrium, Glass fibers

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Evidence against 'ultrahard' thermal turbulence at very high Rayleigh numbers

Article Abstract:

There are several theories that predict a limiting and universal turbulent regime, ultrahard turbulence, occurs at large Rayleigh numbers in a closed, rigid-walled cell. The ultrahard state is thought to support more efficient thermal transport than hard turbulence. However no evidence of a transition to an ultrahard state was found in experiments on Rayleigh-Benard convection in mercury at thigh effective Rayleigh numbers, suggesting that the limiting state is ordinary hard turbulence.

Usage, Rayleigh number, Turbulence

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Bulk glasses and ultrahard nanoceramics based on alumina and rare-earth oxides

Article Abstract:

A process using alumina-rare-earth oxide systems (Al2O3-RE2O3) for preparing very-high-alumina glasses and nanoscale glass-ceramics is presented. The techniques used can be extended to form glasses and nanoceramics in other oxide systems that do not include a conventional glass-forming component.

Primary Metal Manufacturing, PRIMARY METAL INDUSTRIES, Metal ores, not elsewhere classified, All Other Metal Ore Mining, Alumina, Amorphous Metals, Spectra, Aluminum oxide, Metallic glasses

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