Vesuvius Crucible Company

David Stephenson

Eric Hanse

Paul M Benson

Quentin K Robinson

Duane L DeBastiani

Phillipe Dumas

A dense carbon free surface is provided on a carbon bonded refractory shape which is particularly useful as a pouring tube liner to prevent the formation and build-up of alumina particles which may cause blockage of the tube. The carbon free, dense layer is also hard and erosion resistant making it ideal for use in other applications such as stopper rod noses. The material comprises a refractory mix having a major component of refractory oxides such as alumina and zirconia-mullite. Less than 10 wt. % carbon in the form of graphite and binder is in the mix plus about 2-5 wt. % of a metal such as silicon and an effective mount of sintering aids is also present. The pressed shape is preheated to a temperature of 1000.degree. -1400.degree. C. in air to oxidize the exposed surface of the shape and then to sinter the oxidized surface to form the desired dense, carbon free surface over the entire shape or on selected surface portions thereof.

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Troon, United Kingdom

David Stephenson