GB860904A - Refractory lined centrifugal casting molds - Google Patents

Abstract

860,904. Moulding-processes. AMERICAN CAST IRON PIPE CO. Nov. 13, 1959, No. 38533/59. Class 83 (1). A metal centrifugal casting-mould is lined with a refractory by introducing an aqueous slurry of the refractory into the mould. which is rotated at a speed sufficient to distribute the slurry by centrifugal force over the inner surface of the mould and to compact the solid particles of the slurry against the mould wall to form a high-density lining while simultaneously causing the major portion of the water of the slurry to collect freely at the inner surface of the lining so that it may be removed, thereafter drying the lined mould to evaporate substantially all the remaining water. After removal of the free water, the mould lining may be washed by the introduction of fresh water. The slurry comprises a major proportion of silica sand and a minor proportion of silica-fines, and preferably a small amount of a gel-forming material or dispersing-agent such as western-bentonite or other clays, methyl-cellulose sodium-carboxymethylcellulose and hydroxyethylcellulose. Thickeners such as Glutrin (containing tannins and non-tannins), Cyoulac (derived from sulphite pulp process waste) and sodium-aluminate may also be added. When lining a vented mould, the slurry includes a proportion of larger particles which block the vents to prevent escape of the finer particles. A number of specific examples of slurry-compositions and spinning-procedures are given.