Hazelett Strip-casting Corporation

James G Villa

Jerome B Allyn

Wojtek S Szczypiorski

J F Wood

Norman J Bergeron

S Richard Hazelett

Woitek Szczypiorski

A method and belt composition for improving the performance and flatness of thin revolving flexible casting belts of continuous casting machines wherein at least one wall of the moving mold is provided by a thin flexible endless metallic casting belt having a permanent insulative coating with fluid-accessible porosity in this permanent coating. Contrary to prior methods and apparatus which have sought to protect the wide thin casting belts, the present method for improving belt flatness and performance involves providing a Helium-containing gaseous film between the metal and the front face of the casting belt which is coated with a permanent insulative porous coating. For significantly improved results, this gaseous film contains at least 8 percent and preferably 15 percent and optimally 20 percent or more of Helium by volume and is non-reactive with the metal being cast, resulting in a controlled increase in the rate of heat transfer and for causing such heat transfer to become more nearly uniform and stabilized across the width of the flexible casting belt than in prior continuous casting machines of the same moving mold cross-sectional shape and size. The freezing rate advantageously becomes stabilized at a substantially higher and more uniform rate, the belt flatness becomes stabilized and the cast metallic product is thereby substantially improved both in metallurgy and surface appearance. Also, copper or copper alloy casting belts are used in certain embodiments for enhancing heat-transfer effects and belt flatness. During casting at a given speed, the freezing rate and exit temperature of the metal being continuously cast can be controlled by varying the helium percentage in the gaseous film itself. In twin-belt machines, relative heat-transfer rates into upper and lower belts are controlled by adjusting the relative helium percentages in their respective gas films.

Belt composition for improving performance and flatness of thin

Method and belt composition for improving performance and flatness in

A unitary-layer partially metallic, suitably adherent, mechanically and thermally durable, non-wetting, fusion-bonded matrix coating on endless, flexible metallic casting belts for continuous casting machines is described. This fusion-bonded matrix coating is also advantageous for coating other molten-metal-contacting surfaces, in continuous casting machines, such as edge-dam blocks that define moving side walls of a mold cavity. The fusion-bonded matrix (or reticulum) coating provides advantageous accessible porosity throughout the coating and comprises a nonmetallic refractory material interspersed substantially uniformly throughout a matrix of heat-resistant metal or metal alloy, for example nickel or nickel alloy, which is fusion-bonded to the grit-blasted surface of the belt and anchors and holds the nonmetallic material. The coating is applied by thermally spraying a powdered mixture directly on the roughened surface. The result is to insulate and protect the underlying belt from intimate molten metal contact, from heat stress and consequent distortion and from chemical or stress-corrosive action by the molten metal or its oxides or slags. The nonmetallic material may be present, at least partly, in the form of isolated particles encased within the metallic reticulum and/or in the form of a second reticulum intertwined with the metallic reticulum. The life of the coated belts is dramatically increased, and the surface quality and properties of the cast product are significantly improved. The coating controls and renders more uniform the rate of freezing of the metal being cast, resulting in improved metallurgical properties. Formulations are described and a method of forming such coatings by thermal spraying.

Matrix coatings on endless flexible metallic belts for continuous

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Winooski, VT, United States of America

James G Villa