| abstract |
The mfr. of tubular products by centrifuging a hollow cylinder (I) in the horizontal plane and feeding in a material (II) which forms a uniform layer in the bore of cylinder (I). Specifically material (II) is a thermite mixt. contg. >=1 metal oxide and a redn. agent, the powdered mixt. (II) being ignited to form a melt resulting in a metal layer and a layer of corundum, thereby producing a composite tubular product. The thermite mixt. (II) is pref. Fe2O3 plus Al; or Fe2O3 and MnO plus an Al-Mg alloy. Before feeding in the thermite mixt. (II), the bore of cylinder (I) is pref. protected with a layer of electro-corundum or a mixt. of silica sand and blast furnace slag. Used in the horizontal centrifugal casting of a metal tube with a corundum bore suitable e.g. for conveying, using compressed air as a carrier, of very abrasive materials such as sand, gravel, slag, cement,c oal, ores, etc. |