Treatment of Metals

Abstract

A composition for application to slabs, billets or other articles of metal such as tools which are to undergo heat treatment comprises ferrosilicon, finely divided refractory material including aluminium hydroxide, and a fusible glazeforming material. Oxidation and decarbonization are thereby reduced. The refractory, other than the aluminium hydroxide which includes hydrated alumina, may be alumina, magnesia, silica or a silicate or mixture thereof; the fusible material may be powdered glass or a mixture of silicates, borates or phosphates with iron oxide or lead oxide. The composition may contain aluminium and an oxidizing agent such as a nitrate, chlorate of an alkali metal or alkaline earth metal, iron oxide, manganese dioxide, and also preferably includes a fluoride. The composition may comprise 40 to 80% refractory, at least 30% being aluminium hydroxide, 6 to 60% ferrosilicon, 1 to 65% fusible material, 1 to 15% fluoride. The mixture may be suspended in water or organic solvent with a montriorillonite, bentonite or sodium carboxy-methyl cellulose as a dispersing agent. A resinous adhesive may also be present. The composition may be applied by brushing, dipping or spraying. In the Example a composition comprising aluminium hydroxide, ferrosilicon, silica flour, bentonite, powdered glass, sodium cryolite is suspended in water and applied to steel ingot surfaces. A metal object may be subjected to a carburizing treatment on only part of its surface, the area not requiring carburizing being coated with the composition.ALSO:A composition for application to slabs, billets or other articles of metal such as tools which are to undergo heat treatment comprises ferro-silicon, finely divided refractory material including aluminium hydroxide, and a fusible glaze-forming material. Oxidation and decarbonization are thereby reduced. The refractory other than the aluminium hydroxide which includes hydrated alumina, may be alumina, magnesia, silica or a silicate or mixture thereof; the fusible material may be powdered glass or a mixture of silicates, borates or phosphates with iron oxide or lead oxide. The composition may contain aluminium and an oxidizing agent such as a nitrate, chlorate of an alkali metal or alkaline earth metal, iron oxide, manganese dioxide, and also preferably includes a fluoride. The composition may comprise 40 to 80% refractory, at least 30% being aluminium hydroxide, 6 to 60% ferrosilicon, I to 65% fusible material, 1 to 15% fluoride. The mixture may be suspended in water or organic solvent with a montmorillonite, bentonite or sodium carboxy-methyl celulose as a dispersing agent. A resinous adhesive may also be present.ALSO:A composition for application to slabs, billets or other articles of metal such as tools which are to undergo heat treatment comprises ferrosilicon, finely divided refractory material including aluminium hydroxide, and a fusible glaze-forming material. Oxidation and decarbonization are thereby reduced. The refractory other than the aluminium hydroxide which includes hydrated alumina, may be alumina, magnesia, silica or a silicate or mixture thereof; the fusible material may be powdered glass or a mixture of silicates, borates or phosphates with iron oxide or lead oxide. The composition may contain aluminium and an oxidising agent such as a nitrate, chlorate of an alkali metal or alkaline earth metal, iron oxide, manganese dioxide, and also preferably includes a fluoride. The composition may comprise 40 to 80% refractory, at least 30% being aluminium hydroxide, 6 to 60% ferrosilicon, 1 to 65% fusible material, 1 to 15% fluoride. The mixture may be suspended in water or organic solvent with a montmorillonite, bentonite or sodium carboxy-methyl cellulose as a dispersing agent. A resinous adhesive may also be present. The composition may be applied by brushing, dipping or spraying. In the Example a composition comprising aluminium hydroxide, ferrosilicon silica flour bentonite, powdered glass, sodium cryolite is suspended in water and applied to steel ingot surfaces. A metal object may be subjected to a carburising treatment on only part of its surface, the area not requiring carburising being coated with the composition.