GB772273A - Improvements in or relating to exothermic mixtures - Google Patents

Abstract

A heat producing mixture comprises an oxidisable metal or alloy and an oxidising agent in amount insufficient to react with the metal or alloy to oxidize it completely, the metal or alloy comprising magnesium, or magnesium alloy alone, or mixed with aluminium or silicon or their alloys or mixtures thereof. If aluminium or its alloys are present the mixture preferably contains also 1-10 per cent of a fluoride such as cryolite. The magnesium may be in granular form. The oxidizing agent is preferably one or both of iron oxide and manganese dioxide. One or more refractory fillers, such as grog, limestone, carbon or sand should be present in a major proportion, and in granular form to make the mixture permeable, and the whole may be formed into shaped articles, e.g. in shapes suitable for generation of heat in the risers and feeding heads of casting moulds, by use of a binder such as dextrine or gum arabic. Suitable compositions comprise magnesium alloy 10-35 per cent; aluminium or silicon or their alloys 0-35 per cent; filler 40-70; oxidizing agents 5-20 per cent; binder 0.-10 per cent; fluoride 0-10 per cent. Specification 627,678 is referred to.