Abstract
The scientific and practical issues of the development of core mixtures for foundry, based on phosphate binding materials, are considered. The binder presented in this article differ from those previously known by the fact that scarce prepared metal phosphate binding components and powder solidifiers are not used to produce them. As a result, all developed binders are different forms of aluminum phosphates. It is shown that to obtain them it is possible to use combinations of orthophosphoric acid with aluminum-containing materials of different chemical nature.The formation of high-strength phosphate binders in the interaction of phosphoric acid with aluminosilicates and sludge wastes of aluminum production has been established. They are rationally used for processes of thermal strengthening of cores in the temperature range of 200…300 °C.The formation of binders in the interaction of orthophosphoric acid with inorganic aluminum salts are theoretically proved and practically confirmed. The results are confirmed by thermodynamic calculations, as well as by X-ray phase analysis.The compositions of the developed core mixtures and examples of their application for obtaining high-quality castings from iron and steel are presented.
Highlights
Phosphates occupy a special place among the binder materials
Core mixtures based on orthophosphoric acid, aluminophosphate and alumina-chromophosphate binders were developed for the foundry industry
Thermodynamic calculations are substantiated and experimentally proved that as a result of the interaction of orthophosphoric acid with nitrate aluminum at a temperature of 200...250 °C, a binder is formed which has the form of the orthophosphate of aluminum and allows to achieve the compressive strength of the mixture in the range of 2.3...2.8 MPa
Summary
Phosphates occupy a special place among the binder materials. They have a number of valuable properties due to which they are known as heat-resistant, corrosionresistant and heat-resistant materials [1].Today a significant amount of information has been accumulated regarding the chemical, thermal and other properties of phosphorus compounds. Phosphates occupy a special place among the binder materials. They have a number of valuable properties due to which they are known as heat-resistant, corrosionresistant and heat-resistant materials [1]. Core mixtures based on orthophosphoric acid, aluminophosphate and alumina-chromophosphate binders were developed for the foundry industry. These mixtures as an obligatory component include hardeners – pure oxides or complex oxide compounds, which are a scarce and expensive raw material. Such binder systems are practically not used [1, 2, 3]
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