Hydrous Solid Silicates in New Foundry Binders

Abstract

Inorganic binders are becoming more widely used in the foundry industry. This is especially facilitated by the development of a new, two-component alkaline silicate binder system and its very successful introduction into the mass production of sand cores for the critical aluminum cast parts of automotive engines. This article is dedicated to the further improvement of the process of manufacturing sodium silicate bonded sand molds and cores by using modified two-component binder systems with solid silicates instead of traditional liquid silicates. The comparative tests of binders in a warm core box process showed the conditions at which it is possible to replace traditional liquid silicates with silicate powders and thereby substantially simplify the technological process of preparation, using and handling of the binders. Another promising area of application of binders based on hydrous solid alkaline silicates is three-dimensional printing of sand molds and cores. Based on the special experimental procedure, which took in account the principal features of the three-dimensional printing process, the binder systems with liquid and solid silicates were tested. The results of the tests were explained by the difference in formation of sand articles when using dried pourable silicate coated sand mixtures or binder systems with liquid silicates and silicate powders.