Materials selection and tests for precise execution of foundry molds designed to geopolymer casts

Abstract

The paper presents the results of research on the selection of material for molds intended for geopolymer castings as well as an appropriate technological process for the preparation of such castings. Three silicons with different elasticity and hardness of 30, 40 and 60Sh were tested. The above-mentioned rubbers were used to make one-piece open molds and test the performance of each material. A model having several details and a small flat surface was chosen for the replica. Based on this variation in the wall structure, it was possible to assess the accuracy of mapping, both small elements and straight cast planes. In the prepared forms 10 tests of geopolymer casting were carried out to develop the best technological process. The appropriate result was achieved when the molds covered with the divider were flooded with raw material by vibrating them on a vibrating table, and then allowed to react for an hour for free mass components and leaking gases to the surface. After a set time, the compaction was carried out again to more accurately eliminate the resulting air bubbles. The effect of this method is to obtain a cast with precisely mapped details and a smooth even surface, and almost complete elimination of air bubbles from representative surfaces.