Publikationsserver der RWTH Aachen University
AeroSande - ein neuer Formstoff für Geißereianwendungen
Abstract
dc:descriptionIn the present work, organic aerogels are used as a new binding material for mould and core production in foundry application. The work is motivated by the problems occurring during the mould and core removal in aluminium casting. In contrary to steel and iron casting the low casting temperatures lead to low temperatures in the mold and core material and therefore the bonding efficiency remains on a high level. Therefore a complete core removal is only possible by an increased mechanical effort. Thin wall parts of the casting are as much problematic as backdrafts and cavities. With AeroSands, the combination of aerogels and sands, a novel molding material for core and mold production are presented. In the present dissertation preparation methods of organic aerogels and AeroSands are presented. AeroSands are prepared by mixing conventionally foundry sands with a certain amount of aerogel sol, consisting of resorcinol, formaldehyde, sodium carbonate and water. After gelling and drying, AeroSands prepared in that way are characterized as a mold and core material. The sand types are varied (corundum, silicon carbide, quartz, mullit-hollow spheres), their grain sizes and the amount of aerogel solution in the range of 4-24%. The AeroSands are characterized according to their mechanical properties ,bending strength, compression strength, elastic modulus, permeability and core strength, and according to their thermophysical properties, thermal conductivity and specific heat. AeroSands made by organic aerogels have two characteristics which are quite interesting for foundry applications. The polymeric aerogel decomposes totally at temperatures above 350°C, i.e. far below the solidus temperature of common aluminium foundry alloys. The thermal decomposition was analysed at different temperatures. The second characteristic makes the polymeric aerogels even interesting for thin walled steel castings: The thermal conductivity depends on the sand type, its grain size and the amount of aerogel. Optimizing these three parameters the effective thermal conductivity can adjusted such that thin walled steel casting can be realized. The basic research and development of this new binding material is completed by casting experiments with a conventional aluminium alloy. They showed that this new binding material leads to castings with a high surface quality and that cores can be removed without any mechanical effort by only thermal disintegration.
Degree
thesis:*- Grantor dc:publisher
- Publikationsserver der RWTH Aachen University
- Year dc:date
- 2003
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Brück, Sabine
- Contributors dc:contributor
-
- Ratke, Lorenz
Subjects
dc:subject × 9Rights
dc:rights- Statement dc:rights
-
- info:eu-repo/semantics/openAccess
- Language dc:language
- ger