The study of the properties of moulding sands containing lignosulfonates and polyethylenepolyamine

Abstract

The experience of foundry shows that the quality of castings, manufactured in sand moulds, directly depends on the properties of moulding and core sands. These properties depend on the type and characteristics of the binding materials. None of the existing sands compositions provide an ideal combination of properties. Therefore, you have to look for all new alternatives. Technical ligosulfonates have been used for a long time as an inexpensive binder. Based on literary data, the conclusion has been made that lignosulfonates have not found wide use as an independent binder in moulding sands due to low strength of sands in the dried state. As an additional component improving the binding properties of lignosulfonates, the authors have proposed to use polyethylenepolyamine. In the process of research, a high-strength binder based on technical lignosulfonates and high molecular weight polyethylenepolyamine has been developed. A complex of physical, mechanical and technological properties of the binder, as well as the strength properties of moulding sands prepared on its basis, has been investigated. It has been shown that the experimental sands have strength characteristics both in the green and in the dried state of 6-10 times higher as compared to the sands containing lignosulfonates only. In doing so, high dry strength values are achieved at a relatively low drying temperature (180°C), both for sands without clay, and for the ones containing clay. Based on this, it has been concluded that it is possible to reduce the amount of the binding in the sands to achieve the optimal level of their strength properties. The achieved results, if introduced into production, will make it possible to increase not only the geometric accuracy of castings and the surface quality, but also to reduce the costs of knocking off and cleaning operations as well