1.
G. Gyarmati, G. Fegyverneki, D. Molnár and M. Tokár
Foundry Institute, University of Miskolc, Miskolc-Egyetemváros,
THE MELT CLEANING EFFICIENCY OF DIFFERENT FLUXES AND THEIR EFFECT ON THE EUTECTIC MODIFICATION LEVEL OF ALSI7MGCU ALLOY

2.
C. Delgado1, E. Garitaonandia1, L. Una Munzaga1, A. Martínez2, I. García3, J. Ríos4, J. Luis Rodríguez5
1IK4-AZTERLAN - R&D of Metallurgical Processes. Sustainability and Environment Team, Durango, Spain
2ACCIONA CONSTRUCIÓN S.A. – Technological Research Area, Alcobendas, Spain
3FUNDICIONES DEL ESTANDA, S.A., Beasain, Spain
4GAIKER-IK4 - Environment & Recycling Dept., Zamudio, Spain
5ONDARLAN, S.L., Renteria, Spain
INTEGRATION OF A NOVEL MECHANICAL SAND RECLAMATION TECHNOLOGY IN A STEEL FOUNDRY TO MAXIMISE SFS VALORISATION IN FOUNDRY AND CONSTRUCTION APPLICATIONS

3.
M. Žbontar1, M. Petrič1, M. Vončina1, J. Čevka3, J. Medved1, R. Cerc Korošec2
1University of Ljubljana, Faculty of Natural Sciences and Engineering, Department for Materials and Metallurgy, Ljubljana, Slovenia
2 University of Ljubljana, Faculty of Chemistry and Chemical Technology, Ljubljana, Slovenia
3Exoterm d.d., Kranj, Slovenia
APPLICATON OF SOL-GEL TECHNOLOGY IN FOUNDRY COATINGS ABSTRACT

4.
F. Zupanič1, M. Steinacher2, T. Bončina1
1 University of Maribor, Faculty of Mechanical Engineering, Maribor, Slovenia,
2 Impol 2000 d. d., Slovenska Bistrica, Slovenia
AS-CAST MICROSTRUCTURE OF A NOVEL AL-MG-SI ALLOY

Abstract

Nowadays, solid fluxes are widely used in foundries in order to reduce the inclusion content of aluminium alloy melts. The effect of fluxes is determined by their chemical composition, morphology, added quantity, as well as the temperature of the melt and the method of flux addition. On the other hand, the reactions promoted by the flux can result in the increased oxidation rate of alloying elements which are prone to oxidation. Thus, the application of highly reactive fluxes in case of Sr-treated melts can cause accelerated Sr-fading and inappropriate eutectic modification level. In this study, the effect of four different fluxes on the melt quality and Sr fading is described. First, the inclusion content and then, the Sr fading of the flux-treated metal was examined.

Key words: Aluminium alloy, Inclusions, Melt treatment, Modification

Abstract

One of the most pressing environmental concerns that metal casting industry faces nowadays is the disposal of Spent Foundry Sand (SFS). Landfill of foundry sand remains a severe environmental problem in Europe, not because of hazardousness of waste, but due to its significant quantity.

The approach taken in LIFE ECO-SANDFILL project involves turning waste from the casting industry into useful feedstock for foundry and other industrial sectors, leading to reducing landfill of waste and decreasing the environmental impacts associated with disposal and extraction of non-renewable mineral resources. To this end, a prototype of a novel mechanical SFS reclamation system has been constructed and integrated in the moulding sand circuit of a steel foundry located in the Basque Country (ES). The SFS generated in the foundry is treated in the prototype to remove impurities from binders and the casting process and to make the reclaimed sand reach the required quality for the different applications envisaged in the project. The environmental, technical and economic performance of the solution is planned to be validated in three full-scale case studies to be executed in the construction works for the Madrid- Irun High-Speed Railway Network, in the vicinity of the foundry, and through a pilot casting trial of steel parts in the foundry itself, using reclaimed sand in the manufacture of the moulds.

This paper describes the preparatory activities carried out before executing the casting and construction demos, focused on dosage studies and characterisation tests of a series of sand samples and specimens manufactured using SFS (untreated and reclaimed) in their formulations. From the chemical analysis results, it has been concluded that the reclaimed sand obtained in the prototype coupled to the sand circuit of the foundry fulfils environmental conditions for construction applications and could be safely used in mortar, CLSM and embankment demos, provided that applicable technical requirements are met. In the case of foundry applications, it has been found, that reclaimed sand does not meet the stringent specifications for coremaking, but it might be a partial replacement for the thermally recovered sand used as facing sand in moulds (PEP-SET system).

Key words: Spent Foundry Sand, SFS, Moulding Sand Reclamation, Secondary Aggregates, Waste Recovery, Circular Economy

Abstract

The mould or core coating creates a high thermal integrity barrier between the metal and the mould in the reduction of the thermal shock experienced by the sand system. The basic requirements for refractory coatings are to ensure adequate porosity and high refractoriness, and to prevent the physicochemical reaction at the metal-coating interface (lubrication, solution, penetration). Optimization of the composite coatings to fulfil all the above-mentioned requirements can be achieved by adding the sol-gel component. The use of the sol-gel process in the production of foundry coatings has been a new technology. The addition of sol-gel components significantly improves the surface of castings and its rheological properties; where an important role also has the ratio of sol relative to other components. The added sol-gel component reduces the viscosity of the coating, which improves its lubricity and consequently enables a better casting surface. The purpose of this research was to investigate the effect of using the sol-gel component as an additive to the water-based coating with a zircon filler.
We studied the influence of three chemically different sol-gel components and the influence of various mass ratios between the basic coating and the sol-gel component on the casting surfaces. The results indicate that the use of the sol-gel component significantly improves the quality of casting surfaces.

Key words: water-based coating with zirconium filler, coating with added sol-gel component, surface of casting, coating penetration depth

Abstract

We have investigated the microstructure of a modified aluminium alloy 6082 with additions of copper and zirconium. The billets of this alloy, with the diameter of 282 mm, were semi-continuously cast using HTAS (Hot Top - Air Slip). Samples from the bottom and head of a billet were prepared by metallographic methods, and investigated using different methods, such as light microscopy, scanning electron microscopy with microchemical analysis, differential scanning calorimetry and X-ray diffraction.
The microstructure consisted of equiaxed dendritic grains of aluminium solid solution
a-Al and different phases in the interdendritic regions and crystal grains. The metallographic investigation revealed seven additional phases: a-AlMnSi, Mg2Si, Al3Zr, Si2Zr, b-Si, Al2Cu in Q-AlCuMgSi. Among them, the highest volume fraction belongs to a-AlMnSi that also contained some Fe in Cr. The phase Mg2Si was in the shape of Chinese script. Zirconium was mainly present in Al3Zr and partly in Si2Zr. The phases Al2Cu, b-Si in Q-AlCuMgSi were present with the islands that formed via a multicomponent eutectic reaction of the remaining liquid during the last stage of solidification.
The processes during solidification were modelled by using the Scheil model, which gave rather good matching with the experimental data. By analysing the results of the experiments and of the Scheil model, we proposed a probable course of solidification of the investigated alloy.

Key words: aluminium alloy, zirconium, as-cast condition, microstructure, solidification