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Studies on the Gases Emission under High Temperature Condition from Moulding Sands Bonded by Modified Starch CMS-Na

Kaczmarska K., Bobrowski A., Żymankowska-Kumon S., Grabowska B.

Archives of Foundry Engineering

2017

Vol. 17, iss. 1

79--82

Emission of gases under high temperature after pouring molten metal into moulds, which contain the organic binder or other additives (solvents or curing agent), may be an important factor influencing both on the quality of the produced castings, and on the state of environment. Therefore, a comprehensive studies of the emitted gases would allow to determine restrictions on the use of the moulding sands in foundry technologies, eg. the probability of occurrence of casting defects, and identify the gaseous pollutants emitted to the environment. The aim of the research presented in this paper was to determine the amount of gases that are released at high temperatures from moulding sands bonded by biopolymer binder and the quantitative assessment of the emitted pollutants with particular emphasis on chemical compounds: benzene, toluene, ethylbenzene and xylenes (BTEX). The water-soluble modified potato starch as a sodium carboxymethyl starch with low (CMS-NaL) or high (CMS-NaH) degree of substitution was a binder in the tested moulding sands. A tests of gases emission level were conducted according to the procedure developed at the Faculty of Foundry Engineering (AGH University of Science and Technology) involving gas chromatography method (GC). The obtained results of the determination of amount of BTEX compounds generated during the decomposition process of starch binders showed lower emission of aromatic hydrocarbons in comparison with binder based on resin Kaltharz U404 with the acidic curing agent commonly used in the foundries.

Analysis of Selected Properties of Green Sands with Modified Starch-based Additives

Kaczmarska K., Grabowska B., Drożyński D.

Archives of Foundry Engineering

2015

Vol. 15, iss. 3 spec.

127--131

The aim of this study was the preliminary assessment the effectiveness of application of sodium carboxymethyl starch (CMS-Na) as an additives to green sands with bentonite. Two modified starches CMS-Na having a low and a high degree of substitution (DS), 0.2 and 0.9 respectively, were chosen for preparing moulding sands. Influence of modified starch with different DS on the properties of the green sand was determined based on the results of the determination: apparent density, permeability, free flowability, friability and compressive strength, tensile and shear green sands with the addition of starch. The properties of the starch without starch-based additives were compared with the properties of green sand containing in the composition of CMS-Na with different degree of substitution.

Achieving Control of Coating Process in your Foundry

Di Muoio G. L., Tiedje N. S.

Archives of Foundry Engineering

2015

Vol. 15, iss. 4

110--114

Achieving control of coating thickness in foundry moulds is needed in order to guarantee uniform properties of the mould but also to achieve control of drying time. Since drying time of water based coatings is heavily dependent on the amount of water present in the coating layer, a stable coating process is prerequisite for a stable drying process. In this study, we analyse the effect of different variables on the coating layer properties. We start by considering four critical variables identified in a previous study such as sand compaction, coating density, dipping time and gravity and then we add centre points to the original experimental plans to identify possible non-linear effects and variation in process stability. Finally, we investigate the relation between coating penetration (a variable that is relatively simple to measure in production) and other coating layer thickness properties (relevant for the drying process design). Correlations are found and equations are provided. In particular it is found that water thickness can be directly correlated to penetration with a simple linear equation and without the need to account for other variables.