Effects of Composition on the Physical Properties of Water-Soluble Salt Cores
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Copyright Ó 2020 American Foundry Society https://doi.org/10.1007/s40962-020-00511-5
Abstract The demand for producing essential cast parts and the design requirements for superior engineering performance have increased in recent years. Sand cores used in conventional aluminum cast parts are harmful to the environment, which limits their application. Utilizing water-soluble cores in the aluminum casting industry is expected to be an environmentally friendly approach due to recyclability of the salt cores. In this study, water-soluble salt cores were made from chloride- and/or carbonate-containing salts in various amounts. The salts were melted and cast into steel molds to obtain salt cores. The salt cores were subjected to threepoint bending tests to determine their mechanical strength, the melting points were determined with thermal analyses, and the water solubility was measured at room temperature and 50 °C. A maximum bending strength of 17.19 MPa, a maximum melting point of 776 °C and a maximum water solubility of 89 g salt/100 ml water were obtained for the samples with compositions of 75% KCl–25% K2CO3 and
25% Na2CO3–75% K2CO3, respectively. Fractographs of the samples used in bending tests were taken by a still camera in macro mode, and from these fractured surfaces, scanning electron microscopy studies were performed. The X-ray diffraction pattern of the sample exhibiting optimal properties (28.3% Na2CO3 and 71.7% K2CO3) also showed that K2CO3, NaKCO3 and KNaCO3 phases were present in the structure, as expected. An actual casting process with aluminum die casting of an automotive part was also performed. The diecast aluminum part was subjected to a leakproof test, and X-ray images were used to check for porosity in the part.
Introduction
the design step a constraining factor in the production of complex-shaped parts. The difficulty in the mechanical cleaning of sand cores after casting is that it is time intensive, results in energy losses and suffers from surface quality deterioration and deformation; in addition, the burnt sand core contains organic compounds that form hazardous waste, posing a serious problem in the industry. To overcome all these problems, in this study, the use of recyclable salt cores in the casting of low-melting-temperature metals or alloys is discussed.
There is an increasing demand for components that can provide increased performance, efficient designs and complex internal passages. Although conventional sand core technology is used in a multitude of casting techniques to meet these needs, it has achieved limited success in processes that utilize pressures, such as low-pressure casting and, especially, high-pressure die casting (HPDC). The cores used in aluminum gravity die casting and lowpressure die casting are sand based and can be produced by cold box, hot box or shell methods. In high-pressure (injection) die casting, steel cores are often used, which makes
International Journal of Metalcasting
Keywords: salt core, water solubility, bending strength, microstructure ch
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