Effect of reclaimed sand additions on mechanical properties and fracture behavior of furan no-bake resin sand

Abstract

National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; 2. Shanghai Light Alloy Net Forming National Engineering Research Center Co., Ltd., Shanghai 201615, China F uran no-bake resin sands possess a good combination of high dimension accuracy, good surface finish, and room temperature curing, which make them attractive for industrial applications of producing moulds for different kinds of castings, such as steel, iron and non-ferrous alloy castings [1][2][3] . However, it is commonly considered that after pouring, the furan no-bake resin sand may exhibit some shortcomings, such as poor collapsibility, various types of gases released, residual resin, and waste sand, which would cause environmental pollution, increased casting production cost and waste of natural resources [4,5] . Furthermore, the foundry industry is under great pressure due to national policy restrictions on resource conservation and environmental protection [6][7][8][9] . Therefore, the low cost, effective, and eco-friendly furan Abstract: In this work, the effects of reclaimed sand additions on the microstructure characteristics, mechanical properties and fracture behavior of furan no-bake resin sand have been investigated systematically within the temperature range from 25 to 600 ºC. The addition of 20%-100% reclaimed sand showed dramatic strength deterioration effect at the same temperature, which is associated with the formation of bonding bridges. Both the ultimate tensile strength (UTS) and compressive strength (CS) of the moulding sand initially increase with the increase of temperature, and then sharply decrease with the further increase of temperature, which is attributed to the thermal decomposition of furan resin. The addition amount of reclaimed sand has a remarkable effect on the room temperature fracture mode, i.e., with the addition of 0-20% reclaimed sand, the fracture mode was mainly cohesive fracture; the fracture mode converts to be mixture fracture mode as the addition of reclaimed sand increases to 35%-70%; further increasing the addition to 100% results in the fracture mode of typical adhesive fracture. The fracture surface of the bonding bridge changes from a semblance of cotton or holes to smooth with the increase of test temperature. The application of reclaimed sand has a clear economical advantage for mass production of components due to their short reprocessing cycle and low assembly costs. Previous research found the possibility of reclaimed sand in casting, i.e., green moulding sand [10][11][12][13][14][15] , furan resin sand [16][17][18][19] , and sodium silicate sand [20][21][22] . It was found that the mixture of reclaimed sand and new sand satisfies the standards for moulding sands, and sustainable sand casting was developed. In the process of casting, heat will be generated through liquid metals so that the temperature of the moulding sand may be ...

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