Mechanical properties of chemically bonded sand core materials dipped in sol–gel coating impregnated with filter dust: novel approach to improve casting quality

Abstract

A novel sol-gel coating impregnated with filter dust was applied on chemically bonded sand core materials by dipping. After curing, the strengths of the core materials were measured under uniaxial loading using a new strength testing machine (STM). The STM presents the loading history as a force-displacement curve from which the mechanical properties of the materials are deduced. The fracture surfaces were examined using a stereomicroscope and a scanning electron microscope. From the results, the strengths of the core materials were slightly reduced by the coating in tensile and flexural modes, while the strengths were increased under compression. The mode of fracture of the chemically bonded sand core materials was observed to be intergranular through the binder. The stiffness of the chemically bonded sand core materials was determined. For better understanding of the mechanical properties of the chemically bonded sand core materials, a combination of flexural and compression tests is suggested for improving the casting quality.

Experimental Evaluation of Ceramic Coatings for Die Protection in Low-Pressure Die-Casting Process

“…LPDC die coating failures usually come from the loss of adherence or excessive wear originated in the successive filling processes, which requires stopping production for the reapplication of the coating. Even though chemical and physical parameters of refractory foundry coatings are known to specialists in the field [27][28][29][30], there is a lack of knowledge regarding the relationship of particle size of the refractory filler and the final appearance and erosion resistance of the layer deposited on the mould [20,[31][32][33]. Several authors have claim for the need of a bridge between the foundry coating characteristics and tribological science in order to prove that an improved erosion resistance coating will help to produce better quality cast parts [20,31,32,34,35].…”