Synthesis of the new lost foam refractory coatings based on talc Scientific paper

Abstract

This paper is focused on the preparation procedures, using a talc-based filler, to improve the rheologic properties of the lost foam refractory coatings. Talc, with grain size of 40 mm, was mechanically activated in a vibration mill over the following times: 10, 20 and 30 min. Depending on the time required for the mechanical activation, the change in the filler grain size and shape was ana­lysed along their effects on the talc-filled lost foam coating dispersion abil­ity and stability. In order to characterize the filler, the following methods were used: X-ray diffraction, scanning electron microscopy and optic microscopy. The coat­ing compo­sition was tuned by choosing the suitable grain size and shape factor of the activated filler. In addition, different coating components (additives, solvent) were applied to alter the coating generation procedure. It was shown that the application of this type of the lost foam refractory coatings – water-based coat­ings – have a positive influence on quality of the aluminium alloy castings, which contributes to reducing the cost of cleaning and process­ing of the castings. Also, alcohol-based refractory coatings with talc-based act­ivated fillers were tested and used to have the castings produced in the sand moulds.