Role of Sand Grains in Sorption Processes by Surface Layers of Components of Sand Moulds

Abstract

The results of researches of sorption processes of surface layers of components of sand moulds covered by protective coatings are presented in the hereby paper. Investigations comprised various types of sand grains of moulding sands with furan resin: silica sand, reclaimed sand and calcined in temperature of 700°C silica sand. Two kinds of alcoholic protective coatings were used - zirconium and zirconium - graphite. Tests were performed under condition of a constant temperature within the range 30 - 35°C and high relative air humidity 75 - 80%. To analyze the role of sand grains in sorption processes quantitavie moisture sorption with use of gravimetric method and ultrasonic method were used in measurements. The tendency to moisture sorption of surface layers of sand moulds according to the different kinds of sand grains was specified. The effectiveness of protective action of coatings from moisture sorption was analyzed as well.

Keywords

• Castings defects
• Moisture sorption
• Surface layer
• Furan moulding sands
• Sand grains