Kinetics of Gas Emissions from Moulding and Core Sands, Gasification Patterns and Protective Coatings - the New Investigation Method

Abstract

Gases evolving from moulds, cores, coatings deposited on sand and metal moulds constitute one of the basic reasons of several casting surface defects: blow-holes, pinholes, pitted skin, etc. In research performed up to now the moulding sands gas evolution is determined in two ways: normalised, in which the gas amount emitted from the sample placed in a heated flask is determined or in the other way, in which the gas amount emitted from the core - covered with liquid metal - is determined. In these both methods the result constitutes the total amount of gases emitted from 1g of a moulding sand and the emission procedure as a time function. The new method of investigating the kinetics of gases evolution from moulding sands (and coatings), applied for making moulds, is presented in this paper. The kinetics is tested not only as the heating time function but also as the temperature function. The method was developed in the Department of Mould Technology of the Faculty of Foundry Engineering, AGH. Amounts of gases emitted from the moulding sand at the given temperature in the time unit are obtained in investigations. The results of testing the group of moulding sands (furan, alkide, moulding sands with water glass) and the group of protective coatings applied for sand and metal moulds, are presented in this paper.