INDICATOR OF THE EFFICIENT PROTECTION AGAINST THE HUMIDITY Wso, AS A NEW PARAMETER CHARACTERISING PROTECTIVE COATINGS

摘要

The hereby paper concerns the development of the indicator of the efficient protection against the humidity W_(so), as a new parameter characterising protective coatings. This indicator's aim is a determination, to what degree covering of cores and sand moulds influences advantageously or disadvantageously the humidity absorption from surroundings into surface layers, in comparison with layers without covering, which at a high humid conditions of the atmospheric air absorb the moisture. Simultaneously, this indicator will allow the efficient comparison of tendencies of individual coatings and their layers number for the moisture sorption. Thus, it can constitute a practical information in selecting the coating kind for the moulding sand, on which it will be deposited. Especially taking into account the time of waiting - of moulds and cores covered with coatings - for pouring with liquid metal and the atmospheric conditions to the influences of which they will be exposed.