The paper presents the results of research on the impact of impurities in the feed ingots (master heat) on the precipitation of impurities in

the ATD thermal analysis probe castings. This impurities occur mostly inside shrinkage cavities and in interdendritic space. Additionally,

insufficient filtration of liquid alloy during pouring promotes the transfer of impurities into the casting. The technology of melting

superalloys in vacuum furnace prevents the removal of slag from the surface of molten metal. Because of that, the effective method of

quality assessment of feed ingots in order to evaluate the existence of impurities is needed. The effectiveness of ATD analysis in

evaluation of purity of feed ingots was researched. In addition the similarities of non-metallic inclusions in feed ingots and in castings

were observed.

Abstract The influence of selected factors on drying ceramic moulds applied in the investment casting technology was determined by the gravimetric method. Moulds produced of ceramic sands based on the new generation binders - colloidal silica, were investigated. It was found that each successive layer, of a similar thickness, is drying longer than the previous one. The drying time of layers forming closed spaces is several times longer as compared with drying open surfaces (external). Grain size of matrix used for moulds sprinkling has none significant influence on drying rates.