An important role in the investment casting process is played by the surface condition of the first coating of a multi-layer ceramic mould, as it directly affects the quality of the obtained cast. In industrial conditions, it is not possible to assess surface quality of the first ceramic mould cover without breaking it. The paper presents the analysis of the structure and surface roughness tests results of the first model coatings of model and production ceramic moulds. Ceramic moulds were made of 7 coatings. Three different ceramic mixtures were used to make them, differing in the used filler (molochite, quartz) or binder (Remasol aqueous binder, hydrolyzed ethyl silicate, Ludox water binder). Samples of industrial moulds were obtained by breaking them while model moulds in the form of rectangular shaped samples were made in specially designed wax dies. Model and production moulds were heat treated at 850 °C, 900 °C and 950 °C, and then the roughness of the first coating was tested using the WYKO NT9300 optical profilometer. Samples were also subjected to microscopic examination to determine the structure of the model layer and the cross-section of the moulds. The research allowed to obtain the results of the impact of materials intended for moulds and heat treatment on the quality of the model layer.Keywords: Ceramic moulds, roughness, structure, investment casting, lost-wax
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