MICA BASED COATING FOR APPLICATION IN LOST FOAM CASTING PROCESS

This paper presents the results of mechanical activation of filler based on mica and the influence on the quality of foundry coatings. The coating was applied for lining of evaporable model in Lost foam casting process. The examinations of synthesis, characterization and application of refractory coatings showed that sediment stability of coating suspension was crucial quality parameter. Coating composition optimization with the controlled reologic properties was achieved by applying different coating components and by alteration of coating production procedure. For the assessment of possibilities of using mica as refractory fillers the comparative test were done with the coating on the basis of talk Ceramic powders talk and mica were, first, grind down in the so-called fine fractions, and then used as a heat-resisting fillers. The talc and mica samples were tested by the following methods.: Xray diffraction analysis, diffraction thermal analysis and qualitative mineralogical analysis on scanning electronic micrpscope. The shape and grain size were analyzed by the program package OZARIA 2.5. For assessing the quality of the coatings and the effects of their application detailed analysis of structural and mechanical properties of the castings were done. Also, the radiographic examination of castings on the type of x-ray device SAIFORT-S200 was done. Application of refractory coatings on the basis of talk and mica showed a positive influence on the structural and mechanical properties of castings of aluminum-silicon alloys.