Influence of the Mould Material Coatings on the Microstructure of AlSi7Mg Alloy
Treść / Zawartość
Family of the aluminium alloys with silicon addition is an important group of non-ferrous casting alloys. They exhibit very good technological properties, especially castability. Aluminium alloys are known for their low density, which in connection with high mechanical properties and relatively low price create very good structural material. Magnesium addition to the Al-Si alloys enables their age-hardening, resulting in even better mechanical properties. However, formation of the microstructure of the alloy has to be precisely controlled to avoid formation of massive, brittle silicon crystal. Presence of large, platelet-like particles of silicon, dramatically decreases material mechanical properties. Second factor, which must be taken into consideration is casting porosity, which may significantly decrease fatigue life of the element. Many researches consider effect of modification or refining on the microstructure of the castings made from the Al-Si alloys. However there is lack of detailed investigation on the mould components influence on the microstructure. Such components may be protective coatings applied for the mould sand during the gravity casting of Al-Si alloys. Following paper presents results of the research on the influence of applied mould protective coatings on the microstructure of AlSi7Mg sand cast alloy. Five different protective coatings were applied. Macro observations, qualitative and quantitative microstructure evaluation of the AlSi7Mg alloy was conducted during the researches. Results revealed, that application of the coatings does not influence the size and distribution of the α- Al dendrites, however it influences size of Si particles in a significant way. It was revealed that application of water-based coatings affects the heat flow in the mould material-liquid alloy system, thus causing growth of silicon particles.
Bibliogr. 11 poz., rys., tab.
- Institute of Materials Science, Materials Engineering and Metallurgy Faculy, Silesian University of Technology, Krasińskiego 8 Str., 40-019 Katowice, Poland , email@example.com
- Department of Production Engineering, Materials Engineering and Metallurgy Faculy Silesian University of Technology, Krasińskiego 8 Str., 40-019 Katowice, Poland
- ZM „WSK Rzeszów” Sp. z o.o. Hetmańska120 Str., 35-078 Rzeszów, Poland
- Institute of Materials Science, Materials Engineering and Metallurgy Faculy, Silesian University of Technology, Krasińskiego 8 Str., 40-019 Katowice, Poland
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