Vliv forem s cementovými pojivy na strukturu odlitků

Influence of cement moulding sands on the structure of castings

journal article - other

en

In the interface between cement cores and iron with flake graphite were certified generation of komplex allied substances – on the base Si, Fe, Al, O and Ca. These complex allied substances originate as a result of chemical reactions between molten metal and cement sand. In many cases FeS has been found. Its occurrence is evoked by CaSO4 (Bassanite) from Portland cement. Elements such as Si, Al, Ca and Fe may be released by thermal dissociation from products of cement setting. Created mathematical model proved influence of temperature and chemical composition of liquid metal on occurrence of mechanical penetration in this case. With increasing temperature and higher content of carbon in cast iron is chance of mechanical penetration higher. Average grain size of opening material is remarkable too. The higher content of sulphur is dangerous for castings of nodular iron. In additional trials the rest content of magnesium was liquidated by this element and particles of flake graphite and other forms of graphite have been found in the surface layers of nodular iron castings.

Článek prezentuje výsledky výzkumu a vývoje ekologicky přátelských formovacích směsí na bázi portlandského cementu a popisuje reakce na rozhraní při odlévání litin s lupínkovým a kuličkovým grafitem.

In the interface between cement cores and iron with flake graphite were certified generation of komplex allied substances – on the base Si, Fe, Al, O and Ca. These complex allied substances originate as a result of chemical reactions between molten metal and cement sand. In many cases FeS has been found. Its occurrence is evoked by CaSO4 (Bassanite) from Portland cement. Elements such as Si, Al, Ca and Fe may be released by thermal dissociation from products of cement setting. Created mathematical model proved influence of temperature and chemical composition of liquid metal on occurrence of mechanical penetration in this case. With increasing temperature and higher content of carbon in cast iron is chance of mechanical penetration higher. Average grain size of opening material is remarkable too. The higher content of sulphur is dangerous for castings of nodular iron. In additional trials the rest content of magnesium was liquidated by this element and particles of flake graphite and other forms of graphite have been found in the surface layers of nodular iron castings.

Cementová formovací směs; interakce; litina s lupínkovým grafitem; litina s kuličkovým grafitem; komplexní sloučeniny.

Cement Sand; Interaction, Gray Cast Iron; Nodular Iron; Complex Allied Substances

2010

15.09.2010

0046-5933

International Foundry Research

62 (2010)

No.3

16–25

45