Anti-veining agent for metal casting
View Patent ↗Additives to foundry sand cores are provided for reducing or eliminating surface defects in metal castings. The additives general comprise an iron oxide component and a glass component which is preferably free of lithium oxide.
1. An anti-veining additive composition for sand cores used in metal casting, said composition comprising:
(a) from about 20 to about 70% by weight iron(III) oxide;
(b) from about 20 to about 70% by weight iron(II,III) oxide; and
(c) from about 10 to about 60% by weight of a glass that is substantially free of lithium oxide;
wherein said iron (III) oxide, iron, (II,III) oxide, and glass are blended toether in intimate admixture; wherein said iron(III) oxide and said iron(II,III) oxide are each comprised predominately of particles having a particle size less than about 75 microns; and wherein said anti-veining additive is substantually free of lithium-bearing minerals.
2. The composition according to claim 1 , wherein said iron(III) oxide comprises hematite.
3. The composition according to claim 1 , wherein said iron(II,III) oxide comprises magnetite.
4. The composition according to claim 1 , wherein said glass comprises soda-lime-silica glass.
5. The composition according to claim 4 wherein said soda-lime-silica glass is selected from the group consisting of container glass, window plate glass, glass cullet, and combinations thereof.
6. The composition according to claim 5 , wherein said soda-lime-silica glass is cullet.
7. The composition according to claim 1 , wherein said glass comprises borosilicate glass.
8. The composition according to claim 1 , further comprising from about 0.1 to about 25% by weight carbon.
9. The composition according to claim 8 , wherein said carbon comprises amorphous graphite.