| 摘要 |
A modified mold sand composition comprising bentonite, gilsonite and/or sea coal as well as silicon sand is provided to improve durability and surface condition of a casting metal article and to inhibit generation of harmful gas by preparing an additive consisting of bentonite and gilsonite or gilsonite and sea coal then adding the additive to the silicon sand to form the modified mold sand. The composition is formed by adding binder and additive to silicon sand. The composition includes: 79 to 90wt.% of silicon sand; 9.8 to 16wt.% of bentonite; and 0.2 to 0.61wt.% of gilsonite. Alternatively, the composition includes: 79 to 90wt.% of silicon sand; 9.8 to 16wt.% of bentonite; 0.12 to 0.46wt.% of sea coal; and 0.08 to 0.17wt.% of gilsonite. Bentonite is used as the binder and combined with other materials and does not generate chemical activity and affect chemical properties of materials to be binded together. Gilsonite is natural asphalt resin and contains large amount of bright carbon to be slowly fused and burned by applying heat.
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