| 摘要 |
The invention relates to insulating lightweight refractory materials which are resistant to attack by molten metals, particularly molten aluminum and its alloys and compositions used to form such materials. More particularly, the invention provides a settable composition which comprises a mixture of ceramic fibres, wollastonite powder and aqueous colloidal silica having a solids content of about 5-25% and preferably 12-15% by weight. The weight ratio of the ceramic fibers to the wollastonite powder is 0.8-1.2 : 1.5-2.5, respectively. The composition optionally contains carbon fibres or metal fibres as reinforcements. The composition can be cast to form shaped products or used as a joining material or as a "face-off" material to protect an underlying article. When dried, the composition forms a material which is insulating, lightweight and resistant to high temperatures and chemical attack by metals. The material can be made even more resistant to attack by a silicate and/or fluoride surface treatment. The material is useful for forming items used in metal foundries and the like. |
