| 摘要 |
An improved refractory investment material for use in making refractory mold s is provided. The material comprises an investment powder including a binder, a refractory selected from calcined mullite and pyrophyllite, additives for controlling setting and about .01 to about .04 % by weight of a sulfate salt. The investment powder is formed into a slurry with a solution of a water based colloidal silica in an amount providing about 3 % to about 6 % by weig ht colloidal silica based on the weight of the water and a chloride salt in an amount of at least about 0.5 % by weight based on the weight of said investment powder.
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