| 配方類型： |
METALS AND THEIR TREATMENT |
| 配方說明： |
Dip Coat |
| 配方組成： |
China Clay/27
Ethyl Silicate (Solution 1)/33
Silica (120 Mesh)/40 |
| 配制方法： |
Immediately after application, dust with 35- to 80-mesh Ottawa sand or similar.
If erratic results are obtained, they are usually caused by improper control of the setting time. To correct the trouble, check the factors summarized here.
DELAYED SETTING TIME IS CAUSED BY: Insufficient water for complete hydrolysis; or drop in the temperature of the sand-binder mixture; or insufficient neutralizing agent (magnesium oxide) in the investment mixture; or too low a silicate content-appreciable effect only below 10%; or too low a ratio of dry investment to ethyl silicate solution.
ACCELERATED SETTING TIME IS CAUSED BY: Excess water over the amount required to complete hydrolysis; or increase in temperature of the sand-binding mixture; or increase in silica content-appreciable effect only above about 17% silica; or prolonged aging of solution containing excess water. |
|
