First of all, it should be clearly pointed out that it is absolutely wrong to apply water coating (or cement bar) to repair the interface when packing, which is not allowed. Otherwise, when pouring high-temperature steel water here, it will produce “water gas” explosion to crack or loosen the coating and wash it. Once the gap is opened, the steel water will directly wash the dry sand layer, which is really like a mountain of defeat. There must be a large number of sand holes in the casting.
The sprue, such as the throat, is the only way for steel water to enter the mold cavity, where the temperature is the highest, the scouring time is the longest, and the punching force is the largest. Therefore, no matter what is used to repair the bonding interface of the sprue, the sprue should first be coated with a coating that can withstand the high temperature scouring for a long time. For example, although the coating thickness of Guilin No.5 coating is 1-2mm thin, even 3-5t castings do not need ceramic casting at all Avenue. Under the premise of high temperature and scour resistance of the whole pouring channel, the bonding interface during packing must be filled with the same high temperature resistant porcelain alcohol based coating paste (mud shape), and it is not easy to use cement bar casually.
Many people mistakenly think that “the binders in alcohol based quick drying coatings, such as resins and rosin, are not resistant to high temperature, so it is easy to wash them out after repairing.”. A variety of alcohol based coatings on the market are indeed based on resins and rosin as binders. The high-temperature steel water dissolves soon after flushing. This kind of alcohol based coating can not be used for the application of repair gate. On the contrary, Guilin No. 5 porcelain based alcohol based coating can harden and porcelain rapidly in a few seconds under high temperature. The so-called vitrification is the transformation of ceramics, which becomes as resistant to high temperature and scour as ceramic flakes. The usage of this alcohol based coating is very simple: 100g alcohol based No.5 powder + 1000g aggregate powder + 300g alcohol with a concentration of about 90%, mix and mix to form a rotten mud, and then smear on the interface.
The fundamental difference between Guilin No.5 alcohol based coating and common alcohol based coating is that the binder composition is different, and there are many components which can promote the ceramic of aggregate powder at high temperature – high-strength high-temperature ceramic alcohol based coating.