Crystalline aluminum chloride can replace ammonium chloride in investment casting to be used as shell hardener in investment casting. It has the advantages of stable quality, high shell strength, convenient use and adjustment, improved worker operating conditions, and good comprehensive economic benefits.

At present, the majority of precision casting production in China uses sodium silicate as the binder. Ammonium chloride, magnesium chloride and aluminum chloride are usually used as hardeners, but in the process of use, the working conditions are seriously deteriorated due to the release of ammonia from ammonium chloride; The hardening and drying speed of magnesium chloride is affected by the high viscosity of the solution.

Moreover, high impurity content is easy to cause defects such as shell delamination, peeling, sand inclusion, etc. Therefore, ammonium chloride and magnesium chloride as hardeners are not suitable for the development of investment casting, and various manufacturers have adopted crystalline aluminum chloride as hardeners instead of ammonium chloride and magnesium chloride.

Advantages of crystalline aluminum chloride:

1、 The shell mold has high strength at room temperature and high temperature, good dimensional stability of shell mold, and high yield of castings.

2、 In the hardening process, no harmful gas is produced, and the equipment is not easy to corrode, thus improving the working conditions.

3、 The molded shell is not only high in strength, but also can eliminate the phenomenon of steel leakage and fire escape. The number of sand layers is small and the shell layer is thin, which increases the permeability and reduces the generation of pores.

4、 In the process of use, the cost is greatly saved due to the reduction of consumption, and the hardening process is easy to control, which is conducive to reducing the scrap rate of castings and increasing economic efficiency.

Advantages of crystalline alumina compared with other flocculants:

1. Replace liquid or solid aluminum sulfate, polyaluminum chloride, polymeric ferric sulfate and other flocculants, and reduce the treatment cost by more than 30%;

2. The flocculating performance is excellent, the settling speed is higher than that of aluminum salt flocculants (such as aluminum sulfate, polyaluminum chloride, etc.), and the formed alum flocs are dense;

3. The amount of sludge generated is small, greatly saving the cost of sludge treatment;

4. It is suitable for a wide range of pH values of water bodies, ranging from 4 to 12, and the ideal pH value range is 6 to 10.