Direct solidification injection molding method

Direct Coagulation Casting, abbreviated as DCC, is a net size in-situ solidification colloidal forming method invented by Professor L. Gaucker and Dr. T. Graule from the University of Zurich in Switzerland.

1. The process principle of direct solidification injection molding.

For the micro ceramic particles dispersed in the liquid medium, the main forces acting on them are the repulsion force of colloidal double electric layer and Van der Waals force force, while gravity and inertia force have little influence. According to the basic theory of colloidal chemistry (DLVO), the total potential energy of colloidal particles in the medium depends on the repulsive energy of the electric double layer and the attractive energy caused by Van der Waals force.

2 The Process and Application of Direct Solidification Injection Molding

(1) Process: The direct solidification injection molding process is different from traditional injection molding. This molding process has two main steps: firstly, preparing ceramic slurry with high solid content and low viscosity by adding dispersants; The second is to introduce biological enzymes to control the solidification process of the slurry.

(2) The application of DCC molding process is mainly reflected in the following aspects:

① Oxide ceramics: DCC shaping technology has been successfully applied in the preparation of alumina ceramic components.

② The direct solidification injection molding process of non radon based ceramic silicon carbide and silicon nitride is different from that of alumina. This solidification process is not achieved by moving the pH value to the Isoelectric point, but by increasing the concentration of salt ions in the slurry and compressing the double electric layer.

3 Characteristics of Direct Solidification Injection Molding

The DCC molding process can directly solidify various complex shaped ceramic bodies, with high density and good uniformity. The organic matter used for molding is non-toxic and has a low content (less than 1%). The dry body can be directly sintered without the need for degreasing. In addition, the selection range of mold materials used in this molding method is wide (such as metal, rubber, glass, etc.), and the processing cost is low. In addition, this molding process also has shortcomings: First, the ceramic powder used for this molding has limitations. The aluminum oxide ceramic powder with a Isoelectric point pH value of about 9 is the most suitable, and other ceramic powder molding control processes are complex; Secondly, the strength of the formed body is low and cannot be machined.

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