Centrifugal deposition molding method for advanced ceramics

The characteristic of introducing centrifugal technology in the material forming process is that it is formed under the action of centrifugal force. Centrifugal casting of metal materials is a casting method that pours molten metal into a rotating mold, causing liquid metal to fill the mold under centrifugal force and solidify to form a certain shape and size. Centrifugal technology is widely used in metal material forming.

1. The process principle and process of centrifugal deposition molding

Centrifugal deposition casting, also known as CDC, is a method for preparing plate-like and layered nano multilayer composite materials. The Lange group at the University of California, Santa Barbara, USA, first applied centrifugal molding technology to the preparation of ceramic materials. Due to the uniform application of centrifugal force on each particle, it has the advantage of forming a uniform structure. Therefore, centrifugal technology was first applied in the formation of uniform and dense ceramic materials.

The process of centrifugal deposition molding technology: Firstly, raw material powder, molding aids, water, etc. are added to a ball mill for ball milling, in order to prepare a slurry with appropriate viscosity; Secondly, inject the prepared slurry into the mold inside the centrifugal molding machine for molding; Then, demould the formed ceramic body; Finally, the green body is sintered to prepare ceramic materials with a certain size.

2. Application of centrifugal deposition molding

Due to the unique characteristics of centrifugal molding technology that cannot be compared to other molding processes, it is widely used for the preparation of gradient materials, porous materials, and layered materials.

Layered ceramic composite material is a biomimetic structural material designed to simulate the shell structure. The special structure of this material enables ceramic materials to overcome the brittleness of monomers. In addition, the material structure can significantly improve the toughness and reliability of the material while maintaining its high strength and good oxidation resistance. K. Professor P. Trumble prepared layered ceramic composites using multiple centrifugation processes, and the research results showed that. Compared with ordinary ceramic block materials, this material has nearly doubled its toughness. This structure can cause cracks to deflect and harden when they propagate to the interlayer interface, thereby greatly improving their toughness. Due to the use of centrifugal technology to control the interfacial bonding state of materials after forming by controlling the dispersion state of the original slurry, centrifugal deposition molding technology is considered a promising preparation process for layered materials.

3. Main defects of centrifugal deposition molding

Although centrifugal deposition molding technology has an unparalleled effect in material preparation compared to other molding methods, improper control of its molding process can bring significant defects to the material. The key problem in the process of preparing materials through centrifugal deposition is to prepare a suspension solution with appropriate viscosity. If the viscosity of the suspension solution is large, it will cause agglomeration of the suspension during the centrifugal deposition process, which is not conducive to the formation of uniform materials; If its viscosity exceeds that of the powder in the liquid, it cannot be evenly distributed on the surface of the substrate with the liquid.

In addition, the centrifugal rate of the centrifugal forming equipment is also a key process parameter. When the centrifugal rate is too high, the suspension only moves at high speed with a portion of the substrate under the action of a large centrifugal force, and cannot form a uniform and complete surface; When the centrifugal rate is low, the suspension cannot form a uniform layer at the bottom of the matrix or its strength is low, and its porosity is large. Therefore, during its sintering process, the sintering shrinkage is large, which is not conducive to the formation of the bond.

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