Ceramic forming is an important part of the ceramic preparation process, the forming technology to a large extent determines the uniformity of the green body and the ability to prepare complex shaped parts, and directly affects the reliability of the material and the cost of the final ceramic parts.

7. Hot die-casting molding
Hot die casting molding is to use the characteristics of paraffin wax melting and cold solidification, the ceramic powder without plasticity and hot paraffin liquid evenly mixed to form a flowing slurry, injected into the metal mold under a certain pressure, and so on after cooling, demoulding to take out the formed body.  The green body is properly trimmed, buried in the adsorbent, heated, dewaxed, and finally burned to form the final product.

The difference between hot die casting and general grouting molding method:

It does not use solvents, but uses the high-temperature rheological properties of the binder - paraffin wax, casting under pressure, and then dewaxing and sintering at high temperatures to make ceramics.

Advantages:
① Can produce complex shape ceramic products, high dimensional accuracy, almost no need for follow-up processing, is the main molding process for making special-shaped ceramic products;

② The equipment is cheap, the mold wear is small, and the production cost is relatively low;

③ Convenient operation, low labor intensity, high production efficiency;

④Strong applicability to raw materials, such as oxides, non-oxides, composite raw materials and various mineral raw materials can be applied.

Disadvantages:
①The slurry has high wax content and low molding pressure, which easily leads to low product density and long wax discharge time;

②High porosity, relatively more internal defects, low density, mechanical properties and performance stability of products are relatively poor;

③It is not suitable for preparing large-size ceramic products and high-purity ceramic products.

Application: Engineering ceramic parts with various complex shapes.

8. Gel casting molding
Gel casting molding is a new ceramic molding technology. Firstly, the ceramic powder is dispersed in a solution containing organic monomers to prepare a suspension with a high solid phase volume fraction (> 50%), and then injected into a mold with a certain shape, under certain catalytic and temperature conditions, the organic monomers are polymerized, resulting in the suspension solidification, and finally, a high strength green bady can be obtained after drying.

In the process of changing from liquid to solid, the green body does not shrink or shrink very little, and the amount of medium does not change. It can manufacture complex shape ceramic parts, and the content of organic impurities in the green body is less, the produced ceramic parts have good uniformity and high strength of the green body.

Gel casting molding is divided into two categories: one is water-soluble gel casting molding, and the other is non-water-soluble gel casting molding. The former is suitable for most ceramic molding, and the latter is mainly suitable for the molding of those systems that react with water.

Advantages:
① No special requirements for ceramic powder;
② Can achieve near net size molding, can prepare large size and complex shape and wall thickness parts, mold can choose a variety of materials;

③ The forming cycle is short, the strength of the wet and dry billet is high, which is obviously better than the billet made by the traditional forming process, and can be machined;

④ The process is easy to control;The process and operation is relatively simple, simple equipment, low cost.

Disadvantages:

①Defects such as bubbles and cracks may occur during the molding and drying process;
②Toxicity of organic monomers.

Applications:
Coarse particle system ceramics, high-grade refractory materials, ceramic composite materials, structural ceramics, functional and bioceramics, porous materials and powder metallurgy.