The Forming Methods and Differences of Zirconia Ceramic Rods

(1) Hot Die Casting Forming of Ceramic Rods

Ceramic rod hot press casting is also a type of injection molding, but the difference is that it is a method of mixing paraffin wax into the billet, utilizing the heat flow characteristics of paraffin wax, forming using a metal mold under pressure, and obtaining the billet after condensation. The working principle of hot die casting forming is as follows: first, the quantitative paraffin wax is melted into wax liquid, then mixed with dried ceramic powder, and the wax plate is made after solidification. Then, the wax plate is placed in the hot die casting machine barrel, heated to melt into slurry, pressed into the mold cavity through the casting suction port, maintained, pressured, cooled and formed, and then demoulded to take out the body. The body formed by hot die casting must be dewaxed before sintering. This process is suitable for the production of small and medium-sized products with complex shapes and high precision requirements. It has simple equipment, convenient operation, low labor intensity, and high production efficiency. It is often used in the production of special ceramics. The disadvantages of hot die casting ceramic rods are low density, porosity, and average mechanical strength.

(2) Ceramic rod extrusion forming

Mix the powder, binder, lubricant, etc. evenly with water, and then squeeze the plastic material out of a rigid mold to obtain a rod-shaped shape. The main drawback of extruded ceramic rods is that they have low material strength and are prone to deformation, and may produce defects such as surface pits, blistering, cracking, and internal cracks. The materials used for extrusion forming use binders and water as plastic carriers, especially clay to improve material compatibility, so they are widely used in traditional refractory materials.

(3) Ceramic rod gel casting

Gel casting is a colloidal forming process, which organically combines the traditional ceramic process and chemical theory, flexibly introduces the method of Polymer chemistry monomer polymerization into the ceramic forming process, and makes a concentrated suspension with low viscosity and high solid volume fraction by dispersing the organic polymer monomer and ceramic powder particles in the medium, and adds initiator and catalyst, Then, the concentrated suspension (slurry) is injected into the non porous mold, and the organic polymer monomer is crosslinked and polymerized to form a three-dimensional mesh polymer gel through the action of initiator and catalyst, and the ceramic particles are bonded in situ and solidified into a green body. As a new colloidal forming method, gel casting can form green bodies with complex shape, high strength, uniform microstructure and high density in net size. The sintered ceramic parts have better electrical properties than the dry pressed ceramic parts. At present, it has been widely used in electronic, optical, automotive and other fields.

(4) Ceramic rod injection molding

Grouting forming is suitable for manufacturing large, complex, and thin-walled ceramic products. There are also certain requirements for the performance of the slurry, such as good flowability, low viscosity, favorable for slurry filling, and good stability. The slurry can maintain stability for a long time, is not prone to sedimentation and stratification, and has a minimum water and gas content. The methods of grouting forming include hollow grouting and solid grouting. To improve the grouting speed and quality of the billet, new methods such as pressure grouting, centrifugal grouting, and vacuum grouting can be used. The injection molding process has low cost, simple process, easy operation and control, but the forming shape is rough, the injection time is long, and the density and strength of the billet are not high. On the basis of traditional injection molding, new pressure filtration molding and centrifugal injection molding processes have been developed one after another. With the help of external pressure and centrifugal force, the density and strength of the blank are improved, avoiding the complex degreasing process in injection molding. The uniformity of the ceramic rod body formed by injection molding is poor, thus it cannot meet the requirements for preparing high-performance and high reliability ceramic materials.

(5) Ceramic rod injection molding

Ceramic rod injection molding is formed by utilizing the characteristics of polymer melting at high temperatures and solidification at low temperatures. After forming, the polymer is removed. The advantage of injection molded ceramic rods is that they can form complex shaped components, and have high dimensional accuracy and uniform microstructure. The disadvantage is that the cost of mold design, processing, and organic matter removal is relatively high. On the basis of overcoming the shortcomings of traditional injection molding, aqueous solution injection molding and gas-assisted injection molding processes have developed. Aqueous solution injection molding uses water-soluble polymers as organic carriers, which effectively solves the problem of degreasing. The water solution injection molding technology can easily achieve automatic control, which is lower in cost compared to traditional injection molding. Gas assisted injection molding is the process of introducing gas into polymer melts to make the forming process easier.

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