Zirconia ceramic structural parts use zirconia (ZrO2) as the main material, which has high hardness, high temperature resistance, corrosion resistance and wear resistance. It is an inorganic non-metallic material with excellent electrical conductivity. There are many molding methods for zirconia ceramic structural parts. They are all formed with powder as raw material. Dry pressing belongs to dry forming. In addition, there is isostatic pressing. How much do you know about the dry pressing forming process of zirconia ceramic structural parts?
The so-called dry pressing molding is based on powder, that is, a mixture of solid particles and air. In order to reduce friction and increase the strength of the formed body, the powder may contain a small amount of liquid wrapped around the particles, such as binders, lubricants, etc. For densification, it is usually necessary to exclude the air between the particles as much as possible. Generally, pressurization is used to force the particles to approach each other to exclude air. According to the way of pressurization during the molding process. Dry forming of zirconia ceramics can be divided into dry pressing and isostatic pressing. These two molding methods differ greatly in the quality of the produced green bodies due to the different pressurization methods.
Dry pressing, also known as molding, is a process in which the granulated powder is placed in a steel mold and pressed on a press to form a certain shape blank. Dry pressing is commonly used in the production of advanced ceramic solid materials: dry pressing is characterized by low binder content, generally 7% to 8%, which can be directly sintered without drying. It has many advantages such as small body shrinkage and automatic production. It can be widely used in the production of various functional ceramics and electronic components in circular and flake shape. shaped products.
During dry pressing, the pressing method, pressing pressure, such as pressing speed and pressure holding time will have an important impact on the density of the green body, especially the internal density distribution of the green body due to uneven pressure distribution. inconsistent, which affects performance.
In dry pressing, there are one-way pressing and two-way pressing. Due to the different pressing methods, the distribution and transmission of pressure in the mold are also different. When pressing in one direction, there will be a significant pressure gradient. The greater the green body pressure difference is, the greater the green body density is at the top. The lower part is less dense in the center. This is mainly because when the pressure is transmitted to the billet through the indenter, the particles of the comparative group in the billet layer close to the indenter separate the fine and ultrafine particles of this layer, making them close to each other not only vertically but also laterally. Then the indenter is further advanced, and the pressure is transferred to the inner layer through the dense layer close to the indenter, and gradually decreases. Part of the pressure is also transmitted to the die wall by the pressure head. The blanks therefore have different densities at different heights and sections.