Jiangxi Antiy Advanced Materials Co., Ltd.
Honeycomb Ceramic Carrier Division
13387029211 Manager Gao
Hollow flat ceramic membrane division
13479895372 Manager Cheng
Binders can be divided into lubricants, plasticizers, dispersants, surfactants (with dispersant and lubricating functions), etc. In order to meet the molding needs, a combination of multiple organic materials is usually used. When selecting a binder, consider the following:
1. It is a necessary condition that the binding agent can be wetted by the powder. When the critical surface tension (yoc) or surface free energy (yos) of the powder is greater than the surface tension (yoc) of the binder, it can be well wetted.
2. Red binding occurs between the binding agent and the powder (primary binding). At the same time, cohesion (secondary binding) occurs due to the orientation, induction, and dispersion effects in the binding agent molecule. Although water can also fully wet poplar, but water is volatile, molecular weight is small, cohesion is small, it is not a good binder. According to the order of the cohesion of various organic materials, they can be arranged as follows:
-CONH-> -CONH2> -COOH> -OH> -NO2> -COOC2H5> -COOCH5> -CHO> = CO> -CH3> = CH2> -CH2
3. The molecular weight of the binding agent should be moderate. In order to fully wet, it is desirable that the molecular weight is small, but the cohesion is weak. As the molecular weight increases, the binding capacity increases. However, when the molecular weight is too large, the cohesion is too large to be easily wetted, and the green body is liable to deform. In order to help the intra-molecular chain segment to move, a plasticizer should be appropriately added at this time. While it is easy to wet, the binding agent is softer and easier to form.
4. In order to ensure product quality, it is also necessary to prevent impurities from being mixed in from the binding agent, raw materials and preparation process, which will cause harmful defects in the product. In the preparation of raw materials, mechanical methods such as pulverization and mixing are used in combination with a binding agent and a dispersant to achieve dispersion without containing agglomerated particles as much as possible. The binding agent is affected by the type and its molecular weight, the properties of the particle surface, and the solubility of the solvent, etc., and is adsorbed on the surface of the raw material particles, and through the effect of three-dimensional stabilization, it prevents the aggregation of the powder raw material. In the forming process, the binder imparts plasticity to the raw materials, has a water retention function, and improves the strength and workability of the formed body. In general, since the bonding agent hinders the sintering of the ceramic, it should be decomposed and evaporated by heating in the degreasing step. Therefore, it is necessary to select organic materials that can be easily scattered and removed and do not contain harmful inorganic salts and metal ions to ensure product quality.