Because nanopowder has a large specific surface and surface energy, the powder particles have a tendency to agglomerate with each other to reduce their surface energy, so the powder particles are actually It exists in the form of reunion. In nanoceramic slurry, the powder particles undergo endless disordered Brownian motion. Particles will often collide with each other when performing “Brownian motion”, and they will be connected together due to attraction. Secondary particles move slower than single particles, but they may still collide with other particles, forming larger agglomerates until they are too large to move and settle out of the suspension. This process is called “aggregation.” The purpose of adding a dispersant to the nanocolloid dispersion system is to prevent the formation of this “aggregation” and enable the nanoparticles to be fully dispersed in the dispersion medium.
There are many kinds of nano ceramic powders, such as glaze, alumina, zirconia, etc. Nano powder generally refers to ultra-fine particles with a particle size less than 1000 nanometers. Particles, and the use of nano-ceramic powder as the raw material for the ceramic body means that the gaps between the particles are smaller. The sintered nano-ceramic glaze is smoother and more delicate than the traditional ceramic glaze, and has better heat resistance and anti-corrosion properties. good.
However, nanopowder has small particle size, large specific surface area, and high surface energy. The glaze particles are seriously agglomerated, which can easily lead to the hardness, tensile strength, and The anti-fracture performance becomes lower, so it is necessary to add appropriate nano-dispersants during the preparation of nano-ceramic slurry to reduce the surface energy of nano-ceramic powder and achieve uniform dispersion.
Currently, a nano-sand mill is generally used, adding a suitable dispersant, and the nano-aggregates are opened by the mechanical force exerted by the sand mill, and then the slurry is The dispersant forms steric hindrance and electrostatic force through adsorption/grafting/method to achieve uniform dispersion effect. At the same time, during the process of die-casting ceramic powder into a green body, the high temperature will burn the dispersant, which will not remain on the ceramic and will not affect the performance of the ceramic products. What’s more, the dispersant will not interact with other elements in the ceramic slurry. Reaction
微信扫一扫打赏
