Stability and dispersibility of nano lubricants stability Lubricating oils generally function in high temperature, high pressure and high load environments. In the environment of oil in the lubricating oil and the nanoparticles in suspension, it is easy to coagulate and lose the anti-wear and anti-friction function in the friction process. There are two ways to improve the stability of nanomaterials in lubricating oils: one is chemical adsorption or chemical reaction between the substance and the surface groups of the nanoparticles; the other is polymer coated nanomaterials, which are mainly used on the surface of nanomaterials. The polymerization of the monomers gives a capsular coating material. The choice of a suitable monomer material allows the resulting polymer to be coated with nanomaterials to provide good compatibility with the lubricating oil. Dispersibility The degree of nano-particles is very small, on the one hand, it can be well dispersed in the lubricating oil, but at the same time, due to the small particle size, large specific surface area and specific surface energy, it is easy to aggregate into larger particles, resulting in poor monodispersity. If the dispersibility of the nanoparticles is to achieve the intended purpose, it is necessary to add some dispersant or the coupling agent. (1) Polymeric dispersant for water system - hyperdispersant Its relative molecular mass is between 1000 and 10000, and the molecular structure contains two parts with different properties. A part is an anchoring group, which can be tightly bound to the surface of the particle by a single point or multiple points by ion pair, hydrogen bond, van der Waals force, etc.; the other part is a polymer chain having a certain length, and has a good dispersion with the dispersion medium. Compatibility, known as solvation chain. When the particles adsorbed with the hyperdispersant are close to each other, the particles are bounced off each other due to the space barrier of the solvation chain, thereby achieving the stability of the particles in the medium. (2) Coupling agent The coupling agent is generally an amphoteric structure substance, and a part of the group in the molecule can react with various functional groups on the surface of the powder to form a strong chemical bond. The other part is chemically entangled or physically entangled with the organic polymer to provide a special "molecular bridge" between the inorganic filler and the organic polymer molecule, so that the nanoparticles are well dispersed in the lubricating oil.
