Is grease fluid or solid?
Grease is a thick grease-like semi-solid. Grease is a stable solid or semi-solid product composed of a thickener dispersed in a liquid lubricant. Additives designed to improve certain characteristics of the grease can be added. A phenomenon in which the consistency of grease increases with storage time (hardening). This reaction is called age hardening.
Grease can adhere to the vertical surface without loss at room temperature, and can work for open or poorly sealed friction parts, and has a holding point that other lubricants cannot replace. Generally speaking, greases with the same soap base have better compatibility. The organoclay base is incompatible with other bases. Therefore, grease is used as lubricating material in many parts of automobiles and construction machinery, which is what we often call butter! It is used for the friction part of the machine to play the role of lubrication and sealing. It is also used on metal surfaces to fill gaps and prevent rust. It is mainly made of mineral oil (or synthetic lubricating oil) and thickener.
There are some greases mainly used to prevent rust or corrosion of metals, called protective greases. For example, industrial petroleum jelly has a small number of greases specially used for sealing, which are called sealing greases, such as thread grease. Lubricating greases are mostly semi-solid substances with unique fluidity.
It is also very important that the selected grease should be compatible with the grease supply mode of the friction pair. For centralized grease supply, you should choose No. 00～1 grease; for parts where grease is regularly filled with grease guns, grease cups, etc., choose No. 1～3 grease; for parts that are used for a long time without changing the grease, you should Choose No. 2 or No. 3 grease.
The strict physical definition of solid is crystal, including polycrystalline and single crystal. Grease, as well as many polymer materials, are not solids in the strict sense. To describe them in a very spoof way, they are liquids that do not have fluidity. At normal temperature and at rest, it is like a solid, it can maintain its shape without flowing, and it can adhere to metal without slipping off. When the temperature is high or the external force exceeds a certain limit, it can flow like a liquid. When the grease is subjected to the shearing action of the moving parts in the machine, it can generate flow and lubricate, reducing the friction and wear between the moving surfaces. When the shearing action stops, it can restore a certain consistency. The special fluidity of the grease determines that it can be lubricated in parts that are not suitable for lubricating oil. In addition, because it is a semi-solid substance, its sealing and protective effects are better than lubricating oil.