Boundary friction in the application of mechanical seals-

Boundary friction in the application of mechanical seals

　2017-03-18　　

Boundary friction in the application of mechanical seals

In the actual application of mechanical seals, boundary friction is the friction when there is a very thin molecular film between relatively moving surfaces. During fluid friction, the fluid completely separates the surface of the friction pair, and there is no surface wear without solid surface contact. At this time, the viscosity of the fluid determines the size of the friction and the lubrication characteristics. However, it is the boundary film (physical adsorption film, chemical adsorption film or chemical reaction film) that plays a lubricating role in boundary friction. The polar molecules in the lubricant are adsorbed on the metal surface, have directionality, and form a molecular grid arranged in a directional arrangement, and can also form a molecular layer structure.

Generally speaking, the boundary film has 3~4 layers, and its thickness is about 200A. If the molecules exceed 4 layers, the molecules begin to flow with the lubricant and cannot be aligned, the boundary film does not have a lubricating effect, and the viscosity of the lubricant starts to play a lubricating effect. When the molecules are adsorbed on the metal surface to reach the saturation state, the polar molecules are tightly arranged and adsorbed very tightly to the surface of the gold rot, and there is a certain film strength. When the friction interface slides or rolls, the surface film has the ability to prevent the surface peaks from contacting and the film is not damaged. It plays a good lubrication effect. The surface polar molecular mode plays a part of the bearing role, while the fluid part only plays a role. Weak effect.

In short, the boundary lubrication mechanism is quite complicated. This is due to the physical and chemical properties of the surface and the lubricant, the complexity of the interaction between the surface film and the solid, and the influencing parameters. It must be further Only by microscopic research can we understand its essence deeply.　　364.html,

Friction coefficient of fluid mechanical seal 　　 Mixed friction in mechanical seal application