What are the main aspects of mechanical seal wear?

What are the main aspects of mechanical seal wear?

22/06/06 08:52:06

The main wear manifestations of mechanical seals are: adhesive wear, abrasive wear, fatigue wear, fretting wear and corrosion wear. Because damage is one way in which seals often fail. It is a key issue to grasp the damage regularity of seals, predict the wear rate, and find ways to increase the wear-resistant service life.

1. Adhesive wear

Due to the presence of rough asperities on the surface, surface contact occurs at scattered asperities. When the friction occurs at the contact point, the direct contact between the metals will appear when the lubricating film and the surface film are broken, the connection point is continuously sheared off, and a new connection point is generated at the same time.

If the shearing occurs on the joint interface, there is no wear on the two surfaces; if the shearing occurs inside the metal, there will be transfer of surface metal, and the surface will be damaged and worn. The phenomenon of metal transfer is the main characteristic of adhesive wear.

2. Abrasive wear

Abrasive wear is a common form of wear, accounting for about half of the total wear. Abrasive wear is when the contact surface is in relative motion, the hard particles or the asperities on the harder surface will scratch the surface and the surface material will fall off during the friction process.

Abrasive wear is a 'microscopic cutting process'. Abrasives will cause the surface layer material to be deformed alternately, resulting in alternating contact stress and causing fatigue damage to the surface. However, the mechanical action of abrasive particles on the surface always dominates.

3. Fatigue wear

The friction surface is subjected to alternating stress, and the surface material of the mechanical seal is damaged due to fatigue. Gears, rolling bearings and other parts often suffer from such damage.

Fatigue cracks may occur at the place of greater shear stress under the contact surface, because the plastic deformation is more severe here. The cracks that appear first will propagate toward the surface along the direction of greater shear stress, and eventually cause fatigue wear. Mass transfer due to fatigue of the surface material due to alternating stresses is called fatigue wear, sometimes also called contact fatigue.

4. Fretting wear

The wear phenomenon between the surfaces due to the relative vibration with small amplitude is called fretting wear. If the chemical reaction between the two surfaces plays a major role in the process of fretting wear, it is called fretting wear.

If there is a certain pressure between the surfaces that are in contact with each other to make the surface asperities adhere, the adhesion will be continuously sheared due to the vibration caused by the small amplitude of the outside world. During the shearing process, the adhesion point will be gradually oxidized, resulting in Reddish-brown ferric oxide grinding dust. As this process continues, the oxidized wear debris breaks away from the body, and the adhesion points are destroyed. At the same time, these wear debris also act as abrasives, causing abrasive wear on the contact surface. When the wear area continues to expand, the contact surface is completely damaged. destroy. This is the mechanism of fretting wear formation.

5. Corrosion and wear

The wear process of the surface mainly under the action of chemical or electrochemical reaction is called corrosion wear. Generally, during the corrosion process, the wear is moderate. However, due to the corrosive effect, it can produce very serious results, especially in high temperature or humid environments, and this wear will be exacerbated.

The above is the introduction of the five wear forms of mechanical seals. According to the introduction, the prevention and solution of equipment wear can be better carried out, so as to effectively prolong the use of its equipment.