mainly refers to the use of a certain combination of sealing materials, sealing elements and the corresponding seal structure form, to prevent or cut off the mass transfer process between the medium. The ceramic seal ring is one of the sealing means. According to the contact of the sealing surface, it can be divided into two types: 1) contact seal: it is the use of sealing force to make the cover contact with each other to reduce or eliminate all kinds of seals, such as cover packing, oil seal, mechanical seal, slip ring seal and so on. 2) non - contact seal: it is a fixed assembly gap between the sealing surface, without sealing the tight cover of all kinds of seals, such as floating ring seal, labyrinth seal, air cushion seal, etc.
The essence of the seal is to prevent the mass exchange between the sealing space and the surrounding medium, in fact, it is to prevent the leakage of logistics. The causes of leakage usually include two points. First, there are gaps on the sealing surface. Second, there is pressure difference or concentration difference on both sides of the seal. Elimination (or reduction) of any factor can prevent (or reduce) leakage, so the key of sealing technology is to eliminate the leakage of various parts.
There are many ways to seal the joints in the mechanical equipment. The following methods are mainly used: 1) close coordination of the contact parts. This method is to ensure that the contour of the connection surface is consistent to the maximum, that is, the connection surface is in the machining process to reach the minimum surface roughness. 2) the joint is subjected to pressure, resulting in distortion of the microscopic part of the contact area. 3) fill gaps with auxiliary media to prevent leakage of sealing medium. 4) electromagnetic field is applied to interact with the medium in the gap. 5) use inertial force and vortex force to form a resistance that impede the flow of sealing medium. 6) form permanent connections by means of welding, brazing and bonding.
No matter what kind of seal is used, it is necessary to ensure that the required function is completed in the working time required by the connecting place, and the working life of the seal must be completed. At the same time, the process performance and production cost of the sealing device from the design to the process and use must be considered.