What are the sealing materials?
Sealing materials can be divided into shaped sealing materials and amorphous sealing materials.
1. Unshaped sealing material
Plastic sealing paste, which is mainly made of coal tar and modified asphalt, has certain durability and elastoplasticity, is cheap and affordable, but lacks certain extensibility and elasticity.
Elastic-plastic sealing paste, which is mainly made of various plastic ointments and poly-recorded vinyl cement. Compared with plastic sealing paste, it has strong extensibility and cohesiveness, but its elasticity is still weak.
Elastomeric sealant, made of polysulfide rubber, silicone rubber, neoprene, polyurethane and acrylic naphthalene, is durable.
2. Styling sealing material means that the cross-sectional shape of the sealing material is made into a cushion shape, a strip shape and a belt shape according to different engineering requirements. It can be used to specifically handle cracks in underground structures and buildings to achieve water and water retention. Commonly used such sealing materials are mainly two types of gaskets and waterstops.
Eight major requirements for sealing materials
1. If the sealed working medium is a liquid, the compatibility of the material and the liquid should be considered. If it is incompatible, the liquid will shrink and expand, which is prone to failure. If the working medium is a gas, consider the compatibility of the material with the grease and lubricant.
2. The sealing material has corresponding requirements for wear and friction. It is necessary to select the sealing material according to the moving speed and stroke, so as to extend the service life of the sealing material, so pay special attention to the friction factors of the sealing material and the dynamic and static friction factors. difference.
3. Different structural types, its sealing work principle is also different, and has different requirements on the mechanical properties such as strength, deformation rate and elasticity of the sealing material.
4. Different sealing materials also have various differences in the applicable temperature range, so it is necessary to closely control and control the operating temperature of the sealing member according to the range of the working temperature of the material.
5. The pressure resistance of the sealing material is required to be compatible with the surrounding working pressure, and it can be kept within a certain range.
6. If the working environment generates dust, it will cause wear and tear on the material and reduce its service life. Therefore, it is required to select a sealing material with high abrasion resistance.
7. In the working environment of vibration and impact conditions, it is required to use elastic and high-strength sealing materials, so as to compensate for the insufficient contact stress caused by vibration.
8. The assembly process of the seal requires that the seal material should be selected and used with reference to the assembly performance of the seal.