Publish Time: 2021-09-06 Origin: Site
One of the advantages of PTFE is its good surface cohesiveness. But since it has such good non stickiness, how can it be prepared on the metal without falling off? Do they have high bonding strength? And by what way? Now let's take a look below.
PTFE material has the least surface tension in solid materials and does not adhere to any substance. Therefore, the adhesion between PTFE and metal is certainly not good. When metal plate and PTFE plate are bonded, special adhesive can be applied between them. Or a surface coating (primer) can be applied on the metal surface to increase the adhesion between PTFE and metal. This kind of coating has the characteristics of low surface energy, small friction coefficient, easy sliding and so on. It is widely applied in household appliances, cooking utensils, automobile, machinery, chemical industry and other industries. PTFE materials include PTFE tape for gas, PTFE plumbers tape, PTFE unsintered tape, etc.
Pure PTFE is white. Only after a special process of chemical treatment, it will adhere to the metal surface. The chemical etchant formula is proprietary. Once etched, the surface of PTFE turns brown. This brown surface can be easily bonded with standard industrial grade adhesives.
The metal surface to install PTFE can be prepared by normal processing methods, such as grinding, milling, molding, etc. After the metal surface is rough, it can be cleaned with trichloroethylene, perchloroethylene or acetone, and it should be ensured that the metal surface is free of gravel and debris.
Apply adhesive to the metal and PTFE plates and apply as evenly as possible with a serrated spatula. In order to obtain the best dispersibility of the adhesive, when it is applied on the surface, it should be applied longitudinally. When it is spread on metal, it should be brushed horizontally.
It is recommended that the clamping pressure should be between 10-15 kg/cm2 after PTFE is installed on the metal plate. It is important to keep the pressure constant during hardening. Due to the different thermal expansion coefficient of materials, the maximum curing temperature should not exceed 40℃.
After adhesive curing, PTFE can be processed by conventional methods. For example, the utilization of alumina with rubber adhesion for soft fine grinding, pre polishing and pre matching treatment.
Bonded PTFE must be maintained as bond strength may be affected by adverse environmental factors, such as excessive light, corrosion and high temperature. Even after etching, polytetrafluoroethylene is still a kind of anti bonding material and its bonding strength with metal is still limited. Therefore, in the area where the expected shear load is high, it is necessary to support the PTFE plate by clamping or bolt connection.
There are two kinds of anti sticking process for PTFE material. One is to install PTFE parts or sheets on the metal substrate. Second, the PTFE coating or the lacquered cloth compounded with glass is covered on the metal substrate after heat shrinkage. PTFE materials include PTFE wraping film, PTFE sealing tape, color PTFE tape, etc.
With the continuous development of material application technology, the three major shortcomings of PTFE material, including cold flow, difficult welding and difficult melting processing, are gradually being overcome. Therefore, it has a wider application prospect in many fields, such as optics, sub medicine, petrochemical industry, oil transportation and seepage control.
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