Reasons why graphite is used as soft materials for sealing surfaces

Carbon graphite contains carbon graphite with higher purity, which can be called high-purity carbon graphite. Generally, it is widely used in the metallurgical industry, and is involved in the military industry, light industry, and electrical industry, and has excellent chemical and physical properties. There are many kinds of graphite raw materials. According to the molding method of the production era, it can be divided into  molded graphite, and extruded graphite. The finished product will be formed.

Carbon graphite is the most widely applicable friction pairing material in the mechanical seal industry. It has good self-lubricating properties, low friction coefficient, good corrosion resistance, good thermal conductivity, low linear expansion coefficient, good pairing performance and temperature resistance. and other excellent features

Excellent properties of carbon graphite

1. High thermal conductivity. The thermal conductivity of carbon is 20-40W/(m K), second only to silver, copper and aluminum. alloys, etc.) have a much higher thermal conductivity. Therefore, the generated friction heat can be dissipated in time, thereby reducing the temperature of the sealing end face, which is very necessary to improve its reliability and service life.

2. Lower coefficient of linear expansion. The linear expansion coefficient of graphite is 2×10-6～6×10-6/℃, which is about 1/2～1/4 of that of metal. When the temperature rises, its thermal deformation is small, which is beneficial to keep the parallel of the sealing end face. The low expansion coefficient and high thermal conductivity make it have good thermal stability, good heat resistance, cold resistance and thermal shock resistance, and will not crack when subjected to drastic temperature changes.

3. Good corrosion resistance: The chemical stability of graphite is very good. It is stable below 400°C in the air. Except for strong oxidizing media such as aqua regia, chromic acid, concentrated sulfuric acid and halogen elements, it can resist the corrosion of other acids, alkalis, salts and all organic compounds. . It should be noted that the degree of corrosion resistance varies with the type of graphite and the impregnating agent.

4. Excellent self-lubrication: This is because when graphite rubs against metal or other materials, a thin layer of graphite transfer film is quickly coated on the sealing surface microscopically, forming the relative friction between graphite and graphite. This low-friction film plays an important role in controlling temperature rise. In addition, graphite has a low friction coefficient. The friction coefficient between graphite and metal is 0.04-0.05. Under the condition of full fluid lubrication, the friction coefficient is only 0.008-0.01.

5. Graphite has low tensile strength and high compressive strength, and is a brittle material. Due to its low hardness, it is often used as a soft ring in a friction pair. Various processing can be carried out very conveniently. Its outstanding disadvantage is that the porosity is relatively large, generally between 18% and 22%. In order to make up for this shortcoming, the graphite used in practice is impregnated to block the pores and improve the sealing performance.

The application of high-purity carbon graphite in the downstream of process technology is constantly developing. With the continuous increase of residents’ income, the quality level of carbon and graphite is continuously improved. Manufacturers continue to improve production process technology, product quality has been greatly improved, and demand has continued to grow.

Its application value is also infinitely expanded. In order to make the development of the carbon graphite industry more orderly, the Franli factory provides a high-quality production workshop for the research of high-purity carbon graphite, so as to better develop and produce carbon graphite and ensure the quality of the products.