Carbon black (carbon black) significantly increases the wear resistance of the sealing ring, mainly due to its unique physical structure, chemical properties, and interaction with the rubber matrix. Here is a detailed explanation of the specific reasons:
1. Reinforcement effect: Construction of a three-dimensional network structure
High specific surface area and adsorption properties: Carbon black is composed of micron-sized carbon particles, with a very large specific surface area (up to several hundred square meters per gram). This characteristic enables it to form a three-dimensional cross-linked network through physical adsorption (such as van der Waals forces, hydrogen bonds) and chemical bonding with the rubber molecular chains.
Dispersing stress: When the sealing ring is subjected to friction, this network structure can evenly distribute the stress throughout the rubber matrix, avoiding local stress concentration that leads to molecular chain breakage, thereby reducing wear.
Enhancing mechanical properties: The addition of carbon black significantly increases the tensile strength, tear strength, and hardness of the rubber, enabling the sealing ring to better resist mechanical damage during the friction process.
2. Formation of lubricating film: Reduction of friction coefficient
Adsorbing lubricants: The surface of carbon black has a porous structure, which can adsorb oils or other lubricants, forming a stable lubricating film on the sealing ring surface.
Reducing direct contact: The presence of the lubricating film causes the friction between the rubber and the contact surface to change from "dry friction" to "boundary lubrication" or "mixed lubrication", significantly reducing the friction coefficient and reducing wear.
Advantages of dynamic sealing: In high-speed movement or frequently opening and closing sealing scenarios, the lubricating film can persist, maintaining a low wear rate.
3. Filling pores: Improving structural density
Filling microscopic defects: Rubber may have tiny pores or bubbles during processing, which can become stress concentration points and accelerate wear. Carbon black particles can fill these pores, making the sealing ring structure more dense.
Reducing deformation and energy loss: The dense structure reduces the deformation of rubber during the friction process, reduces the loss of energy to heat, and thus delays wear.
Suppressing the generation of wear particles: The reduction of pores also reduces the possibility of rubber particles shedding during the friction process, further extending the service life of the sealing ring.
4. Thermal conductivity: Delaying thermal aging
Efficient heat dissipation: Carbon black has good thermal conductivity, which can quickly conduct the heat generated by the sealing ring during friction to the surrounding environment, avoiding local overheating.
Preventing thermal cracking: High temperatures accelerate the oxidation and cracking reactions of rubber, leading to performance degradation. The thermal conductivity of carbon black helps maintain the sealing ring in an appropriate temperature range, delaying thermal aging.
Stabilizing friction performance: In high-temperature conditions, the presence of carbon black makes the friction coefficient of the sealing ring more stable, reducing the exacerbation of wear caused by temperature fluctuations.
5. Resistance to ultraviolet rays and chemical stability
Shielding ultraviolet rays: Carbon black can absorb ultraviolet rays, preventing them from penetrating the rubber matrix and triggering photo-oxidation reactions, thereby delaying the aging process of the sealing ring.
Resisting chemical erosion: When exposed to corrosive media (such as oil, acid, and alkali), carbon black can enhance the chemical stability of rubber, reducing the swelling or corrosion of the rubber by the medium, maintaining wear resistance.
6. Practical application verification
Tire industry case: In tire manufacturing, tires with 30% reinforcing carbon black can have a driving mileage of 4-6 kilometers, with significantly improved wear resistance. Similar principles also apply to sealing rings, and the reinforcing effect of carbon black makes it perform exceptionally well in dynamic sealing scenarios.
Improvement of sealing ring performance: Experiments show that the sealing ring with carbon black added has a wear reduction of 30%-50% in the wear test while maintaining good elasticity and sealing performance.
Carbon black enhances the sealing ring's wear resistance through multiple mechanisms, such as reinforcing the rubber matrix, forming a lubricating film, filling pores, conducting heat dissipation, resisting ultraviolet rays, and maintaining chemical stability. This comprehensive effect makes carbon black an indispensable additive in sealing materials, widely used in the manufacturing of high-performance sealing components in automotive, aerospace, and petrochemical industries.
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