As a core component in mechanical transmission, the surface treatment of national standard bearing pulleys plays a crucial role in their corrosion resistance and durability. Under complex operating conditions, national standard bearing pulleys are subject to long-term friction, impact, and environmental erosion. Therefore, surface treatment must balance the density of the protective layer, its bond strength with the substrate, and its resistance to environmental damage. This process involves five key steps: physical deformation hardening, chemical conversion coating treatment, surface heat treatment, thin-film coating technology, and anti-rust material management, collectively forming a multi-layered corrosion protection system.
Physical deformation hardening mechanically induces plastic deformation on the surface of national standard bearing pulleys, forming a high-strength hardened layer. Shot peening and sand blasting processes utilize high-velocity projectiles to impact the surface, introducing a residual compressive stress layer that significantly improves fatigue life. Polishing and superfinishing indirectly enhance corrosion resistance by reducing surface roughness, minimizing friction and wear, and improving the conditions for oil film formation. These processes optimize surface mechanical properties, providing a more stable substrate for subsequent protective coatings.
Chemical conversion coating treatment creates a protective film on the surface of national standard bearing pulleys through a chemical reaction. Blackening treatment involves heating with a strong alkaline solution to form a dense, ferroferric oxide film on the surface, providing rust-proof, wear-resistant, and self-lubricating properties. Phosphating treatment improves lubricity through a phosphate film and also serves as a pretreatment layer before electroplating, enhancing coating adhesion. This conversion coating adheres tightly to the substrate, effectively isolating it from corrosive media and is particularly suitable for use in humid or salty environments.
Surface heat treatment involves rapid heating and cooling to create a surface phase transformation, enhancing hardness and wear resistance. Flame quenching and high-frequency induction hardening can locally form a high-hardness martensitic layer while maintaining a tough core. This "hard outside, tough inside" structure resists surface wear and prevents crack propagation. The heat-treated National Standard Bearing Pulley surface is denser, reducing the penetration pathways for corrosive media. The increased hardness also reduces the likelihood of microcracks.
Thin-film coating technology deposits a protective layer on the surface of National Standard Bearing Pulley through physical or chemical methods. Electroplating processes such as chrome and nickel plating can create a corrosion-resistant metallic layer, particularly suitable for use in marine or chemical environments. This type of coating completely isolates the substrate from the corrosive medium while reducing frictional heat and slowing the corrosion process through its self-lubricating properties.
The selection and management of rust-preventive materials directly impacts the durability of the protective effect. Rust-preventive greases must possess excellent film-forming properties, maintaining a thick film over time and being compatible with subsequent lubricants, eliminating the need for cleaning. Vapor-phase rust inhibitors volatilize their corrosion-inhibiting components, creating a protective atmosphere within the packaging and suitable for long-term storage. Material acceptance requires rigorous testing of physical and chemical properties, and regular testing of solution concentration to ensure process stability. For example, the ratio of sodium nitrite to sodium carbonate in the rust-preventive solution must be precisely controlled; otherwise, the rust-preventive period will be shortened.
Electrochemical protection fundamentally inhibits corrosion reactions by altering the electrode potential of the national standard bearing pulley. The sacrificial anode method connects zinc or zinc alloy to the bearing, acting as a negative electrode for preferential oxidation and protecting the base metal. The impressed current method uses direct current to accumulate negative charges on the bearing surface, suppressing electron loss. This method is often used for underwater or soil-based equipment, such as ship propellers and underground pipelines, to actively intervene in the corrosion cell reaction and extend its service life.
The combined application of these processes requires optimization based on the specific operating conditions of the National Standard Bearing Pulley. For example, high-load applications require enhanced surface hardness and residual compressive stress, while humid environments prioritize coating density and conversion film stability. Long-term storage relies on the continued protection of rust-proofing materials. By synergizing these multiple processes, the corrosion resistance and durability of the National Standard Bearing Pulley are comprehensively enhanced, ensuring reliable operation within mechanical systems.
