The surface treatment process of metal hoses has a decisive influence on their wear resistance. This effect is achieved by modifying the material's surface structure, chemical composition, and physical properties, significantly improving their service life and operational stability under complex operating conditions. As a key component in pipeline systems, metal hoses are often used to transport granular media, corrosive fluids, or withstand high-frequency vibrations. The choice of surface treatment directly impacts the optimal wear resistance.
One of the core goals of metal hose surface treatment is to create a high-hardness protective layer. Through heat treatment processes such as quenching, carburizing, and nitriding, the metal surface can acquire high-hardness microstructures such as martensite and bainite, which effectively resist the cutting and impact of granular media. For example, carburizing creates a carbon concentration gradient layer on the inner wall of the hose, significantly increasing the hardness of the surface while maintaining toughness in the core. This "hard outside, tough inside" structure is particularly effective in sand and gravel pipelines, significantly reducing wall thickness reduction caused by particle friction.
Coating technology is another important means of improving the wear resistance of metal hoses. Hard chromium plating creates a dense chromium layer on the hose surface through electroplating. Its hardness can reach HV800-1000, far exceeding that of the base material, effectively resisting abrasion from particles such as coal dust and cement. Thermal spraying technology applies ceramic materials such as aluminum oxide and tungsten carbide to the hose surface, creating a wear-resistant layer of controlled thickness. In pneumatic conveying systems, such coatings can significantly reduce the friction coefficient of the pipe inner wall, reducing energy loss and extending service life.
Surface hardening processes improve wear resistance by altering the stress state of the material surface. Shot peening uses high-speed projectiles to impact the hose surface, creating a residual compressive stress layer. This stress state inhibits crack initiation and propagation, effectively preventing fatigue wear under vibration conditions. Rolling refines the surface metal grains through extrusion, forming a hardened layer. This process also improves surface roughness and reduces the adhesion of particulate media. Metal hoses used in marine environments often use this process to withstand the dual erosion of salt spray and fluids.
Chemical treatments improve wear resistance by altering the surface chemical composition. Phosphating forms a phosphate film on the hose surface, which not only improves corrosion resistance but also serves as a good base for subsequent coatings, strengthening the adhesion between the coating and the substrate. Passivation, through an oxidation reaction, creates a dense oxide film on the surface of stainless steel hoses. This film is stable in acidic media, effectively preventing corrosion and wear, and is widely used in chemical piping systems.
Combined treatment processes combine multiple technologies to synergistically improve wear resistance. For example, a metal hose is first sandblasted to increase surface roughness, then electroplated with a nickel-based alloy coating, and finally laser hardened. This combination of processes can achieve a hose surface with high hardness, low friction, and excellent corrosion resistance, maintaining stable performance even under extreme operating conditions.
In practical applications, the choice of surface treatment process must be comprehensively considered based on operating parameters. For high-temperature environments, an anti-oxidation coating is required; for highly corrosive media, a chemical-resistant alloy coating should be selected; and for high-frequency vibration environments, shot peening and other strengthening processes are preferred. By scientifically matching the surface treatment process with the usage conditions, the wear resistance of the metal hose can be optimized, thereby achieving efficient and reliable operation in the mining, cement, chemical and other fields.
