Chemical polishing of chemical engine cylinder liners selectively dissolves raised areas on the surface, achieving microscopic surface smoothing. This significantly improves their wear resistance, corrosion resistance, fatigue resistance, and thermal efficiency. The core of this process lies in utilizing the interaction between chemical reagents and the metal surface to eliminate machining defects at the microscale, optimizing surface quality and thus extending the service life of the chemical engine cylinder liner and improving overall engine performance.
The improvement in wear resistance of chemical engine cylinder liners through chemical polishing is mainly reflected in the reduction of surface roughness. Traditional machining easily leaves micro-scratches or protrusions on the inner wall of the chemical engine cylinder liner. These defects accelerate friction between the piston rings and cylinder liners, leading to increased wear. Chemical polishing, by dissolving the raised areas, significantly reduces surface roughness, creating a smoother contact surface. This smooth surface reduces frictional resistance during piston ring movement, lowering the wear rate. Simultaneously, chemical polishing eliminates surface stress concentration caused by machining, preventing the propagation of microcracks due to stress release, further improving wear resistance.
Corrosion resistance is one of the key performance indicators of chemical engine cylinder liners. Chemical polishing removes surface oxide layers and impurities, forming a uniform passivation film that effectively prevents direct contact between corrosive media (such as sulfur in fuel oil and chloride ions in coolant) and the substrate. For example, in polishing solutions containing sulfuric acid or phosphoric acid, a dense oxide film forms on the surface of the chemical engine cylinder liner. This film not only inhibits corrosion reactions but also repairs minor damage caused by friction or thermal stress. Compared to mechanical polishing, chemically polished surfaces are less prone to corrosion cell formation, thus significantly extending the service life of the chemical engine cylinder liner in harsh environments.
The improved fatigue resistance is closely related to the improved surface integrity achieved through chemical polishing. Machining often leaves work-hardened layers or residual tensile stress on the surface of the chemical engine cylinder liner, which reduces the material's fatigue limit. Chemical polishing removes these hardened layers and utilizes the penetration of chemical reagents to alleviate residual surface stress, making the chemical engine cylinder liner less prone to fatigue cracking under alternating loads. Furthermore, the smooth surface after polishing reduces stress concentration points, further lowering the risk of fatigue failure. This translates to higher reliability and longer maintenance intervals for chemical engine cylinder liners, which withstand high temperatures and pressures over extended periods.
The improvement in thermal efficiency of chemical engine cylinder liners through chemical polishing is primarily due to optimized surface quality. A smooth cylinder liner inner wall reduces frictional power consumption during piston movement, allowing more energy to be converted into effective output. Simultaneously, the uniform surface structure helps improve lubricant distribution, forming a more stable oil film, thus reducing the coefficient of friction. This dual effect not only improves engine thermal efficiency but also reduces heat generated by friction, lowering the thermal load on the cylinder liner. Under high-temperature conditions, chemically polished chemical engine cylinder liners better maintain dimensional stability, preventing performance degradation caused by uneven thermal expansion.
The chemical polishing process also improves the surface morphology of the chemical engine cylinder liner, enhancing its fit with piston rings. The polished cylinder liner inner wall geometry is more precise, resulting in a higher degree of contact with the piston rings and effectively reducing air leakage. This not only increases the compression ratio but also reduces fuel consumption. Furthermore, chemical polishing eliminates surface ripples caused by machining, significantly reducing the arithmetic mean deviation (Ra) of the cylinder liner inner wall profile, further improving sealing performance.
From a process adaptability perspective, chemical polishing has unique advantages in processing complex-shaped chemical engine cylinder liners. Traditional mechanical polishing struggles to uniformly process internal holes, grooves, and other areas, while chemical polishing, through solution penetration, can achieve comprehensive treatment of these areas. This characteristic makes chemical polishing more widely used in irregularly shaped chemical engine cylinder liners or structures with cooling chambers, meeting the demands of modern engines for high-performance chemical engine cylinder liners.
