Boundary lubrication under harsh working conditions results in severe wear of water-lubricated bearing materials, e.g., the tail bearing in a ship. Inspired by cartilage lubrication, we prepare a smart hydrogel with balanced hydration and load-bearing properties through the construction of PVA-chitosan/sodium alginate double networks and the introduction of aramid nanofiber. The hydrogels are blended with UHMWPE into new bionic biphasic hydrogel-containing composites. The thorough assessments (chemical, thermal, surface, and bulk mechanical properties) of the hydrogels and the composites reveal that the high hydrophilicity of the hydrogel particles encapsulated in bulk UHMWPE facilitates water absorption leading to improved friction performance under boundary lubrication mode, e.g. at the startup. while the stripped hydrogel pits and induced micro-texture between friction interfaces as hydration layer play the role of separating the friction interface, effectively reducing the friction contact. Under 40 N load, the friction coefficient and wear rate of one composite are 28.7% and 14% lower than those of the plain UHMWPE, respectively. After soaking in seawater for 28 days and holding at 50℃ for 1 hour, the mechanical properties of the composite material are still better than plain UHMWPE. Altogether, the smart biphasic hydrogel-containing composites the intelligent biphasic hydrogel composites were able to improve the lubrication state according to operation conditions.

The running-in of cylinder liner-piston rings (CLPRs) is the most important process that must be performed before a marine diesel engine can be operated. The quality of running-in directly affects the reliability of a CLPR. The surface texture of a CLPR has been proven to significantly affect its lubrication performance. In this study, the tribological behavior of a CLPR during running-in is investigated. Three types of surface textures are generated on the CLPR via laser processing: dimple texture on piston rings, groove texture on cylinder liners, and co-texture on both sides. Subsequently, a series of tests are performed on a slice tester. A load of 300 N (1.64 MPa) is applied, and two speeds (50 and 100 rpm) are adopted. The CLPR running-in quality is characterized based on three parameters, i.e., the friction coefficient, contact resistance, and wear topography. Experimental results show that, compared with a non-textured surface, the three types of surface textures mentioned above improved the friction performance during running-in. The lubricant supply capacity of the dimple texture on the piston ring, as a mobile oil reservoir, is stronger than that of the groove texture on the cylinder liner serving as a static oil reservoir. By contrast, the wear resistance of the dimple texture, as a movable debris trap on the piston ring, is weaker than that of the groove texture on the cylinder liner, which serves as a static debris trap. It is demonstrated that the co-texture combines the advantages of dimples and groove textures. Compared with non-textured surfaces, the friction coefficient decreased the most at 100 rpm (44.5%), and the contact resistance improved the most at 50 rpm (352.9%). The coupling effect provides the surface with improved running-in quality by optimizing the tribological performance, particularly at the dead center. This study provides guidance for the tribological design and manufacturing of CLPR in marine diesel engines.